1 /**
2  * @file
3  * Dynamic Host Configuration Protocol client
4  *
5  */
6 
7 /*
8  *
9  * Copyright (c) 2001-2004 Leon Woestenberg <leon.woestenberg@gmx.net>
10  * Copyright (c) 2001-2004 Axon Digital Design B.V., The Netherlands.
11  * All rights reserved.
12  *
13  * Redistribution and use in source and binary forms, with or without modification,
14  * are permitted provided that the following conditions are met:
15  *
16  * 1. Redistributions of source code must retain the above copyright notice,
17  *    this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright notice,
19  *    this list of conditions and the following disclaimer in the documentation
20  *    and/or other materials provided with the distribution.
21  * 3. The name of the author may not be used to endorse or promote products
22  *    derived from this software without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
25  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
26  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
27  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
28  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
29  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
32  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
33  * OF SUCH DAMAGE.
34  *
35  * This file is a contribution to the lwIP TCP/IP stack.
36  * The Swedish Institute of Computer Science and Adam Dunkels
37  * are specifically granted permission to redistribute this
38  * source code.
39  *
40  * Author: Leon Woestenberg <leon.woestenberg@gmx.net>
41  *
42  * This is a DHCP client for the lwIP TCP/IP stack. It aims to conform
43  * with RFC 2131 and RFC 2132.
44  *
45  * TODO:
46  * - Support for interfaces other than Ethernet (SLIP, PPP, ...)
47  *
48  * Please coordinate changes and requests with Leon Woestenberg
49  * <leon.woestenberg@gmx.net>
50  *
51  * Integration with your code:
52  *
53  * In lwip/dhcp.h
54  * #define DHCP_COARSE_TIMER_SECS (recommended 60 which is a minute)
55  * #define DHCP_FINE_TIMER_MSECS (recommended 500 which equals TCP coarse timer)
56  *
57  * Then have your application call dhcp_coarse_tmr() and
58  * dhcp_fine_tmr() on the defined intervals.
59  *
60  * dhcp_start(struct netif *netif);
61  * starts a DHCP client instance which configures the interface by
62  * obtaining an IP address lease and maintaining it.
63  *
64  * Use dhcp_release(netif) to end the lease and use dhcp_stop(netif)
65  * to remove the DHCP client.
66  *
67  */
68 
69 #include "lwip/opt.h"
70 
71 #if LWIP_DHCP /* don't build if not configured for use in lwipopts.h */
72 
73 #include "lwip/stats.h"
74 #include "lwip/mem.h"
75 #include "lwip/udp.h"
76 #include "lwip/ip_addr.h"
77 #include "lwip/netif.h"
78 #include "lwip/def.h"
79 #include "lwip/dhcp.h"
80 #include "lwip/autoip.h"
81 #include "lwip/dns.h"
82 #include "netif/etharp.h"
83 
84 #include <string.h>
85 
86 /** DHCP_CREATE_RAND_XID: if this is set to 1, the xid is created using
87  * LWIP_RAND() (this overrides DHCP_GLOBAL_XID)
88  */
89 #ifndef DHCP_CREATE_RAND_XID
90 #define DHCP_CREATE_RAND_XID 1
91 #endif
92 
93 /** Default for DHCP_GLOBAL_XID is 0xABCD0000
94  * This can be changed by defining DHCP_GLOBAL_XID and DHCP_GLOBAL_XID_HEADER, e.g.
95  *  #define DHCP_GLOBAL_XID_HEADER "stdlib.h"
96  *  #define DHCP_GLOBAL_XID rand()
97  */
98 #ifdef DHCP_GLOBAL_XID_HEADER
99 #include DHCP_GLOBAL_XID_HEADER /* include optional starting XID generation prototypes */
100 #endif
101 
102 /** DHCP_OPTION_MAX_MSG_SIZE is set to the MTU
103  * MTU is checked to be big enough in dhcp_start */
104 #define DHCP_MAX_MSG_LEN(netif)        (netif->mtu)
105 #define DHCP_MAX_MSG_LEN_MIN_REQUIRED  576
106 /** Minimum length for reply before packet is parsed */
107 #define DHCP_MIN_REPLY_LEN             44
108 
109 #define REBOOT_TRIES 2
110 
111 /** Option handling: options are parsed in dhcp_parse_reply
112  * and saved in an array where other functions can load them from.
113  * This might be moved into the struct dhcp (not necessarily since
114  * lwIP is single-threaded and the array is only used while in recv
115  * callback). */
116 #define DHCP_OPTION_IDX_OVERLOAD    0
117 #define DHCP_OPTION_IDX_MSG_TYPE    1
118 #define DHCP_OPTION_IDX_SERVER_ID   2
119 #define DHCP_OPTION_IDX_LEASE_TIME  3
120 #define DHCP_OPTION_IDX_T1          4
121 #define DHCP_OPTION_IDX_T2          5
122 #define DHCP_OPTION_IDX_SUBNET_MASK 6
123 #define DHCP_OPTION_IDX_ROUTER      7
124 #define DHCP_OPTION_IDX_DNS_SERVER  8
125 #define DHCP_OPTION_IDX_MAX         (DHCP_OPTION_IDX_DNS_SERVER + DNS_MAX_SERVERS)
126 
127 /** Holds the decoded option values, only valid while in dhcp_recv.
128     @todo: move this into struct dhcp? */
129 u32_t dhcp_rx_options_val[DHCP_OPTION_IDX_MAX];
130 /** Holds a flag which option was received and is contained in dhcp_rx_options_val,
131     only valid while in dhcp_recv.
