1  /**
2   * \file ssl.h
3   *
4   * \brief SSL/TLS functions.
5   */
6  /*
7   *  Copyright The Mbed TLS Contributors
8   *  SPDX-License-Identifier: Apache-2.0
9   *
10   *  Licensed under the Apache License, Version 2.0 (the "License"); you may
11   *  not use this file except in compliance with the License.
12   *  You may obtain a copy of the License at
13   *
14   *  http://www.apache.org/licenses/LICENSE-2.0
15   *
16   *  Unless required by applicable law or agreed to in writing, software
17   *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
18   *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19   *  See the License for the specific language governing permissions and
20   *  limitations under the License.
21   */
22  #ifndef MBEDTLS_SSL_H
23  #define MBEDTLS_SSL_H
24  #include "mbedtls/platform_util.h"
25  #include "mbedtls/private_access.h"
26  
27  #include "mbedtls/build_info.h"
28  
29  #include "mbedtls/bignum.h"
30  #include "mbedtls/ecp.h"
31  
32  #include "mbedtls/ssl_ciphersuites.h"
33  
34  #if defined(MBEDTLS_X509_CRT_PARSE_C)
35  #include "mbedtls/x509_crt.h"
36  #include "mbedtls/x509_crl.h"
37  #endif
38  
39  #if defined(MBEDTLS_DHM_C)
40  #include "mbedtls/dhm.h"
41  #endif
42  
43  /* Adding guard for MBEDTLS_ECDSA_C to ensure no compile errors due
44   * to guards also being in ssl_srv.c and ssl_cli.c. There is a gap
45   * in functionality that access to ecdh_ctx structure is needed for
46   * MBEDTLS_ECDSA_C which does not seem correct.
47   */
48  #if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C)
49  #include "mbedtls/ecdh.h"
50  #endif
51  
52  #if defined(MBEDTLS_HAVE_TIME)
53  #include "mbedtls/platform_time.h"
54  #endif
55  
56  #if defined(MBEDTLS_USE_PSA_CRYPTO)
57  #include "psa/crypto.h"
58  #endif /* MBEDTLS_USE_PSA_CRYPTO */
59  
60  /*
61   * SSL Error codes
62   */
63  /** A cryptographic operation is in progress. Try again later. */
64  #define MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS                -0x7000
65  /** The requested feature is not available. */
66  #define MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE               -0x7080
67  /** Bad input parameters to function. */
68  #define MBEDTLS_ERR_SSL_BAD_INPUT_DATA                    -0x7100
69  /** Verification of the message MAC failed. */
70  #define MBEDTLS_ERR_SSL_INVALID_MAC                       -0x7180
71  /** An invalid SSL record was received. */
72  #define MBEDTLS_ERR_SSL_INVALID_RECORD                    -0x7200
73  /** The connection indicated an EOF. */
74  #define MBEDTLS_ERR_SSL_CONN_EOF                          -0x7280
75  /** A message could not be parsed due to a syntactic error. */
76  #define MBEDTLS_ERR_SSL_DECODE_ERROR                      -0x7300
77  /* Error space gap */
78  /** No RNG was provided to the SSL module. */
79  #define MBEDTLS_ERR_SSL_NO_RNG                            -0x7400
80  /** No client certification received from the client, but required by the authentication mode. */
81  #define MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE             -0x7480
82  /** Client received an extended server hello containing an unsupported extension */
83  #define MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION             -0x7500
84  /** No ALPN protocols supported that the client advertises */
85  #define MBEDTLS_ERR_SSL_NO_APPLICATION_PROTOCOL           -0x7580
86  /** The own private key or pre-shared key is not set, but needed. */
87  #define MBEDTLS_ERR_SSL_PRIVATE_KEY_REQUIRED              -0x7600
88  /** No CA Chain is set, but required to operate. */
89  #define MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED                 -0x7680
90  /** An unexpected message was received from our peer. */
91  #define MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE                -0x7700
92  /** A fatal alert message was received from our peer. */
93  #define MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE               -0x7780
94  /** No server could be identified matching the client's SNI. */
95  #define MBEDTLS_ERR_SSL_UNRECOGNIZED_NAME                 -0x7800
96  /** The peer notified us that the connection is going to be closed. */
97  #define MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY                 -0x7880
98  /* Error space gap */
99  /* Error space gap */
100  /** Processing of the Certificate handshake message failed. */
101  #define MBEDTLS_ERR_SSL_BAD_CERTIFICATE                   -0x7A00
102  /* Error space gap */
103  /* Error space gap */
104  /* Error space gap */
105  /* Error space gap */
106  /* Error space gap */
107  /* Error space gap */
108  /* Error space gap */
109  /* Error space gap */
110  /* Error space gap */
111  /** Memory allocation failed */
112  #define MBEDTLS_ERR_SSL_ALLOC_FAILED                      -0x7F00
113  /** Hardware acceleration function returned with error */
114  #define MBEDTLS_ERR_SSL_HW_ACCEL_FAILED                   -0x7F80
115  /** Hardware acceleration function skipped / left alone data */
116  #define MBEDTLS_ERR_SSL_HW_ACCEL_FALLTHROUGH              -0x6F80
117  /** Handshake protocol not within min/max boundaries */
118  #define MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION              -0x6E80
119  /** The handshake negotiation failed. */
120  #define MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE                 -0x6E00
121  /** Session ticket has expired. */
122  #define MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED            -0x6D80
123  /** Public key type mismatch (eg, asked for RSA key exchange and presented EC key) */
124  #define MBEDTLS_ERR_SSL_PK_TYPE_MISMATCH                  -0x6D00
125  /** Unknown identity received (eg, PSK identity) */
126  #define MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY                  -0x6C80
127  /** Internal error (eg, unexpected failure in lower-level module) */
128  #define MBEDTLS_ERR_SSL_INTERNAL_ERROR                    -0x6C00
129  /** A counter would wrap (eg, too many messages exchanged). */
130  #define MBEDTLS_ERR_SSL_COUNTER_WRAPPING                  -0x6B80
131  /** Unexpected message at ServerHello in renegotiation. */
132  #define MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO       -0x6B00
133  /** DTLS client must retry for hello verification */
134  #define MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED             -0x6A80
135  /** A buffer is too small to receive or write a message */
136  #define MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL                  -0x6A00
137  /* Error space gap */
138  /** No data of requested type currently available on underlying transport. */
139  #define MBEDTLS_ERR_SSL_WANT_READ                         -0x6900
140  /** Connection requires a write call. */
141  #define MBEDTLS_ERR_SSL_WANT_WRITE                        -0x6880
142  /** The operation timed out. */
143  #define MBEDTLS_ERR_SSL_TIMEOUT                           -0x6800
144  /** The client initiated a reconnect from the same port. */
145  #define MBEDTLS_ERR_SSL_CLIENT_RECONNECT                  -0x6780
146  /** Record header looks valid but is not expected. */
147  #define MBEDTLS_ERR_SSL_UNEXPECTED_RECORD                 -0x6700
148  /** The alert message received indicates a non-fatal error. */
149  #define MBEDTLS_ERR_SSL_NON_FATAL                         -0x6680
150  /** A field in a message was incorrect or inconsistent with other fields. */
151  #define MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER                 -0x6600
152  /** Internal-only message signaling that further message-processing should be done */
153  #define MBEDTLS_ERR_SSL_CONTINUE_PROCESSING               -0x6580
154  /** The asynchronous operation is not completed yet. */
155  #define MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS                 -0x6500
156  /** Internal-only message signaling that a message arrived early. */
157  #define MBEDTLS_ERR_SSL_EARLY_MESSAGE                     -0x6480
158  /* Error space gap */
159  /* Error space gap */
160  /* Error space gap */
161  /* Error space gap */
162  /* Error space gap */
163  /* Error space gap */
164  /* Error space gap */
165  /* Error space gap */
166  /** An encrypted DTLS-frame with an unexpected CID was received. */
167  #define MBEDTLS_ERR_SSL_UNEXPECTED_CID                    -0x6000
168  /** An operation failed due to an unexpected version or configuration. */
169  #define MBEDTLS_ERR_SSL_VERSION_MISMATCH                  -0x5F00
170  /** Invalid value in SSL config */
171  #define MBEDTLS_ERR_SSL_BAD_CONFIG                        -0x5E80
172  
173  /*
174   * TLS 1.3 NamedGroup values
175   *
176   * From RF 8446
177   *    enum {
178   *         // Elliptic Curve Groups (ECDHE)
179   *         secp256r1(0x0017), secp384r1(0x0018), secp521r1(0x0019),
180   *         x25519(0x001D), x448(0x001E),
181   *         // Finite Field Groups (DHE)
182   *         ffdhe2048(0x0100), ffdhe3072(0x0101), ffdhe4096(0x0102),
183   *         ffdhe6144(0x0103), ffdhe8192(0x0104),
184   *         // Reserved Code Points
185   *         ffdhe_private_use(0x01FC..0x01FF),
186   *         ecdhe_private_use(0xFE00..0xFEFF),
187   *         (0xFFFF)
188   *     } NamedGroup;
189   *
190   */
191  
192  /* Elliptic Curve Groups (ECDHE) */
193  #define MBEDTLS_SSL_IANA_TLS_GROUP_NONE               0
194  #define MBEDTLS_SSL_IANA_TLS_GROUP_SECP192K1     0x0012
195  #define MBEDTLS_SSL_IANA_TLS_GROUP_SECP192R1     0x0013
196  #define MBEDTLS_SSL_IANA_TLS_GROUP_SECP224K1     0x0014
197  #define MBEDTLS_SSL_IANA_TLS_GROUP_SECP224R1     0x0015
198  #define MBEDTLS_SSL_IANA_TLS_GROUP_SECP256K1     0x0016
199  #define MBEDTLS_SSL_IANA_TLS_GROUP_SECP256R1     0x0017
200  #define MBEDTLS_SSL_IANA_TLS_GROUP_SECP384R1     0x0018
201  #define MBEDTLS_SSL_IANA_TLS_GROUP_SECP521R1     0x0019
202  #define MBEDTLS_SSL_IANA_TLS_GROUP_BP256R1       0x001A
203  #define MBEDTLS_SSL_IANA_TLS_GROUP_BP384R1       0x001B
204  #define MBEDTLS_SSL_IANA_TLS_GROUP_BP512R1       0x001C
205  #define MBEDTLS_SSL_IANA_TLS_GROUP_X25519        0x001D
206  #define MBEDTLS_SSL_IANA_TLS_GROUP_X448          0x001E
207  /* Finite Field Groups (DHE) */
208  #define MBEDTLS_SSL_IANA_TLS_GROUP_FFDHE2048     0x0100
209  #define MBEDTLS_SSL_IANA_TLS_GROUP_FFDHE3072     0x0101
210  #define MBEDTLS_SSL_IANA_TLS_GROUP_FFDHE4096     0x0102
211  #define MBEDTLS_SSL_IANA_TLS_GROUP_FFDHE6144     0x0103
212  #define MBEDTLS_SSL_IANA_TLS_GROUP_FFDHE8192     0x0104
213  
214  /*
215   * TLS 1.3 Key Exchange Modes
216   *
217   * Mbed TLS internal identifiers for use with the SSL configuration API
218   * mbedtls_ssl_conf_tls13_key_exchange_modes().
219   */
220  
221  #define MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK            ( 1u << 0 ) /*!< Pure-PSK TLS 1.3 key exchange,
222                                                                          *   encompassing both externally agreed PSKs
223                                                                          *   as well as resumption PSKs. */
224  #define MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL      ( 1u << 1 ) /*!< Pure-Ephemeral TLS 1.3 key exchanges,
225                                                                          *   including for example ECDHE and DHE
226                                                                          *   key exchanges. */
227  #define MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_EPHEMERAL  ( 1u << 2 ) /*!< PSK-Ephemeral TLS 1.3 key exchanges,
228                                                                          *   using both a PSK and an ephemeral
229                                                                          *   key exchange. */
230  
231  /* Convenience macros for sets of key exchanges. */
232  #define MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_ALL                         \
233      ( MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK              |            \
234        MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_EPHEMERAL    |            \
235        MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL )        /*!< All TLS 1.3 key exchanges           */
236  #define MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_ALL                     \
237      ( MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK              |            \
238        MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_EPHEMERAL    ) /*!< All PSK-based TLS 1.3 key exchanges */
239  #define MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL_ALL               \
240      ( MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL        |            \
241        MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_EPHEMERAL    ) /*!< All ephemeral TLS 1.3 key exchanges */
242  
243  /*
244   * Various constants
245   */
246  
247  /* These are the high an low bytes of ProtocolVersion as defined by:
248   * - RFC 5246: ProtocolVersion version = { 3, 3 };     // TLS v1.2
249   * - RFC 8446: see section 4.2.1
250   */
251  #define MBEDTLS_SSL_MAJOR_VERSION_3             3
252  #define MBEDTLS_SSL_MINOR_VERSION_3             3   /*!< TLS v1.2 */
253  #define MBEDTLS_SSL_MINOR_VERSION_4             4   /*!< TLS v1.3 (experimental) */
254  
255  #define MBEDTLS_SSL_TRANSPORT_STREAM            0   /*!< TLS      */
256  #define MBEDTLS_SSL_TRANSPORT_DATAGRAM          1   /*!< DTLS     */
257  
258  #define MBEDTLS_SSL_MAX_HOST_NAME_LEN           255 /*!< Maximum host name defined in RFC 1035 */
259  #define MBEDTLS_SSL_MAX_ALPN_NAME_LEN           255 /*!< Maximum size in bytes of a protocol name in alpn ext., RFC 7301 */
260  
261  #define MBEDTLS_SSL_MAX_ALPN_LIST_LEN           65535 /*!< Maximum size in bytes of list in alpn ext., RFC 7301          */
262  
263  /* RFC 6066 section 4, see also mfl_code_to_length in ssl_tls.c
264   * NONE must be zero so that memset()ing structure to zero works */
265  #define MBEDTLS_SSL_MAX_FRAG_LEN_NONE           0   /*!< don't use this extension   */
266  #define MBEDTLS_SSL_MAX_FRAG_LEN_512            1   /*!< MaxFragmentLength 2^9      */
267  #define MBEDTLS_SSL_MAX_FRAG_LEN_1024           2   /*!< MaxFragmentLength 2^10     */
268  #define MBEDTLS_SSL_MAX_FRAG_LEN_2048           3   /*!< MaxFragmentLength 2^11     */
269  #define MBEDTLS_SSL_MAX_FRAG_LEN_4096           4   /*!< MaxFragmentLength 2^12     */
270  #define MBEDTLS_SSL_MAX_FRAG_LEN_INVALID        5   /*!< first invalid value        */
271  
272  #define MBEDTLS_SSL_IS_CLIENT                   0
273  #define MBEDTLS_SSL_IS_SERVER                   1
274  
275  #define MBEDTLS_SSL_EXTENDED_MS_DISABLED        0
276  #define MBEDTLS_SSL_EXTENDED_MS_ENABLED         1
277  
278  #define MBEDTLS_SSL_CID_DISABLED                0
279  #define MBEDTLS_SSL_CID_ENABLED                 1
280  
281  #define MBEDTLS_SSL_ETM_DISABLED                0
282  #define MBEDTLS_SSL_ETM_ENABLED                 1
283  
284  #define MBEDTLS_SSL_COMPRESS_NULL               0
285  
286  #define MBEDTLS_SSL_VERIFY_NONE                 0
287  #define MBEDTLS_SSL_VERIFY_OPTIONAL             1
288  #define MBEDTLS_SSL_VERIFY_REQUIRED             2
289  #define MBEDTLS_SSL_VERIFY_UNSET                3 /* Used only for sni_authmode */
290  
291  #define MBEDTLS_SSL_LEGACY_RENEGOTIATION        0
292  #define MBEDTLS_SSL_SECURE_RENEGOTIATION        1
293  
294  #define MBEDTLS_SSL_RENEGOTIATION_DISABLED      0
295  #define MBEDTLS_SSL_RENEGOTIATION_ENABLED       1
296  
297  #define MBEDTLS_SSL_ANTI_REPLAY_DISABLED        0
298  #define MBEDTLS_SSL_ANTI_REPLAY_ENABLED         1
299  
300  #define MBEDTLS_SSL_RENEGOTIATION_NOT_ENFORCED  -1
301  #define MBEDTLS_SSL_RENEGO_MAX_RECORDS_DEFAULT  16
302  
303  #define MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION     0
304  #define MBEDTLS_SSL_LEGACY_ALLOW_RENEGOTIATION  1
305  #define MBEDTLS_SSL_LEGACY_BREAK_HANDSHAKE      2
306  
307  #define MBEDTLS_SSL_TRUNC_HMAC_DISABLED         0
308  #define MBEDTLS_SSL_TRUNC_HMAC_ENABLED          1
309  #define MBEDTLS_SSL_TRUNCATED_HMAC_LEN          10  /* 80 bits, rfc 6066 section 7 */
310  
311  #define MBEDTLS_SSL_SESSION_TICKETS_DISABLED     0
312  #define MBEDTLS_SSL_SESSION_TICKETS_ENABLED      1
313  
314  #define MBEDTLS_SSL_PRESET_DEFAULT              0
315  #define MBEDTLS_SSL_PRESET_SUITEB               2
316  
317  #define MBEDTLS_SSL_CERT_REQ_CA_LIST_ENABLED       1
318  #define MBEDTLS_SSL_CERT_REQ_CA_LIST_DISABLED      0
319  
320  #define MBEDTLS_SSL_DTLS_SRTP_MKI_UNSUPPORTED    0
321  #define MBEDTLS_SSL_DTLS_SRTP_MKI_SUPPORTED      1
322  
323  #define MBEDTLS_SSL_SRV_CIPHERSUITE_ORDER_CLIENT  1
324  #define MBEDTLS_SSL_SRV_CIPHERSUITE_ORDER_SERVER  0
325  
326  /*
327   * Default range for DTLS retransmission timer value, in milliseconds.
328   * RFC 6347 4.2.4.1 says from 1 second to 60 seconds.
329   */
330  #define MBEDTLS_SSL_DTLS_TIMEOUT_DFL_MIN    1000
331  #define MBEDTLS_SSL_DTLS_TIMEOUT_DFL_MAX   60000
332  
333  /**
334   * \name SECTION: Module settings
335   *
336   * The configuration options you can set for this module are in this section.
337   * Either change them in mbedtls_config.h or define them on the compiler command line.
338   * \{
339   */
340  
341  /*
342   * Maximum fragment length in bytes,
343   * determines the size of each of the two internal I/O buffers.
344   *
345   * Note: the RFC defines the default size of SSL / TLS messages. If you
346   * change the value here, other clients / servers may not be able to
347   * communicate with you anymore. Only change this value if you control
348   * both sides of the connection and have it reduced at both sides, or
349   * if you're using the Max Fragment Length extension and you know all your
350   * peers are using it too!
351   */
352  #if !defined(MBEDTLS_SSL_IN_CONTENT_LEN)
353  #define MBEDTLS_SSL_IN_CONTENT_LEN 16384
354  #endif
355  
356  #if !defined(MBEDTLS_SSL_OUT_CONTENT_LEN)
357  #define MBEDTLS_SSL_OUT_CONTENT_LEN 16384
358  #endif
359  
360  /*
361   * Maximum number of heap-allocated bytes for the purpose of
362   * DTLS handshake message reassembly and future message buffering.
363   */
364  #if !defined(MBEDTLS_SSL_DTLS_MAX_BUFFERING)
365  #define MBEDTLS_SSL_DTLS_MAX_BUFFERING 32768
366  #endif
367  
368  /*
369   * Maximum length of CIDs for incoming and outgoing messages.
370   */
371  #if !defined(MBEDTLS_SSL_CID_IN_LEN_MAX)
372  #define MBEDTLS_SSL_CID_IN_LEN_MAX          32
373  #endif
374  
375  #if !defined(MBEDTLS_SSL_CID_OUT_LEN_MAX)
376  #define MBEDTLS_SSL_CID_OUT_LEN_MAX         32
377  #endif
378  
379  #if !defined(MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY)
380  #define MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY 16
381  #endif
382  
383  /* \} name SECTION: Module settings */
384  
385  /*
386   * Length of the verify data for secure renegotiation
387   */
388  #define MBEDTLS_SSL_VERIFY_DATA_MAX_LEN 12
389  
390  /*
391   * Signaling ciphersuite values (SCSV)
392   */
393  #define MBEDTLS_SSL_EMPTY_RENEGOTIATION_INFO    0xFF   /**< renegotiation info ext */
394  
395  /*
396   * Supported Signature and Hash algorithms (For TLS 1.2)
397   * RFC 5246 section 7.4.1.4.1
398   */
399  #define MBEDTLS_SSL_HASH_NONE                0
400  #define MBEDTLS_SSL_HASH_MD5                 1
401  #define MBEDTLS_SSL_HASH_SHA1                2
402  #define MBEDTLS_SSL_HASH_SHA224              3
403  #define MBEDTLS_SSL_HASH_SHA256              4
404  #define MBEDTLS_SSL_HASH_SHA384              5
405  #define MBEDTLS_SSL_HASH_SHA512              6
406  
407  #define MBEDTLS_SSL_SIG_ANON                 0
408  #define MBEDTLS_SSL_SIG_RSA                  1
409  #define MBEDTLS_SSL_SIG_ECDSA                3
410  
411  /*
412   * TLS 1.3 signature algorithms
413   * RFC 8446, Section 4.2.2
414   */
415  
416  /* RSASSA-PKCS1-v1_5 algorithms */
417  #define MBEDTLS_TLS13_SIG_RSA_PKCS1_SHA256 0x0401
418  #define MBEDTLS_TLS13_SIG_RSA_PKCS1_SHA384 0x0501
419  #define MBEDTLS_TLS13_SIG_RSA_PKCS1_SHA512 0x0601
420  
421  /* ECDSA algorithms */
422  #define MBEDTLS_TLS13_SIG_ECDSA_SECP256R1_SHA256 0x0403
423  #define MBEDTLS_TLS13_SIG_ECDSA_SECP384R1_SHA384 0x0503
424  #define MBEDTLS_TLS13_SIG_ECDSA_SECP521R1_SHA512 0x0603
425  
426  /* RSASSA-PSS algorithms with public key OID rsaEncryption */
427  #define MBEDTLS_TLS13_SIG_RSA_PSS_RSAE_SHA256 0x0804
428  #define MBEDTLS_TLS13_SIG_RSA_PSS_RSAE_SHA384 0x0805
429  #define MBEDTLS_TLS13_SIG_RSA_PSS_RSAE_SHA512 0x0806
430  
431  /* EdDSA algorithms */
432  #define MBEDTLS_TLS13_SIG_ED25519 0x0807
433  #define MBEDTLS_TLS13_SIG_ED448 0x0808
434  
435  /* RSASSA-PSS algorithms with public key OID RSASSA-PSS  */
436  #define MBEDTLS_TLS13_SIG_RSA_PSS_PSS_SHA256 0x0809
437  #define MBEDTLS_TLS13_SIG_RSA_PSS_PSS_SHA384 0x080A
438  #define MBEDTLS_TLS13_SIG_RSA_PSS_PSS_SHA512 0x080B
439  
440  /* LEGACY ALGORITHMS */
441  #define MBEDTLS_TLS13_SIG_RSA_PKCS1_SHA1 0x0201
442  #define MBEDTLS_TLS13_SIG_ECDSA_SHA1     0x0203
443  
444  #define MBEDTLS_TLS13_SIG_NONE 0x0
445  
446  /*
447   * Client Certificate Types
448   * RFC 5246 section 7.4.4 plus RFC 4492 section 5.5
449   */
450  #define MBEDTLS_SSL_CERT_TYPE_RSA_SIGN       1
451  #define MBEDTLS_SSL_CERT_TYPE_ECDSA_SIGN    64
452  
453  /*
454   * Message, alert and handshake types
455   */
456  #define MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC     20
457  #define MBEDTLS_SSL_MSG_ALERT                  21
458  #define MBEDTLS_SSL_MSG_HANDSHAKE              22
459  #define MBEDTLS_SSL_MSG_APPLICATION_DATA       23
460  #define MBEDTLS_SSL_MSG_CID                    25
461  
462  #define MBEDTLS_SSL_ALERT_LEVEL_WARNING         1
463  #define MBEDTLS_SSL_ALERT_LEVEL_FATAL           2
464  
465  #define MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY           0  /* 0x00 */
466  #define MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE    10  /* 0x0A */
467  #define MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC        20  /* 0x14 */
468  #define MBEDTLS_SSL_ALERT_MSG_DECRYPTION_FAILED     21  /* 0x15 */
469  #define MBEDTLS_SSL_ALERT_MSG_RECORD_OVERFLOW       22  /* 0x16 */
470  #define MBEDTLS_SSL_ALERT_MSG_DECOMPRESSION_FAILURE 30  /* 0x1E */
471  #define MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE     40  /* 0x28 */
472  #define MBEDTLS_SSL_ALERT_MSG_NO_CERT               41  /* 0x29 */
473  #define MBEDTLS_SSL_ALERT_MSG_BAD_CERT              42  /* 0x2A */
474  #define MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT      43  /* 0x2B */
475  #define MBEDTLS_SSL_ALERT_MSG_CERT_REVOKED          44  /* 0x2C */
476  #define MBEDTLS_SSL_ALERT_MSG_CERT_EXPIRED          45  /* 0x2D */
477  #define MBEDTLS_SSL_ALERT_MSG_CERT_UNKNOWN          46  /* 0x2E */
478  #define MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER     47  /* 0x2F */
479  #define MBEDTLS_SSL_ALERT_MSG_UNKNOWN_CA            48  /* 0x30 */
480  #define MBEDTLS_SSL_ALERT_MSG_ACCESS_DENIED         49  /* 0x31 */
481  #define MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR          50  /* 0x32 */
482  #define MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR         51  /* 0x33 */
483  #define MBEDTLS_SSL_ALERT_MSG_EXPORT_RESTRICTION    60  /* 0x3C */
484  #define MBEDTLS_SSL_ALERT_MSG_PROTOCOL_VERSION      70  /* 0x46 */
485  #define MBEDTLS_SSL_ALERT_MSG_INSUFFICIENT_SECURITY 71  /* 0x47 */
486  #define MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR        80  /* 0x50 */
487  #define MBEDTLS_SSL_ALERT_MSG_INAPROPRIATE_FALLBACK 86  /* 0x56 */
488  #define MBEDTLS_SSL_ALERT_MSG_USER_CANCELED         90  /* 0x5A */
489  #define MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION     100  /* 0x64 */
490  #define MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT      110  /* 0x6E */
491  #define MBEDTLS_SSL_ALERT_MSG_UNRECOGNIZED_NAME    112  /* 0x70 */
492  #define MBEDTLS_SSL_ALERT_MSG_UNKNOWN_PSK_IDENTITY 115  /* 0x73 */
493  #define MBEDTLS_SSL_ALERT_MSG_NO_APPLICATION_PROTOCOL 120 /* 0x78 */
494  
495  #define MBEDTLS_SSL_HS_HELLO_REQUEST            0
496  #define MBEDTLS_SSL_HS_CLIENT_HELLO             1
497  #define MBEDTLS_SSL_HS_SERVER_HELLO             2
498  #define MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST     3
499  #define MBEDTLS_SSL_HS_NEW_SESSION_TICKET       4
500  #define MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS     8 // NEW IN TLS 1.3
501  #define MBEDTLS_SSL_HS_CERTIFICATE             11
502  #define MBEDTLS_SSL_HS_SERVER_KEY_EXCHANGE     12
503  #define MBEDTLS_SSL_HS_CERTIFICATE_REQUEST     13
504  #define MBEDTLS_SSL_HS_SERVER_HELLO_DONE       14
505  #define MBEDTLS_SSL_HS_CERTIFICATE_VERIFY      15
506  #define MBEDTLS_SSL_HS_CLIENT_KEY_EXCHANGE     16
507  #define MBEDTLS_SSL_HS_FINISHED                20
508  
509  /*
510   * TLS extensions
511   */
512  #define MBEDTLS_TLS_EXT_SERVERNAME                   0
513  #define MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME          0
514  
515  #define MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH          1
516  
517  #define MBEDTLS_TLS_EXT_TRUNCATED_HMAC               4
518  #define MBEDTLS_TLS_EXT_STATUS_REQUEST               5 /* RFC 6066 TLS 1.2 and 1.3 */
519  
520  #define MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES   10
521  #define MBEDTLS_TLS_EXT_SUPPORTED_GROUPS            10 /* RFC 8422,7919 TLS 1.2 and 1.3 */
522  #define MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS     11
523  
524  #define MBEDTLS_TLS_EXT_SIG_ALG                     13 /* RFC 8446 TLS 1.3 */
525  #define MBEDTLS_TLS_EXT_USE_SRTP                    14
526  #define MBEDTLS_TLS_EXT_HEARTBEAT                   15 /* RFC 6520 TLS 1.2 and 1.3 */
527  #define MBEDTLS_TLS_EXT_ALPN                        16
528  
529  #define MBEDTLS_TLS_EXT_SCT                         18 /* RFC 6962 TLS 1.2 and 1.3 */
530  #define MBEDTLS_TLS_EXT_CLI_CERT_TYPE               19 /* RFC 7250 TLS 1.2 and 1.3 */
531  #define MBEDTLS_TLS_EXT_SERV_CERT_TYPE              20 /* RFC 7250 TLS 1.2 and 1.3 */
532  #define MBEDTLS_TLS_EXT_PADDING                     21 /* RFC 7685 TLS 1.2 and 1.3 */
533  #define MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC            22 /* 0x16 */
534  #define MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET  0x0017 /* 23 */
535  
536  #define MBEDTLS_TLS_EXT_SESSION_TICKET              35
537  
538  #define MBEDTLS_TLS_EXT_PRE_SHARED_KEY              41 /* RFC 8446 TLS 1.3 */
539  #define MBEDTLS_TLS_EXT_EARLY_DATA                  42 /* RFC 8446 TLS 1.3 */
540  #define MBEDTLS_TLS_EXT_SUPPORTED_VERSIONS          43 /* RFC 8446 TLS 1.3 */
541  #define MBEDTLS_TLS_EXT_COOKIE                      44 /* RFC 8446 TLS 1.3 */
542  #define MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES      45 /* RFC 8446 TLS 1.3 */
543  
544  #define MBEDTLS_TLS_EXT_CERT_AUTH                   47 /* RFC 8446 TLS 1.3 */
545  #define MBEDTLS_TLS_EXT_OID_FILTERS                 48 /* RFC 8446 TLS 1.3 */
546  #define MBEDTLS_TLS_EXT_POST_HANDSHAKE_AUTH         49 /* RFC 8446 TLS 1.3 */
547  #define MBEDTLS_TLS_EXT_SIG_ALG_CERT                50 /* RFC 8446 TLS 1.3 */
548  #define MBEDTLS_TLS_EXT_KEY_SHARE                   51 /* RFC 8446 TLS 1.3 */
549  
550  /* The value of the CID extension is still TBD as of
551   * draft-ietf-tls-dtls-connection-id-05
552   * (https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05).