132     @todo: move this into struct dhcp? */
133 u8_t  dhcp_rx_options_given[DHCP_OPTION_IDX_MAX];
134 
135 #ifdef DHCP_GLOBAL_XID
136 static u32_t xid;
137 static u8_t xid_initialised;
138 #endif /* DHCP_GLOBAL_XID */
139 
140 #define dhcp_option_given(dhcp, idx)          (dhcp_rx_options_given[idx] != 0)
141 #define dhcp_got_option(dhcp, idx)            (dhcp_rx_options_given[idx] = 1)
142 #define dhcp_clear_option(dhcp, idx)          (dhcp_rx_options_given[idx] = 0)
143 #define dhcp_clear_all_options(dhcp)          (memset(dhcp_rx_options_given, 0, sizeof(dhcp_rx_options_given)))
144 #define dhcp_get_option_value(dhcp, idx)      (dhcp_rx_options_val[idx])
145 #define dhcp_set_option_value(dhcp, idx, val) (dhcp_rx_options_val[idx] = (val))
146 
147 
148 /* DHCP client state machine functions */
149 static err_t dhcp_discover(struct netif *netif);
150 static err_t dhcp_select(struct netif *netif);
151 static void dhcp_bind(struct netif *netif);
152 #if DHCP_DOES_ARP_CHECK
153 static err_t dhcp_decline(struct netif *netif);
154 #endif /* DHCP_DOES_ARP_CHECK */
155 static err_t dhcp_rebind(struct netif *netif);
156 static err_t dhcp_reboot(struct netif *netif);
157 static void dhcp_set_state(struct dhcp *dhcp, u8_t new_state);
158 
159 /* receive, unfold, parse and free incoming messages */
160 static void dhcp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *addr, u16_t port);
161 
162 /* set the DHCP timers */
163 static void dhcp_timeout(struct netif *netif);
164 static void dhcp_t1_timeout(struct netif *netif);
165 static void dhcp_t2_timeout(struct netif *netif);
166 
167 /* build outgoing messages */
168 /* create a DHCP message, fill in common headers */
169 static err_t dhcp_create_msg(struct netif *netif, struct dhcp *dhcp, u8_t message_type);
170 /* free a DHCP request */
171 static void dhcp_delete_msg(struct dhcp *dhcp);
172 /* add a DHCP option (type, then length in bytes) */
173 static void dhcp_option(struct dhcp *dhcp, u8_t option_type, u8_t option_len);
174 /* add option values */
175 static void dhcp_option_byte(struct dhcp *dhcp, u8_t value);
176 static void dhcp_option_short(struct dhcp *dhcp, u16_t value);
177 static void dhcp_option_long(struct dhcp *dhcp, u32_t value);
178 #if LWIP_NETIF_HOSTNAME
179 static void dhcp_option_hostname(struct dhcp *dhcp, struct netif *netif);
180 #endif /* LWIP_NETIF_HOSTNAME */
181 /* always add the DHCP options trailer to end and pad */
182 static void dhcp_option_trailer(struct dhcp *dhcp);
183 
184 /**
185  * Back-off the DHCP client (because of a received NAK response).
186  *
187  * Back-off the DHCP client because of a received NAK. Receiving a
188  * NAK means the client asked for something non-sensible, for
189  * example when it tries to renew a lease obtained on another network.
190  *
191  * We clear any existing set IP address and restart DHCP negotiation
192  * afresh (as per RFC2131 3.2.3).
193  *
194  * @param netif the netif under DHCP control
195  */
196 static void
dhcp_handle_nak(struct netif * netif)197 dhcp_handle_nak(struct netif *netif)
198 {
199   struct dhcp *dhcp = netif->dhcp;
200   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_handle_nak(netif=%p) %c%c%"U16_F"\n",
201     (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num));
202   /* Set the interface down since the address must no longer be used, as per RFC2131 */
203   netif_set_down(netif);
204   /* remove IP address from interface */
205   netif_set_ipaddr(netif, IP_ADDR_ANY);
206   netif_set_gw(netif, IP_ADDR_ANY);
207   netif_set_netmask(netif, IP_ADDR_ANY);
208   /* Change to a defined state */
209   dhcp_set_state(dhcp, DHCP_BACKING_OFF);
210   /* We can immediately restart discovery */
211   dhcp_discover(netif);
212 }
213 
214 #if DHCP_DOES_ARP_CHECK
215 /**
216  * Checks if the offered IP address is already in use.
217  *
218  * It does so by sending an ARP request for the offered address and
219  * entering CHECKING state. If no ARP reply is received within a small
220  * interval, the address is assumed to be free for use by us.
221  *
222  * @param netif the netif under DHCP control
223  */
224 static void
dhcp_check(struct netif * netif)225 dhcp_check(struct netif *netif)
226 {
227   struct dhcp *dhcp = netif->dhcp;
228   err_t result;
229   u16_t msecs;
230   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_check(netif=%p) %c%c\n", (void *)netif, (s16_t)netif->name[0],
231     (s16_t)netif->name[1]));
232   dhcp_set_state(dhcp, DHCP_CHECKING);
233   /* create an ARP query for the offered IP address, expecting that no host
234      responds, as the IP address should not be in use. */
235   result = etharp_query(netif, &dhcp->offered_ip_addr, NULL);
236   if (result != ERR_OK) {
237     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("dhcp_check: could not perform ARP query\n"));
238   }
239   dhcp->tries++;
240   msecs = 500;
241   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
242   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_check(): set request timeout %"U16_F" msecs\n", msecs));
243 }
244 #endif /* DHCP_DOES_ARP_CHECK */
245 
246 /**
247  * Remember the configuration offered by a DHCP server.
248  *
249  * @param netif the netif under DHCP control
250  */
251 static void
dhcp_handle_offer(struct netif * netif)252 dhcp_handle_offer(struct netif *netif)
253 {
254   struct dhcp *dhcp = netif->dhcp;
255   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_handle_offer(netif=%p) %c%c%"U16_F"\n",
256     (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num));
257   /* obtain the server address */
258   if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_SERVER_ID)) {
259     ip4_addr_set_u32(&dhcp->server_ip_addr, htonl(dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_SERVER_ID)));
260     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_STATE, ("dhcp_handle_offer(): server 0x%08"X32_F"\n",
261       ip4_addr_get_u32(&dhcp->server_ip_addr)));
262     /* remember offered address */
263     ip_addr_copy(dhcp->offered_ip_addr, dhcp->msg_in->yiaddr);
264     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_STATE, ("dhcp_handle_offer(): offer for 0x%08"X32_F"\n",
265       ip4_addr_get_u32(&dhcp->offered_ip_addr)));
266 
267     dhcp_select(netif);
268   } else {
269     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
270       ("dhcp_handle_offer(netif=%p) did not get server ID!\n", (void*)netif));
271   }
272 }
273 
274 /**
275  * Select a DHCP server offer out of all offers.
276  *
277  * Simply select the first offer received.
278  *
279  * @param netif the netif under DHCP control
280  * @return lwIP specific error (see error.h)
281  */
282 static err_t
dhcp_select(struct netif * netif)283 dhcp_select(struct netif *netif)
284 {
285   struct dhcp *dhcp = netif->dhcp;
286   err_t result;
287   u16_t msecs;
288 
289   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_select(netif=%p) %c%c%"U16_F"\n", (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num));
290   dhcp_set_state(dhcp, DHCP_REQUESTING);
291 
292   /* create and initialize the DHCP message header */
293   result = dhcp_create_msg(netif, dhcp, DHCP_REQUEST);
294   if (result == ERR_OK) {
295     dhcp_option(dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
296     dhcp_option_short(dhcp, DHCP_MAX_MSG_LEN(netif));
297 
298     /* MUST request the offered IP address */
299     dhcp_option(dhcp, DHCP_OPTION_REQUESTED_IP, 4);
300     dhcp_option_long(dhcp, ntohl(ip4_addr_get_u32(&dhcp->offered_ip_addr)));
301 
302     dhcp_option(dhcp, DHCP_OPTION_SERVER_ID, 4);
303     dhcp_option_long(dhcp, ntohl(ip4_addr_get_u32(&dhcp->server_ip_addr)));
304 
305     dhcp_option(dhcp, DHCP_OPTION_PARAMETER_REQUEST_LIST, 4/*num options*/);
306     dhcp_option_byte(dhcp, DHCP_OPTION_SUBNET_MASK);
307     dhcp_option_byte(dhcp, DHCP_OPTION_ROUTER);
308     dhcp_option_byte(dhcp, DHCP_OPTION_BROADCAST);
309     dhcp_option_byte(dhcp, DHCP_OPTION_DNS_SERVER);
310 
311 #if LWIP_NETIF_HOSTNAME
312     dhcp_option_hostname(dhcp, netif);
313 #endif /* LWIP_NETIF_HOSTNAME */
314 
315     dhcp_option_trailer(dhcp);
316     /* shrink the pbuf to the actual content length */
317     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
318 
319     /* send broadcast to any DHCP server */
320     udp_sendto_if(dhcp->pcb, dhcp->p_out, IP_ADDR_BROADCAST, DHCP_SERVER_PORT, netif);
321     dhcp_delete_msg(dhcp);
322     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_select: REQUESTING\n"));
323   } else {
324     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("dhcp_select: could not allocate DHCP request\n"));
325   }
326   dhcp->tries++;
327   msecs = (dhcp->tries < 6 ? 1 << dhcp->tries : 60) * 1000;
328   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
329   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_STATE, ("dhcp_select(): set request timeout %"U16_F" msecs\n", msecs));
330   return result;
331 }
332 
333 /**
334  * The DHCP timer that checks for lease renewal/rebind timeouts.
335  */
336 void
dhcp_coarse_tmr()337 dhcp_coarse_tmr()
338 {
339   struct netif *netif = netif_list;
340   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_coarse_tmr()\n"));
341   /* iterate through all network interfaces */
342   while (netif != NULL) {
343     /* only act on DHCP configured interfaces */
344     if (netif->dhcp != NULL) {
345       /* timer is active (non zero), and triggers (zeroes) now? */
346       if (netif->dhcp->t2_timeout-- == 1) {
347         LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_coarse_tmr(): t2 timeout\n"));
348         /* this clients' rebind timeout triggered */
349         dhcp_t2_timeout(netif);
350       /* timer is active (non zero), and triggers (zeroes) now */
351       } else if (netif->dhcp->t1_timeout-- == 1) {
352         LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_coarse_tmr(): t1 timeout\n"));
353         /* this clients' renewal timeout triggered */
354         dhcp_t1_timeout(netif);
355       }
356     }
357     /* proceed to next netif */
358     netif = netif->next;
359   }
360 }
361 
362 /**
363  * DHCP transaction timeout handling
364  *
365  * A DHCP server is expected to respond within a short period of time.
366  * This timer checks whether an outstanding DHCP request is timed out.
367  */
368 void
dhcp_fine_tmr()369 dhcp_fine_tmr()
370 {
371   struct netif *netif = netif_list;
372   /* loop through netif's */
373   while (netif != NULL) {
374     /* only act on DHCP configured interfaces */
375     if (netif->dhcp != NULL) {
376       /* timer is active (non zero), and is about to trigger now */
377       if (netif->dhcp->request_timeout > 1) {
378         netif->dhcp->request_timeout--;
379       }
380       else if (netif->dhcp->request_timeout == 1) {
381         netif->dhcp->request_timeout--;
382         /* { netif->dhcp->request_timeout == 0 } */
383         LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_fine_tmr(): request timeout\n"));
384         /* this client's request timeout triggered */
385         dhcp_timeout(netif);
386       }
387     }
388     /* proceed to next network interface */
389     netif = netif->next;
390   }
391 }
392 
393 /**
394  * A DHCP negotiation transaction, or ARP request, has timed out.