553   *
554   * A future minor revision of Mbed TLS may change the default value of
555   * this option to match evolving standards and usage.
556   */
557  #if !defined(MBEDTLS_TLS_EXT_CID)
558  #define MBEDTLS_TLS_EXT_CID                        254 /* TBD */
559  #endif
560  
561  #define MBEDTLS_TLS_EXT_ECJPAKE_KKPP               256 /* experimental */
562  
563  #define MBEDTLS_TLS_EXT_RENEGOTIATION_INFO      0xFF01
564  
565  /*
566   * Size defines
567   */
568  #if !defined(MBEDTLS_PSK_MAX_LEN)
569  #define MBEDTLS_PSK_MAX_LEN            32 /* 256 bits */
570  #endif
571  
572  /* Dummy type used only for its size */
573  union mbedtls_ssl_premaster_secret
574  {
575  #if defined(MBEDTLS_KEY_EXCHANGE_RSA_ENABLED)
576      unsigned char _pms_rsa[48];                         /* RFC 5246 8.1.1 */
577  #endif
578  #if defined(MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED)
579      unsigned char _pms_dhm[MBEDTLS_MPI_MAX_SIZE];      /* RFC 5246 8.1.2 */
580  #endif
581  #if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED)    || \
582      defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED)  || \
583      defined(MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED)     || \
584      defined(MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED)
585      unsigned char _pms_ecdh[MBEDTLS_ECP_MAX_BYTES];    /* RFC 4492 5.10 */
586  #endif
587  #if defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
588      unsigned char _pms_psk[4 + 2 * MBEDTLS_PSK_MAX_LEN];       /* RFC 4279 2 */
589  #endif
590  #if defined(MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED)
591      unsigned char _pms_dhe_psk[4 + MBEDTLS_MPI_MAX_SIZE
592                                   + MBEDTLS_PSK_MAX_LEN];       /* RFC 4279 3 */
593  #endif
594  #if defined(MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED)
595      unsigned char _pms_rsa_psk[52 + MBEDTLS_PSK_MAX_LEN];      /* RFC 4279 4 */
596  #endif
597  #if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED)
598      unsigned char _pms_ecdhe_psk[4 + MBEDTLS_ECP_MAX_BYTES
599                                     + MBEDTLS_PSK_MAX_LEN];     /* RFC 5489 2 */
600  #endif
601  #if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
602      unsigned char _pms_ecjpake[32];     /* Thread spec: SHA-256 output */
603  #endif
604  };
605  
606  #define MBEDTLS_PREMASTER_SIZE     sizeof( union mbedtls_ssl_premaster_secret )
607  
608  #define MBEDTLS_TLS1_3_MD_MAX_SIZE         MBEDTLS_MD_MAX_SIZE
609  
610  /* Length in number of bytes of the TLS sequence number */
611  #define MBEDTLS_SSL_SEQUENCE_NUMBER_LEN 8
612  
613  #ifdef __cplusplus
614  extern "C" {
615  #endif
616  
617  /*
618   * SSL state machine
619   */
620  typedef enum
621  {
622      MBEDTLS_SSL_HELLO_REQUEST,
623      MBEDTLS_SSL_CLIENT_HELLO,
624      MBEDTLS_SSL_SERVER_HELLO,
625      MBEDTLS_SSL_SERVER_CERTIFICATE,
626      MBEDTLS_SSL_SERVER_KEY_EXCHANGE,
627      MBEDTLS_SSL_CERTIFICATE_REQUEST,
628      MBEDTLS_SSL_SERVER_HELLO_DONE,
629      MBEDTLS_SSL_CLIENT_CERTIFICATE,
630      MBEDTLS_SSL_CLIENT_KEY_EXCHANGE,
631      MBEDTLS_SSL_CERTIFICATE_VERIFY,
632      MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC,
633      MBEDTLS_SSL_CLIENT_FINISHED,
634      MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC,
635      MBEDTLS_SSL_SERVER_FINISHED,
636      MBEDTLS_SSL_FLUSH_BUFFERS,
637      MBEDTLS_SSL_HANDSHAKE_WRAPUP,
638      MBEDTLS_SSL_HANDSHAKE_OVER,
639      MBEDTLS_SSL_SERVER_NEW_SESSION_TICKET,
640      MBEDTLS_SSL_SERVER_HELLO_VERIFY_REQUEST_SENT,
641  #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
642      MBEDTLS_SSL_ENCRYPTED_EXTENSIONS,
643      MBEDTLS_SSL_CLIENT_CERTIFICATE_VERIFY,
644  #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
645  }
646  mbedtls_ssl_states;
647  
648  /**
649   * \brief          Callback type: send data on the network.
650   *
651   * \note           That callback may be either blocking or non-blocking.
652   *
653   * \param ctx      Context for the send callback (typically a file descriptor)
654   * \param buf      Buffer holding the data to send
655   * \param len      Length of the data to send
656   *
657   * \return         The callback must return the number of bytes sent if any,
658   *                 or a non-zero error code.
659   *                 If performing non-blocking I/O, \c MBEDTLS_ERR_SSL_WANT_WRITE
660   *                 must be returned when the operation would block.
661   *
662   * \note           The callback is allowed to send fewer bytes than requested.
663   *                 It must always return the number of bytes actually sent.
664   */
665  typedef int mbedtls_ssl_send_t( void *ctx,
666                                  const unsigned char *buf,
667                                  size_t len );
668  
669  /**
670   * \brief          Callback type: receive data from the network.
671   *
672   * \note           That callback may be either blocking or non-blocking.
673   *
674   * \param ctx      Context for the receive callback (typically a file
675   *                 descriptor)
676   * \param buf      Buffer to write the received data to
677   * \param len      Length of the receive buffer
678   *
679   * \returns        If data has been received, the positive number of bytes received.
680   * \returns        \c 0 if the connection has been closed.
681   * \returns        If performing non-blocking I/O, \c MBEDTLS_ERR_SSL_WANT_READ
682   *                 must be returned when the operation would block.
683   * \returns        Another negative error code on other kinds of failures.
684   *
685   * \note           The callback may receive fewer bytes than the length of the
686   *                 buffer. It must always return the number of bytes actually
687   *                 received and written to the buffer.
688   */
689  typedef int mbedtls_ssl_recv_t( void *ctx,
690                                  unsigned char *buf,
691                                  size_t len );
692  
693  /**
694   * \brief          Callback type: receive data from the network, with timeout
695   *
696   * \note           That callback must block until data is received, or the
697   *                 timeout delay expires, or the operation is interrupted by a
698   *                 signal.
699   *
700   * \param ctx      Context for the receive callback (typically a file descriptor)
701   * \param buf      Buffer to write the received data to
702   * \param len      Length of the receive buffer
703   * \param timeout  Maximum number of milliseconds to wait for data
704   *                 0 means no timeout (potentially waiting forever)
705   *
706   * \return         The callback must return the number of bytes received,
707   *                 or a non-zero error code:
708   *                 \c MBEDTLS_ERR_SSL_TIMEOUT if the operation timed out,
709   *                 \c MBEDTLS_ERR_SSL_WANT_READ if interrupted by a signal.
710   *
711   * \note           The callback may receive fewer bytes than the length of the
712   *                 buffer. It must always return the number of bytes actually
713   *                 received and written to the buffer.
714   */
715  typedef int mbedtls_ssl_recv_timeout_t( void *ctx,
716                                          unsigned char *buf,
717                                          size_t len,
718                                          uint32_t timeout );
719  /**
720   * \brief          Callback type: set a pair of timers/delays to watch
721   *
722   * \param ctx      Context pointer
723   * \param int_ms   Intermediate delay in milliseconds
724   * \param fin_ms   Final delay in milliseconds
725   *                 0 cancels the current timer.
726   *
727   * \note           This callback must at least store the necessary information
728   *                 for the associated \c mbedtls_ssl_get_timer_t callback to
729   *                 return correct information.
730   *
731   * \note           If using a event-driven style of programming, an event must
732   *                 be generated when the final delay is passed. The event must
733   *                 cause a call to \c mbedtls_ssl_handshake() with the proper
734   *                 SSL context to be scheduled. Care must be taken to ensure
735   *                 that at most one such call happens at a time.
736   *
737   * \note           Only one timer at a time must be running. Calling this
738   *                 function while a timer is running must cancel it. Cancelled
739   *                 timers must not generate any event.
740   */
741  typedef void mbedtls_ssl_set_timer_t( void * ctx,
742                                        uint32_t int_ms,
743                                        uint32_t fin_ms );
744  
745  /**
746   * \brief          Callback type: get status of timers/delays
747   *
748   * \param ctx      Context pointer
749   *
750   * \return         This callback must return:
751   *                 -1 if cancelled (fin_ms == 0),
752   *                  0 if none of the delays have passed,
753   *                  1 if only the intermediate delay has passed,
754   *                  2 if the final delay has passed.
755   */
756  typedef int mbedtls_ssl_get_timer_t( void * ctx );
757  
758  /* Defined below */
759  typedef struct mbedtls_ssl_session mbedtls_ssl_session;
760  typedef struct mbedtls_ssl_context mbedtls_ssl_context;
761  typedef struct mbedtls_ssl_config  mbedtls_ssl_config;
762  
763  /* Defined in library/ssl_misc.h */
764  typedef struct mbedtls_ssl_transform mbedtls_ssl_transform;
765  typedef struct mbedtls_ssl_handshake_params mbedtls_ssl_handshake_params;
766  typedef struct mbedtls_ssl_sig_hash_set_t mbedtls_ssl_sig_hash_set_t;
767  #if defined(MBEDTLS_X509_CRT_PARSE_C)
768  typedef struct mbedtls_ssl_key_cert mbedtls_ssl_key_cert;
769  #endif
770  #if defined(MBEDTLS_SSL_PROTO_DTLS)
771  typedef struct mbedtls_ssl_flight_item mbedtls_ssl_flight_item;
772  #endif
773  
774  /**
775   * \brief          Callback type: server-side session cache getter
776   *
777   *                 The session cache is logically a key value store, with
778   *                 keys being session IDs and values being instances of
779   *                 mbedtls_ssl_session.
780   *
781   *                 This callback retrieves an entry in this key-value store.
782   *
783   * \param data            The address of the session cache structure to query.
784   * \param session_id      The buffer holding the session ID to query.
785   * \param session_id_len  The length of \p session_id in Bytes.
786   * \param session         The address of the session structure to populate.
787   *                        It is initialized with mbdtls_ssl_session_init(),
788   *                        and the callback must always leave it in a state
789   *                        where it can safely be freed via
790   *                        mbedtls_ssl_session_free() independent of the
791   *                        return code of this function.
792   *
793   * \return                \c 0 on success
794   * \return                A non-zero return value on failure.
795   *
796   */
797  typedef int mbedtls_ssl_cache_get_t( void *data,
798                                       unsigned char const *session_id,
799                                       size_t session_id_len,
800                                       mbedtls_ssl_session *session );
801  /**
802   * \brief          Callback type: server-side session cache setter
803   *
804   *                 The session cache is logically a key value store, with
805   *                 keys being session IDs and values being instances of
806   *                 mbedtls_ssl_session.
807   *
808   *                 This callback sets an entry in this key-value store.
809   *
810   * \param data            The address of the session cache structure to modify.
811   * \param session_id      The buffer holding the session ID to query.
812   * \param session_id_len  The length of \p session_id in Bytes.
813   * \param session         The address of the session to be stored in the
814   *                        session cache.
815   *
816   * \return                \c 0 on success
817   * \return                A non-zero return value on failure.
818   */
819  typedef int mbedtls_ssl_cache_set_t( void *data,
820                                       unsigned char const *session_id,
821                                       size_t session_id_len,
822                                       const mbedtls_ssl_session *session );
823  
824  #if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
825  #if defined(MBEDTLS_X509_CRT_PARSE_C)
826  /**
827   * \brief           Callback type: start external signature operation.
828   *
829   *                  This callback is called during an SSL handshake to start
830   *                  a signature decryption operation using an
831   *                  external processor. The parameter \p cert contains
832   *                  the public key; it is up to the callback function to
833   *                  determine how to access the associated private key.
834   *
835   *                  This function typically sends or enqueues a request, and
836   *                  does not wait for the operation to complete. This allows
837   *                  the handshake step to be non-blocking.
838   *
839   *                  The parameters \p ssl and \p cert are guaranteed to remain
840   *                  valid throughout the handshake. On the other hand, this
841   *                  function must save the contents of \p hash if the value
842   *                  is needed for later processing, because the \p hash buffer
843   *                  is no longer valid after this function returns.
844   *
845   *                  This function may call mbedtls_ssl_set_async_operation_data()
846   *                  to store an operation context for later retrieval
847   *                  by the resume or cancel callback.
848   *
849   * \note            For RSA signatures, this function must produce output
850   *                  that is consistent with PKCS#1 v1.5 in the same way as
851   *                  mbedtls_rsa_pkcs1_sign(). Before the private key operation,
852   *                  apply the padding steps described in RFC 8017, section 9.2
853   *                  "EMSA-PKCS1-v1_5" as follows.
854   *                  - If \p md_alg is #MBEDTLS_MD_NONE, apply the PKCS#1 v1.5
855   *                    encoding, treating \p hash as the DigestInfo to be
856   *                    padded. In other words, apply EMSA-PKCS1-v1_5 starting
857   *                    from step 3, with `T = hash` and `tLen = hash_len`.
858   *                  - If `md_alg != MBEDTLS_MD_NONE`, apply the PKCS#1 v1.5
859   *                    encoding, treating \p hash as the hash to be encoded and
860   *                    padded. In other words, apply EMSA-PKCS1-v1_5 starting
861   *                    from step 2, with `digestAlgorithm` obtained by calling
862   *                    mbedtls_oid_get_oid_by_md() on \p md_alg.
863   *
864   * \note            For ECDSA signatures, the output format is the DER encoding
865   *                  `Ecdsa-Sig-Value` defined in
866   *                  [RFC 4492 section 5.4](https://tools.ietf.org/html/rfc4492#section-5.4).
867   *
868   * \param ssl             The SSL connection instance. It should not be
869   *                        modified other than via
870   *                        mbedtls_ssl_set_async_operation_data().
871   * \param cert            Certificate containing the public key.
872   *                        In simple cases, this is one of the pointers passed to
873   *                        mbedtls_ssl_conf_own_cert() when configuring the SSL
874   *                        connection. However, if other callbacks are used, this
875   *                        property may not hold. For example, if an SNI callback
876   *                        is registered with mbedtls_ssl_conf_sni(), then
877   *                        this callback determines what certificate is used.
878   * \param md_alg          Hash algorithm.
879   * \param hash            Buffer containing the hash. This buffer is
880   *                        no longer valid when the function returns.
881   * \param hash_len        Size of the \c hash buffer in bytes.
882   *
883   * \return          0 if the operation was started successfully and the SSL
884   *                  stack should call the resume callback immediately.
885   * \return          #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS if the operation
886   *                  was started successfully and the SSL stack should return
887   *                  immediately without calling the resume callback yet.
888   * \return          #MBEDTLS_ERR_SSL_HW_ACCEL_FALLTHROUGH if the external
889   *                  processor does not support this key. The SSL stack will
890   *                  use the private key object instead.
891   * \return          Any other error indicates a fatal failure and is
892   *                  propagated up the call chain. The callback should
893   *                  use \c MBEDTLS_ERR_PK_xxx error codes, and <b>must not</b>
894   *                  use \c MBEDTLS_ERR_SSL_xxx error codes except as
895   *                  directed in the documentation of this callback.
896   */
897  typedef int mbedtls_ssl_async_sign_t( mbedtls_ssl_context *ssl,
898                                        mbedtls_x509_crt *cert,
899                                        mbedtls_md_type_t md_alg,
900                                        const unsigned char *hash,
901                                        size_t hash_len );
902  
903  /**
904   * \brief           Callback type: start external decryption operation.
905   *
906   *                  This callback is called during an SSL handshake to start
907   *                  an RSA decryption operation using an
908   *                  external processor. The parameter \p cert contains
909   *                  the public key; it is up to the callback function to
910   *                  determine how to access the associated private key.
911   *
912   *                  This function typically sends or enqueues a request, and
913   *                  does not wait for the operation to complete. This allows
914   *                  the handshake step to be non-blocking.
915   *
916   *                  The parameters \p ssl and \p cert are guaranteed to remain
917   *                  valid throughout the handshake. On the other hand, this
918   *                  function must save the contents of \p input if the value
919   *                  is needed for later processing, because the \p input buffer
920   *                  is no longer valid after this function returns.
921   *
922   *                  This function may call mbedtls_ssl_set_async_operation_data()
923   *                  to store an operation context for later retrieval
924   *                  by the resume or cancel callback.
925   *
926   * \warning         RSA decryption as used in TLS is subject to a potential
927   *                  timing side channel attack first discovered by Bleichenbacher
928   *                  in 1998. This attack can be remotely exploitable
929   *                  in practice. To avoid this attack, you must ensure that
930   *                  if the callback performs an RSA decryption, the time it
931   *                  takes to execute and return the result does not depend
932   *                  on whether the RSA decryption succeeded or reported
933   *                  invalid padding.
934   *
935   * \param ssl             The SSL connection instance. It should not be
936   *                        modified other than via
937   *                        mbedtls_ssl_set_async_operation_data().
938   * \param cert            Certificate containing the public key.
939   *                        In simple cases, this is one of the pointers passed to
940   *                        mbedtls_ssl_conf_own_cert() when configuring the SSL
941   *                        connection. However, if other callbacks are used, this
942   *                        property may not hold. For example, if an SNI callback
943   *                        is registered with mbedtls_ssl_conf_sni(), then
944   *                        this callback determines what certificate is used.
945   * \param input           Buffer containing the input ciphertext. This buffer
946   *                        is no longer valid when the function returns.
947   * \param input_len       Size of the \p input buffer in bytes.
948   *
949   * \return          0 if the operation was started successfully and the SSL
950   *                  stack should call the resume callback immediately.
951   * \return          #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS if the operation
952   *                  was started successfully and the SSL stack should return
953   *                  immediately without calling the resume callback yet.
954   * \return          #MBEDTLS_ERR_SSL_HW_ACCEL_FALLTHROUGH if the external
955   *                  processor does not support this key. The SSL stack will
956   *                  use the private key object instead.
957   * \return          Any other error indicates a fatal failure and is
958   *                  propagated up the call chain. The callback should
959   *                  use \c MBEDTLS_ERR_PK_xxx error codes, and <b>must not</b>
960   *                  use \c MBEDTLS_ERR_SSL_xxx error codes except as
961   *                  directed in the documentation of this callback.
962   */
963  typedef int mbedtls_ssl_async_decrypt_t( mbedtls_ssl_context *ssl,
964                                           mbedtls_x509_crt *cert,
965                                           const unsigned char *input,
966                                           size_t input_len );
967  #endif /* MBEDTLS_X509_CRT_PARSE_C */
968  
969  /**
970   * \brief           Callback type: resume external operation.
971   *
972   *                  This callback is called during an SSL handshake to resume
973   *                  an external operation started by the
974   *                  ::mbedtls_ssl_async_sign_t or
975   *                  ::mbedtls_ssl_async_decrypt_t callback.
976   *
977   *                  This function typically checks the status of a pending
978   *                  request or causes the request queue to make progress, and
979   *                  does not wait for the operation to complete. This allows
980   *                  the handshake step to be non-blocking.
981   *
982   *                  This function may call mbedtls_ssl_get_async_operation_data()
983   *                  to retrieve an operation context set by the start callback.
984   *                  It may call mbedtls_ssl_set_async_operation_data() to modify
985   *                  this context.
986   *
987   *                  Note that when this function returns a status other than
988   *                  #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS, it must free any
989   *                  resources associated with the operation.
990   *
991   * \param ssl             The SSL connection instance. It should not be
992   *                        modified other than via
993   *                        mbedtls_ssl_set_async_operation_data().
994   * \param output          Buffer containing the output (signature or decrypted
995   *                        data) on success.
996   * \param output_len      On success, number of bytes written to \p output.
997   * \param output_size     Size of the \p output buffer in bytes.
998   *
999   * \return          0 if output of the operation is available in the
1000   *                  \p output buffer.
1001   * \return          #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS if the operation
1002   *                  is still in progress. Subsequent requests for progress
1003   *                  on the SSL connection will call the resume callback
1004   *                  again.
1005   * \return          Any other error means that the operation is aborted.
1006   *                  The SSL handshake is aborted. The callback should
1007   *                  use \c MBEDTLS_ERR_PK_xxx error codes, and <b>must not</b>
1008   *                  use \c MBEDTLS_ERR_SSL_xxx error codes except as
1009   *                  directed in the documentation of this callback.
1010   */
1011  typedef int mbedtls_ssl_async_resume_t( mbedtls_ssl_context *ssl,
1012                                          unsigned char *output,
1013                                          size_t *output_len,
1014                                          size_t output_size );
1015  
1016  /**
1017   * \brief           Callback type: cancel external operation.
1018   *
1019   *                  This callback is called if an SSL connection is closed
1020   *                  while an asynchronous operation is in progress. Note that
1021   *                  this callback is not called if the
1022   *                  ::mbedtls_ssl_async_resume_t callback has run and has
1023   *                  returned a value other than
1024   *                  #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS, since in that case
1025   *                  the asynchronous operation has already completed.
1026   *
1027   *                  This function may call mbedtls_ssl_get_async_operation_data()
1028   *                  to retrieve an operation context set by the start callback.
1029   *
1030   * \param ssl             The SSL connection instance. It should not be
1031   *                        modified.
1032   */
1033  typedef void mbedtls_ssl_async_cancel_t( mbedtls_ssl_context *ssl );
1034  #endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
1035  
1036  #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED) &&        \
1037      !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
1038  #define MBEDTLS_SSL_PEER_CERT_DIGEST_MAX_LEN  48
1039  #if defined(MBEDTLS_SHA256_C)
1040  #define MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE MBEDTLS_MD_SHA256
1041  #define MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN  32
1042  #elif defined(MBEDTLS_SHA384_C)
1043  #define MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE MBEDTLS_MD_SHA384
1044  #define MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN  48
1045  #elif defined(MBEDTLS_SHA1_C)
1046  #define MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE MBEDTLS_MD_SHA1
1047  #define MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN  20
1048  #else
1049  /* This is already checked in check_config.h, but be sure. */
1050  #error "Bad configuration - need SHA-1, SHA-256 or SHA-512 enabled to compute digest of peer CRT."
1051  #endif
1052  #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED &&
1053            !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
1054  
1055  typedef struct
1056  {
1057      unsigned char client_application_traffic_secret_N[ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
1058      unsigned char server_application_traffic_secret_N[ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
1059      unsigned char exporter_master_secret             [ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
1060      unsigned char resumption_master_secret           [ MBEDTLS_TLS1_3_MD_MAX_SIZE ];
1061  } mbedtls_ssl_tls1_3_application_secrets;
1062  
1063  #if defined(MBEDTLS_SSL_DTLS_SRTP)
1064  
1065  #define MBEDTLS_TLS_SRTP_MAX_MKI_LENGTH             255
1066  #define MBEDTLS_TLS_SRTP_MAX_PROFILE_LIST_LENGTH    4
1067  /*
1068   * For code readability use a typedef for DTLS-SRTP profiles
1069   *
1070   * Use_srtp extension protection profiles values as defined in
1071   * http://www.iana.org/assignments/srtp-protection/srtp-protection.xhtml
1072   *
1073   * Reminder: if this list is expanded mbedtls_ssl_check_srtp_profile_value
1074   * must be updated too.
1075   */
1076  #define MBEDTLS_TLS_SRTP_AES128_CM_HMAC_SHA1_80     ( (uint16_t) 0x0001)
1077  #define MBEDTLS_TLS_SRTP_AES128_CM_HMAC_SHA1_32     ( (uint16_t) 0x0002)
1078  #define MBEDTLS_TLS_SRTP_NULL_HMAC_SHA1_80          ( (uint16_t) 0x0005)
1079  #define MBEDTLS_TLS_SRTP_NULL_HMAC_SHA1_32          ( (uint16_t) 0x0006)
1080  /* This one is not iana defined, but for code readability. */
1081  #define MBEDTLS_TLS_SRTP_UNSET                      ( (uint16_t) 0x0000)
1082  
1083  typedef uint16_t mbedtls_ssl_srtp_profile;
1084  
1085  typedef struct mbedtls_dtls_srtp_info_t
1086  {
1087      /*! The SRTP profile that was negotiated. */
1088      mbedtls_ssl_srtp_profile MBEDTLS_PRIVATE(chosen_dtls_srtp_profile);
1089      /*! The length of mki_value. */
1090      uint16_t MBEDTLS_PRIVATE(mki_len);
1091      /*! The mki_value used, with max size of 256 bytes. */
1092      unsigned char MBEDTLS_PRIVATE(mki_value)[MBEDTLS_TLS_SRTP_MAX_MKI_LENGTH];
1093  }
1094  mbedtls_dtls_srtp_info;
1095  
1096  #endif /* MBEDTLS_SSL_DTLS_SRTP */
1097  
1098  /*
1099   * This structure is used for storing current session data.