395  *
396  * The timer that was started with the DHCP or ARP request has
397  * timed out, indicating no response was received in time.
398  *
399  * @param netif the netif under DHCP control
400  */
401 static void
dhcp_timeout(struct netif * netif)402 dhcp_timeout(struct netif *netif)
403 {
404   struct dhcp *dhcp = netif->dhcp;
405   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_timeout()\n"));
406   /* back-off period has passed, or server selection timed out */
407   if ((dhcp->state == DHCP_BACKING_OFF) || (dhcp->state == DHCP_SELECTING)) {
408     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_timeout(): restarting discovery\n"));
409     dhcp_discover(netif);
410   /* receiving the requested lease timed out */
411   } else if (dhcp->state == DHCP_REQUESTING) {
412     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_timeout(): REQUESTING, DHCP request timed out\n"));
413     if (dhcp->tries <= 5) {
414       dhcp_select(netif);
415     } else {
416       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_timeout(): REQUESTING, releasing, restarting\n"));
417       dhcp_release(netif);
418       dhcp_discover(netif);
419     }
420 #if DHCP_DOES_ARP_CHECK
421   /* received no ARP reply for the offered address (which is good) */
422   } else if (dhcp->state == DHCP_CHECKING) {
423     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_timeout(): CHECKING, ARP request timed out\n"));
424     if (dhcp->tries <= 1) {
425       dhcp_check(netif);
426     /* no ARP replies on the offered address,
427        looks like the IP address is indeed free */
428     } else {
429       /* bind the interface to the offered address */
430       dhcp_bind(netif);
431     }
432 #endif /* DHCP_DOES_ARP_CHECK */
433   }
434   /* did not get response to renew request? */
435   else if (dhcp->state == DHCP_RENEWING) {
436     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_timeout(): RENEWING, DHCP request timed out\n"));
437     /* just retry renewal */
438     /* note that the rebind timer will eventually time-out if renew does not work */
439     dhcp_renew(netif);
440   /* did not get response to rebind request? */
441   } else if (dhcp->state == DHCP_REBINDING) {
442     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_timeout(): REBINDING, DHCP request timed out\n"));
443     if (dhcp->tries <= 8) {
444       dhcp_rebind(netif);
445     } else {
446       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_timeout(): RELEASING, DISCOVERING\n"));
447       dhcp_release(netif);
448       dhcp_discover(netif);
449     }
450   } else if (dhcp->state == DHCP_REBOOTING) {
451     if (dhcp->tries < REBOOT_TRIES) {
452       dhcp_reboot(netif);
453     } else {
454       dhcp_discover(netif);
455     }
456   }
457 }
458 
459 /**
460  * The renewal period has timed out.
461  *
462  * @param netif the netif under DHCP control
463  */
464 static void
dhcp_t1_timeout(struct netif * netif)465 dhcp_t1_timeout(struct netif *netif)
466 {
467   struct dhcp *dhcp = netif->dhcp;
468   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_STATE, ("dhcp_t1_timeout()\n"));
469   if ((dhcp->state == DHCP_REQUESTING) || (dhcp->state == DHCP_BOUND) ||
470       (dhcp->state == DHCP_RENEWING)) {
471     /* just retry to renew - note that the rebind timer (t2) will
472      * eventually time-out if renew tries fail. */
473     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
474                 ("dhcp_t1_timeout(): must renew\n"));
475     /* This slightly different to RFC2131: DHCPREQUEST will be sent from state
476        DHCP_RENEWING, not DHCP_BOUND */
477     dhcp_renew(netif);
478   }
479 }
480 
481 /**
482  * The rebind period has timed out.
483  *
484  * @param netif the netif under DHCP control
485  */
486 static void
dhcp_t2_timeout(struct netif * netif)487 dhcp_t2_timeout(struct netif *netif)
488 {
489   struct dhcp *dhcp = netif->dhcp;
490   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_t2_timeout()\n"));
491   if ((dhcp->state == DHCP_REQUESTING) || (dhcp->state == DHCP_BOUND) ||
492       (dhcp->state == DHCP_RENEWING)) {
493     /* just retry to rebind */
494     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
495                 ("dhcp_t2_timeout(): must rebind\n"));
496     /* This slightly different to RFC2131: DHCPREQUEST will be sent from state
497        DHCP_REBINDING, not DHCP_BOUND */
498     dhcp_rebind(netif);
499   }
500 }
501 
502 /**
503  * Handle a DHCP ACK packet
504  *
505  * @param netif the netif under DHCP control
506  */
507 static void
dhcp_handle_ack(struct netif * netif)508 dhcp_handle_ack(struct netif *netif)
509 {
510   struct dhcp *dhcp = netif->dhcp;
511 #if LWIP_DNS
512   u8_t n;
513 #endif /* LWIP_DNS */
514 
515   /* clear options we might not get from the ACK */
516   ip_addr_set_zero(&dhcp->offered_sn_mask);
517   ip_addr_set_zero(&dhcp->offered_gw_addr);
518 #if LWIP_DHCP_BOOTP_FILE
519   ip_addr_set_zero(&dhcp->offered_si_addr);
520 #endif /* LWIP_DHCP_BOOTP_FILE */
521 
522   /* lease time given? */
523   if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_LEASE_TIME)) {
524     /* remember offered lease time */
525     dhcp->offered_t0_lease = dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_LEASE_TIME);
526   }
527   /* renewal period given? */
528   if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_T1)) {
529     /* remember given renewal period */
530     dhcp->offered_t1_renew = dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_T1);
531   } else {
532     /* calculate safe periods for renewal */
533     dhcp->offered_t1_renew = dhcp->offered_t0_lease / 2;
534   }
535 
536   /* renewal period given? */
537   if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_T2)) {
538     /* remember given rebind period */
539     dhcp->offered_t2_rebind = dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_T2);
540   } else {
541     /* calculate safe periods for rebinding */
542     dhcp->offered_t2_rebind = dhcp->offered_t0_lease;
543   }
544 
545   /* (y)our internet address */
546   ip_addr_copy(dhcp->offered_ip_addr, dhcp->msg_in->yiaddr);
547 
548 #if LWIP_DHCP_BOOTP_FILE
549   /* copy boot server address,
550      boot file name copied in dhcp_parse_reply if not overloaded */
551   ip_addr_copy(dhcp->offered_si_addr, dhcp->msg_in->siaddr);
552 #endif /* LWIP_DHCP_BOOTP_FILE */
553 
554   /* subnet mask given? */
555   if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_SUBNET_MASK)) {
556     /* remember given subnet mask */
557     ip4_addr_set_u32(&dhcp->offered_sn_mask, htonl(dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_SUBNET_MASK)));
558     dhcp->subnet_mask_given = 1;
559   } else {
560     dhcp->subnet_mask_given = 0;
561   }
562 
563   /* gateway router */
564   if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_ROUTER)) {
565     ip4_addr_set_u32(&dhcp->offered_gw_addr, htonl(dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_ROUTER)));
566   }
567 
568 #if LWIP_DNS
569   /* DNS servers */
570   n = 0;
571   while(dhcp_option_given(dhcp, DHCP_OPTION_IDX_DNS_SERVER + n) && (n < DNS_MAX_SERVERS)) {
572     ip_addr_t dns_addr;
573     ip4_addr_set_u32(&dns_addr, htonl(dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_DNS_SERVER + n)));
574     dns_setserver(n, &dns_addr);
575     n++;
576   }
577 #endif /* LWIP_DNS */
578 }
579 
580 /** Set a statically allocated struct dhcp to work with.
581  * Using this prevents dhcp_start to allocate it using mem_malloc.
582  *
583  * @param netif the netif for which to set the struct dhcp
584  * @param dhcp (uninitialised) dhcp struct allocated by the application
585  */
586 void
dhcp_set_struct(struct netif * netif,struct dhcp * dhcp)587 dhcp_set_struct(struct netif *netif, struct dhcp *dhcp)
588 {
589   LWIP_ASSERT("netif != NULL", netif != NULL);
590   LWIP_ASSERT("dhcp != NULL", dhcp != NULL);
591   LWIP_ASSERT("netif already has a struct dhcp set", netif->dhcp == NULL);
592 
593   /* clear data structure */
594   memset(dhcp, 0, sizeof(struct dhcp));
595   /* dhcp_set_state(&dhcp, DHCP_OFF); */
596   netif->dhcp = dhcp;
597 }
598 
599 /** Removes a struct dhcp from a netif.
600  *
601  * ATTENTION: Only use this when not using dhcp_set_struct() to allocate the
602  *            struct dhcp since the memory is passed back to the heap.
603  *
604  * @param netif the netif from which to remove the struct dhcp
605  */
dhcp_cleanup(struct netif * netif)606 void dhcp_cleanup(struct netif *netif)
607 {
608   LWIP_ASSERT("netif != NULL", netif != NULL);
609 
610   if (netif->dhcp != NULL) {
611     mem_free(netif->dhcp);
612     netif->dhcp = NULL;
613   }
614 }
615 
616 /**
617  * Start DHCP negotiation for a network interface.
618  *
619  * If no DHCP client instance was attached to this interface,
620  * a new client is created first. If a DHCP client instance
621  * was already present, it restarts negotiation.
622  *
623  * @param netif The lwIP network interface
624  * @return lwIP error code
625  * - ERR_OK - No error
626  * - ERR_MEM - Out of memory
627  */
628 err_t
dhcp_start(struct netif * netif)629 dhcp_start(struct netif *netif)
630 {
631   struct dhcp *dhcp;
632   err_t result = ERR_OK;
633 
634   LWIP_ERROR("netif != NULL", (netif != NULL), return ERR_ARG;);
635   dhcp = netif->dhcp;
636   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_start(netif=%p) %c%c%"U16_F"\n", (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num));
637   /* Remove the flag that says this netif is handled by DHCP,
638      it is set when we succeeded starting. */
639   netif->flags &= ~NETIF_FLAG_DHCP;
640 
641   /* check hwtype of the netif */
642   if ((netif->flags & NETIF_FLAG_ETHARP) == 0) {
643     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): No ETHARP netif\n"));
644     return ERR_ARG;
645   }
646 
647   /* check MTU of the netif */
648   if (netif->mtu < DHCP_MAX_MSG_LEN_MIN_REQUIRED) {
649     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): Cannot use this netif with DHCP: MTU is too small\n"));
650     return ERR_MEM;
651   }
652 
653   /* no DHCP client attached yet? */
654   if (dhcp == NULL) {
655     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): starting new DHCP client\n"));
656     dhcp = (struct dhcp *)mem_malloc(sizeof(struct dhcp));
657     if (dhcp == NULL) {
658       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): could not allocate dhcp\n"));
659       return ERR_MEM;
660     }
661     /* store this dhcp client in the netif */
662     netif->dhcp = dhcp;
663     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): allocated dhcp"));
664   /* already has DHCP client attached */
665   } else {
666     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_start(): restarting DHCP configuration\n"));
667     if (dhcp->pcb != NULL) {
668       udp_remove(dhcp->pcb);
669     }
670     LWIP_ASSERT("pbuf p_out wasn't freed", dhcp->p_out == NULL);
671     LWIP_ASSERT("reply wasn't freed", dhcp->msg_in == NULL );
672   }
673 
674   /* clear data structure */
675   memset(dhcp, 0, sizeof(struct dhcp));
676   /* dhcp_set_state(&dhcp, DHCP_OFF); */
677   /* allocate UDP PCB */
678   dhcp->pcb = udp_new();
679   if (dhcp->pcb == NULL) {
680     LWIP_DEBUGF(DHCP_DEBUG  | LWIP_DBG_TRACE, ("dhcp_start(): could not obtain pcb\n"));
681     return ERR_MEM;
682   }
683   ip_set_option(dhcp->pcb, SOF_BROADCAST);
684   /* set up local and remote port for the pcb */
685   udp_bind(dhcp->pcb, IP_ADDR_ANY, DHCP_CLIENT_PORT);
686   udp_connect(dhcp->pcb, IP_ADDR_ANY, DHCP_SERVER_PORT);
687   /* set up the recv callback and argument */
688   udp_recv(dhcp->pcb, dhcp_recv, netif);
689   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): starting DHCP configuration\n"));
690   /* (re)start the DHCP negotiation */
691   result = dhcp_discover(netif);
692   if (result != ERR_OK) {
693     /* free resources allocated above */
694     dhcp_stop(netif);
695     return ERR_MEM;
696   }
697   /* Set the flag that says this netif is handled by DHCP. */
698   netif->flags |= NETIF_FLAG_DHCP;
699   return result;
700 }
701 
702 /**
703  * Inform a DHCP server of our manual configuration.