1100   *
1101   * Note: when changing this definition, we need to check and update:
1102   *  - in tests/suites/test_suite_ssl.function:
1103   *      ssl_populate_session() and ssl_serialize_session_save_load()
1104   *  - in library/ssl_tls.c:
1105   *      mbedtls_ssl_session_init() and mbedtls_ssl_session_free()
1106   *      mbedtls_ssl_session_save() and ssl_session_load()
1107   *      ssl_session_copy()
1108   */
1109  struct mbedtls_ssl_session
1110  {
1111  #if defined(MBEDTLS_HAVE_TIME)
1112      mbedtls_time_t MBEDTLS_PRIVATE(start);       /*!< starting time      */
1113  #endif
1114      int MBEDTLS_PRIVATE(ciphersuite);            /*!< chosen ciphersuite */
1115      int MBEDTLS_PRIVATE(compression);            /*!< chosen compression */
1116      size_t MBEDTLS_PRIVATE(id_len);              /*!< session id length  */
1117      unsigned char MBEDTLS_PRIVATE(id)[32];       /*!< session identifier */
1118      unsigned char MBEDTLS_PRIVATE(master)[48];   /*!< the master secret  */
1119  
1120      unsigned char MBEDTLS_PRIVATE(exported);
1121  
1122      /* This field is temporarily duplicated with mbedtls_ssl_context.minor_ver.
1123       * Once runtime negotiation of TLS 1.2 and TLS 1.3 is implemented, it needs
1124       * to be studied whether one of them can be removed. */
1125      unsigned char MBEDTLS_PRIVATE(minor_ver);    /*!< The TLS version used in the session. */
1126  
1127  #if defined(MBEDTLS_X509_CRT_PARSE_C)
1128  #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
1129      mbedtls_x509_crt *MBEDTLS_PRIVATE(peer_cert);       /*!< peer X.509 cert chain */
1130  #else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
1131      /*! The digest of the peer's end-CRT. This must be kept to detect CRT
1132       *  changes during renegotiation, mitigating the triple handshake attack. */
1133      unsigned char *MBEDTLS_PRIVATE(peer_cert_digest);
1134      size_t MBEDTLS_PRIVATE(peer_cert_digest_len);
1135      mbedtls_md_type_t MBEDTLS_PRIVATE(peer_cert_digest_type);
1136  #endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
1137  #endif /* MBEDTLS_X509_CRT_PARSE_C */
1138      uint32_t MBEDTLS_PRIVATE(verify_result);          /*!<  verification result     */
1139  
1140  #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
1141      unsigned char *MBEDTLS_PRIVATE(ticket);      /*!< RFC 5077 session ticket */
1142      size_t MBEDTLS_PRIVATE(ticket_len);          /*!< session ticket length   */
1143      uint32_t MBEDTLS_PRIVATE(ticket_lifetime);   /*!< ticket lifetime hint    */
1144  #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
1145  
1146  #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
1147      unsigned char MBEDTLS_PRIVATE(mfl_code);     /*!< MaxFragmentLength negotiated by peer */
1148  #endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
1149  
1150  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
1151      int MBEDTLS_PRIVATE(encrypt_then_mac);       /*!< flag for EtM activation                */
1152  #endif
1153  
1154  #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
1155      mbedtls_ssl_tls1_3_application_secrets MBEDTLS_PRIVATE(app_secrets);
1156  #endif
1157  };
1158  
1159  /*
1160   * Identifiers for PRFs used in various versions of TLS.
1161   */
1162  typedef enum
1163  {
1164     MBEDTLS_SSL_TLS_PRF_NONE,
1165     MBEDTLS_SSL_TLS_PRF_SHA384,
1166     MBEDTLS_SSL_TLS_PRF_SHA256,
1167     MBEDTLS_SSL_HKDF_EXPAND_SHA384,
1168     MBEDTLS_SSL_HKDF_EXPAND_SHA256
1169  }
1170  mbedtls_tls_prf_types;
1171  
1172  typedef enum
1173  {
1174      MBEDTLS_SSL_KEY_EXPORT_TLS12_MASTER_SECRET = 0,
1175  #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
1176      MBEDTLS_SSL_KEY_EXPORT_TLS13_CLIENT_EARLY_SECRET,
1177      MBEDTLS_SSL_KEY_EXPORT_TLS13_EARLY_EXPORTER_SECRET,
1178      MBEDTLS_SSL_KEY_EXPORT_TLS13_CLIENT_HANDSHAKE_TRAFFIC_SECRET,
1179      MBEDTLS_SSL_KEY_EXPORT_TLS13_SERVER_HANDSHAKE_TRAFFIC_SECRET,
1180      MBEDTLS_SSL_KEY_EXPORT_TLS13_CLIENT_APPLICATION_TRAFFIC_SECRET,
1181      MBEDTLS_SSL_KEY_EXPORT_TLS13_SERVER_APPLICATION_TRAFFIC_SECRET,
1182  #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
1183  } mbedtls_ssl_key_export_type;
1184  
1185  /**
1186   * \brief           Callback type: Export key alongside random values for
1187   *                                 session identification, and PRF for
1188   *                                 implementation of TLS key exporters.
1189   *
1190   * \param p_expkey   Context for the callback.
1191   * \param type       The type of the key that is being exported.
1192   * \param secret     The address of the buffer holding the secret
1193   *                   that's being exporterd.
1194   * \param secret_len The length of \p secret in bytes.
1195   * \param client_random The client random bytes.
1196   * \param server_random The server random bytes.
1197   * \param tls_prf_type The identifier for the PRF used in the handshake
1198   *                     to which the key belongs.
1199   */
1200  typedef void mbedtls_ssl_export_keys_t( void *p_expkey,
1201                                          mbedtls_ssl_key_export_type type,
1202                                          const unsigned char *secret,
1203                                          size_t secret_len,
1204                                          const unsigned char client_random[32],
1205                                          const unsigned char server_random[32],
1206                                          mbedtls_tls_prf_types tls_prf_type );
1207  
1208  /**
1209   * SSL/TLS configuration to be shared between mbedtls_ssl_context structures.
1210   */
1211  struct mbedtls_ssl_config
1212  {
1213      /* Group items by size (largest first) to minimize padding overhead */
1214  
1215      /*
1216       * Pointers
1217       */
1218  
1219      /** Allowed ciphersuites for (D)TLS 1.2 (0-terminated)                  */
1220      const int *MBEDTLS_PRIVATE(ciphersuite_list);
1221  
1222  #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
1223      /** Allowed TLS 1.3 key exchange modes.                                 */
1224      int MBEDTLS_PRIVATE(tls13_kex_modes);
1225  #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
1226  
1227      /** Callback for printing debug output                                  */
1228      void (*MBEDTLS_PRIVATE(f_dbg))(void *, int, const char *, int, const char *);
1229      void *MBEDTLS_PRIVATE(p_dbg);                    /*!< context for the debug function     */
1230  
1231      /** Callback for getting (pseudo-)random numbers                        */
1232      int  (*MBEDTLS_PRIVATE(f_rng))(void *, unsigned char *, size_t);
1233      void *MBEDTLS_PRIVATE(p_rng);                    /*!< context for the RNG function       */
1234  
1235      /** Callback to retrieve a session from the cache                       */
1236      mbedtls_ssl_cache_get_t *MBEDTLS_PRIVATE(f_get_cache);
1237      /** Callback to store a session into the cache                          */
1238      mbedtls_ssl_cache_set_t *MBEDTLS_PRIVATE(f_set_cache);
1239      void *MBEDTLS_PRIVATE(p_cache);                  /*!< context for cache callbacks        */
1240  
1241  #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
1242      /** Callback for setting cert according to SNI extension                */
1243      int (*MBEDTLS_PRIVATE(f_sni))(void *, mbedtls_ssl_context *, const unsigned char *, size_t);
1244      void *MBEDTLS_PRIVATE(p_sni);                    /*!< context for SNI callback           */
1245  #endif
1246  
1247  #if defined(MBEDTLS_X509_CRT_PARSE_C)
1248      /** Callback to customize X.509 certificate chain verification          */
1249      int (*MBEDTLS_PRIVATE(f_vrfy))(void *, mbedtls_x509_crt *, int, uint32_t *);
1250      void *MBEDTLS_PRIVATE(p_vrfy);                   /*!< context for X.509 verify calllback */
1251  #endif
1252  
1253  #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
1254      /** Callback to retrieve PSK key from identity                          */
1255      int (*MBEDTLS_PRIVATE(f_psk))(void *, mbedtls_ssl_context *, const unsigned char *, size_t);
1256      void *MBEDTLS_PRIVATE(p_psk);                    /*!< context for PSK callback           */
1257  #endif
1258  
1259  #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
1260      /** Callback to create & write a cookie for ClientHello veirifcation    */
1261      int (*MBEDTLS_PRIVATE(f_cookie_write))( void *, unsigned char **, unsigned char *,
1262                             const unsigned char *, size_t );
1263      /** Callback to verify validity of a ClientHello cookie                 */
1264      int (*MBEDTLS_PRIVATE(f_cookie_check))( void *, const unsigned char *, size_t,
1265                             const unsigned char *, size_t );
1266      void *MBEDTLS_PRIVATE(p_cookie);                 /*!< context for the cookie callbacks   */
1267  #endif
1268  
1269  #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_SRV_C)
1270      /** Callback to create & write a session ticket                         */
1271      int (*MBEDTLS_PRIVATE(f_ticket_write))( void *, const mbedtls_ssl_session *,
1272              unsigned char *, const unsigned char *, size_t *, uint32_t * );
1273      /** Callback to parse a session ticket into a session structure         */
1274      int (*MBEDTLS_PRIVATE(f_ticket_parse))( void *, mbedtls_ssl_session *, unsigned char *, size_t);
1275      void *MBEDTLS_PRIVATE(p_ticket);                 /*!< context for the ticket callbacks   */
1276  #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_SRV_C */
1277  
1278  #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1279      size_t MBEDTLS_PRIVATE(cid_len); /*!< The length of CIDs for incoming DTLS records.      */
1280  #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
1281  
1282  #if defined(MBEDTLS_X509_CRT_PARSE_C)
1283      const mbedtls_x509_crt_profile *MBEDTLS_PRIVATE(cert_profile); /*!< verification profile */
1284      mbedtls_ssl_key_cert *MBEDTLS_PRIVATE(key_cert); /*!< own certificate/key pair(s)        */
1285      mbedtls_x509_crt *MBEDTLS_PRIVATE(ca_chain);     /*!< trusted CAs                        */
1286      mbedtls_x509_crl *MBEDTLS_PRIVATE(ca_crl);       /*!< trusted CAs CRLs                   */
1287  #if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
1288      mbedtls_x509_crt_ca_cb_t MBEDTLS_PRIVATE(f_ca_cb);
1289      void *MBEDTLS_PRIVATE(p_ca_cb);
1290  #endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
1291  #endif /* MBEDTLS_X509_CRT_PARSE_C */
1292  
1293  #if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
1294  #if defined(MBEDTLS_X509_CRT_PARSE_C)
1295      mbedtls_ssl_async_sign_t *MBEDTLS_PRIVATE(f_async_sign_start); /*!< start asynchronous signature operation */
1296      mbedtls_ssl_async_decrypt_t *MBEDTLS_PRIVATE(f_async_decrypt_start); /*!< start asynchronous decryption operation */
1297  #endif /* MBEDTLS_X509_CRT_PARSE_C */
1298      mbedtls_ssl_async_resume_t *MBEDTLS_PRIVATE(f_async_resume); /*!< resume asynchronous operation */
1299      mbedtls_ssl_async_cancel_t *MBEDTLS_PRIVATE(f_async_cancel); /*!< cancel asynchronous operation */
1300      void *MBEDTLS_PRIVATE(p_async_config_data); /*!< Configuration data set by mbedtls_ssl_conf_async_private_cb(). */
1301  #endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
1302  
1303  #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
1304      const int *MBEDTLS_PRIVATE(sig_hashes);          /*!< allowed signature hashes           */
1305  
1306  #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
1307      const uint16_t *MBEDTLS_PRIVATE(tls13_sig_algs); /*!< allowed signature algorithms for TLS 1.3 */
1308  #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
1309  #endif
1310  
1311  #if defined(MBEDTLS_ECP_C) && !defined(MBEDTLS_DEPRECATED_REMOVED)
1312      const mbedtls_ecp_group_id *MBEDTLS_PRIVATE(curve_list); /*!< allowed curves             */
1313  #endif
1314  
1315      const uint16_t *MBEDTLS_PRIVATE(group_list);     /*!< allowed IANA NamedGroups */
1316  
1317  #if defined(MBEDTLS_DHM_C)
1318      mbedtls_mpi MBEDTLS_PRIVATE(dhm_P);              /*!< prime modulus for DHM              */
1319      mbedtls_mpi MBEDTLS_PRIVATE(dhm_G);              /*!< generator for DHM                  */
1320  #endif
1321  
1322  #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
1323  
1324  #if defined(MBEDTLS_USE_PSA_CRYPTO)
1325      psa_key_id_t MBEDTLS_PRIVATE(psk_opaque); /*!< PSA key slot holding opaque PSK. This field
1326                                *   should only be set via
1327                                *   mbedtls_ssl_conf_psk_opaque().
1328                                *   If either no PSK or a raw PSK have been
1329                                *   configured, this has value \c 0.
1330                                */
1331  #endif /* MBEDTLS_USE_PSA_CRYPTO */
1332  
1333      unsigned char *MBEDTLS_PRIVATE(psk);      /*!< The raw pre-shared key. This field should
1334                                *   only be set via mbedtls_ssl_conf_psk().
1335                                *   If either no PSK or an opaque PSK
1336                                *   have been configured, this has value NULL. */
1337      size_t         MBEDTLS_PRIVATE(psk_len);  /*!< The length of the raw pre-shared key.
1338                                *   This field should only be set via
1339                                *   mbedtls_ssl_conf_psk().
1340                                *   Its value is non-zero if and only if
1341                                *   \c psk is not \c NULL. */
1342  
1343      unsigned char *MBEDTLS_PRIVATE(psk_identity);    /*!< The PSK identity for PSK negotiation.
1344                                       *   This field should only be set via
1345                                       *   mbedtls_ssl_conf_psk().
1346                                       *   This is set if and only if either
1347                                       *   \c psk or \c psk_opaque are set. */
1348      size_t         MBEDTLS_PRIVATE(psk_identity_len);/*!< The length of PSK identity.
1349                                       *   This field should only be set via
1350                                       *   mbedtls_ssl_conf_psk().
1351                                       *   Its value is non-zero if and only if
1352                                       *   \c psk is not \c NULL or \c psk_opaque
1353                                       *   is not \c 0. */
1354  #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
1355  
1356  #if defined(MBEDTLS_SSL_ALPN)
1357      const char **MBEDTLS_PRIVATE(alpn_list);         /*!< ordered list of protocols          */
1358  #endif
1359  
1360  #if defined(MBEDTLS_SSL_DTLS_SRTP)
1361      /*! ordered list of supported srtp profile */
1362      const mbedtls_ssl_srtp_profile *MBEDTLS_PRIVATE(dtls_srtp_profile_list);
1363      /*! number of supported profiles */
1364      size_t MBEDTLS_PRIVATE(dtls_srtp_profile_list_len);
1365  #endif /* MBEDTLS_SSL_DTLS_SRTP */
1366  
1367      /*
1368       * Numerical settings (int then char)
1369       */
1370  
1371      uint32_t MBEDTLS_PRIVATE(read_timeout);          /*!< timeout for mbedtls_ssl_read (ms)  */
1372  
1373  #if defined(MBEDTLS_SSL_PROTO_DTLS)
1374      uint32_t MBEDTLS_PRIVATE(hs_timeout_min);        /*!< initial value of the handshake
1375                                           retransmission timeout (ms)        */
1376      uint32_t MBEDTLS_PRIVATE(hs_timeout_max);        /*!< maximum value of the handshake
1377                                           retransmission timeout (ms)        */
1378  #endif
1379  
1380  #if defined(MBEDTLS_SSL_RENEGOTIATION)
1381      int MBEDTLS_PRIVATE(renego_max_records);         /*!< grace period for renegotiation     */
1382      unsigned char MBEDTLS_PRIVATE(renego_period)[8]; /*!< value of the record counters
1383                                           that triggers renegotiation        */
1384  #endif
1385  
1386      unsigned int MBEDTLS_PRIVATE(badmac_limit);      /*!< limit of records with a bad MAC    */
1387  
1388  #if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_CLI_C)
1389      unsigned int MBEDTLS_PRIVATE(dhm_min_bitlen);    /*!< min. bit length of the DHM prime   */
1390  #endif
1391  
1392      unsigned char MBEDTLS_PRIVATE(max_major_ver);    /*!< max. major version used            */
1393      unsigned char MBEDTLS_PRIVATE(max_minor_ver);    /*!< max. minor version used            */
1394      unsigned char MBEDTLS_PRIVATE(min_major_ver);    /*!< min. major version used            */
1395      unsigned char MBEDTLS_PRIVATE(min_minor_ver);    /*!< min. minor version used            */
1396  
1397      /*
1398       * Flags (bitfields)
1399       */
1400  
1401      unsigned int MBEDTLS_PRIVATE(endpoint) : 1;      /*!< 0: client, 1: server               */
1402      unsigned int MBEDTLS_PRIVATE(transport) : 1;     /*!< stream (TLS) or datagram (DTLS)    */
1403      unsigned int MBEDTLS_PRIVATE(authmode) : 2;      /*!< MBEDTLS_SSL_VERIFY_XXX             */
1404      /* needed even with renego disabled for LEGACY_BREAK_HANDSHAKE          */
1405      unsigned int MBEDTLS_PRIVATE(allow_legacy_renegotiation) : 2 ; /*!< MBEDTLS_LEGACY_XXX   */
1406  #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
1407      unsigned int MBEDTLS_PRIVATE(mfl_code) : 3;      /*!< desired fragment length            */
1408  #endif
1409  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
1410      unsigned int MBEDTLS_PRIVATE(encrypt_then_mac) : 1 ; /*!< negotiate encrypt-then-mac?    */
1411  #endif
1412  #if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
1413      unsigned int MBEDTLS_PRIVATE(extended_ms) : 1;   /*!< negotiate extended master secret?  */
1414  #endif
1415  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
1416      unsigned int MBEDTLS_PRIVATE(anti_replay) : 1;   /*!< detect and prevent replay?         */
1417  #endif
1418  #if defined(MBEDTLS_SSL_RENEGOTIATION)
1419      unsigned int MBEDTLS_PRIVATE(disable_renegotiation) : 1; /*!< disable renegotiation?     */
1420  #endif
1421  #if defined(MBEDTLS_SSL_SESSION_TICKETS)
1422      unsigned int MBEDTLS_PRIVATE(session_tickets) : 1;   /*!< use session tickets?           */
1423  #endif
1424  #if defined(MBEDTLS_SSL_SRV_C)
1425      unsigned int MBEDTLS_PRIVATE(cert_req_ca_list) : 1;  /*!< enable sending CA list in
1426                                            Certificate Request messages?     */
1427      unsigned int MBEDTLS_PRIVATE(respect_cli_pref) : 1;  /*!< pick the ciphersuite according to
1428                                            the client's preferences rather
1429                                            than ours                         */
1430  #endif
1431  #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1432      unsigned int MBEDTLS_PRIVATE(ignore_unexpected_cid) : 1; /*!< Determines whether DTLS
1433                                               *   record with unexpected CID
1434                                               *   should lead to failure.    */
1435  #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
1436  #if defined(MBEDTLS_SSL_DTLS_SRTP)
1437      unsigned int MBEDTLS_PRIVATE(dtls_srtp_mki_support) : 1; /* support having mki_value
1438                                                 in the use_srtp extension     */
1439  #endif
1440  };
1441  
1442  struct mbedtls_ssl_context
1443  {
1444      const mbedtls_ssl_config *MBEDTLS_PRIVATE(conf); /*!< configuration information          */
1445  
1446      /*
1447       * Miscellaneous
1448       */
1449      int MBEDTLS_PRIVATE(state);                  /*!< SSL handshake: current state     */
1450  #if defined(MBEDTLS_SSL_RENEGOTIATION)
1451      int MBEDTLS_PRIVATE(renego_status);          /*!< Initial, in progress, pending?   */
1452      int MBEDTLS_PRIVATE(renego_records_seen);    /*!< Records since renego request, or with DTLS,
1453                                    number of retransmissions of request if
1454                                    renego_max_records is < 0           */
1455  #endif /* MBEDTLS_SSL_RENEGOTIATION */
1456  
1457      int MBEDTLS_PRIVATE(major_ver);              /*!< equal to  MBEDTLS_SSL_MAJOR_VERSION_3    */
1458  
1459      /* This field is temporarily duplicated with mbedtls_ssl_context.minor_ver.
1460       * Once runtime negotiation of TLS 1.2 and TLS 1.3 is implemented, it needs
1461       * to be studied whether one of them can be removed. */
1462      int MBEDTLS_PRIVATE(minor_ver);              /*!< one of MBEDTLS_SSL_MINOR_VERSION_x macros */
1463      unsigned MBEDTLS_PRIVATE(badmac_seen);       /*!< records with a bad MAC received    */
1464  
1465  #if defined(MBEDTLS_X509_CRT_PARSE_C)
1466      /** Callback to customize X.509 certificate chain verification          */
1467      int (*MBEDTLS_PRIVATE(f_vrfy))(void *, mbedtls_x509_crt *, int, uint32_t *);
1468      void *MBEDTLS_PRIVATE(p_vrfy);                   /*!< context for X.509 verify callback */
1469  #endif
1470  
1471      mbedtls_ssl_send_t *MBEDTLS_PRIVATE(f_send); /*!< Callback for network send */
1472      mbedtls_ssl_recv_t *MBEDTLS_PRIVATE(f_recv); /*!< Callback for network receive */
1473      mbedtls_ssl_recv_timeout_t *MBEDTLS_PRIVATE(f_recv_timeout);
1474                                  /*!< Callback for network receive with timeout */
1475  
1476      void *MBEDTLS_PRIVATE(p_bio);                /*!< context for I/O operations   */
1477  
1478      /*
1479       * Session layer
1480       */
1481      mbedtls_ssl_session *MBEDTLS_PRIVATE(session_in);            /*!<  current session data (in)   */
1482      mbedtls_ssl_session *MBEDTLS_PRIVATE(session_out);           /*!<  current session data (out)  */
1483      mbedtls_ssl_session *MBEDTLS_PRIVATE(session);               /*!<  negotiated session data     */
1484      mbedtls_ssl_session *MBEDTLS_PRIVATE(session_negotiate);     /*!<  session data in negotiation */
1485  
1486      mbedtls_ssl_handshake_params *MBEDTLS_PRIVATE(handshake);    /*!<  params required only during
1487                                                the handshake process        */
1488  
1489      /*
1490       * Record layer transformations
1491       */
1492      mbedtls_ssl_transform *MBEDTLS_PRIVATE(transform_in);        /*!<  current transform params (in)
1493                                                                    *    This is always a reference,
1494                                                                    *    never an owning pointer.        */
1495      mbedtls_ssl_transform *MBEDTLS_PRIVATE(transform_out);       /*!<  current transform params (out)
1496                                                                    *    This is always a reference,
1497                                                                    *    never an owning pointer.        */
1498      mbedtls_ssl_transform *MBEDTLS_PRIVATE(transform);           /*!<  negotiated transform params
1499                                                                    *    This pointer owns the transform
1500                                                                    *    it references.                  */
1501      mbedtls_ssl_transform *MBEDTLS_PRIVATE(transform_negotiate); /*!<  transform params in negotiation
1502                                                                    *    This pointer owns the transform
1503                                                                    *    it references.                  */
1504  
1505  #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
1506      /*! The application data transform in TLS 1.3.
1507       *  This pointer owns the transform it references. */
1508      mbedtls_ssl_transform *MBEDTLS_PRIVATE(transform_application);
1509  #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
1510  
1511      /*
1512       * Timers
1513       */
1514      void *MBEDTLS_PRIVATE(p_timer);              /*!< context for the timer callbacks */
1515  
1516      mbedtls_ssl_set_timer_t *MBEDTLS_PRIVATE(f_set_timer);       /*!< set timer callback */
1517      mbedtls_ssl_get_timer_t *MBEDTLS_PRIVATE(f_get_timer);       /*!< get timer callback */
1518  
1519      /*
1520       * Record layer (incoming data)
1521       */
1522      unsigned char *MBEDTLS_PRIVATE(in_buf);      /*!< input buffer                     */
1523      unsigned char *MBEDTLS_PRIVATE(in_ctr);      /*!< 64-bit incoming message counter
1524                                       TLS: maintained by us
1525                                       DTLS: read from peer             */
1526      unsigned char *MBEDTLS_PRIVATE(in_hdr);      /*!< start of record header           */
1527  #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1528      unsigned char *MBEDTLS_PRIVATE(in_cid);      /*!< The start of the CID;
1529                                   *   (the end is marked by in_len).   */
1530  #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
1531      unsigned char *MBEDTLS_PRIVATE(in_len);      /*!< two-bytes message length field   */
1532      unsigned char *MBEDTLS_PRIVATE(in_iv);       /*!< ivlen-byte IV                    */
1533      unsigned char *MBEDTLS_PRIVATE(in_msg);      /*!< message contents (in_iv+ivlen)   */
1534      unsigned char *MBEDTLS_PRIVATE(in_offt);     /*!< read offset in application data  */
1535  
1536      int MBEDTLS_PRIVATE(in_msgtype);             /*!< record header: message type      */
1537      size_t MBEDTLS_PRIVATE(in_msglen);           /*!< record header: message length    */
1538      size_t MBEDTLS_PRIVATE(in_left);             /*!< amount of data read so far       */
1539  #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
1540      size_t MBEDTLS_PRIVATE(in_buf_len);          /*!< length of input buffer           */
1541  #endif
1542  #if defined(MBEDTLS_SSL_PROTO_DTLS)
1543      uint16_t MBEDTLS_PRIVATE(in_epoch);          /*!< DTLS epoch for incoming records  */
1544      size_t MBEDTLS_PRIVATE(next_record_offset);  /*!< offset of the next record in datagram
1545                                       (equal to in_left if none)       */
1546  #endif /* MBEDTLS_SSL_PROTO_DTLS */
1547  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
1548      uint64_t MBEDTLS_PRIVATE(in_window_top);     /*!< last validated record seq_num    */
1549      uint64_t MBEDTLS_PRIVATE(in_window);         /*!< bitmask for replay detection     */
1550  #endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
1551  
1552      size_t MBEDTLS_PRIVATE(in_hslen);            /*!< current handshake message length,
1553                                       including the handshake header   */
1554      int MBEDTLS_PRIVATE(nb_zero);                /*!< # of 0-length encrypted messages */
1555  
1556      int MBEDTLS_PRIVATE(keep_current_message);   /*!< drop or reuse current message
1557                                       on next call to record layer? */
1558  
1559      /* The following three variables indicate if and, if yes,
1560       * what kind of alert is pending to be sent.
1561       */
1562      unsigned char MBEDTLS_PRIVATE(send_alert);   /*!< Determines if a fatal alert
1563                                                  should be sent. Values:
1564                                                  - \c 0 , no alert is to be sent.