704  *
705  * This informs DHCP servers of our fixed IP address configuration
706  * by sending an INFORM message. It does not involve DHCP address
707  * configuration, it is just here to be nice to the network.
708  *
709  * @param netif The lwIP network interface
710  */
711 void
dhcp_inform(struct netif * netif)712 dhcp_inform(struct netif *netif)
713 {
714   struct dhcp dhcp;
715   err_t result = ERR_OK;
716   struct udp_pcb *pcb;
717 
718   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
719 
720   memset(&dhcp, 0, sizeof(struct dhcp));
721   dhcp_set_state(&dhcp, DHCP_INFORM);
722 
723   if ((netif->dhcp != NULL) && (netif->dhcp->pcb != NULL)) {
724     /* re-use existing pcb */
725     pcb = netif->dhcp->pcb;
726   } else {
727     pcb = udp_new();
728     if (pcb == NULL) {
729       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("dhcp_inform(): could not obtain pcb"));
730       return;
731     }
732     dhcp.pcb = pcb;
733     ip_set_option(dhcp.pcb, SOF_BROADCAST);
734     udp_bind(dhcp.pcb, IP_ADDR_ANY, DHCP_CLIENT_PORT);
735     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_inform(): created new udp pcb\n"));
736   }
737   /* create and initialize the DHCP message header */
738   result = dhcp_create_msg(netif, &dhcp, DHCP_INFORM);
739   if (result == ERR_OK) {
740     dhcp_option(&dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
741     dhcp_option_short(&dhcp, DHCP_MAX_MSG_LEN(netif));
742 
743     dhcp_option_trailer(&dhcp);
744 
745     pbuf_realloc(dhcp.p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp.options_out_len);
746 
747     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_inform: INFORMING\n"));
748     udp_sendto_if(pcb, dhcp.p_out, IP_ADDR_BROADCAST, DHCP_SERVER_PORT, netif);
749     dhcp_delete_msg(&dhcp);
750   } else {
751     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("dhcp_inform: could not allocate DHCP request\n"));
752   }
753 
754   if (dhcp.pcb != NULL) {
755     /* otherwise, the existing pcb was used */
756     udp_remove(dhcp.pcb);
757   }
758 }
759 
760 /** Handle a possible change in the network configuration.
761  *
762  * This enters the REBOOTING state to verify that the currently bound
763  * address is still valid.
764  */
765 void
dhcp_network_changed(struct netif * netif)766 dhcp_network_changed(struct netif *netif)
767 {
768   struct dhcp *dhcp = netif->dhcp;
769   if (!dhcp)
770     return;
771   switch (dhcp->state) {
772   case DHCP_REBINDING:
773   case DHCP_RENEWING:
774   case DHCP_BOUND:
775   case DHCP_REBOOTING:
776     netif_set_down(netif);
777     dhcp->tries = 0;
778     dhcp_reboot(netif);
779     break;
780   case DHCP_OFF:
781     /* stay off */
782     break;
783   default:
784     dhcp->tries = 0;
785 #if LWIP_DHCP_AUTOIP_COOP
786     if(dhcp->autoip_coop_state == DHCP_AUTOIP_COOP_STATE_ON) {
787       autoip_stop(netif);
788       dhcp->autoip_coop_state = DHCP_AUTOIP_COOP_STATE_OFF;
789     }
790 #endif /* LWIP_DHCP_AUTOIP_COOP */
791     dhcp_discover(netif);
792     break;
793   }
794 }
795 
796 #if DHCP_DOES_ARP_CHECK
797 /**
798  * Match an ARP reply with the offered IP address.
799  *
800  * @param netif the network interface on which the reply was received
801  * @param addr The IP address we received a reply from
802  */
dhcp_arp_reply(struct netif * netif,ip_addr_t * addr)803 void dhcp_arp_reply(struct netif *netif, ip_addr_t *addr)
804 {
805   LWIP_ERROR("netif != NULL", (netif != NULL), return;);
806   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_arp_reply()\n"));
807   /* is a DHCP client doing an ARP check? */
808   if ((netif->dhcp != NULL) && (netif->dhcp->state == DHCP_CHECKING)) {
809     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_arp_reply(): CHECKING, arp reply for 0x%08"X32_F"\n",
810       ip4_addr_get_u32(addr)));
811     /* did a host respond with the address we
812        were offered by the DHCP server? */
813     if (ip_addr_cmp(addr, &netif->dhcp->offered_ip_addr)) {
814       /* we will not accept the offered address */
815       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | LWIP_DBG_LEVEL_WARNING,
816         ("dhcp_arp_reply(): arp reply matched with offered address, declining\n"));
817       dhcp_decline(netif);
818     }
819   }
820 }
821 
822 /**
823  * Decline an offered lease.