1565                                                  - \c 1 , alert is to be sent. */
1566      unsigned char MBEDTLS_PRIVATE(alert_type);   /*!< Type of alert if send_alert
1567                                                   != 0 */
1568      int MBEDTLS_PRIVATE(alert_reason);           /*!< The error code to be returned
1569                                                   to the user once the fatal alert
1570                                                   has been sent. */
1571  
1572  #if defined(MBEDTLS_SSL_PROTO_DTLS)
1573      uint8_t MBEDTLS_PRIVATE(disable_datagram_packing);  /*!< Disable packing multiple records
1574                                          *   within a single datagram.  */
1575  #endif /* MBEDTLS_SSL_PROTO_DTLS */
1576  
1577      /*
1578       * Record layer (outgoing data)
1579       */
1580      unsigned char *MBEDTLS_PRIVATE(out_buf);     /*!< output buffer                    */
1581      unsigned char *MBEDTLS_PRIVATE(out_ctr);     /*!< 64-bit outgoing message counter  */
1582      unsigned char *MBEDTLS_PRIVATE(out_hdr);     /*!< start of record header           */
1583  #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1584      unsigned char *MBEDTLS_PRIVATE(out_cid);     /*!< The start of the CID;
1585                                   *   (the end is marked by in_len).   */
1586  #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
1587      unsigned char *MBEDTLS_PRIVATE(out_len);     /*!< two-bytes message length field   */
1588      unsigned char *MBEDTLS_PRIVATE(out_iv);      /*!< ivlen-byte IV                    */
1589      unsigned char *MBEDTLS_PRIVATE(out_msg);     /*!< message contents (out_iv+ivlen)  */
1590  
1591      int MBEDTLS_PRIVATE(out_msgtype);            /*!< record header: message type      */
1592      size_t MBEDTLS_PRIVATE(out_msglen);          /*!< record header: message length    */
1593      size_t MBEDTLS_PRIVATE(out_left);            /*!< amount of data not yet written   */
1594  #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
1595      size_t MBEDTLS_PRIVATE(out_buf_len);         /*!< length of output buffer          */
1596  #endif
1597  
1598      unsigned char MBEDTLS_PRIVATE(cur_out_ctr)[MBEDTLS_SSL_SEQUENCE_NUMBER_LEN]; /*!<  Outgoing record sequence  number. */
1599  
1600  #if defined(MBEDTLS_SSL_PROTO_DTLS)
1601      uint16_t MBEDTLS_PRIVATE(mtu);               /*!< path mtu, used to fragment outgoing messages */
1602  #endif /* MBEDTLS_SSL_PROTO_DTLS */
1603  
1604      /*
1605       * PKI layer
1606       */
1607      int MBEDTLS_PRIVATE(client_auth);                    /*!<  flag for client auth.   */
1608  
1609      /*
1610       * User settings
1611       */
1612  #if defined(MBEDTLS_X509_CRT_PARSE_C)
1613      char *MBEDTLS_PRIVATE(hostname);             /*!< expected peer CN for verification
1614                                       (and SNI if available)                 */
1615  #endif /* MBEDTLS_X509_CRT_PARSE_C */
1616  
1617  #if defined(MBEDTLS_SSL_ALPN)
1618      const char *MBEDTLS_PRIVATE(alpn_chosen);    /*!<  negotiated protocol                   */
1619  #endif /* MBEDTLS_SSL_ALPN */
1620  
1621  #if defined(MBEDTLS_SSL_DTLS_SRTP)
1622      /*
1623       * use_srtp extension
1624       */
1625      mbedtls_dtls_srtp_info MBEDTLS_PRIVATE(dtls_srtp_info);
1626  #endif /* MBEDTLS_SSL_DTLS_SRTP */
1627  
1628      /*
1629       * Information for DTLS hello verify
1630       */
1631  #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
1632      unsigned char  *MBEDTLS_PRIVATE(cli_id);         /*!<  transport-level ID of the client  */
1633      size_t          MBEDTLS_PRIVATE(cli_id_len);     /*!<  length of cli_id                  */
1634  #endif /* MBEDTLS_SSL_DTLS_HELLO_VERIFY && MBEDTLS_SSL_SRV_C */
1635  
1636      /*
1637       * Secure renegotiation
1638       */
1639      /* needed to know when to send extension on server */
1640      int MBEDTLS_PRIVATE(secure_renegotiation);           /*!<  does peer support legacy or
1641                                                secure renegotiation           */
1642  #if defined(MBEDTLS_SSL_RENEGOTIATION)
1643      size_t MBEDTLS_PRIVATE(verify_data_len);             /*!<  length of verify data stored   */
1644      char MBEDTLS_PRIVATE(own_verify_data)[MBEDTLS_SSL_VERIFY_DATA_MAX_LEN]; /*!<  previous handshake verify data */
1645      char MBEDTLS_PRIVATE(peer_verify_data)[MBEDTLS_SSL_VERIFY_DATA_MAX_LEN]; /*!<  previous handshake verify data */
1646  #endif /* MBEDTLS_SSL_RENEGOTIATION */
1647  
1648  #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1649      /* CID configuration to use in subsequent handshakes. */
1650  
1651      /*! The next incoming CID, chosen by the user and applying to
1652       *  all subsequent handshakes. This may be different from the
1653       *  CID currently used in case the user has re-configured the CID
1654       *  after an initial handshake. */
1655      unsigned char MBEDTLS_PRIVATE(own_cid)[ MBEDTLS_SSL_CID_IN_LEN_MAX ];
1656      uint8_t MBEDTLS_PRIVATE(own_cid_len);   /*!< The length of \c own_cid. */
1657      uint8_t MBEDTLS_PRIVATE(negotiate_cid); /*!< This indicates whether the CID extension should
1658                              *   be negotiated in the next handshake or not.
1659                              *   Possible values are #MBEDTLS_SSL_CID_ENABLED
1660                              *   and #MBEDTLS_SSL_CID_DISABLED. */
1661  #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
1662  
1663      /** Callback to export key block and master secret                      */
1664      mbedtls_ssl_export_keys_t *MBEDTLS_PRIVATE(f_export_keys);
1665      void *MBEDTLS_PRIVATE(p_export_keys);            /*!< context for key export callback    */
1666  };
1667  
1668  /**
1669   * \brief               Return the name of the ciphersuite associated with the
1670   *                      given ID
1671   *
1672   * \param ciphersuite_id SSL ciphersuite ID
1673   *
1674   * \return              a string containing the ciphersuite name
1675   */
1676  const char *mbedtls_ssl_get_ciphersuite_name( const int ciphersuite_id );
1677  
1678  /**
1679   * \brief               Return the ID of the ciphersuite associated with the
1680   *                      given name
1681   *
1682   * \param ciphersuite_name SSL ciphersuite name
1683   *
1684   * \return              the ID with the ciphersuite or 0 if not found
1685   */
1686  int mbedtls_ssl_get_ciphersuite_id( const char *ciphersuite_name );
1687  
1688  /**
1689   * \brief          Initialize an SSL context
1690   *                 Just makes the context ready for mbedtls_ssl_setup() or
1691   *                 mbedtls_ssl_free()
1692   *
1693   * \param ssl      SSL context
1694   */
1695  void mbedtls_ssl_init( mbedtls_ssl_context *ssl );
1696  
1697  /**
1698   * \brief          Set up an SSL context for use
1699   *
1700   * \note           No copy of the configuration context is made, it can be
1701   *                 shared by many mbedtls_ssl_context structures.
1702   *
1703   * \warning        The conf structure will be accessed during the session.
1704   *                 It must not be modified or freed as long as the session
1705   *                 is active.
1706   *
1707   * \warning        This function must be called exactly once per context.
1708   *                 Calling mbedtls_ssl_setup again is not supported, even
1709   *                 if no session is active.
1710   *
1711   * \param ssl      SSL context
1712   * \param conf     SSL configuration to use
1713   *
1714   * \return         0 if successful, or MBEDTLS_ERR_SSL_ALLOC_FAILED if
1715   *                 memory allocation failed
1716   */
1717  int mbedtls_ssl_setup( mbedtls_ssl_context *ssl,
1718                         const mbedtls_ssl_config *conf );
1719  
1720  /**
1721   * \brief          Reset an already initialized SSL context for re-use
1722   *                 while retaining application-set variables, function
1723   *                 pointers and data.
1724   *
1725   * \param ssl      SSL context
1726   * \return         0 if successful, or MBEDTLS_ERR_SSL_ALLOC_FAILED or
1727                     MBEDTLS_ERR_SSL_HW_ACCEL_FAILED
1728   */
1729  int mbedtls_ssl_session_reset( mbedtls_ssl_context *ssl );
1730  
1731  /**
1732   * \brief          Set the current endpoint type
1733   *
1734   * \param conf     SSL configuration
1735   * \param endpoint must be MBEDTLS_SSL_IS_CLIENT or MBEDTLS_SSL_IS_SERVER
1736   */
1737  void mbedtls_ssl_conf_endpoint( mbedtls_ssl_config *conf, int endpoint );
1738  
1739  /**
1740   * \brief           Set the transport type (TLS or DTLS).
1741   *                  Default: TLS
1742   *
1743   * \note            For DTLS, you must either provide a recv callback that
1744   *                  doesn't block, or one that handles timeouts, see
1745   *                  \c mbedtls_ssl_set_bio(). You also need to provide timer
1746   *                  callbacks with \c mbedtls_ssl_set_timer_cb().
1747   *
1748   * \param conf      SSL configuration
1749   * \param transport transport type:
1750   *                  MBEDTLS_SSL_TRANSPORT_STREAM for TLS,
1751   *                  MBEDTLS_SSL_TRANSPORT_DATAGRAM for DTLS.
1752   */
1753  void mbedtls_ssl_conf_transport( mbedtls_ssl_config *conf, int transport );
1754  
1755  /**
1756   * \brief          Set the certificate verification mode
1757   *                 Default: NONE on server, REQUIRED on client
1758   *
1759   * \param conf     SSL configuration
1760   * \param authmode can be:
1761   *
1762   *  MBEDTLS_SSL_VERIFY_NONE:      peer certificate is not checked
1763   *                        (default on server)
1764   *                        (insecure on client)
1765   *
1766   *  MBEDTLS_SSL_VERIFY_OPTIONAL:  peer certificate is checked, however the
1767   *                        handshake continues even if verification failed;
1768   *                        mbedtls_ssl_get_verify_result() can be called after the
1769   *                        handshake is complete.
1770   *
1771   *  MBEDTLS_SSL_VERIFY_REQUIRED:  peer *must* present a valid certificate,
1772   *                        handshake is aborted if verification failed.
1773   *                        (default on client)
1774   *
1775   * \note On client, MBEDTLS_SSL_VERIFY_REQUIRED is the recommended mode.
1776   * With MBEDTLS_SSL_VERIFY_OPTIONAL, the user needs to call mbedtls_ssl_get_verify_result() at
1777   * the right time(s), which may not be obvious, while REQUIRED always perform
1778   * the verification as soon as possible. For example, REQUIRED was protecting
1779   * against the "triple handshake" attack even before it was found.
1780   */
1781  void mbedtls_ssl_conf_authmode( mbedtls_ssl_config *conf, int authmode );
1782  
1783  #if defined(MBEDTLS_X509_CRT_PARSE_C)
1784  /**
1785   * \brief          Set the verification callback (Optional).
1786   *
1787   *                 If set, the provided verify callback is called for each
1788   *                 certificate in the peer's CRT chain, including the trusted
1789   *                 root. For more information, please see the documentation of
1790   *                 \c mbedtls_x509_crt_verify().
1791   *
1792   * \note           For per context callbacks and contexts, please use
1793   *                 mbedtls_ssl_set_verify() instead.
1794   *
1795   * \param conf     The SSL configuration to use.
1796   * \param f_vrfy   The verification callback to use during CRT verification.
1797   * \param p_vrfy   The opaque context to be passed to the callback.
1798   */
1799  void mbedtls_ssl_conf_verify( mbedtls_ssl_config *conf,
1800                       int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
1801                       void *p_vrfy );
1802  #endif /* MBEDTLS_X509_CRT_PARSE_C */
1803  
1804  /**
1805   * \brief          Set the random number generator callback
1806   *
1807   * \param conf     SSL configuration
1808   * \param f_rng    RNG function (mandatory)
1809   * \param p_rng    RNG parameter
1810   */
1811  void mbedtls_ssl_conf_rng( mbedtls_ssl_config *conf,
1812                    int (*f_rng)(void *, unsigned char *, size_t),
1813                    void *p_rng );
1814  
1815  /**
1816   * \brief          Set the debug callback
1817   *
1818   *                 The callback has the following argument:
1819   *                 void *           opaque context for the callback
1820   *                 int              debug level
1821   *                 const char *     file name
1822   *                 int              line number
1823   *                 const char *     message
1824   *
1825   * \param conf     SSL configuration
1826   * \param f_dbg    debug function
1827   * \param p_dbg    debug parameter
1828   */
1829  void mbedtls_ssl_conf_dbg( mbedtls_ssl_config *conf,
1830                    void (*f_dbg)(void *, int, const char *, int, const char *),
1831                    void  *p_dbg );
1832  
1833  /**
1834   * \brief          Set the underlying BIO callbacks for write, read and
1835   *                 read-with-timeout.
1836   *
1837   * \param ssl      SSL context
1838   * \param p_bio    parameter (context) shared by BIO callbacks
1839   * \param f_send   write callback
1840   * \param f_recv   read callback
1841   * \param f_recv_timeout blocking read callback with timeout.
1842   *
1843   * \note           One of f_recv or f_recv_timeout can be NULL, in which case
1844   *                 the other is used. If both are non-NULL, f_recv_timeout is
1845   *                 used and f_recv is ignored (as if it were NULL).
1846   *
1847   * \note           The two most common use cases are:
1848   *                 - non-blocking I/O, f_recv != NULL, f_recv_timeout == NULL
1849   *                 - blocking I/O, f_recv == NULL, f_recv_timout != NULL
1850   *
1851   * \note           For DTLS, you need to provide either a non-NULL
1852   *                 f_recv_timeout callback, or a f_recv that doesn't block.
1853   *
1854   * \note           See the documentations of \c mbedtls_ssl_send_t,
1855   *                 \c mbedtls_ssl_recv_t and \c mbedtls_ssl_recv_timeout_t for
1856   *                 the conventions those callbacks must follow.
1857   *
1858   * \note           On some platforms, net_sockets.c provides
1859   *                 \c mbedtls_net_send(), \c mbedtls_net_recv() and
1860   *                 \c mbedtls_net_recv_timeout() that are suitable to be used
1861   *                 here.
1862   */
1863  void mbedtls_ssl_set_bio( mbedtls_ssl_context *ssl,
1864                            void *p_bio,
1865                            mbedtls_ssl_send_t *f_send,
1866                            mbedtls_ssl_recv_t *f_recv,
1867                            mbedtls_ssl_recv_timeout_t *f_recv_timeout );
1868  
1869  #if defined(MBEDTLS_SSL_PROTO_DTLS)
1870  
1871  #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
1872  
1873  
1874  /**
1875   * \brief             Configure the use of the Connection ID (CID)
1876   *                    extension in the next handshake.
1877   *
1878   *                    Reference: draft-ietf-tls-dtls-connection-id-05
1879   *                    https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05
1880   *
1881   *                    The DTLS CID extension allows the reliable association of
1882   *                    DTLS records to DTLS connections across changes in the
1883   *                    underlying transport (changed IP and Port metadata) by
1884   *                    adding explicit connection identifiers (CIDs) to the
1885   *                    headers of encrypted DTLS records. The desired CIDs are
1886   *                    configured by the application layer and are exchanged in
1887   *                    new `ClientHello` / `ServerHello` extensions during the
1888   *                    handshake, where each side indicates the CID it wants the
1889   *                    peer to use when writing encrypted messages. The CIDs are
1890   *                    put to use once records get encrypted: the stack discards
1891   *                    any incoming records that don't include the configured CID
1892   *                    in their header, and adds the peer's requested CID to the
1893   *                    headers of outgoing messages.
1894   *
1895   *                    This API enables or disables the use of the CID extension
1896   *                    in the next handshake and sets the value of the CID to
1897   *                    be used for incoming messages.
1898   *
1899   * \param ssl         The SSL context to configure. This must be initialized.
1900   * \param enable      This value determines whether the CID extension should
1901   *                    be used or not. Possible values are:
1902   *                    - MBEDTLS_SSL_CID_ENABLED to enable the use of the CID.
1903   *                    - MBEDTLS_SSL_CID_DISABLED (default) to disable the use
1904   *                      of the CID.
1905   * \param own_cid     The address of the readable buffer holding the CID we want
1906   *                    the peer to use when sending encrypted messages to us.
1907   *                    This may be \c NULL if \p own_cid_len is \c 0.
1908   *                    This parameter is unused if \p enabled is set to
1909   *                    MBEDTLS_SSL_CID_DISABLED.
1910   * \param own_cid_len The length of \p own_cid.
1911   *                    This parameter is unused if \p enabled is set to
1912   *                    MBEDTLS_SSL_CID_DISABLED.
1913   *
1914   * \note              The value of \p own_cid_len must match the value of the
1915   *                    \c len parameter passed to mbedtls_ssl_conf_cid()
1916   *                    when configuring the ::mbedtls_ssl_config that \p ssl
1917   *                    is bound to.
1918   *
1919   * \note              This CID configuration applies to subsequent handshakes
1920   *                    performed on the SSL context \p ssl, but does not trigger
1921   *                    one. You still have to call `mbedtls_ssl_handshake()`
1922   *                    (for the initial handshake) or `mbedtls_ssl_renegotiate()`
1923   *                    (for a renegotiation handshake) explicitly after a
1924   *                    successful call to this function to run the handshake.
1925   *
1926   * \note              This call cannot guarantee that the use of the CID
1927   *                    will be successfully negotiated in the next handshake,
1928   *                    because the peer might not support it. Specifically:
1929   *                    - On the Client, enabling the use of the CID through
1930   *                      this call implies that the `ClientHello` in the next
1931   *                      handshake will include the CID extension, thereby
1932   *                      offering the use of the CID to the server. Only if
1933   *                      the `ServerHello` contains the CID extension, too,
1934   *                      the CID extension will actually be put to use.
1935   *                    - On the Server, enabling the use of the CID through
1936   *                      this call implies that that the server will look for
1937   *                      the CID extension in a `ClientHello` from the client,
1938   *                      and, if present, reply with a CID extension in its
1939   *                      `ServerHello`.
1940   *
1941   * \note              To check whether the use of the CID was negotiated
1942   *                    after the subsequent handshake has completed, please
1943   *                    use the API mbedtls_ssl_get_peer_cid().
1944   *
1945   * \warning           If the use of the CID extension is enabled in this call
1946   *                    and the subsequent handshake negotiates its use, Mbed TLS
1947   *                    will silently drop every packet whose CID does not match
1948   *                    the CID configured in \p own_cid. It is the responsibility
1949   *                    of the user to adapt the underlying transport to take care
1950   *                    of CID-based demultiplexing before handing datagrams to
1951   *                    Mbed TLS.
1952   *
1953   * \return            \c 0 on success. In this case, the CID configuration
1954   *                    applies to the next handshake.
1955   * \return            A negative error code on failure.
1956   */
1957  int mbedtls_ssl_set_cid( mbedtls_ssl_context *ssl,
1958                           int enable,
1959                           unsigned char const *own_cid,
1960                           size_t own_cid_len );
1961  
1962  /**
1963   * \brief              Get information about the use of the CID extension
1964   *                     in the current connection.
1965   *
1966   * \param ssl          The SSL context to query.
1967   * \param enabled      The address at which to store whether the CID extension
1968   *                     is currently in use or not. If the CID is in use,
1969   *                     `*enabled` is set to MBEDTLS_SSL_CID_ENABLED;
1970   *                     otherwise, it is set to MBEDTLS_SSL_CID_DISABLED.
1971   * \param peer_cid     The address of the buffer in which to store the CID
1972   *                     chosen by the peer (if the CID extension is used).
1973   *                     This may be \c NULL in case the value of peer CID
1974   *                     isn't needed. If it is not \c NULL, \p peer_cid_len
1975   *                     must not be \c NULL.
1976   * \param peer_cid_len The address at which to store the size of the CID
1977   *                     chosen by the peer (if the CID extension is used).
1978   *                     This is also the number of Bytes in \p peer_cid that
1979   *                     have been written.
1980   *                     This may be \c NULL in case the length of the peer CID
1981   *                     isn't needed. If it is \c NULL, \p peer_cid must be
1982   *                     \c NULL, too.
1983   *
1984   * \note               This applies to the state of the CID negotiated in
1985   *                     the last complete handshake. If a handshake is in
1986   *                     progress, this function will attempt to complete
1987   *                     the handshake first.
1988   *
1989   * \note               If CID extensions have been exchanged but both client
1990   *                     and server chose to use an empty CID, this function
1991   *                     sets `*enabled` to #MBEDTLS_SSL_CID_DISABLED
1992   *                     (the rationale for this is that the resulting
1993   *                     communication is the same as if the CID extensions
1994   *                     hadn't been used).
1995   *
1996   * \return            \c 0 on success.
1997   * \return            A negative error code on failure.
1998   */
1999  int mbedtls_ssl_get_peer_cid( mbedtls_ssl_context *ssl,
2000                       int *enabled,
2001                       unsigned char peer_cid[ MBEDTLS_SSL_CID_OUT_LEN_MAX ],
2002                       size_t *peer_cid_len );
2003  
2004  #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
2005  
2006  /**
2007   * \brief          Set the Maximum Tranport Unit (MTU).
2008   *                 Special value: 0 means unset (no limit).
2009   *                 This represents the maximum size of a datagram payload
2010   *                 handled by the transport layer (usually UDP) as determined
2011   *                 by the network link and stack. In practice, this controls
2012   *                 the maximum size datagram the DTLS layer will pass to the
2013   *                 \c f_send() callback set using \c mbedtls_ssl_set_bio().
2014   *
2015   * \note           The limit on datagram size is converted to a limit on
2016   *                 record payload by subtracting the current overhead of
2017   *                 encapsulation and encryption/authentication if any.
2018   *
2019   * \note           This can be called at any point during the connection, for
2020   *                 example when a Path Maximum Transfer Unit (PMTU)
2021   *                 estimate becomes available from other sources,
2022   *                 such as lower (or higher) protocol layers.
2023   *
2024   * \note           This setting only controls the size of the packets we send,
2025   *                 and does not restrict the size of the datagrams we're
2026   *                 willing to receive. Client-side, you can request the
2027   *                 server to use smaller records with \c
2028   *                 mbedtls_ssl_conf_max_frag_len().
2029   *
2030   * \note           If both a MTU and a maximum fragment length have been
2031   *                 configured (or negotiated with the peer), the resulting
2032   *                 lower limit on record payload (see first note) is used.
2033   *
2034   * \note           This can only be used to decrease the maximum size
2035   *                 of datagrams (hence records, see first note) sent. It
2036   *                 cannot be used to increase the maximum size of records over
2037   *                 the limit set by #MBEDTLS_SSL_OUT_CONTENT_LEN.
2038   *
2039   * \note           Values lower than the current record layer expansion will
2040   *                 result in an error when trying to send data.
2041   *
2042   * \param ssl      SSL context
2043   * \param mtu      Value of the path MTU in bytes
2044   */
2045  void mbedtls_ssl_set_mtu( mbedtls_ssl_context *ssl, uint16_t mtu );
2046  #endif /* MBEDTLS_SSL_PROTO_DTLS */
2047  
2048  #if defined(MBEDTLS_X509_CRT_PARSE_C)
2049  /**
2050   * \brief          Set a connection-specific verification callback (optional).
2051   *
2052   *                 If set, the provided verify callback is called for each
2053   *                 certificate in the peer's CRT chain, including the trusted
2054   *                 root. For more information, please see the documentation of
2055   *                 \c mbedtls_x509_crt_verify().
2056   *
2057   * \note           This call is analogous to mbedtls_ssl_conf_verify() but
2058   *                 binds the verification callback and context to an SSL context
2059   *                 as opposed to an SSL configuration.
2060   *                 If mbedtls_ssl_conf_verify() and mbedtls_ssl_set_verify()
2061   *                 are both used, mbedtls_ssl_set_verify() takes precedence.
2062   *
2063   * \param ssl      The SSL context to use.
2064   * \param f_vrfy   The verification callback to use during CRT verification.
2065   * \param p_vrfy   The opaque context to be passed to the callback.
2066   */
2067  void mbedtls_ssl_set_verify( mbedtls_ssl_context *ssl,
2068                       int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
2069                       void *p_vrfy );
2070  #endif /* MBEDTLS_X509_CRT_PARSE_C */
2071  
2072  /**
2073   * \brief          Set the timeout period for mbedtls_ssl_read()
2074   *                 (Default: no timeout.)
2075   *
2076   * \param conf     SSL configuration context
2077   * \param timeout  Timeout value in milliseconds.
2078   *                 Use 0 for no timeout (default).
2079   *
2080   * \note           With blocking I/O, this will only work if a non-NULL
2081   *                 \c f_recv_timeout was set with \c mbedtls_ssl_set_bio().
2082   *                 With non-blocking I/O, this will only work if timer
2083   *                 callbacks were set with \c mbedtls_ssl_set_timer_cb().
2084   *
2085   * \note           With non-blocking I/O, you may also skip this function
2086   *                 altogether and handle timeouts at the application layer.
2087   */
2088  void mbedtls_ssl_conf_read_timeout( mbedtls_ssl_config *conf, uint32_t timeout );
2089  
2090  /**
2091   * \brief          Check whether a buffer contains a valid and authentic record
2092   *                 that has not been seen before. (DTLS only).
2093   *
2094   *                 This function does not change the user-visible state
2095   *                 of the SSL context. Its sole purpose is to provide
2096   *                 an indication of the legitimacy of an incoming record.
2097   *
2098   *                 This can be useful e.g. in distributed server environments
2099   *                 using the DTLS Connection ID feature, in which connections
2100   *                 might need to be passed between service instances on a change
2101   *                 of peer address, but where such disruptive operations should
2102   *                 only happen after the validity of incoming records has been
2103   *                 confirmed.
2104   *
2105   * \param ssl      The SSL context to use.
2106   * \param buf      The address of the buffer holding the record to be checked.
2107   *                 This must be a read/write buffer of length \p buflen Bytes.
2108   * \param buflen   The length of \p buf in Bytes.
2109   *
2110   * \note           This routine only checks whether the provided buffer begins
2111   *                 with a valid and authentic record that has not been seen
2112   *                 before, but does not check potential data following the
2113   *                 initial record. In particular, it is possible to pass DTLS
2114   *                 datagrams containing multiple records, in which case only
2115   *                 the first record is checked.
2116   *
2117   * \note           This function modifies the input buffer \p buf. If you need
2118   *                 to preserve the original record, you have to maintain a copy.
2119   *
2120   * \return         \c 0 if the record is valid and authentic and has not been
2121   *                 seen before.
2122   * \return         MBEDTLS_ERR_SSL_INVALID_MAC if the check completed
2123   *                 successfully but the record was found to be not authentic.
2124   * \return         MBEDTLS_ERR_SSL_INVALID_RECORD if the check completed
2125   *                 successfully but the record was found to be invalid for
2126   *                 a reason different from authenticity checking.
2127   * \return         MBEDTLS_ERR_SSL_UNEXPECTED_RECORD if the check completed
2128   *                 successfully but the record was found to be unexpected
2129   *                 in the state of the SSL context, including replayed records.
2130   * \return         Another negative error code on different kinds of failure.
2131   *                 In this case, the SSL context becomes unusable and needs
2132   *                 to be freed or reset before reuse.
2133   */
2134  int mbedtls_ssl_check_record( mbedtls_ssl_context const *ssl,
2135                                unsigned char *buf,
2136                                size_t buflen );
2137  
2138  /**
2139   * \brief          Set the timer callbacks (Mandatory for DTLS.)
2140   *
2141   * \param ssl      SSL context
2142   * \param p_timer  parameter (context) shared by timer callbacks
2143   * \param f_set_timer   set timer callback
2144   * \param f_get_timer   get timer callback. Must return:
2145   *
2146   * \note           See the documentation of \c mbedtls_ssl_set_timer_t and
2147   *                 \c mbedtls_ssl_get_timer_t for the conventions this pair of
2148   *                 callbacks must follow.
2149   *
2150   * \note           On some platforms, timing.c provides
2151   *                 \c mbedtls_timing_set_delay() and
2152   *                 \c mbedtls_timing_get_delay() that are suitable for using
2153   *                 here, except if using an event-driven style.
2154   *
2155   * \note           See also the "DTLS tutorial" article in our knowledge base.
2156   *                 https://tls.mbed.org/kb/how-to/dtls-tutorial
2157   */
2158  void mbedtls_ssl_set_timer_cb( mbedtls_ssl_context *ssl,
2159                                 void *p_timer,
2160                                 mbedtls_ssl_set_timer_t *f_set_timer,
2161                                 mbedtls_ssl_get_timer_t *f_get_timer );
2162  
2163  /**
2164   * \brief           Callback type: generate and write session ticket
2165   *
2166   * \note            This describes what a callback implementation should do.
2167   *                  This callback should generate an encrypted and
2168   *                  authenticated ticket for the session and write it to the
2169   *                  output buffer. Here, ticket means the opaque ticket part
2170   *                  of the NewSessionTicket structure of RFC 5077.
2171   *
2172   * \param p_ticket  Context for the callback
2173   * \param session   SSL session to be written in the ticket
2174   * \param start     Start of the output buffer
2175   * \param end       End of the output buffer
2176   * \param tlen      On exit, holds the length written
2177   * \param lifetime  On exit, holds the lifetime of the ticket in seconds
2178   *
2179   * \return          0 if successful, or
2180   *                  a specific MBEDTLS_ERR_XXX code.
2181   */
2182  typedef int mbedtls_ssl_ticket_write_t( void *p_ticket,
2183                                          const mbedtls_ssl_session *session,
2184                                          unsigned char *start,
2185                                          const unsigned char *end,
2186                                          size_t *tlen,
2187                                          uint32_t *lifetime );
2188  
2189  /**
2190   * \brief           Callback type: parse and load session ticket
2191   *
2192   * \note            This describes what a callback implementation should do.
2193   *                  This callback should parse a session ticket as generated
2194   *                  by the corresponding mbedtls_ssl_ticket_write_t function,
2195   *                  and, if the ticket is authentic and valid, load the
2196   *                  session.
2197   *
2198   * \note            The implementation is allowed to modify the first len
2199   *                  bytes of the input buffer, eg to use it as a temporary
2200   *                  area for the decrypted ticket contents.
2201   *
2202   * \param p_ticket  Context for the callback
2203   * \param session   SSL session to be loaded
2204   * \param buf       Start of the buffer containing the ticket
2205   * \param len       Length of the ticket.
2206   *
2207   * \return          0 if successful, or
2208   *                  MBEDTLS_ERR_SSL_INVALID_MAC if not authentic, or
2209   *                  MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED if expired, or
2210   *                  any other non-zero code for other failures.
2211   */
2212  typedef int mbedtls_ssl_ticket_parse_t( void *p_ticket,
2213                                          mbedtls_ssl_session *session,
2214                                          unsigned char *buf,
2215                                          size_t len );
2216  
2217  #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_SRV_C)
2218  /**
2219   * \brief           Configure SSL session ticket callbacks (server only).
2220   *                  (Default: none.)
2221   *
2222   * \note            On server, session tickets are enabled by providing
2223   *                  non-NULL callbacks.
2224   *
2225   * \note            On client, use \c mbedtls_ssl_conf_session_tickets().
2226   *
2227   * \param conf      SSL configuration context
2228   * \param f_ticket_write    Callback for writing a ticket
2229   * \param f_ticket_parse    Callback for parsing a ticket
2230   * \param p_ticket          Context shared by the two callbacks
2231   */
2232  void mbedtls_ssl_conf_session_tickets_cb( mbedtls_ssl_config *conf,
2233          mbedtls_ssl_ticket_write_t *f_ticket_write,
2234          mbedtls_ssl_ticket_parse_t *f_ticket_parse,
2235          void *p_ticket );
2236  #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_SRV_C */
2237  
2238  /**
2239   * \brief   Configure a key export callback.
2240   *          (Default: none.)
2241   *
2242   *          This API can be used for two purposes:
2243   *          - Debugging: Use this API to e.g. generate an NSSKeylog
2244   *            file and use it to inspect encrypted traffic in tools
2245   *            such as Wireshark.
2246   *          - Application-specific export: Use this API to implement
2247   *            key exporters, e.g. for EAP-TLS or DTLS-SRTP.
2248   *
2249   *
2250   * \param ssl            The SSL context to which the export
2251   *                       callback should be attached.
2252   * \param f_export_keys  The callback for the key export.
2253   * \param p_export_keys  The opaque context pointer to be passed to the
2254   *                       callback \p f_export_keys.
2255   */
2256  void mbedtls_ssl_set_export_keys_cb( mbedtls_ssl_context *ssl,
2257                                       mbedtls_ssl_export_keys_t *f_export_keys,
2258                                       void *p_export_keys );
2259  
2260  #if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
2261  /**
2262   * \brief           Configure asynchronous private key operation callbacks.
2263   *
2264   * \param conf              SSL configuration context
2265   * \param f_async_sign      Callback to start a signature operation. See
2266   *                          the description of ::mbedtls_ssl_async_sign_t
2267   *                          for more information. This may be \c NULL if the
2268   *                          external processor does not support any signature
2269   *                          operation; in this case the private key object
2270   *                          associated with the certificate will be used.
2271   * \param f_async_decrypt   Callback to start a decryption operation. See
2272   *                          the description of ::mbedtls_ssl_async_decrypt_t
2273   *                          for more information. This may be \c NULL if the
2274   *                          external processor does not support any decryption
2275   *                          operation; in this case the private key object
2276   *                          associated with the certificate will be used.
2277   * \param f_async_resume    Callback to resume an asynchronous operation. See
2278   *                          the description of ::mbedtls_ssl_async_resume_t
2279   *                          for more information. This may not be \c NULL unless
2280   *                          \p f_async_sign and \p f_async_decrypt are both
2281   *                          \c NULL.
2282   * \param f_async_cancel    Callback to cancel an asynchronous operation. See
2283   *                          the description of ::mbedtls_ssl_async_cancel_t
2284   *                          for more information. This may be \c NULL if
2285   *                          no cleanup is needed.
2286   * \param config_data       A pointer to configuration data which can be
2287   *                          retrieved with
2288   *                          mbedtls_ssl_conf_get_async_config_data(). The
2289   *                          library stores this value without dereferencing it.
2290   */
2291  void mbedtls_ssl_conf_async_private_cb( mbedtls_ssl_config *conf,
2292                                          mbedtls_ssl_async_sign_t *f_async_sign,
2293                                          mbedtls_ssl_async_decrypt_t *f_async_decrypt,
2294                                          mbedtls_ssl_async_resume_t *f_async_resume,
2295                                          mbedtls_ssl_async_cancel_t *f_async_cancel,
2296                                          void *config_data );
2297  
2298  /**
2299   * \brief           Retrieve the configuration data set by
2300   *                  mbedtls_ssl_conf_async_private_cb().
2301   *
2302   * \param conf      SSL configuration context
2303   * \return          The configuration data set by
2304   *                  mbedtls_ssl_conf_async_private_cb().
2305   */
2306  void *mbedtls_ssl_conf_get_async_config_data( const mbedtls_ssl_config *conf );
2307  
2308  /**
2309   * \brief           Retrieve the asynchronous operation user context.
2310   *
2311   * \note            This function may only be called while a handshake
2312   *                  is in progress.
2313   *
2314   * \param ssl       The SSL context to access.
2315   *
2316   * \return          The asynchronous operation user context that was last
2317   *                  set during the current handshake. If
2318   *                  mbedtls_ssl_set_async_operation_data() has not yet been
2319   *                  called during the current handshake, this function returns
2320   *                  \c NULL.
2321   */
2322  void *mbedtls_ssl_get_async_operation_data( const mbedtls_ssl_context *ssl );
2323  
2324  /**
2325   * \brief           Retrieve the asynchronous operation user context.
2326   *
2327   * \note            This function may only be called while a handshake
2328   *                  is in progress.
2329   *
2330   * \param ssl       The SSL context to access.
2331   * \param ctx       The new value of the asynchronous operation user context.
2332   *                  Call mbedtls_ssl_get_async_operation_data() later during the
2333   *                  same handshake to retrieve this value.
2334   */
2335  void mbedtls_ssl_set_async_operation_data( mbedtls_ssl_context *ssl,
2336                                   void *ctx );
2337  #endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
2338  
2339  /**
2340   * \brief          Callback type: generate a cookie
2341   *
2342   * \param ctx      Context for the callback
2343   * \param p        Buffer to write to,
2344   *                 must be updated to point right after the cookie
2345   * \param end      Pointer to one past the end of the output buffer
2346   * \param info     Client ID info that was passed to
2347   *                 \c mbedtls_ssl_set_client_transport_id()
2348   * \param ilen     Length of info in bytes
2349   *
2350   * \return         The callback must return 0 on success,
2351   *                 or a negative error code.
2352   */
2353  typedef int mbedtls_ssl_cookie_write_t( void *ctx,
2354                                  unsigned char **p, unsigned char *end,
2355                                  const unsigned char *info, size_t ilen );
2356  
2357  /**
2358   * \brief          Callback type: verify a cookie
2359   *
2360   * \param ctx      Context for the callback
2361   * \param cookie   Cookie to verify
2362   * \param clen     Length of cookie
2363   * \param info     Client ID info that was passed to
2364   *                 \c mbedtls_ssl_set_client_transport_id()
2365   * \param ilen     Length of info in bytes
2366   *
2367   * \return         The callback must return 0 if cookie is valid,
2368   *                 or a negative error code.
2369   */
2370  typedef int mbedtls_ssl_cookie_check_t( void *ctx,
2371                                  const unsigned char *cookie, size_t clen,
2372                                  const unsigned char *info, size_t ilen );
2373  
2374  #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
2375  /**
2376   * \brief           Register callbacks for DTLS cookies
2377   *                  (Server only. DTLS only.)
2378   *
2379   *                  Default: dummy callbacks that fail, in order to force you to
2380   *                  register working callbacks (and initialize their context).
2381   *
2382   *                  To disable HelloVerifyRequest, register NULL callbacks.
2383   *
2384   * \warning         Disabling hello verification allows your server to be used
2385   *                  for amplification in DoS attacks against other hosts.
2386   *                  Only disable if you known this can't happen in your
2387   *                  particular environment.
2388   *
2389   * \note            See comments on \c mbedtls_ssl_handshake() about handling
2390   *                  the MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED that is expected
2391   *                  on the first handshake attempt when this is enabled.
2392   *
2393   * \note            This is also necessary to handle client reconnection from
2394   *                  the same port as described in RFC 6347 section 4.2.8 (only
2395   *                  the variant with cookies is supported currently). See
2396   *                  comments on \c mbedtls_ssl_read() for details.
2397   *
2398   * \param conf              SSL configuration
2399   * \param f_cookie_write    Cookie write callback
2400   * \param f_cookie_check    Cookie check callback
2401   * \param p_cookie          Context for both callbacks
2402   */
2403  void mbedtls_ssl_conf_dtls_cookies( mbedtls_ssl_config *conf,
2404                             mbedtls_ssl_cookie_write_t *f_cookie_write,
2405                             mbedtls_ssl_cookie_check_t *f_cookie_check,
2406                             void *p_cookie );
2407  
2408  /**
2409   * \brief          Set client's transport-level identification info.
2410   *                 (Server only. DTLS only.)
2411   *
2412   *                 This is usually the IP address (and port), but could be
2413   *                 anything identify the client depending on the underlying
2414   *                 network stack. Used for HelloVerifyRequest with DTLS.
2415   *                 This is *not* used to route the actual packets.
2416   *
2417   * \param ssl      SSL context
2418   * \param info     Transport-level info identifying the client (eg IP + port)
2419   * \param ilen     Length of info in bytes
2420   *
2421   * \note           An internal copy is made, so the info buffer can be reused.
2422   *
2423   * \return         0 on success,
2424   *                 MBEDTLS_ERR_SSL_BAD_INPUT_DATA if used on client,
2425   *                 MBEDTLS_ERR_SSL_ALLOC_FAILED if out of memory.
2426   */
2427  int mbedtls_ssl_set_client_transport_id( mbedtls_ssl_context *ssl,
2428                                   const unsigned char *info,
2429                                   size_t ilen );
2430  
2431  #endif /* MBEDTLS_SSL_DTLS_HELLO_VERIFY && MBEDTLS_SSL_SRV_C */
2432  
2433  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
2434  /**
2435   * \brief          Enable or disable anti-replay protection for DTLS.
2436   *                 (DTLS only, no effect on TLS.)
2437   *                 Default: enabled.
2438   *
2439   * \param conf     SSL configuration
2440   * \param mode     MBEDTLS_SSL_ANTI_REPLAY_ENABLED or MBEDTLS_SSL_ANTI_REPLAY_DISABLED.
2441   *
2442   * \warning        Disabling this is a security risk unless the application
2443   *                 protocol handles duplicated packets in a safe way. You
2444   *                 should not disable this without careful consideration.
2445   *                 However, if your application already detects duplicated
2446   *                 packets and needs information about them to adjust its
2447   *                 transmission strategy, then you'll want to disable this.
2448   */
2449  void mbedtls_ssl_conf_dtls_anti_replay( mbedtls_ssl_config *conf, char mode );
2450  #endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
2451  
2452  /**
2453   * \brief          Set a limit on the number of records with a bad MAC
2454   *                 before terminating the connection.
2455   *                 (DTLS only, no effect on TLS.)
2456   *                 Default: 0 (disabled).
2457   *
2458   * \param conf     SSL configuration
2459   * \param limit    Limit, or 0 to disable.
2460   *
2461   * \note           If the limit is N, then the connection is terminated when
2462   *                 the Nth non-authentic record is seen.
2463   *
2464   * \note           Records with an invalid header are not counted, only the
2465   *                 ones going through the authentication-decryption phase.
2466   *
2467   * \note           This is a security trade-off related to the fact that it's
2468   *                 often relatively easy for an active attacker ot inject UDP
2469   *                 datagrams. On one hand, setting a low limit here makes it
2470   *                 easier for such an attacker to forcibly terminated a
2471   *                 connection. On the other hand, a high limit or no limit
2472   *                 might make us waste resources checking authentication on
2473   *                 many bogus packets.
2474   */
2475  void mbedtls_ssl_conf_dtls_badmac_limit( mbedtls_ssl_config *conf, unsigned limit );
2476  
2477  #if defined(MBEDTLS_SSL_PROTO_DTLS)
2478  
2479  /**
2480   * \brief          Allow or disallow packing of multiple handshake records
2481   *                 within a single datagram.
2482   *
2483   * \param ssl           The SSL context to configure.
2484   * \param allow_packing This determines whether datagram packing may
2485   *                      be used or not. A value of \c 0 means that every
2486   *                      record will be sent in a separate datagram; a
2487   *                      value of \c 1 means that, if space permits,
2488   *                      multiple handshake messages (including CCS) belonging to
2489   *                      a single flight may be packed within a single datagram.
2490   *
2491   * \note           This is enabled by default and should only be disabled
2492   *                 for test purposes, or if datagram packing causes
2493   *                 interoperability issues with peers that don't support it.
2494   *
2495   * \note           Allowing datagram packing reduces the network load since
2496   *                 there's less overhead if multiple messages share the same
2497   *                 datagram. Also, it increases the handshake efficiency
2498   *                 since messages belonging to a single datagram will not
2499   *                 be reordered in transit, and so future message buffering
2500   *                 or flight retransmission (if no buffering is used) as
2501   *                 means to deal with reordering are needed less frequently.
2502   *
2503   * \note           Application records are not affected by this option and
2504   *                 are currently always sent in separate datagrams.
2505   *
2506   */
2507  void mbedtls_ssl_set_datagram_packing( mbedtls_ssl_context *ssl,
2508                                         unsigned allow_packing );
2509  
2510  /**
2511   * \brief          Set retransmit timeout values for the DTLS handshake.
2512   *                 (DTLS only, no effect on TLS.)
2513   *
2514   * \param conf     SSL configuration
2515   * \param min      Initial timeout value in milliseconds.
2516   *                 Default: 1000 (1 second).
2517   * \param max      Maximum timeout value in milliseconds.
2518   *                 Default: 60000 (60 seconds).
2519   *
2520   * \note           Default values are from RFC 6347 section 4.2.4.1.
2521   *
2522   * \note           The 'min' value should typically be slightly above the
2523   *                 expected round-trip time to your peer, plus whatever time
2524   *                 it takes for the peer to process the message. For example,
2525   *                 if your RTT is about 600ms and you peer needs up to 1s to
2526   *                 do the cryptographic operations in the handshake, then you
2527   *                 should set 'min' slightly above 1600. Lower values of 'min'
2528   *                 might cause spurious resends which waste network resources,
2529   *                 while larger value of 'min' will increase overall latency
2530   *                 on unreliable network links.
2531   *
2532   * \note           The more unreliable your network connection is, the larger
2533   *                 your max / min ratio needs to be in order to achieve
2534   *                 reliable handshakes.
2535   *
2536   * \note           Messages are retransmitted up to log2(ceil(max/min)) times.
2537   *                 For example, if min = 1s and max = 5s, the retransmit plan
2538   *                 goes: send ... 1s -> resend ... 2s -> resend ... 4s ->
2539   *                 resend ... 5s -> give up and return a timeout error.
2540   */
2541  void mbedtls_ssl_conf_handshake_timeout( mbedtls_ssl_config *conf, uint32_t min, uint32_t max );
2542  #endif /* MBEDTLS_SSL_PROTO_DTLS */
2543  
2544  #if defined(MBEDTLS_SSL_SRV_C)
2545  /**
2546   * \brief          Set the session cache callbacks (server-side only)
2547   *                 If not set, no session resuming is done (except if session
2548   *                 tickets are enabled too).
2549   *
2550   *                 The session cache has the responsibility to check for stale
2551   *                 entries based on timeout. See RFC 5246 for recommendations.
2552   *
2553   *                 Warning: session.peer_cert is cleared by the SSL/TLS layer on
2554   *                 connection shutdown, so do not cache the pointer! Either set
2555   *                 it to NULL or make a full copy of the certificate.
2556   *
2557   *                 The get callback is called once during the initial handshake
2558   *                 to enable session resuming. The get function has the
2559   *                 following parameters: (void *parameter, mbedtls_ssl_session *session)
2560   *                 If a valid entry is found, it should fill the master of
2561   *                 the session object with the cached values and return 0,
2562   *                 return 1 otherwise. Optionally peer_cert can be set as well
2563   *                 if it is properly present in cache entry.
2564   *
2565   *                 The set callback is called once during the initial handshake
2566   *                 to enable session resuming after the entire handshake has
2567   *                 been finished. The set function has the following parameters:
2568   *                 (void *parameter, const mbedtls_ssl_session *session). The function
2569   *                 should create a cache entry for future retrieval based on
2570   *                 the data in the session structure and should keep in mind
2571   *                 that the mbedtls_ssl_session object presented (and all its referenced
2572   *                 data) is cleared by the SSL/TLS layer when the connection is
2573   *                 terminated. It is recommended to add metadata to determine if
2574   *                 an entry is still valid in the future. Return 0 if
2575   *                 successfully cached, return 1 otherwise.
2576   *
2577   * \param conf           SSL configuration
2578   * \param p_cache        parmater (context) for both callbacks
2579   * \param f_get_cache    session get callback
2580   * \param f_set_cache    session set callback
2581   */
2582  void mbedtls_ssl_conf_session_cache( mbedtls_ssl_config *conf,
2583                                       void *p_cache,
2584                                       mbedtls_ssl_cache_get_t *f_get_cache,
2585                                       mbedtls_ssl_cache_set_t *f_set_cache );
2586  #endif /* MBEDTLS_SSL_SRV_C */
2587  
2588  #if defined(MBEDTLS_SSL_CLI_C)
2589  /**
2590   * \brief          Load a session for session resumption.
2591   *
2592   *                 Sessions loaded through this call will be considered
2593   *                 for session resumption in the next handshake.
2594   *
2595   * \note           Even if this call succeeds, it is not guaranteed that
2596   *                 the next handshake will indeed be shortened through the
2597   *                 use of session resumption: The server is always free
2598   *                 to reject any attempt for resumption and fall back to
2599   *                 a full handshake.
2600   *
2601   * \note           This function can handle a variety of mechanisms for session
2602   *                 resumption: For TLS 1.2, both session ID-based resumption and
2603   *                 ticket-based resumption will be considered. For TLS 1.3,
2604   *                 once implemented, sessions equate to tickets, and loading
2605   *                 one or more sessions via this call will lead to their
2606   *                 corresponding tickets being advertised as resumption PSKs
2607   *                 by the client.
2608   *
2609   * \note           Calling this function multiple times will only be useful
2610   *                 once TLS 1.3 is supported. For TLS 1.2 connections, this
2611   *                 function should be called at most once.
2612   *
2613   * \param ssl      The SSL context representing the connection which should
2614   *                 be attempted to be setup using session resumption. This
2615   *                 must be initialized via mbedtls_ssl_init() and bound to
2616   *                 an SSL configuration via mbedtls_ssl_setup(), but
2617   *                 the handshake must not yet have been started.
2618   * \param session  The session to be considered for session resumption.
2619   *                 This must be a session previously exported via
2620   *                 mbedtls_ssl_get_session(), and potentially serialized and
2621   *                 deserialized through mbedtls_ssl_session_save() and
2622   *                 mbedtls_ssl_session_load() in the meantime.
2623   *
2624   * \return         \c 0 if successful.
2625   * \return         \c MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE if the session
2626   *                 could not be loaded because of an implementation limitation.
2627   *                 This error is non-fatal, and has no observable effect on
2628   *                 the SSL context or the session that was attempted to be loaded.
2629   * \return         Another negative error code on other kinds of failure.
2630   *
2631   * \sa             mbedtls_ssl_get_session()
2632   * \sa             mbedtls_ssl_session_load()
2633   */
2634  int mbedtls_ssl_set_session( mbedtls_ssl_context *ssl, const mbedtls_ssl_session *session );
2635  #endif /* MBEDTLS_SSL_CLI_C */
2636  
2637  /**
2638   * \brief          Load serialized session data into a session structure.
2639   *                 On client, this can be used for loading saved sessions
2640   *                 before resuming them with mbedstls_ssl_set_session().
2641   *                 On server, this can be used for alternative implementations
2642   *                 of session cache or session tickets.
2643   *
2644   * \warning        If a peer certificate chain is associated with the session,
2645   *                 the serialized state will only contain the peer's
2646   *                 end-entity certificate and the result of the chain
2647   *                 verification (unless verification was disabled), but not
2648   *                 the rest of the chain.
2649   *
2650   * \see            mbedtls_ssl_session_save()
2651   * \see            mbedtls_ssl_set_session()
2652   *
2653   * \param session  The session structure to be populated. It must have been
2654   *                 initialised with mbedtls_ssl_session_init() but not
2655   *                 populated yet.
2656   * \param buf      The buffer holding the serialized session data. It must be a
2657   *                 readable buffer of at least \p len bytes.
2658   * \param len      The size of the serialized data in bytes.
2659   *
2660   * \return         \c 0 if successful.
2661   * \return         #MBEDTLS_ERR_SSL_ALLOC_FAILED if memory allocation failed.
2662   * \return         #MBEDTLS_ERR_SSL_BAD_INPUT_DATA if input data is invalid.
2663   * \return         #MBEDTLS_ERR_SSL_VERSION_MISMATCH if the serialized data
2664   *                 was generated in a different version or configuration of
2665   *                 Mbed TLS.
2666   * \return         Another negative value for other kinds of errors (for
2667   *                 example, unsupported features in the embedded certificate).
2668   */
2669  int mbedtls_ssl_session_load( mbedtls_ssl_session *session,
2670                                const unsigned char *buf,
2671                                size_t len );
2672  
2673  /**
2674   * \brief          Save session structure as serialized data in a buffer.
2675   *                 On client, this can be used for saving session data,
2676   *                 potentially in non-volatile storage, for resuming later.
2677   *                 On server, this can be used for alternative implementations
2678   *                 of session cache or session tickets.
2679   *
2680   * \see            mbedtls_ssl_session_load()
2681   *
2682   * \param session  The session structure to be saved.
2683   * \param buf      The buffer to write the serialized data to. It must be a
2684   *                 writeable buffer of at least \p len bytes, or may be \c
2685   *                 NULL if \p len is \c 0.
2686   * \param buf_len  The number of bytes available for writing in \p buf.
2687   * \param olen     The size in bytes of the data that has been or would have
2688   *                 been written. It must point to a valid \c size_t.
2689   *
2690   * \note           \p olen is updated to the correct value regardless of
2691   *                 whether \p buf_len was large enough. This makes it possible
2692   *                 to determine the necessary size by calling this function
2693   *                 with \p buf set to \c NULL and \p buf_len to \c 0.
2694   *
2695   * \return         \c 0 if successful.
2696   * \return         #MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL if \p buf is too small.
2697   */
2698  int mbedtls_ssl_session_save( const mbedtls_ssl_session *session,
2699                                unsigned char *buf,
2700                                size_t buf_len,
2701                                size_t *olen );
2702  
2703  /**
2704   * \brief               Set the list of allowed ciphersuites and the preference
2705   *                      order. First in the list has the highest preference.
2706   *
2707   *                      For TLS 1.2, the notion of ciphersuite determines both
2708   *                      the key exchange mechanism and the suite of symmetric
2709   *                      algorithms to be used during and after the handshake.
2710   *
2711   *                      For TLS 1.3 (in development), the notion of ciphersuite
2712   *                      only determines the suite of symmetric algorithms to be
2713   *                      used during and after the handshake, while key exchange
2714   *                      mechanisms are configured separately.
2715   *
2716   *                      In Mbed TLS, ciphersuites for both TLS 1.2 and TLS 1.3
2717   *                      are configured via this function. For users of TLS 1.3,
2718   *                      there will be separate API for the configuration of key
2719   *                      exchange mechanisms.
2720   *
2721   *                      The list of ciphersuites passed to this function may
2722   *                      contain a mixture of TLS 1.2 and TLS 1.3 ciphersuite
2723   *                      identifiers. This is useful if negotiation of TLS 1.3
2724   *                      should be attempted, but a fallback to TLS 1.2 would
2725   *                      be tolerated.
2726   *
2727   * \note                By default, the server chooses its preferred
2728   *                      ciphersuite among those that the client supports. If
2729   *                      mbedtls_ssl_conf_preference_order() is called to prefer
2730   *                      the client's preferences, the server instead chooses
2731   *                      the client's preferred ciphersuite among those that
2732   *                      the server supports.
2733   *
2734   * \warning             The ciphersuites array \p ciphersuites is not copied.
2735   *                      It must remain valid for the lifetime of the SSL
2736   *                      configuration \p conf.
2737   *
2738   * \param conf          The SSL configuration to modify.
2739   * \param ciphersuites  A 0-terminated list of IANA identifiers of supported
2740   *                      ciphersuites, accessible through \c MBEDTLS_TLS_XXX
2741   *                      and \c MBEDTLS_TLS1_3_XXX macros defined in
2742   *                      ssl_ciphersuites.h.
2743   */
2744  void mbedtls_ssl_conf_ciphersuites( mbedtls_ssl_config *conf,
2745                                      const int *ciphersuites );
2746  
2747  #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
2748  /**
2749   * \brief Set the supported key exchange modes for TLS 1.3 connections.
2750   *
2751   *        In contrast to TLS 1.2, the ciphersuite concept in TLS 1.3 does not
2752   *        include the choice of key exchange mechanism. It is therefore not
2753   *        covered by the API mbedtls_ssl_conf_ciphersuites(). See the
2754   *        documentation of mbedtls_ssl_conf_ciphersuites() for more
2755   *        information on the ciphersuite concept in TLS 1.2 and TLS 1.3.
2756   *
2757   *        The present function is specific to TLS 1.3 and allows users to
2758   *        configure the set of supported key exchange mechanisms in TLS 1.3.
2759   *
2760   * \param conf       The SSL configuration the change should apply to.
2761   * \param kex_modes  A bitwise combination of one or more of the following:
2762   *                   - MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK
2763   *                     This flag enables pure-PSK key exchanges.
2764   *                   - MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_EPHEMERAL
2765   *                     This flag enables combined PSK-ephemeral key exchanges.
2766   *                   - MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL
2767   *                     This flag enables pure-ephemeral key exchanges.
2768   *                   For convenience, the following pre-defined macros are
2769   *                   available for combinations of the above:
2770   *                   - MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_ALL
2771   *                     Includes all of pure-PSK, PSK-ephemeral and pure-ephemeral.