824  *
825  * Tell the DHCP server we do not accept the offered address.
826  * One reason to decline the lease is when we find out the address
827  * is already in use by another host (through ARP).
828  *
829  * @param netif the netif under DHCP control
830  */
831 static err_t
dhcp_decline(struct netif * netif)832 dhcp_decline(struct netif *netif)
833 {
834   struct dhcp *dhcp = netif->dhcp;
835   err_t result = ERR_OK;
836   u16_t msecs;
837   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_decline()\n"));
838   dhcp_set_state(dhcp, DHCP_BACKING_OFF);
839   /* create and initialize the DHCP message header */
840   result = dhcp_create_msg(netif, dhcp, DHCP_DECLINE);
841   if (result == ERR_OK) {
842     dhcp_option(dhcp, DHCP_OPTION_REQUESTED_IP, 4);
843     dhcp_option_long(dhcp, ntohl(ip4_addr_get_u32(&dhcp->offered_ip_addr)));
844 
845     dhcp_option_trailer(dhcp);
846     /* resize pbuf to reflect true size of options */
847     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
848 
849     /* per section 4.4.4, broadcast DECLINE messages */
850     udp_sendto_if(dhcp->pcb, dhcp->p_out, IP_ADDR_BROADCAST, DHCP_SERVER_PORT, netif);
851     dhcp_delete_msg(dhcp);
852     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_decline: BACKING OFF\n"));
853   } else {
854     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
855       ("dhcp_decline: could not allocate DHCP request\n"));
856   }
857   dhcp->tries++;
858   msecs = 10*1000;
859   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
860   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_decline(): set request timeout %"U16_F" msecs\n", msecs));
861   return result;
862 }
863 #endif /* DHCP_DOES_ARP_CHECK */
864 
865 
866 /**
867  * Start the DHCP process, discover a DHCP server.
868  *
869  * @param netif the netif under DHCP control
870  */
871 static err_t
dhcp_discover(struct netif * netif)872 dhcp_discover(struct netif *netif)
873 {
874   struct dhcp *dhcp = netif->dhcp;
875   err_t result = ERR_OK;
876   u16_t msecs;
877   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_discover()\n"));
878   ip_addr_set_any(&dhcp->offered_ip_addr);
879   dhcp_set_state(dhcp, DHCP_SELECTING);
880   /* create and initialize the DHCP message header */
881   result = dhcp_create_msg(netif, dhcp, DHCP_DISCOVER);
882   if (result == ERR_OK) {
883     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_discover: making request\n"));
884 
885     dhcp_option(dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
886     dhcp_option_short(dhcp, DHCP_MAX_MSG_LEN(netif));
887 
888     dhcp_option(dhcp, DHCP_OPTION_PARAMETER_REQUEST_LIST, 4/*num options*/);
889     dhcp_option_byte(dhcp, DHCP_OPTION_SUBNET_MASK);
890     dhcp_option_byte(dhcp, DHCP_OPTION_ROUTER);
891     dhcp_option_byte(dhcp, DHCP_OPTION_BROADCAST);
892     dhcp_option_byte(dhcp, DHCP_OPTION_DNS_SERVER);
893 
894     dhcp_option_trailer(dhcp);
895 
896     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_discover: realloc()ing\n"));
897     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
898 
899     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_discover: sendto(DISCOVER, IP_ADDR_BROADCAST, DHCP_SERVER_PORT)\n"));
900     udp_sendto_if(dhcp->pcb, dhcp->p_out, IP_ADDR_BROADCAST, DHCP_SERVER_PORT, netif);
901     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_discover: deleting()ing\n"));
902     dhcp_delete_msg(dhcp);
903     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_discover: SELECTING\n"));
904   } else {
905     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("dhcp_discover: could not allocate DHCP request\n"));
906   }
907   dhcp->tries++;
908 #if LWIP_DHCP_AUTOIP_COOP
909   if(dhcp->tries >= LWIP_DHCP_AUTOIP_COOP_TRIES && dhcp->autoip_coop_state == DHCP_AUTOIP_COOP_STATE_OFF) {
910     dhcp->autoip_coop_state = DHCP_AUTOIP_COOP_STATE_ON;
911     autoip_start(netif);
912   }
913 #endif /* LWIP_DHCP_AUTOIP_COOP */
914   msecs = (dhcp->tries < 6 ? 1 << dhcp->tries : 60) * 1000;
915   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
916   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_discover(): set request timeout %"U16_F" msecs\n", msecs));
917   return result;
918 }
919 
920 
921 /**
922  * Bind the interface to the offered IP address.