2772   *                   - MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_ALL
2773   *                     Includes both pure-PSK and combined PSK-ephemeral
2774   *                     key exchanges, but excludes pure-ephemeral key exchanges.
2775   *                   - MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL_ALL
2776   *                     Includes both pure-ephemeral and combined PSK-ephemeral
2777   *                     key exchanges.
2778   *
2779   * \note  If a PSK-based key exchange mode shall be supported, applications
2780   *        must also use the APIs mbedtls_ssl_conf_psk() or
2781   *        mbedtls_ssl_conf_psk_cb() or mbedtls_ssl_conf_psk_opaque()
2782   *        to configure the PSKs to be used.
2783   *
2784   * \note  If a pure-ephemeral key exchange mode shall be supported,
2785   *        server-side applications must also provide a certificate via
2786   *        mbedtls_ssl_conf_own_cert().
2787   *
2788   */
2789  
2790  void mbedtls_ssl_conf_tls13_key_exchange_modes( mbedtls_ssl_config* conf,
2791                                                  const int kex_modes );
2792  #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
2793  
2794  #if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
2795  #define MBEDTLS_SSL_UNEXPECTED_CID_IGNORE 0
2796  #define MBEDTLS_SSL_UNEXPECTED_CID_FAIL   1
2797  /**
2798   * \brief               Specify the length of Connection IDs for incoming
2799   *                      encrypted DTLS records, as well as the behaviour
2800   *                      on unexpected CIDs.
2801   *
2802   *                      By default, the CID length is set to \c 0,
2803   *                      and unexpected CIDs are silently ignored.
2804   *
2805   * \param conf          The SSL configuration to modify.
2806   * \param len           The length in Bytes of the CID fields in encrypted
2807   *                      DTLS records using the CID mechanism. This must
2808   *                      not be larger than #MBEDTLS_SSL_CID_OUT_LEN_MAX.
2809   * \param ignore_other_cids This determines the stack's behaviour when
2810   *                          receiving a record with an unexpected CID.
2811   *                          Possible values are:
2812   *                          - #MBEDTLS_SSL_UNEXPECTED_CID_IGNORE
2813   *                            In this case, the record is silently ignored.
2814   *                          - #MBEDTLS_SSL_UNEXPECTED_CID_FAIL
2815   *                            In this case, the stack fails with the specific
2816   *                            error code #MBEDTLS_ERR_SSL_UNEXPECTED_CID.
2817   *
2818   * \note                The CID specification allows implementations to either
2819   *                      use a common length for all incoming connection IDs or
2820   *                      allow variable-length incoming IDs. Mbed TLS currently
2821   *                      requires a common length for all connections sharing the
2822   *                      same SSL configuration; this allows simpler parsing of
2823   *                      record headers.
2824   *
2825   * \return              \c 0 on success.
2826   * \return              #MBEDTLS_ERR_SSL_BAD_INPUT_DATA if \p own_cid_len
2827   *                      is too large.
2828   */
2829  int mbedtls_ssl_conf_cid( mbedtls_ssl_config *conf, size_t len,
2830                            int ignore_other_cids );
2831  #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
2832  
2833  #if defined(MBEDTLS_X509_CRT_PARSE_C)
2834  /**
2835   * \brief          Set the X.509 security profile used for verification
2836   *
2837   * \note           The restrictions are enforced for all certificates in the
2838   *                 chain. However, signatures in the handshake are not covered
2839   *                 by this setting but by \b mbedtls_ssl_conf_sig_hashes().
2840   *
2841   * \param conf     SSL configuration
2842   * \param profile  Profile to use
2843   */
2844  void mbedtls_ssl_conf_cert_profile( mbedtls_ssl_config *conf,
2845                                      const mbedtls_x509_crt_profile *profile );
2846  
2847  /**
2848   * \brief          Set the data required to verify peer certificate
2849   *
2850   * \note           See \c mbedtls_x509_crt_verify() for notes regarding the
2851   *                 parameters ca_chain (maps to trust_ca for that function)
2852   *                 and ca_crl.
2853   *
2854   * \param conf     SSL configuration
2855   * \param ca_chain trusted CA chain (meaning all fully trusted top-level CAs)
2856   * \param ca_crl   trusted CA CRLs
2857   */
2858  void mbedtls_ssl_conf_ca_chain( mbedtls_ssl_config *conf,
2859                                 mbedtls_x509_crt *ca_chain,
2860                                 mbedtls_x509_crl *ca_crl );
2861  
2862  #if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
2863  /**
2864   * \brief          Set the trusted certificate callback.
2865   *
2866   *                 This API allows to register the set of trusted certificates
2867   *                 through a callback, instead of a linked list as configured
2868   *                 by mbedtls_ssl_conf_ca_chain().
2869   *
2870   *                 This is useful for example in contexts where a large number
2871   *                 of CAs are used, and the inefficiency of maintaining them
2872   *                 in a linked list cannot be tolerated. It is also useful when
2873   *                 the set of trusted CAs needs to be modified frequently.
2874   *
2875   *                 See the documentation of `mbedtls_x509_crt_ca_cb_t` for
2876   *                 more information.
2877   *
2878   * \param conf     The SSL configuration to register the callback with.
2879   * \param f_ca_cb  The trusted certificate callback to use when verifying
2880   *                 certificate chains.
2881   * \param p_ca_cb  The context to be passed to \p f_ca_cb (for example,
2882   *                 a reference to a trusted CA database).
2883   *
2884   * \note           This API is incompatible with mbedtls_ssl_conf_ca_chain():
2885   *                 Any call to this function overwrites the values set through
2886   *                 earlier calls to mbedtls_ssl_conf_ca_chain() or
2887   *                 mbedtls_ssl_conf_ca_cb().
2888   *
2889   * \note           This API is incompatible with CA indication in
2890   *                 CertificateRequest messages: A server-side SSL context which
2891   *                 is bound to an SSL configuration that uses a CA callback
2892   *                 configured via mbedtls_ssl_conf_ca_cb(), and which requires
2893   *                 client authentication, will send an empty CA list in the
2894   *                 corresponding CertificateRequest message.
2895   *
2896   * \note           This API is incompatible with mbedtls_ssl_set_hs_ca_chain():
2897   *                 If an SSL context is bound to an SSL configuration which uses
2898   *                 CA callbacks configured via mbedtls_ssl_conf_ca_cb(), then
2899   *                 calls to mbedtls_ssl_set_hs_ca_chain() have no effect.
2900   *
2901   * \note           The use of this API disables the use of restartable ECC
2902   *                 during X.509 CRT signature verification (but doesn't affect
2903   *                 other uses).
2904   *
2905   * \warning        This API is incompatible with the use of CRLs. Any call to
2906   *                 mbedtls_ssl_conf_ca_cb() unsets CRLs configured through
2907   *                 earlier calls to mbedtls_ssl_conf_ca_chain().
2908   *
2909   * \warning        In multi-threaded environments, the callback \p f_ca_cb
2910   *                 must be thread-safe, and it is the user's responsibility
2911   *                 to guarantee this (for example through a mutex
2912   *                 contained in the callback context pointed to by \p p_ca_cb).
2913   */
2914  void mbedtls_ssl_conf_ca_cb( mbedtls_ssl_config *conf,
2915                               mbedtls_x509_crt_ca_cb_t f_ca_cb,
2916                               void *p_ca_cb );
2917  #endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
2918  
2919  /**
2920   * \brief          Set own certificate chain and private key
2921   *
2922   * \note           own_cert should contain in order from the bottom up your
2923   *                 certificate chain. The top certificate (self-signed)
2924   *                 can be omitted.
2925   *
2926   * \note           On server, this function can be called multiple times to
2927   *                 provision more than one cert/key pair (eg one ECDSA, one
2928   *                 RSA with SHA-256, one RSA with SHA-1). An adequate
2929   *                 certificate will be selected according to the client's
2930   *                 advertised capabilities. In case multiple certificates are
2931   *                 adequate, preference is given to the one set by the first
2932   *                 call to this function, then second, etc.
2933   *
2934   * \note           On client, only the first call has any effect. That is,
2935   *                 only one client certificate can be provisioned. The
2936   *                 server's preferences in its CertficateRequest message will
2937   *                 be ignored and our only cert will be sent regardless of
2938   *                 whether it matches those preferences - the server can then
2939   *                 decide what it wants to do with it.
2940   *
2941   * \note           The provided \p pk_key needs to match the public key in the
2942   *                 first certificate in \p own_cert, or all handshakes using
2943   *                 that certificate will fail. It is your responsibility
2944   *                 to ensure that; this function will not perform any check.
2945   *                 You may use mbedtls_pk_check_pair() in order to perform
2946   *                 this check yourself, but be aware that this function can
2947   *                 be computationally expensive on some key types.
2948   *
2949   * \param conf     SSL configuration
2950   * \param own_cert own public certificate chain
2951   * \param pk_key   own private key
2952   *
2953   * \return         0 on success or MBEDTLS_ERR_SSL_ALLOC_FAILED
2954   */
2955  int mbedtls_ssl_conf_own_cert( mbedtls_ssl_config *conf,
2956                                mbedtls_x509_crt *own_cert,
2957                                mbedtls_pk_context *pk_key );
2958  #endif /* MBEDTLS_X509_CRT_PARSE_C */
2959  
2960  #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
2961  /**
2962   * \brief          Configure pre-shared keys (PSKs) and their
2963   *                 identities to be used in PSK-based ciphersuites.
2964   *
2965   *                 Only one PSK can be registered, through either
2966   *                 mbedtls_ssl_conf_psk() or mbedtls_ssl_conf_psk_opaque().
2967   *                 If you attempt to register more than one PSK, this function
2968   *                 fails, though this may change in future versions, which
2969   *                 may add support for multiple PSKs.
2970   *
2971   * \note           This is mainly useful for clients. Servers will usually
2972   *                 want to use \c mbedtls_ssl_conf_psk_cb() instead.
2973   *
2974   * \note           A PSK set by \c mbedtls_ssl_set_hs_psk() in the PSK callback
2975   *                 takes precedence over a PSK configured by this function.
2976   *
2977   * \param conf     The SSL configuration to register the PSK with.
2978   * \param psk      The pointer to the pre-shared key to use.
2979   * \param psk_len  The length of the pre-shared key in bytes.
2980   * \param psk_identity      The pointer to the pre-shared key identity.
2981   * \param psk_identity_len  The length of the pre-shared key identity
2982   *                          in bytes.
2983   *
2984   * \note           The PSK and its identity are copied internally and
2985   *                 hence need not be preserved by the caller for the lifetime
2986   *                 of the SSL configuration.
2987   *
2988   * \return         \c 0 if successful.
2989   * \return         #MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE if no more PSKs
2990   *                 can be configured. In this case, the old PSK(s) remain intact.
2991   * \return         Another negative error code on other kinds of failure.
2992   */
2993  int mbedtls_ssl_conf_psk( mbedtls_ssl_config *conf,
2994                  const unsigned char *psk, size_t psk_len,
2995                  const unsigned char *psk_identity, size_t psk_identity_len );
2996  
2997  #if defined(MBEDTLS_USE_PSA_CRYPTO)
2998  /**
2999   * \brief          Configure one or more opaque pre-shared keys (PSKs) and
3000   *                 their identities to be used in PSK-based ciphersuites.
3001   *
3002   *                 Only one PSK can be registered, through either
3003   *                 mbedtls_ssl_conf_psk() or mbedtls_ssl_conf_psk_opaque().
3004   *                 If you attempt to register more than one PSK, this function
3005   *                 fails, though this may change in future versions, which
3006   *                 may add support for multiple PSKs.
3007   *
3008   * \note           This is mainly useful for clients. Servers will usually
3009   *                 want to use \c mbedtls_ssl_conf_psk_cb() instead.
3010   *
3011   * \note           An opaque PSK set by \c mbedtls_ssl_set_hs_psk_opaque() in
3012   *                 the PSK callback takes precedence over an opaque PSK
3013   *                 configured by this function.
3014   *
3015   * \param conf     The SSL configuration to register the PSK with.
3016   * \param psk      The identifier of the key slot holding the PSK.
3017   *                 Until \p conf is destroyed or this function is successfully
3018   *                 called again, the key slot \p psk must be populated with a
3019   *                 key of type PSA_ALG_CATEGORY_KEY_DERIVATION whose policy
3020   *                 allows its use for the key derivation algorithm applied
3021   *                 in the handshake.
3022   * \param psk_identity      The pointer to the pre-shared key identity.
3023   * \param psk_identity_len  The length of the pre-shared key identity
3024   *                          in bytes.
3025   *
3026   * \note           The PSK identity hint is copied internally and hence need
3027   *                 not be preserved by the caller for the lifetime of the
3028   *                 SSL configuration.
3029   *
3030   * \return         \c 0 if successful.
3031   * \return         #MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE if no more PSKs
3032   *                 can be configured. In this case, the old PSK(s) remain intact.
3033   * \return         Another negative error code on other kinds of failure.
3034   */
3035  int mbedtls_ssl_conf_psk_opaque( mbedtls_ssl_config *conf,
3036                                   psa_key_id_t psk,
3037                                   const unsigned char *psk_identity,
3038                                   size_t psk_identity_len );
3039  #endif /* MBEDTLS_USE_PSA_CRYPTO */
3040  
3041  /**
3042   * \brief          Set the pre-shared Key (PSK) for the current handshake.
3043   *
3044   * \note           This should only be called inside the PSK callback,
3045   *                 i.e. the function passed to \c mbedtls_ssl_conf_psk_cb().
3046   *
3047   * \note           A PSK set by this function takes precedence over a PSK
3048   *                 configured by \c mbedtls_ssl_conf_psk().
3049   *
3050   * \param ssl      The SSL context to configure a PSK for.
3051   * \param psk      The pointer to the pre-shared key.
3052   * \param psk_len  The length of the pre-shared key in bytes.
3053   *
3054   * \return         \c 0 if successful.
3055   * \return         An \c MBEDTLS_ERR_SSL_XXX error code on failure.
3056   */
3057  int mbedtls_ssl_set_hs_psk( mbedtls_ssl_context *ssl,
3058                              const unsigned char *psk, size_t psk_len );
3059  
3060  #if defined(MBEDTLS_USE_PSA_CRYPTO)
3061  /**
3062   * \brief          Set an opaque pre-shared Key (PSK) for the current handshake.
3063   *
3064   * \note           This should only be called inside the PSK callback,
3065   *                 i.e. the function passed to \c mbedtls_ssl_conf_psk_cb().
3066   *
3067   * \note           An opaque PSK set by this function takes precedence over an
3068   *                 opaque PSK configured by \c mbedtls_ssl_conf_psk_opaque().
3069   *
3070   * \param ssl      The SSL context to configure a PSK for.
3071   * \param psk      The identifier of the key slot holding the PSK.
3072   *                 For the duration of the current handshake, the key slot
3073   *                 must be populated with a key of type
3074   *                 PSA_ALG_CATEGORY_KEY_DERIVATION whose policy allows its
3075   *                 use for the key derivation algorithm
3076   *                 applied in the handshake.
3077    *
3078   * \return         \c 0 if successful.
3079   * \return         An \c MBEDTLS_ERR_SSL_XXX error code on failure.
3080   */
3081  int mbedtls_ssl_set_hs_psk_opaque( mbedtls_ssl_context *ssl,
3082                                     psa_key_id_t psk );
3083  #endif /* MBEDTLS_USE_PSA_CRYPTO */
3084  
3085  /**
3086   * \brief          Set the PSK callback (server-side only).
3087   *
3088   *                 If set, the PSK callback is called for each
3089   *                 handshake where a PSK-based ciphersuite was negotiated.
3090   *                 The caller provides the identity received and wants to
3091   *                 receive the actual PSK data and length.
3092   *
3093   *                 The callback has the following parameters:
3094   *                 - \c void*: The opaque pointer \p p_psk.
3095   *                 - \c mbedtls_ssl_context*: The SSL context to which
3096   *                                            the operation applies.
3097   *                 - \c const unsigned char*: The PSK identity
3098   *                                            selected by the client.
3099   *                 - \c size_t: The length of the PSK identity
3100   *                              selected by the client.
3101   *
3102   *                 If a valid PSK identity is found, the callback should use
3103   *                 \c mbedtls_ssl_set_hs_psk() or
3104   *                 \c mbedtls_ssl_set_hs_psk_opaque()
3105   *                 on the SSL context to set the correct PSK and return \c 0.
3106   *                 Any other return value will result in a denied PSK identity.
3107   *
3108   * \note           A dynamic PSK (i.e. set by the PSK callback) takes
3109   *                 precedence over a static PSK (i.e. set by
3110   *                 \c mbedtls_ssl_conf_psk() or
3111   *                 \c mbedtls_ssl_conf_psk_opaque()).
3112   *                 This means that if you set a PSK callback using this
3113   *                 function, you don't need to set a PSK using
3114   *                 \c mbedtls_ssl_conf_psk() or
3115   *                 \c mbedtls_ssl_conf_psk_opaque()).
3116   *
3117   * \param conf     The SSL configuration to register the callback with.
3118   * \param f_psk    The callback for selecting and setting the PSK based
3119   *                 in the PSK identity chosen by the client.
3120   * \param p_psk    A pointer to an opaque structure to be passed to
3121   *                 the callback, for example a PSK store.
3122   */
3123  void mbedtls_ssl_conf_psk_cb( mbedtls_ssl_config *conf,
3124                       int (*f_psk)(void *, mbedtls_ssl_context *, const unsigned char *,
3125                                    size_t),
3126                       void *p_psk );
3127  #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
3128  
3129  #if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_SRV_C)
3130  /**
3131   * \brief          Set the Diffie-Hellman public P and G values
3132   *                 from big-endian binary presentations.
3133   *                 (Default values: MBEDTLS_DHM_RFC3526_MODP_2048_[PG]_BIN)
3134   *
3135   * \param conf     SSL configuration
3136   * \param dhm_P    Diffie-Hellman-Merkle modulus in big-endian binary form
3137   * \param P_len    Length of DHM modulus
3138   * \param dhm_G    Diffie-Hellman-Merkle generator in big-endian binary form
3139   * \param G_len    Length of DHM generator
3140   *
3141   * \return         0 if successful
3142   */
3143  int mbedtls_ssl_conf_dh_param_bin( mbedtls_ssl_config *conf,
3144                                     const unsigned char *dhm_P, size_t P_len,
3145                                     const unsigned char *dhm_G,  size_t G_len );
3146  
3147  /**
3148   * \brief          Set the Diffie-Hellman public P and G values,
3149   *                 read from existing context (server-side only)
3150   *
3151   * \param conf     SSL configuration
3152   * \param dhm_ctx  Diffie-Hellman-Merkle context
3153   *
3154   * \return         0 if successful
3155   */
3156  int mbedtls_ssl_conf_dh_param_ctx( mbedtls_ssl_config *conf, mbedtls_dhm_context *dhm_ctx );
3157  #endif /* MBEDTLS_DHM_C && defined(MBEDTLS_SSL_SRV_C) */
3158  
3159  #if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_CLI_C)
3160  /**
3161   * \brief          Set the minimum length for Diffie-Hellman parameters.
3162   *                 (Client-side only.)
3163   *                 (Default: 1024 bits.)
3164   *
3165   * \param conf     SSL configuration
3166   * \param bitlen   Minimum bit length of the DHM prime
3167   */
3168  void mbedtls_ssl_conf_dhm_min_bitlen( mbedtls_ssl_config *conf,
3169                                        unsigned int bitlen );
3170  #endif /* MBEDTLS_DHM_C && MBEDTLS_SSL_CLI_C */
3171  
3172  #if defined(MBEDTLS_ECP_C)
3173  #if !defined(MBEDTLS_DEPRECATED_REMOVED)
3174  /**
3175   * \brief          Set the allowed curves in order of preference.
3176   *
3177   *                 On server: this only affects selection of the ECDHE curve;
3178   *                 the curves used for ECDH and ECDSA are determined by the
3179   *                 list of available certificates instead.
3180   *
3181   *                 On client: this affects the list of curves offered for any
3182   *                 use. The server can override our preference order.
3183   *
3184   *                 Both sides: limits the set of curves accepted for use in
3185   *                 ECDHE and in the peer's end-entity certificate.
3186   *
3187   * \deprecated     Superseeded by mbedtls_ssl_conf_groups().
3188   *
3189   * \note           This has no influence on which curves are allowed inside the
3190   *                 certificate chains, see \c mbedtls_ssl_conf_cert_profile()
3191   *                 for that. For the end-entity certificate however, the key
3192   *                 will be accepted only if it is allowed both by this list
3193   *                 and by the cert profile.
3194   *
3195   * \note           This list should be ordered by decreasing preference
3196   *                 (preferred curve first).
3197   *
3198   * \note           The default list is the same set of curves that
3199   *                 #mbedtls_x509_crt_profile_default allows, plus
3200   *                 ECDHE-only curves selected according to the same criteria.
3201   *                 The order favors curves with the lowest resource usage.
3202   *
3203   * \note           New minor versions of Mbed TLS may extend this list,
3204   *                 for example if new curves are added to the library.
3205   *                 New minor versions of Mbed TLS will not remove items
3206   *                 from this list unless serious security concerns require it.
3207   *                 New minor versions of Mbed TLS may change the order in
3208   *                 keeping with the general principle of favoring the lowest
3209   *                 resource usage.
3210   *
3211   * \param conf     SSL configuration
3212   * \param curves   Ordered list of allowed curves,
3213   *                 terminated by MBEDTLS_ECP_DP_NONE.
3214   */
3215  void MBEDTLS_DEPRECATED mbedtls_ssl_conf_curves( mbedtls_ssl_config *conf,
3216                                                   const mbedtls_ecp_group_id *curves );
3217  #endif /* MBEDTLS_DEPRECATED_REMOVED */
3218  #endif /* MBEDTLS_ECP_C */
3219  
3220  /**
3221   * \brief          Set the allowed groups in order of preference.
3222   *
3223   *                 On server: This only affects the choice of key agreement mechanism
3224   *
3225   *                 On client: this affects the list of groups offered for any
3226   *                 use. The server can override our preference order.
3227   *
3228   *                 Both sides: limits the set of groups accepted for use in
3229   *                 key sharing.
3230   *
3231   * \note           This function replaces the deprecated mbedtls_ssl_conf_curves(),
3232   *                 which only allows ECP curves to be configured.
3233   *
3234   * \note           The most recent invocation of either mbedtls_ssl_conf_curves()
3235   *                 or mbedtls_ssl_conf_groups() nullifies all previous invocations
3236   *                 of both.
3237   *
3238   * \note           This list should be ordered by decreasing preference
3239   *                 (preferred group first).
3240   *
3241   * \note           When this function is not called, a default list is used,
3242   *                 consisting of all supported curves at 255 bits and above,
3243   *                 and all supported finite fields at 2048 bits and above.
3244   *                 The order favors groups with the lowest resource usage.
3245   *
3246   * \note           New minor versions of Mbed TLS will not remove items
3247   *                 from the default list unless serious security concerns require it.
3248   *                 New minor versions of Mbed TLS may change the order in
3249   *                 keeping with the general principle of favoring the lowest
3250   *                 resource usage.
3251   *
3252   * \param conf     SSL configuration
3253   * \param groups   List of allowed groups ordered by preference, terminated by 0.
3254   *                 Must contain valid IANA NamedGroup IDs (provided via either an integer
3255   *                 or using MBEDTLS_TLS13_NAMED_GROUP_XXX macros).
3256   */
3257  void mbedtls_ssl_conf_groups( mbedtls_ssl_config *conf,
3258                                const uint16_t *groups );
3259  
3260  #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
3261  /**
3262   * \brief          Set the allowed hashes for signatures during the handshake.
3263   *
3264   * \note           This only affects which hashes are offered and can be used
3265   *                 for signatures during the handshake. Hashes for message
3266   *                 authentication and the TLS PRF are controlled by the
3267   *                 ciphersuite, see \c mbedtls_ssl_conf_ciphersuites(). Hashes
3268   *                 used for certificate signature are controlled by the
3269   *                 verification profile, see \c mbedtls_ssl_conf_cert_profile().
3270   *
3271   * \note           This list should be ordered by decreasing preference
3272   *                 (preferred hash first).
3273   *
3274   * \note           By default, all supported hashes whose length is at least
3275   *                 256 bits are allowed. This is the same set as the default
3276   *                 for certificate verification
3277   *                 (#mbedtls_x509_crt_profile_default).
3278   *                 The preference order is currently unspecified and may
3279   *                 change in future versions.
3280   *
3281   * \note           New minor versions of Mbed TLS may extend this list,
3282   *                 for example if new curves are added to the library.
3283   *                 New minor versions of Mbed TLS will not remove items
3284   *                 from this list unless serious security concerns require it.
3285   *
3286   * \param conf     SSL configuration
3287   * \param hashes   Ordered list of allowed signature hashes,
3288   *                 terminated by \c MBEDTLS_MD_NONE.
3289   */
3290  void mbedtls_ssl_conf_sig_hashes( mbedtls_ssl_config *conf,
3291                                    const int *hashes );
3292  
3293  #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
3294  /**
3295   * \brief          Configure allowed signature algorithms for use in TLS 1.3
3296   *
3297   * \param conf     The SSL configuration to use.
3298   * \param sig_algs List of allowed IANA values for TLS 1.3 signature algorithms,
3299   *                 terminated by \c MBEDTLS_TLS13_SIG_NONE. The list must remain
3300   *                 available throughout the lifetime of the conf object. Supported
3301   *                 values are available as \c MBEDTLS_TLS13_SIG_XXXX
3302   */
3303  void mbedtls_ssl_conf_sig_algs( mbedtls_ssl_config *conf,
3304                                  const uint16_t* sig_algs );
3305  #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
3306  #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
3307  
3308  #if defined(MBEDTLS_X509_CRT_PARSE_C)
3309  /**
3310   * \brief          Set or reset the hostname to check against the received
3311   *                 server certificate. It sets the ServerName TLS extension,
3312   *                 too, if that extension is enabled. (client-side only)
3313   *
3314   * \param ssl      SSL context
3315   * \param hostname the server hostname, may be NULL to clear hostname
3316  
3317   * \note           Maximum hostname length MBEDTLS_SSL_MAX_HOST_NAME_LEN.
3318   *
3319   * \return         0 if successful, MBEDTLS_ERR_SSL_ALLOC_FAILED on
3320   *                 allocation failure, MBEDTLS_ERR_SSL_BAD_INPUT_DATA on
3321   *                 too long input hostname.
3322   *
3323   *                 Hostname set to the one provided on success (cleared
3324   *                 when NULL). On allocation failure hostname is cleared.
3325   *                 On too long input failure, old hostname is unchanged.
3326   */
3327  int mbedtls_ssl_set_hostname( mbedtls_ssl_context *ssl, const char *hostname );
3328  #endif /* MBEDTLS_X509_CRT_PARSE_C */
3329  
3330  #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
3331  /**
3332   * \brief          Set own certificate and key for the current handshake
3333   *
3334   * \note           Same as \c mbedtls_ssl_conf_own_cert() but for use within
3335   *                 the SNI callback.
3336   *
3337   * \param ssl      SSL context
3338   * \param own_cert own public certificate chain
3339   * \param pk_key   own private key
3340   *
3341   * \return         0 on success or MBEDTLS_ERR_SSL_ALLOC_FAILED
3342   */
3343  int mbedtls_ssl_set_hs_own_cert( mbedtls_ssl_context *ssl,
3344                                   mbedtls_x509_crt *own_cert,
3345                                   mbedtls_pk_context *pk_key );
3346  
3347  /**
3348   * \brief          Set the data required to verify peer certificate for the
3349   *                 current handshake
3350   *
3351   * \note           Same as \c mbedtls_ssl_conf_ca_chain() but for use within
3352   *                 the SNI callback.
3353   *
3354   * \param ssl      SSL context
3355   * \param ca_chain trusted CA chain (meaning all fully trusted top-level CAs)
3356   * \param ca_crl   trusted CA CRLs
3357   */
3358  void mbedtls_ssl_set_hs_ca_chain( mbedtls_ssl_context *ssl,
3359                                    mbedtls_x509_crt *ca_chain,
3360                                    mbedtls_x509_crl *ca_crl );
3361  
3362  /**
3363   * \brief          Set authmode for the current handshake.
3364   *
3365   * \note           Same as \c mbedtls_ssl_conf_authmode() but for use within
3366   *                 the SNI callback.
3367   *
3368   * \param ssl      SSL context
3369   * \param authmode MBEDTLS_SSL_VERIFY_NONE, MBEDTLS_SSL_VERIFY_OPTIONAL or
3370   *                 MBEDTLS_SSL_VERIFY_REQUIRED
3371   */
3372  void mbedtls_ssl_set_hs_authmode( mbedtls_ssl_context *ssl,
3373                                    int authmode );
3374  
3375  /**
3376   * \brief          Set server side ServerName TLS extension callback
3377   *                 (optional, server-side only).
3378   *
3379   *                 If set, the ServerName callback is called whenever the
3380   *                 server receives a ServerName TLS extension from the client
3381   *                 during a handshake. The ServerName callback has the
3382   *                 following parameters: (void *parameter, mbedtls_ssl_context *ssl,
3383   *                 const unsigned char *hostname, size_t len). If a suitable
3384   *                 certificate is found, the callback must set the
3385   *                 certificate(s) and key(s) to use with \c
3386   *                 mbedtls_ssl_set_hs_own_cert() (can be called repeatedly),
3387   *                 and may optionally adjust the CA and associated CRL with \c
3388   *                 mbedtls_ssl_set_hs_ca_chain() as well as the client
3389   *                 authentication mode with \c mbedtls_ssl_set_hs_authmode(),
3390   *                 then must return 0. If no matching name is found, the
3391   *                 callback must either set a default cert, or
3392   *                 return non-zero to abort the handshake at this point.
3393   *
3394   * \param conf     SSL configuration
3395   * \param f_sni    verification function
3396   * \param p_sni    verification parameter
3397   */
3398  void mbedtls_ssl_conf_sni( mbedtls_ssl_config *conf,
3399                    int (*f_sni)(void *, mbedtls_ssl_context *, const unsigned char *,
3400                                 size_t),
3401                    void *p_sni );
3402  #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
3403  
3404  #if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
3405  /**
3406   * \brief          Set the EC J-PAKE password for current handshake.
3407   *
3408   * \note           An internal copy is made, and destroyed as soon as the
3409   *                 handshake is completed, or when the SSL context is reset or
3410   *                 freed.
3411   *
3412   * \note           The SSL context needs to be already set up. The right place
3413   *                 to call this function is between \c mbedtls_ssl_setup() or
3414   *                 \c mbedtls_ssl_reset() and \c mbedtls_ssl_handshake().
3415   *
3416   * \param ssl      SSL context
3417   * \param pw       EC J-PAKE password (pre-shared secret)
3418   * \param pw_len   length of pw in bytes
3419   *
3420   * \return         0 on success, or a negative error code.
3421   */
3422  int mbedtls_ssl_set_hs_ecjpake_password( mbedtls_ssl_context *ssl,
3423                                           const unsigned char *pw,
3424                                           size_t pw_len );
3425  #endif /*MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
3426  
3427  #if defined(MBEDTLS_SSL_ALPN)
3428  /**
3429   * \brief          Set the supported Application Layer Protocols.
3430   *
3431   * \param conf     SSL configuration
3432   * \param protos   Pointer to a NULL-terminated list of supported protocols,
3433   *                 in decreasing preference order. The pointer to the list is
3434   *                 recorded by the library for later reference as required, so
3435   *                 the lifetime of the table must be atleast as long as the
3436   *                 lifetime of the SSL configuration structure.
3437   *
3438   * \return         0 on success, or MBEDTLS_ERR_SSL_BAD_INPUT_DATA.
3439   */
3440  int mbedtls_ssl_conf_alpn_protocols( mbedtls_ssl_config *conf, const char **protos );
3441  
3442  /**
3443   * \brief          Get the name of the negotiated Application Layer Protocol.
3444   *                 This function should be called after the handshake is
3445   *                 completed.
3446   *
3447   * \param ssl      SSL context
3448   *
3449   * \return         Protcol name, or NULL if no protocol was negotiated.
3450   */
3451  const char *mbedtls_ssl_get_alpn_protocol( const mbedtls_ssl_context *ssl );
3452  #endif /* MBEDTLS_SSL_ALPN */
3453  
3454  #if defined(MBEDTLS_SSL_DTLS_SRTP)
3455  #if defined(MBEDTLS_DEBUG_C)
mbedtls_ssl_get_srtp_profile_as_string(mbedtls_ssl_srtp_profile profile)3456  static inline const char *mbedtls_ssl_get_srtp_profile_as_string( mbedtls_ssl_srtp_profile profile )
3457  {
3458      switch( profile )
3459      {
3460          case MBEDTLS_TLS_SRTP_AES128_CM_HMAC_SHA1_80:
3461              return( "MBEDTLS_TLS_SRTP_AES128_CM_HMAC_SHA1_80" );
3462          case MBEDTLS_TLS_SRTP_AES128_CM_HMAC_SHA1_32:
3463              return( "MBEDTLS_TLS_SRTP_AES128_CM_HMAC_SHA1_32" );
3464          case MBEDTLS_TLS_SRTP_NULL_HMAC_SHA1_80:
3465              return( "MBEDTLS_TLS_SRTP_NULL_HMAC_SHA1_80" );
3466          case MBEDTLS_TLS_SRTP_NULL_HMAC_SHA1_32:
3467              return( "MBEDTLS_TLS_SRTP_NULL_HMAC_SHA1_32" );
3468          default: break;
3469      }
3470      return( "" );
3471  }
3472  #endif /* MBEDTLS_DEBUG_C */
3473  /**
3474   * \brief                   Manage support for mki(master key id) value
3475   *                          in use_srtp extension.
3476   *                          MKI is an optional part of SRTP used for key management
3477   *                          and re-keying. See RFC3711 section 3.1 for details.
3478   *                          The default value is
3479   *                          #MBEDTLS_SSL_DTLS_SRTP_MKI_UNSUPPORTED.
3480   *
3481   * \param conf              The SSL configuration to manage mki support.
3482   * \param support_mki_value Enable or disable mki usage. Values are
3483   *                          #MBEDTLS_SSL_DTLS_SRTP_MKI_UNSUPPORTED
3484   *                          or #MBEDTLS_SSL_DTLS_SRTP_MKI_SUPPORTED.
3485   */
3486  void mbedtls_ssl_conf_srtp_mki_value_supported( mbedtls_ssl_config *conf,
3487                                                  int support_mki_value );
3488  
3489  /**
3490   * \brief                   Set the supported DTLS-SRTP protection profiles.
3491   *
3492   * \param conf              SSL configuration
3493   * \param profiles          Pointer to a List of MBEDTLS_TLS_SRTP_UNSET terminated
3494   *                          supported protection profiles
3495   *                          in decreasing preference order.
3496   *                          The pointer to the list is recorded by the library
3497   *                          for later reference as required, so the lifetime
3498   *                          of the table must be at least as long as the lifetime
3499   *                          of the SSL configuration structure.
3500   *                          The list must not hold more than
3501   *                          MBEDTLS_TLS_SRTP_MAX_PROFILE_LIST_LENGTH elements
3502   *                          (excluding the terminating MBEDTLS_TLS_SRTP_UNSET).
3503   *
3504   * \return                  0 on success
3505   * \return                  #MBEDTLS_ERR_SSL_BAD_INPUT_DATA when the list of
3506   *                          protection profiles is incorrect.
3507   */
3508  int mbedtls_ssl_conf_dtls_srtp_protection_profiles
3509                                 ( mbedtls_ssl_config *conf,
3510                                   const mbedtls_ssl_srtp_profile *profiles );
3511  
3512  /**
3513   * \brief                  Set the mki_value for the current DTLS-SRTP session.
3514   *
3515   * \param ssl              SSL context to use.
3516   * \param mki_value        The MKI value to set.
3517   * \param mki_len          The length of the MKI value.
3518   *
3519   * \note                   This function is relevant on client side only.
3520   *                         The server discovers the mki value during handshake.
3521   *                         A mki value set on server side using this function
3522   *                         is ignored.
3523   *
3524   * \return                 0 on success
3525   * \return                 #MBEDTLS_ERR_SSL_BAD_INPUT_DATA
3526   * \return                 #MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE
3527   */
3528  int mbedtls_ssl_dtls_srtp_set_mki_value( mbedtls_ssl_context *ssl,
3529                                           unsigned char *mki_value,
3530                                           uint16_t mki_len );
3531  /**
3532   * \brief                  Get the negotiated DTLS-SRTP informations:
3533   *                         Protection profile and MKI value.
3534   *
3535   * \warning                This function must be called after the handshake is
3536   *                         completed. The value returned by this function must
3537   *                         not be trusted or acted upon before the handshake completes.
3538   *
3539   * \param ssl              The SSL context to query.
3540   * \param dtls_srtp_info   The negotiated DTLS-SRTP informations:
3541   *                         - Protection profile in use.
3542   *                         A direct mapping of the iana defined value for protection
3543   *                         profile on an uint16_t.
3544                     http://www.iana.org/assignments/srtp-protection/srtp-protection.xhtml
3545   *                         #MBEDTLS_TLS_SRTP_UNSET if the use of SRTP was not negotiated
3546   *                         or peer's Hello packet was not parsed yet.
3547   *                         - mki size and value( if size is > 0 ).
3548   */
3549  void mbedtls_ssl_get_dtls_srtp_negotiation_result( const mbedtls_ssl_context *ssl,
3550                                                     mbedtls_dtls_srtp_info *dtls_srtp_info );
3551  #endif /* MBEDTLS_SSL_DTLS_SRTP */
3552  
3553  /**
3554   * \brief          Set the maximum supported version sent from the client side
3555   *                 and/or accepted at the server side
3556   *                 (Default: MBEDTLS_SSL_MAX_MAJOR_VERSION, MBEDTLS_SSL_MAX_MINOR_VERSION)
3557   *
3558   * \note           This ignores ciphersuites from higher versions.
3559   *
3560   * \note           With DTLS, use MBEDTLS_SSL_MINOR_VERSION_3 for DTLS 1.2
3561   *
3562   * \param conf     SSL configuration
3563   * \param major    Major version number (only MBEDTLS_SSL_MAJOR_VERSION_3 supported)
3564   * \param minor    Minor version number (only MBEDTLS_SSL_MINOR_VERSION_3 supported)
3565   */
3566  void mbedtls_ssl_conf_max_version( mbedtls_ssl_config *conf, int major, int minor );
3567  
3568  /**
3569   * \brief          Set the minimum accepted SSL/TLS protocol version
3570   *                 (Default: TLS 1.2)
3571   *
3572   * \note           Input outside of the SSL_MAX_XXXXX_VERSION and
3573   *                 SSL_MIN_XXXXX_VERSION range is ignored.
3574   *
3575   * \note           With DTLS, use MBEDTLS_SSL_MINOR_VERSION_3 for DTLS 1.2
3576   *
3577   * \param conf     SSL configuration
3578   * \param major    Major version number (only MBEDTLS_SSL_MAJOR_VERSION_3 supported)
3579   * \param minor    Minor version number (only MBEDTLS_SSL_MINOR_VERSION_3 supported)
3580   */
3581  void mbedtls_ssl_conf_min_version( mbedtls_ssl_config *conf, int major, int minor );
3582  
3583  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
3584  /**
3585   * \brief           Enable or disable Encrypt-then-MAC
3586   *                  (Default: MBEDTLS_SSL_ETM_ENABLED)
3587   *
3588   * \note            This should always be enabled, it is a security
3589   *                  improvement, and should not cause any interoperability
3590   *                  issue (used only if the peer supports it too).
3591   *
3592   * \param conf      SSL configuration
3593   * \param etm       MBEDTLS_SSL_ETM_ENABLED or MBEDTLS_SSL_ETM_DISABLED
3594   */
3595  void mbedtls_ssl_conf_encrypt_then_mac( mbedtls_ssl_config *conf, char etm );
3596  #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
3597  
3598  #if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
3599  /**
3600   * \brief           Enable or disable Extended Master Secret negotiation.
3601   *                  (Default: MBEDTLS_SSL_EXTENDED_MS_ENABLED)
3602   *
3603   * \note            This should always be enabled, it is a security fix to the
3604   *                  protocol, and should not cause any interoperability issue
3605   *                  (used only if the peer supports it too).
3606   *
3607   * \param conf      SSL configuration
3608   * \param ems       MBEDTLS_SSL_EXTENDED_MS_ENABLED or MBEDTLS_SSL_EXTENDED_MS_DISABLED
3609   */
3610  void mbedtls_ssl_conf_extended_master_secret( mbedtls_ssl_config *conf, char ems );
3611  #endif /* MBEDTLS_SSL_EXTENDED_MASTER_SECRET */
3612  
3613  #if defined(MBEDTLS_SSL_SRV_C)
3614  /**
3615   * \brief          Whether to send a list of acceptable CAs in
3616   *                 CertificateRequest messages.
3617   *                 (Default: do send)
3618   *
3619   * \param conf     SSL configuration
3620   * \param cert_req_ca_list   MBEDTLS_SSL_CERT_REQ_CA_LIST_ENABLED or
3621   *                          MBEDTLS_SSL_CERT_REQ_CA_LIST_DISABLED
3622   */
3623  void mbedtls_ssl_conf_cert_req_ca_list( mbedtls_ssl_config *conf,
3624                                            char cert_req_ca_list );
3625  #endif /* MBEDTLS_SSL_SRV_C */
3626  
3627  #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
3628  /**
3629   * \brief          Set the maximum fragment length to emit and/or negotiate.
3630   *                 (Typical: the smaller of #MBEDTLS_SSL_IN_CONTENT_LEN and
3631   *                 #MBEDTLS_SSL_OUT_CONTENT_LEN, usually `2^14` bytes)
3632   *                 (Server: set maximum fragment length to emit,
3633   *                 usually negotiated by the client during handshake)
3634   *                 (Client: set maximum fragment length to emit *and*
3635   *                 negotiate with the server during handshake)
3636   *                 (Default: #MBEDTLS_SSL_MAX_FRAG_LEN_NONE)
3637   *
3638   * \note           On the client side, the maximum fragment length extension
3639   *                 *will not* be used, unless the maximum fragment length has
3640   *                 been set via this function to a value different than
3641   *                 #MBEDTLS_SSL_MAX_FRAG_LEN_NONE.
3642   *
3643   * \note           With TLS, this currently only affects ApplicationData (sent
3644   *                 with \c mbedtls_ssl_read()), not handshake messages.
3645   *                 With DTLS, this affects both ApplicationData and handshake.
3646   *
3647   * \note           This sets the maximum length for a record's payload,
3648   *                 excluding record overhead that will be added to it, see
3649   *                 \c mbedtls_ssl_get_record_expansion().
3650   *
3651   * \note           For DTLS, it is also possible to set a limit for the total
3652   *                 size of daragrams passed to the transport layer, including
3653   *                 record overhead, see \c mbedtls_ssl_set_mtu().
3654   *
3655   * \param conf     SSL configuration
3656   * \param mfl_code Code for maximum fragment length (allowed values:
3657   *                 MBEDTLS_SSL_MAX_FRAG_LEN_512,  MBEDTLS_SSL_MAX_FRAG_LEN_1024,
3658   *                 MBEDTLS_SSL_MAX_FRAG_LEN_2048, MBEDTLS_SSL_MAX_FRAG_LEN_4096)
3659   *
3660   * \return         0 if successful or MBEDTLS_ERR_SSL_BAD_INPUT_DATA
3661   */
3662  int mbedtls_ssl_conf_max_frag_len( mbedtls_ssl_config *conf, unsigned char mfl_code );
3663  #endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
3664  
3665  #if defined(MBEDTLS_SSL_SRV_C)
3666  /**
3667   * \brief          Pick the ciphersuites order according to the second parameter
3668   *                 in the SSL Server module (MBEDTLS_SSL_SRV_C).
3669   *                 (Default, if never called: MBEDTLS_SSL_SRV_CIPHERSUITE_ORDER_SERVER)
3670   *
3671   * \param conf     SSL configuration
3672   * \param order    Server or client (MBEDTLS_SSL_SRV_CIPHERSUITE_ORDER_SERVER
3673   *                                or MBEDTLS_SSL_SRV_CIPHERSUITE_ORDER_CLIENT)
3674   */
3675  void mbedtls_ssl_conf_preference_order( mbedtls_ssl_config *conf, int order );
3676  #endif /* MBEDTLS_SSL_SRV_C */
3677  
3678  #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
3679  /**
3680   * \brief          Enable / Disable session tickets (client only).
3681   *                 (Default: MBEDTLS_SSL_SESSION_TICKETS_ENABLED.)
3682   *
3683   * \note           On server, use \c mbedtls_ssl_conf_session_tickets_cb().
3684   *
3685   * \param conf     SSL configuration
3686   * \param use_tickets   Enable or disable (MBEDTLS_SSL_SESSION_TICKETS_ENABLED or
3687   *                                         MBEDTLS_SSL_SESSION_TICKETS_DISABLED)
3688   */
3689  void mbedtls_ssl_conf_session_tickets( mbedtls_ssl_config *conf, int use_tickets );
3690  #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
3691  
3692  #if defined(MBEDTLS_SSL_RENEGOTIATION)
3693  /**
3694   * \brief          Enable / Disable renegotiation support for connection when
3695   *                 initiated by peer
3696   *                 (Default: MBEDTLS_SSL_RENEGOTIATION_DISABLED)
3697   *
3698   * \warning        It is recommended to always disable renegotation unless you
3699   *                 know you need it and you know what you're doing. In the
3700   *                 past, there have been several issues associated with
3701   *                 renegotiation or a poor understanding of its properties.
3702   *
3703   * \note           Server-side, enabling renegotiation also makes the server
3704   *                 susceptible to a resource DoS by a malicious client.
3705   *
3706   * \param conf    SSL configuration
3707   * \param renegotiation     Enable or disable (MBEDTLS_SSL_RENEGOTIATION_ENABLED or
3708   *                                             MBEDTLS_SSL_RENEGOTIATION_DISABLED)
3709   */
3710  void mbedtls_ssl_conf_renegotiation( mbedtls_ssl_config *conf, int renegotiation );
3711  #endif /* MBEDTLS_SSL_RENEGOTIATION */
3712  
3713  /**
3714   * \brief          Prevent or allow legacy renegotiation.
3715   *                 (Default: MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION)
3716   *
3717   *                 MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION allows connections to
3718   *                 be established even if the peer does not support
3719   *                 secure renegotiation, but does not allow renegotiation
3720   *                 to take place if not secure.
3721   *                 (Interoperable and secure option)
3722   *
3723   *                 MBEDTLS_SSL_LEGACY_ALLOW_RENEGOTIATION allows renegotiations
3724   *                 with non-upgraded peers. Allowing legacy renegotiation
3725   *                 makes the connection vulnerable to specific man in the
3726   *                 middle attacks. (See RFC 5746)
3727   *                 (Most interoperable and least secure option)
3728   *
3729   *                 MBEDTLS_SSL_LEGACY_BREAK_HANDSHAKE breaks off connections
3730   *                 if peer does not support secure renegotiation. Results
3731   *                 in interoperability issues with non-upgraded peers
3732   *                 that do not support renegotiation altogether.
3733   *                 (Most secure option, interoperability issues)
3734   *
3735   * \param conf     SSL configuration
3736   * \param allow_legacy  Prevent or allow (SSL_NO_LEGACY_RENEGOTIATION,
3737   *                                        SSL_ALLOW_LEGACY_RENEGOTIATION or
3738   *                                        MBEDTLS_SSL_LEGACY_BREAK_HANDSHAKE)
3739   */
3740  void mbedtls_ssl_conf_legacy_renegotiation( mbedtls_ssl_config *conf, int allow_legacy );
3741  
3742  #if defined(MBEDTLS_SSL_RENEGOTIATION)
3743  /**
3744   * \brief          Enforce renegotiation requests.
3745   *                 (Default: enforced, max_records = 16)
3746   *
3747   *                 When we request a renegotiation, the peer can comply or
3748   *                 ignore the request. This function allows us to decide
3749   *                 whether to enforce our renegotiation requests by closing
3750   *                 the connection if the peer doesn't comply.
3751   *
3752   *                 However, records could already be in transit from the peer
3753   *                 when the request is emitted. In order to increase
3754   *                 reliability, we can accept a number of records before the
3755   *                 expected handshake records.
3756   *
3757   *                 The optimal value is highly dependent on the specific usage
3758   *                 scenario.
3759   *
3760   * \note           With DTLS and server-initiated renegotiation, the
3761   *                 HelloRequest is retransmited every time mbedtls_ssl_read() times
3762   *                 out or receives Application Data, until:
3763   *                 - max_records records have beens seen, if it is >= 0, or
3764   *                 - the number of retransmits that would happen during an
3765   *                 actual handshake has been reached.
3766   *                 Please remember the request might be lost a few times
3767   *                 if you consider setting max_records to a really low value.
3768   *
3769   * \warning        On client, the grace period can only happen during
3770   *                 mbedtls_ssl_read(), as opposed to mbedtls_ssl_write() and mbedtls_ssl_renegotiate()
3771   *                 which always behave as if max_record was 0. The reason is,
3772   *                 if we receive application data from the server, we need a
3773   *                 place to write it, which only happens during mbedtls_ssl_read().
3774   *
3775   * \param conf     SSL configuration
3776   * \param max_records Use MBEDTLS_SSL_RENEGOTIATION_NOT_ENFORCED if you don't want to
3777   *                 enforce renegotiation, or a non-negative value to enforce
3778   *                 it but allow for a grace period of max_records records.
3779   */
3780  void mbedtls_ssl_conf_renegotiation_enforced( mbedtls_ssl_config *conf, int max_records );
3781  
3782  /**
3783   * \brief          Set record counter threshold for periodic renegotiation.
3784   *                 (Default: 2^48 - 1)
3785   *
3786   *                 Renegotiation is automatically triggered when a record
3787   *                 counter (outgoing or incoming) crosses the defined
3788   *                 threshold. The default value is meant to prevent the
3789   *                 connection from being closed when the counter is about to
3790   *                 reached its maximal value (it is not allowed to wrap).
3791   *
3792   *                 Lower values can be used to enforce policies such as "keys
3793   *                 must be refreshed every N packets with cipher X".
3794   *
3795   *                 The renegotiation period can be disabled by setting
3796   *                 conf->disable_renegotiation to
3797   *                 MBEDTLS_SSL_RENEGOTIATION_DISABLED.
3798   *
3799   * \note           When the configured transport is
3800   *                 MBEDTLS_SSL_TRANSPORT_DATAGRAM the maximum renegotiation
3801   *                 period is 2^48 - 1, and for MBEDTLS_SSL_TRANSPORT_STREAM,
3802   *                 the maximum renegotiation period is 2^64 - 1.
3803   *
3804   * \param conf     SSL configuration
3805   * \param period   The threshold value: a big-endian 64-bit number.
3806   */
3807  void mbedtls_ssl_conf_renegotiation_period( mbedtls_ssl_config *conf,
3808                                     const unsigned char period[8] );
3809  #endif /* MBEDTLS_SSL_RENEGOTIATION */
3810  
3811  /**
3812   * \brief          Check if there is data already read from the
3813   *                 underlying transport but not yet processed.
3814   *
3815   * \param ssl      SSL context
3816   *
3817   * \return         0 if nothing's pending, 1 otherwise.
3818   *
3819   * \note           This is different in purpose and behaviour from
3820   *                 \c mbedtls_ssl_get_bytes_avail in that it considers
3821   *                 any kind of unprocessed data, not only unread
3822   *                 application data. If \c mbedtls_ssl_get_bytes
3823   *                 returns a non-zero value, this function will
3824   *                 also signal pending data, but the converse does
3825   *                 not hold. For example, in DTLS there might be
3826   *                 further records waiting to be processed from
3827   *                 the current underlying transport's datagram.
3828   *
3829   * \note           If this function returns 1 (data pending), this
3830   *                 does not imply that a subsequent call to
3831   *                 \c mbedtls_ssl_read will provide any data;
3832   *                 e.g., the unprocessed data might turn out
3833   *                 to be an alert or a handshake message.
3834   *
3835   * \note           This function is useful in the following situation:
3836   *                 If the SSL/TLS module successfully returns from an
3837   *                 operation - e.g. a handshake or an application record
3838   *                 read - and you're awaiting incoming data next, you
3839   *                 must not immediately idle on the underlying transport
3840   *                 to have data ready, but you need to check the value
3841   *                 of this function first. The reason is that the desired
3842   *                 data might already be read but not yet processed.
3843   *                 If, in contrast, a previous call to the SSL/TLS module
3844   *                 returned MBEDTLS_ERR_SSL_WANT_READ, it is not necessary
3845   *                 to call this function, as the latter error code entails
3846   *                 that all internal data has been processed.
3847   *
3848   */
3849  int mbedtls_ssl_check_pending( const mbedtls_ssl_context *ssl );
3850  
3851  /**
3852   * \brief          Return the number of application data bytes
3853   *                 remaining to be read from the current record.
3854   *
3855   * \param ssl      SSL context
3856   *
3857   * \return         How many bytes are available in the application
3858   *                 data record read buffer.
3859   *
3860   * \note           When working over a datagram transport, this is
3861   *                 useful to detect the current datagram's boundary
3862   *                 in case \c mbedtls_ssl_read has written the maximal
3863   *                 amount of data fitting into the input buffer.
3864   *
3865   */
3866  size_t mbedtls_ssl_get_bytes_avail( const mbedtls_ssl_context *ssl );
3867  
3868  /**
3869   * \brief          Return the result of the certificate verification
3870   *
3871   * \param ssl      The SSL context to use.
3872   *
3873   * \return         \c 0 if the certificate verification was successful.
3874   * \return         \c -1u if the result is not available. This may happen
3875   *                 e.g. if the handshake aborts early, or a verification
3876   *                 callback returned a fatal error.
3877   * \return         A bitwise combination of \c MBEDTLS_X509_BADCERT_XXX
3878   *                 and \c MBEDTLS_X509_BADCRL_XXX failure flags; see x509.h.
3879   */
3880  uint32_t mbedtls_ssl_get_verify_result( const mbedtls_ssl_context *ssl );
3881  
3882  /**
3883   * \brief          Return the name of the current ciphersuite
3884   *
3885   * \param ssl      SSL context
3886   *
3887   * \return         a string containing the ciphersuite name
3888   */
3889  const char *mbedtls_ssl_get_ciphersuite( const mbedtls_ssl_context *ssl );
3890  
3891  /**
3892   * \brief          Return the current TLS version
3893   *
3894   * \param ssl      SSL context
3895   *
3896   * \return         a string containing the TLS version
3897   */
3898  const char *mbedtls_ssl_get_version( const mbedtls_ssl_context *ssl );
3899  
3900  /**
3901   * \brief          Return the (maximum) number of bytes added by the record
3902   *                 layer: header + encryption/MAC overhead (inc. padding)
3903   *
3904   * \param ssl      SSL context
3905   *
3906   * \return         Current maximum record expansion in bytes
3907   */
3908  int mbedtls_ssl_get_record_expansion( const mbedtls_ssl_context *ssl );
3909  
3910  /**
3911   * \brief          Return the current maximum outgoing record payload in bytes.
3912   *
3913   * \note           The logic to determine the maximum outgoing record payload is
3914   *                 version-specific. It takes into account various factors, such as
3915   *                 the mbedtls_config.h setting \c MBEDTLS_SSL_OUT_CONTENT_LEN, extensions
3916   *                 such as the max fragment length or record size limit extension if
3917   *                 used, and for DTLS the path MTU as configured and current
3918   *                 record expansion.
3919   *
3920   * \note           With DTLS, \c mbedtls_ssl_write() will return an error if
3921   *                 called with a larger length value.
3922   *                 With TLS, \c mbedtls_ssl_write() will fragment the input if
3923   *                 necessary and return the number of bytes written; it is up
3924   *                 to the caller to call \c mbedtls_ssl_write() again in
3925   *                 order to send the remaining bytes if any.
3926   *
3927   * \sa             mbedtls_ssl_get_max_out_record_payload()
3928   * \sa             mbedtls_ssl_get_record_expansion()
3929   *
3930   * \param ssl      SSL context
3931   *
3932   * \return         Current maximum payload for an outgoing record,
3933   *                 or a negative error code.
3934   */
3935  int mbedtls_ssl_get_max_out_record_payload( const mbedtls_ssl_context *ssl );
3936  
3937  /**
3938   * \brief          Return the current maximum incoming record payload in bytes.
3939   *
3940   * \note           The logic to determine the maximum outgoing record payload is
3941   *                 version-specific. It takes into account various factors, such as
3942   *                 the mbedtls_config.h setting \c MBEDTLS_SSL_IN_CONTENT_LEN, extensions
3943   *                 such as the max fragment length extension or record size limit
3944   *                 extension if used, and the current record expansion.
3945   *
3946   * \sa             mbedtls_ssl_set_mtu()
3947   * \sa             mbedtls_ssl_get_max_in_record_payload()
3948   * \sa             mbedtls_ssl_get_record_expansion()
3949   *
3950   * \param ssl      SSL context
3951   *
3952   * \return         Current maximum payload for an outgoing record,
3953   *                 or a negative error code.
3954   */
3955  int mbedtls_ssl_get_max_in_record_payload( const mbedtls_ssl_context *ssl );
3956  
3957  #if defined(MBEDTLS_X509_CRT_PARSE_C)
3958  /**
3959   * \brief          Return the peer certificate from the current connection.
3960   *
3961   * \param  ssl     The SSL context to use. This must be initialized and setup.
3962   *
3963   * \return         The current peer certificate, if available.
3964   *                 The returned certificate is owned by the SSL context and
3965   *                 is valid only until the next call to the SSL API.
3966   * \return         \c NULL if no peer certificate is available. This might
3967   *                 be because the chosen ciphersuite doesn't use CRTs
3968   *                 (PSK-based ciphersuites, for example), or because
3969   *                 #MBEDTLS_SSL_KEEP_PEER_CERTIFICATE has been disabled,
3970   *                 allowing the stack to free the peer's CRT to save memory.
3971   *
3972   * \note           For one-time inspection of the peer's certificate during
3973   *                 the handshake, consider registering an X.509 CRT verification
3974   *                 callback through mbedtls_ssl_conf_verify() instead of calling
3975   *                 this function. Using mbedtls_ssl_conf_verify() also comes at
3976   *                 the benefit of allowing you to influence the verification
3977   *                 process, for example by masking expected and tolerated
3978   *                 verification failures.
3979   *
3980   * \warning        You must not use the pointer returned by this function
3981   *                 after any further call to the SSL API, including
3982   *                 mbedtls_ssl_read() and mbedtls_ssl_write(); this is
3983   *                 because the pointer might change during renegotiation,
3984   *                 which happens transparently to the user.
3985   *                 If you want to use the certificate across API calls,
3986   *                 you must make a copy.
3987   */
3988  const mbedtls_x509_crt *mbedtls_ssl_get_peer_cert( const mbedtls_ssl_context *ssl );
3989  #endif /* MBEDTLS_X509_CRT_PARSE_C */
3990  
3991  #if defined(MBEDTLS_SSL_CLI_C)
3992  /**
3993   * \brief          Export a session in order to resume it later.
3994   *
3995   * \param ssl      The SSL context representing the connection for which to
3996   *                 to export a session structure for later resumption.
3997   * \param session  The target structure in which to store the exported session.
3998   *                 This must have been initialized with mbedtls_ssl_init_session()
3999   *                 but otherwise be unused.
4000   *
4001   * \note           This function can handle a variety of mechanisms for session
4002   *                 resumption: For TLS 1.2, both session ID-based resumption and
4003   *                 ticket-based resumption will be considered. For TLS 1.3,
4004   *                 once implemented, sessions equate to tickets, and calling
4005   *                 this function multiple times will export the available
4006   *                 tickets one a time until no further tickets are available,
4007   *                 in which case MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE will
4008   *                 be returned.
4009   *
4010   * \note           Calling this function multiple times will only be useful
4011   *                 once TLS 1.3 is supported. For TLS 1.2 connections, this
4012   *                 function should be called at most once.
4013   *
4014   * \return         \c 0 if successful. In this case, \p session can be used for
4015   *                 session resumption by passing it to mbedtls_ssl_set_session(),
4016   *                 and serialized for storage via mbedtls_ssl_session_save().
4017   * \return         #MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE if no further session
4018   *                 is available for export.
4019   *                 This error is a non-fatal, and has no observable effect on
4020   *                 the SSL context or the destination session.
4021   * \return         Another negative error code on other kinds of failure.
4022   *
4023   * \sa             mbedtls_ssl_set_session()
4024   * \sa             mbedtls_ssl_session_save()
4025   */
4026  int mbedtls_ssl_get_session( const mbedtls_ssl_context *ssl,
4027                               mbedtls_ssl_session *session );
4028  #endif /* MBEDTLS_SSL_CLI_C */
4029  
4030  /**
4031   * \brief          Perform the SSL handshake
4032   *
4033   * \param ssl      SSL context
4034   *
4035   * \return         \c 0 if successful.
4036   * \return         #MBEDTLS_ERR_SSL_WANT_READ or #MBEDTLS_ERR_SSL_WANT_WRITE
4037   *                 if the handshake is incomplete and waiting for data to
4038   *                 be available for reading from or writing to the underlying
4039   *                 transport - in this case you must call this function again
4040   *                 when the underlying transport is ready for the operation.
4041   * \return         #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS if an asynchronous
4042   *                 operation is in progress (see
4043   *                 mbedtls_ssl_conf_async_private_cb()) - in this case you
4044   *                 must call this function again when the operation is ready.
4045   * \return         #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS if a cryptographic
4046   *                 operation is in progress (see mbedtls_ecp_set_max_ops()) -
4047   *                 in this case you must call this function again to complete
4048   *                 the handshake when you're done attending other tasks.
4049   * \return         #MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED if DTLS is in use
4050   *                 and the client did not demonstrate reachability yet - in
4051   *                 this case you must stop using the context (see below).
4052   * \return         Another SSL error code - in this case you must stop using
4053   *                 the context (see below).
4054   *
4055   * \warning        If this function returns something other than
4056   *                 \c 0,
4057   *                 #MBEDTLS_ERR_SSL_WANT_READ,
4058   *                 #MBEDTLS_ERR_SSL_WANT_WRITE,
4059   *                 #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS or
4060   *                 #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS,
4061   *                 you must stop using the SSL context for reading or writing,
4062   *                 and either free it or call \c mbedtls_ssl_session_reset()
4063   *                 on it before re-using it for a new connection; the current
4064   *                 connection must be closed.
4065   *
4066   * \note           If DTLS is in use, then you may choose to handle
4067   *                 #MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED specially for logging
4068   *                 purposes, as it is an expected return value rather than an
4069   *                 actual error, but you still need to reset/free the context.
4070   *
4071   * \note           Remarks regarding event-driven DTLS:
4072   *                 If the function returns #MBEDTLS_ERR_SSL_WANT_READ, no datagram
4073   *                 from the underlying transport layer is currently being processed,
4074   *                 and it is safe to idle until the timer or the underlying transport
4075   *                 signal a new event. This is not true for a successful handshake,
4076   *                 in which case the datagram of the underlying transport that is
4077   *                 currently being processed might or might not contain further
4078   *                 DTLS records.
4079   */
4080  int mbedtls_ssl_handshake( mbedtls_ssl_context *ssl );
4081  
4082  /**
4083   * \brief          Perform a single step of the SSL handshake
4084   *
4085   * \note           The state of the context (ssl->state) will be at
4086   *                 the next state after this function returns \c 0. Do not
4087   *                 call this function if state is MBEDTLS_SSL_HANDSHAKE_OVER.
4088   *
4089   * \param ssl      SSL context
4090   *
4091   * \return         See mbedtls_ssl_handshake().
4092   *
4093   * \warning        If this function returns something other than \c 0,
4094   *                 #MBEDTLS_ERR_SSL_WANT_READ, #MBEDTLS_ERR_SSL_WANT_WRITE,
4095   *                 #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS or
4096   *                 #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS, you must stop using
4097   *                 the SSL context for reading or writing, and either free it
4098   *                 or call \c mbedtls_ssl_session_reset() on it before
4099   *                 re-using it for a new connection; the current connection
4100   *                 must be closed.
4101   */
4102  int mbedtls_ssl_handshake_step( mbedtls_ssl_context *ssl );
4103  
4104  #if defined(MBEDTLS_SSL_RENEGOTIATION)
4105  /**
4106   * \brief          Initiate an SSL renegotiation on the running connection.
4107   *                 Client: perform the renegotiation right now.
4108   *                 Server: request renegotiation, which will be performed
4109   *                 during the next call to mbedtls_ssl_read() if honored by
4110   *                 client.
4111   *
4112   * \param ssl      SSL context
4113   *
4114   * \return         0 if successful, or any mbedtls_ssl_handshake() return
4115   *                 value except #MBEDTLS_ERR_SSL_CLIENT_RECONNECT that can't
4116   *                 happen during a renegotiation.
4117   *
4118   * \warning        If this function returns something other than \c 0,
4119   *                 #MBEDTLS_ERR_SSL_WANT_READ, #MBEDTLS_ERR_SSL_WANT_WRITE,
4120   *                 #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS or
4121   *                 #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS, you must stop using
4122   *                 the SSL context for reading or writing, and either free it
4123   *                 or call \c mbedtls_ssl_session_reset() on it before
4124   *                 re-using it for a new connection; the current connection
4125   *                 must be closed.
4126   *
4127   */
4128  int mbedtls_ssl_renegotiate( mbedtls_ssl_context *ssl );
4129  #endif /* MBEDTLS_SSL_RENEGOTIATION */
4130  
4131  /**
4132   * \brief          Read at most 'len' application data bytes
4133   *
4134   * \param ssl      SSL context
4135   * \param buf      buffer that will hold the data
4136   * \param len      maximum number of bytes to read
4137   *
4138   * \return         The (positive) number of bytes read if successful.
4139   * \return         \c 0 if the read end of the underlying transport was closed
4140   *                 without sending a CloseNotify beforehand, which might happen
4141   *                 because of various reasons (internal error of an underlying
4142   *                 stack, non-conformant peer not sending a CloseNotify and
4143   *                 such) - in this case you must stop using the context
4144   *                 (see below).
4145   * \return         #MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY if the underlying
4146   *                 transport is still functional, but the peer has
4147   *                 acknowledged to not send anything anymore.
4148   * \return         #MBEDTLS_ERR_SSL_WANT_READ or #MBEDTLS_ERR_SSL_WANT_WRITE
4149   *                 if the handshake is incomplete and waiting for data to
4150   *                 be available for reading from or writing to the underlying
4151   *                 transport - in this case you must call this function again
4152   *                 when the underlying transport is ready for the operation.
4153   * \return         #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS if an asynchronous
4154   *                 operation is in progress (see
4155   *                 mbedtls_ssl_conf_async_private_cb()) - in this case you
4156   *                 must call this function again when the operation is ready.
4157   * \return         #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS if a cryptographic
4158   *                 operation is in progress (see mbedtls_ecp_set_max_ops()) -
4159   *                 in this case you must call this function again to complete
4160   *                 the handshake when you're done attending other tasks.
4161   * \return         #MBEDTLS_ERR_SSL_CLIENT_RECONNECT if we're at the server
4162   *                 side of a DTLS connection and the client is initiating a
4163   *                 new connection using the same source port. See below.
4164   * \return         Another SSL error code - in this case you must stop using
4165   *                 the context (see below).
4166   *
4167   * \warning        If this function returns something other than
4168   *                 a positive value,
4169   *                 #MBEDTLS_ERR_SSL_WANT_READ,
4170   *                 #MBEDTLS_ERR_SSL_WANT_WRITE,
4171   *                 #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS,
4172   *                 #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS or
4173   *                 #MBEDTLS_ERR_SSL_CLIENT_RECONNECT,
4174   *                 you must stop using the SSL context for reading or writing,
4175   *                 and either free it or call \c mbedtls_ssl_session_reset()
4176   *                 on it before re-using it for a new connection; the current
4177   *                 connection must be closed.
4178   *
4179   * \note           When this function returns #MBEDTLS_ERR_SSL_CLIENT_RECONNECT
4180   *                 (which can only happen server-side), it means that a client
4181   *                 is initiating a new connection using the same source port.
4182   *                 You can either treat that as a connection close and wait
4183   *                 for the client to resend a ClientHello, or directly
4184   *                 continue with \c mbedtls_ssl_handshake() with the same
4185   *                 context (as it has been reset internally). Either way, you
4186   *                 must make sure this is seen by the application as a new
4187   *                 connection: application state, if any, should be reset, and
4188   *                 most importantly the identity of the client must be checked
4189   *                 again. WARNING: not validating the identity of the client
4190   *                 again, or not transmitting the new identity to the
4191   *                 application layer, would allow authentication bypass!
4192   *
4193   * \note           Remarks regarding event-driven DTLS:
4194   *                 - If the function returns #MBEDTLS_ERR_SSL_WANT_READ, no datagram
4195   *                   from the underlying transport layer is currently being processed,
4196   *                   and it is safe to idle until the timer or the underlying transport
4197   *                   signal a new event.
4198   *                 - This function may return MBEDTLS_ERR_SSL_WANT_READ even if data was
4199   *                   initially available on the underlying transport, as this data may have
4200   *                   been only e.g. duplicated messages or a renegotiation request.
4201   *                   Therefore, you must be prepared to receive MBEDTLS_ERR_SSL_WANT_READ even
4202   *                   when reacting to an incoming-data event from the underlying transport.
4203   *                 - On success, the datagram of the underlying transport that is currently
4204   *                   being processed may contain further DTLS records. You should call
4205   *                   \c mbedtls_ssl_check_pending to check for remaining records.
4206   *
4207   */
4208  int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len );
4209  
4210  /**
4211   * \brief          Try to write exactly 'len' application data bytes
4212   *
4213   * \warning        This function will do partial writes in some cases. If the
4214   *                 return value is non-negative but less than length, the
4215   *                 function must be called again with updated arguments:
4216   *                 buf + ret, len - ret (if ret is the return value) until
4217   *                 it returns a value equal to the last 'len' argument.
4218   *
4219   * \param ssl      SSL context
4220   * \param buf      buffer holding the data
4221   * \param len      how many bytes must be written
4222   *
4223   * \return         The (non-negative) number of bytes actually written if
4224   *                 successful (may be less than \p len).
4225   * \return         #MBEDTLS_ERR_SSL_WANT_READ or #MBEDTLS_ERR_SSL_WANT_WRITE
4226   *                 if the handshake is incomplete and waiting for data to
4227   *                 be available for reading from or writing to the underlying
4228   *                 transport - in this case you must call this function again
4229   *                 when the underlying transport is ready for the operation.
4230   * \return         #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS if an asynchronous
4231   *                 operation is in progress (see
4232   *                 mbedtls_ssl_conf_async_private_cb()) - in this case you
4233   *                 must call this function again when the operation is ready.
4234   * \return         #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS if a cryptographic
4235   *                 operation is in progress (see mbedtls_ecp_set_max_ops()) -
4236   *                 in this case you must call this function again to complete
4237   *                 the handshake when you're done attending other tasks.
4238   * \return         Another SSL error code - in this case you must stop using
4239   *                 the context (see below).
4240   *
4241   * \warning        If this function returns something other than
4242   *                 a non-negative value,
4243   *                 #MBEDTLS_ERR_SSL_WANT_READ,
4244   *                 #MBEDTLS_ERR_SSL_WANT_WRITE,
4245   *                 #MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS or
4246   *                 #MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS,
4247   *                 you must stop using the SSL context for reading or writing,
4248   *                 and either free it or call \c mbedtls_ssl_session_reset()
4249   *                 on it before re-using it for a new connection; the current
4250   *                 connection must be closed.
4251   *
4252   * \note           When this function returns #MBEDTLS_ERR_SSL_WANT_WRITE/READ,
4253   *                 it must be called later with the *same* arguments,
4254   *                 until it returns a value greater that or equal to 0. When
4255   *                 the function returns #MBEDTLS_ERR_SSL_WANT_WRITE there may be
4256   *                 some partial data in the output buffer, however this is not
4257   *                 yet sent.
4258   *
4259   * \note           If the requested length is greater than the maximum
4260   *                 fragment length (either the built-in limit or the one set
4261   *                 or negotiated with the peer), then:
4262   *                 - with TLS, less bytes than requested are written.
4263   *                 - with DTLS, MBEDTLS_ERR_SSL_BAD_INPUT_DATA is returned.
4264   *                 \c mbedtls_ssl_get_max_out_record_payload() may be used to
4265   *                 query the active maximum fragment length.
4266   *
4267   * \note           Attempting to write 0 bytes will result in an empty TLS
4268   *                 application record being sent.
4269   */
4270  int mbedtls_ssl_write( mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len );
4271  
4272  /**
4273   * \brief           Send an alert message
4274   *
4275   * \param ssl       SSL context
4276   * \param level     The alert level of the message
4277   *                  (MBEDTLS_SSL_ALERT_LEVEL_WARNING or MBEDTLS_SSL_ALERT_LEVEL_FATAL)
4278   * \param message   The alert message (SSL_ALERT_MSG_*)
4279   *
4280   * \return          0 if successful, or a specific SSL error code.
4281   *
4282   * \note           If this function returns something other than 0 or
4283   *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
4284   *                 the SSL context for reading or writing, and either free it or
4285   *                 call \c mbedtls_ssl_session_reset() on it before re-using it
4286   *                 for a new connection; the current connection must be closed.
4287   */
4288  int mbedtls_ssl_send_alert_message( mbedtls_ssl_context *ssl,
4289                              unsigned char level,
4290                              unsigned char message );
4291  /**
4292   * \brief          Notify the peer that the connection is being closed
4293   *
4294   * \param ssl      SSL context
4295   *
4296   * \return          0 if successful, or a specific SSL error code.
4297   *
4298   * \note           If this function returns something other than 0 or
4299   *                 MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
4300   *                 the SSL context for reading or writing, and either free it or
4301   *                 call \c mbedtls_ssl_session_reset() on it before re-using it
4302   *                 for a new connection; the current connection must be closed.
4303   */
4304  int mbedtls_ssl_close_notify( mbedtls_ssl_context *ssl );
4305  
4306  /**
4307   * \brief          Free referenced items in an SSL context and clear memory
4308   *
4309   * \param ssl      SSL context
4310   */
4311  void mbedtls_ssl_free( mbedtls_ssl_context *ssl );
4312  
4313  #if defined(MBEDTLS_SSL_CONTEXT_SERIALIZATION)
4314  /**
4315   * \brief          Save an active connection as serialized data in a buffer.
4316   *                 This allows the freeing or re-using of the SSL context
4317   *                 while still picking up the connection later in a way that
4318   *                 it entirely transparent to the peer.
4319   *
4320   * \see            mbedtls_ssl_context_load()
4321   *
4322   * \note           This feature is currently only available under certain
4323   *                 conditions, see the documentation of the return value
4324   *                 #MBEDTLS_ERR_SSL_BAD_INPUT_DATA for details.
4325   *
4326   * \note           When this function succeeds, it calls
4327   *                 mbedtls_ssl_session_reset() on \p ssl which as a result is
4328   *                 no longer associated with the connection that has been
4329   *                 serialized. This avoids creating copies of the connection
4330   *                 state. You're then free to either re-use the context
4331   *                 structure for a different connection, or call
4332   *                 mbedtls_ssl_free() on it. See the documentation of
4333   *                 mbedtls_ssl_session_reset() for more details.
4334   *
4335   * \param ssl      The SSL context to save. On success, it is no longer
4336   *                 associated with the connection that has been serialized.
4337   * \param buf      The buffer to write the serialized data to. It must be a
4338   *                 writeable buffer of at least \p buf_len bytes, or may be \c
4339   *                 NULL if \p buf_len is \c 0.
4340   * \param buf_len  The number of bytes available for writing in \p buf.
4341   * \param olen     The size in bytes of the data that has been or would have
4342   *                 been written. It must point to a valid \c size_t.
4343   *
4344   * \note           \p olen is updated to the correct value regardless of
4345   *                 whether \p buf_len was large enough. This makes it possible
4346   *                 to determine the necessary size by calling this function
4347   *                 with \p buf set to \c NULL and \p buf_len to \c 0. However,
4348   *                 the value of \p olen is only guaranteed to be correct when
4349   *                 the function returns #MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL or
4350   *                 \c 0. If the return value is different, then the value of
4351   *                 \p olen is undefined.
4352   *
4353   * \return         \c 0 if successful.
4354   * \return         #MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL if \p buf is too small.
4355   * \return         #MBEDTLS_ERR_SSL_ALLOC_FAILED if memory allocation failed
4356   *                 while reseting the context.
4357   * \return         #MBEDTLS_ERR_SSL_BAD_INPUT_DATA if a handshake is in
4358   *                 progress, or there is pending data for reading or sending,
4359   *                 or the connection does not use DTLS 1.2 with an AEAD
4360   *                 ciphersuite, or renegotiation is enabled.
4361   */
4362  int mbedtls_ssl_context_save( mbedtls_ssl_context *ssl,
4363                                unsigned char *buf,
4364                                size_t buf_len,
4365                                size_t *olen );
4366  
4367  /**
4368   * \brief          Load serialized connection data to an SSL context.
4369   *
4370   * \see            mbedtls_ssl_context_save()
4371   *
4372   * \warning        The same serialized data must never be loaded into more
4373   *                 that one context. In order to ensure that, after
4374   *                 successfully loading serialized data to an SSL context, you
4375   *                 should immediately destroy or invalidate all copies of the
4376   *                 serialized data that was loaded. Loading the same data in
4377   *                 more than one context would cause severe security failures
4378   *                 including but not limited to loss of confidentiality.
4379   *
4380   * \note           Before calling this function, the SSL context must be
4381   *                 prepared in one of the two following ways. The first way is
4382   *                 to take a context freshly initialised with
4383   *                 mbedtls_ssl_init() and call mbedtls_ssl_setup() on it with
4384   *                 the same ::mbedtls_ssl_config structure that was used in
4385   *                 the original connection. The second way is to
4386   *                 call mbedtls_ssl_session_reset() on a context that was
4387   *                 previously prepared as above but used in the meantime.
4388   *                 Either way, you must not use the context to perform a
4389   *                 handshake between calling mbedtls_ssl_setup() or
4390   *                 mbedtls_ssl_session_reset() and calling this function. You
4391   *                 may however call other setter functions in that time frame
4392   *                 as indicated in the note below.
4393   *
4394   * \note           Before or after calling this function successfully, you
4395   *                 also need to configure some connection-specific callbacks
4396   *                 and settings before you can use the connection again
4397   *                 (unless they were already set before calling
4398   *                 mbedtls_ssl_session_reset() and the values are suitable for
4399   *                 the present connection). Specifically, you want to call
4400   *                 at least mbedtls_ssl_set_bio() and
4401   *                 mbedtls_ssl_set_timer_cb(). All other SSL setter functions
4402   *                 are not necessary to call, either because they're only used
4403   *                 in handshakes, or because the setting is already saved. You
4404   *                 might choose to call them anyway, for example in order to
4405   *                 share code between the cases of establishing a new
4406   *                 connection and the case of loading an already-established
4407   *                 connection.
4408   *
4409   * \note           If you have new information about the path MTU, you want to
4410   *                 call mbedtls_ssl_set_mtu() after calling this function, as
4411   *                 otherwise this function would overwrite your
4412   *                 newly-configured value with the value that was active when
4413   *                 the context was saved.
4414   *
4415   * \note           When this function returns an error code, it calls
4416   *                 mbedtls_ssl_free() on \p ssl. In this case, you need to
4417   *                 prepare the context with the usual sequence starting with a
4418   *                 call to mbedtls_ssl_init() if you want to use it again.
4419   *
4420   * \param ssl      The SSL context structure to be populated. It must have
4421   *                 been prepared as described in the note above.
4422   * \param buf      The buffer holding the serialized connection data. It must
4423   *                 be a readable buffer of at least \p len bytes.
4424   * \param len      The size of the serialized data in bytes.
4425   *
4426   * \return         \c 0 if successful.
4427   * \return         #MBEDTLS_ERR_SSL_ALLOC_FAILED if memory allocation failed.
4428   * \return         #MBEDTLS_ERR_SSL_VERSION_MISMATCH if the serialized data
4429   *                 comes from a different Mbed TLS version or build.
4430   * \return         #MBEDTLS_ERR_SSL_BAD_INPUT_DATA if input data is invalid.
4431   */
4432  int mbedtls_ssl_context_load( mbedtls_ssl_context *ssl,
4433                                const unsigned char *buf,
4434                                size_t len );
4435  #endif /* MBEDTLS_SSL_CONTEXT_SERIALIZATION */
4436  
4437  /**
4438   * \brief          Initialize an SSL configuration context
4439   *                 Just makes the context ready for
4440   *                 mbedtls_ssl_config_defaults() or mbedtls_ssl_config_free().
4441   *
4442   * \note           You need to call mbedtls_ssl_config_defaults() unless you
4443   *                 manually set all of the relevant fields yourself.
4444   *
4445   * \param conf     SSL configuration context
4446   */
4447  void mbedtls_ssl_config_init( mbedtls_ssl_config *conf );
4448  
4449  /**
4450   * \brief          Load reasonnable default SSL configuration values.
4451   *                 (You need to call mbedtls_ssl_config_init() first.)
4452   *
4453   * \param conf     SSL configuration context
4454   * \param endpoint MBEDTLS_SSL_IS_CLIENT or MBEDTLS_SSL_IS_SERVER
4455   * \param transport MBEDTLS_SSL_TRANSPORT_STREAM for TLS, or
4456   *                  MBEDTLS_SSL_TRANSPORT_DATAGRAM for DTLS
4457   * \param preset   a MBEDTLS_SSL_PRESET_XXX value
4458   *
4459   * \note           See \c mbedtls_ssl_conf_transport() for notes on DTLS.
4460   *
4461   * \return         0 if successful, or
4462   *                 MBEDTLS_ERR_XXX_ALLOC_FAILED on memory allocation error.
4463   */
4464  int mbedtls_ssl_config_defaults( mbedtls_ssl_config *conf,
4465                                   int endpoint, int transport, int preset );
4466  
4467  /**
4468   * \brief          Free an SSL configuration context
4469   *
4470   * \param conf     SSL configuration context
4471   */
4472  void mbedtls_ssl_config_free( mbedtls_ssl_config *conf );
4473  
4474  /**
4475   * \brief          Initialize SSL session structure
4476   *
4477   * \param session  SSL session
4478   */
4479  void mbedtls_ssl_session_init( mbedtls_ssl_session *session );
4480  
4481  /**
4482   * \brief          Free referenced items in an SSL session including the
4483   *                 peer certificate and clear memory
4484   *
4485   * \note           A session object can be freed even if the SSL context
4486   *                 that was used to retrieve the session is still in use.
4487   *
4488   * \param session  SSL session
4489   */
4490  void mbedtls_ssl_session_free( mbedtls_ssl_session *session );
4491  
4492  /**
4493   * \brief          TLS-PRF function for key derivation.
4494   *
4495   * \param prf      The tls_prf type function type to be used.
4496   * \param secret   Secret for the key derivation function.
4497   * \param slen     Length of the secret.
4498   * \param label    String label for the key derivation function,
4499   *                 terminated with null character.
4500   * \param random   Random bytes.
4501   * \param rlen     Length of the random bytes buffer.
4502   * \param dstbuf   The buffer holding the derived key.
4503   * \param dlen     Length of the output buffer.
4504   *
4505   * \return         0 on success. An SSL specific error on failure.
4506   */
4507  int  mbedtls_ssl_tls_prf( const mbedtls_tls_prf_types prf,
4508                            const unsigned char *secret, size_t slen,
4509                            const char *label,
4510                            const unsigned char *random, size_t rlen,
4511                            unsigned char *dstbuf, size_t dlen );
4512  
4513  #ifdef __cplusplus
4514  }
4515  #endif
4516  
4517  #endif /* ssl.h */
4518