923  *
924  * @param netif network interface to bind to the offered address
925  */
926 static void
dhcp_bind(struct netif * netif)927 dhcp_bind(struct netif *netif)
928 {
929   u32_t timeout;
930   struct dhcp *dhcp;
931   ip_addr_t sn_mask, gw_addr;
932   LWIP_ERROR("dhcp_bind: netif != NULL", (netif != NULL), return;);
933   dhcp = netif->dhcp;
934   LWIP_ERROR("dhcp_bind: dhcp != NULL", (dhcp != NULL), return;);
935   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_bind(netif=%p) %c%c%"U16_F"\n", (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num));
936 
937   /* temporary DHCP lease? */
938   if (dhcp->offered_t1_renew != 0xffffffffUL) {
939     /* set renewal period timer */
940     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_bind(): t1 renewal timer %"U32_F" secs\n", dhcp->offered_t1_renew));
941     timeout = (dhcp->offered_t1_renew + DHCP_COARSE_TIMER_SECS / 2) / DHCP_COARSE_TIMER_SECS;
942     if(timeout > 0xffff) {
943       timeout = 0xffff;
944     }
945     dhcp->t1_timeout = (u16_t)timeout;
946     if (dhcp->t1_timeout == 0) {
947       dhcp->t1_timeout = 1;
948     }
949     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_bind(): set request timeout %"U32_F" msecs\n", dhcp->offered_t1_renew*1000));
950   }
951   /* set renewal period timer */
952   if (dhcp->offered_t2_rebind != 0xffffffffUL) {
953     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_bind(): t2 rebind timer %"U32_F" secs\n", dhcp->offered_t2_rebind));
954     timeout = (dhcp->offered_t2_rebind + DHCP_COARSE_TIMER_SECS / 2) / DHCP_COARSE_TIMER_SECS;
955     if(timeout > 0xffff) {
956       timeout = 0xffff;
957     }
958     dhcp->t2_timeout = (u16_t)timeout;
959     if (dhcp->t2_timeout == 0) {
960       dhcp->t2_timeout = 1;
961     }
962     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_bind(): set request timeout %"U32_F" msecs\n", dhcp->offered_t2_rebind*1000));
963   }
964 
965   /* If we have sub 1 minute lease, t2 and t1 will kick in at the same time. */
966   if ((dhcp->t1_timeout >= dhcp->t2_timeout) && (dhcp->t2_timeout > 0)) {
967     dhcp->t1_timeout = 0;
968   }
969 
970   if (dhcp->subnet_mask_given) {
971     /* copy offered network mask */
972     ip_addr_copy(sn_mask, dhcp->offered_sn_mask);
973   } else {
974     /* subnet mask not given, choose a safe subnet mask given the network class */
975     u8_t first_octet = ip4_addr1(&dhcp->offered_ip_addr);
976     if (first_octet <= 127) {
977       ip4_addr_set_u32(&sn_mask, PP_HTONL(0xff000000UL));
978     } else if (first_octet >= 192) {
979       ip4_addr_set_u32(&sn_mask, PP_HTONL(0xffffff00UL));
980     } else {
981       ip4_addr_set_u32(&sn_mask, PP_HTONL(0xffff0000UL));
982     }
983   }
984 
985   ip_addr_copy(gw_addr, dhcp->offered_gw_addr);
986   /* gateway address not given? */
987   if (gw_addr.addr == IPADDR_ANY) {
988     /* copy network address */
989     ip_addr_get_network(&gw_addr, &dhcp->offered_ip_addr, &sn_mask);
990     /* use first host address on network as gateway */
991     ip4_addr_set_u32(&gw_addr, ip4_addr_get_u32(&gw_addr) | PP_HTONL(0x00000001UL));
992   }
993 
994 #if LWIP_DHCP_AUTOIP_COOP
995   if(dhcp->autoip_coop_state == DHCP_AUTOIP_COOP_STATE_ON) {
996     autoip_stop(netif);
997     dhcp->autoip_coop_state = DHCP_AUTOIP_COOP_STATE_OFF;
998   }
999 #endif /* LWIP_DHCP_AUTOIP_COOP */
1000 
1001   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_STATE, ("dhcp_bind(): IP: 0x%08"X32_F"\n",
1002     ip4_addr_get_u32(&dhcp->offered_ip_addr)));
1003   netif_set_ipaddr(netif, &dhcp->offered_ip_addr);
1004   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_STATE, ("dhcp_bind(): SN: 0x%08"X32_F"\n",
1005     ip4_addr_get_u32(&sn_mask)));
1006   netif_set_netmask(netif, &sn_mask);
1007   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_STATE, ("dhcp_bind(): GW: 0x%08"X32_F"\n",
1008     ip4_addr_get_u32(&gw_addr)));
1009   netif_set_gw(netif, &gw_addr);
1010   /* bring the interface up */
1011   netif_set_up(netif);
1012   /* netif is now bound to DHCP leased address */
1013   dhcp_set_state(dhcp, DHCP_BOUND);
1014 }
1015 
1016 /**
1017  * Renew an existing DHCP lease at the involved DHCP server.
1018  *
1019  * @param netif network interface which must renew its lease
1020  */
1021 err_t
dhcp_renew(struct netif * netif)1022 dhcp_renew(struct netif *netif)
1023 {
1024   struct dhcp *dhcp = netif->dhcp;
1025   err_t result;
1026   u16_t msecs;
1027   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_renew()\n"));
1028   dhcp_set_state(dhcp, DHCP_RENEWING);
1029 
1030   /* create and initialize the DHCP message header */
1031   result = dhcp_create_msg(netif, dhcp, DHCP_REQUEST);
1032   if (result == ERR_OK) {
1033     dhcp_option(dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
1034     dhcp_option_short(dhcp, DHCP_MAX_MSG_LEN(netif));
1035 
1036 #if 0
1037     dhcp_option(dhcp, DHCP_OPTION_REQUESTED_IP, 4);
1038     dhcp_option_long(dhcp, ntohl(dhcp->offered_ip_addr.addr));
1039 #endif
1040 
1041 #if 0
1042     dhcp_option(dhcp, DHCP_OPTION_SERVER_ID, 4);
1043     dhcp_option_long(dhcp, ntohl(dhcp->server_ip_addr.addr));
1044 #endif
1045 
1046 #if LWIP_NETIF_HOSTNAME
1047     dhcp_option_hostname(dhcp, netif);
1048 #endif /* LWIP_NETIF_HOSTNAME */
1049 
1050     /* append DHCP message trailer */
1051     dhcp_option_trailer(dhcp);
1052 
1053     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
1054 
1055     udp_sendto_if(dhcp->pcb, dhcp->p_out, &dhcp->server_ip_addr, DHCP_SERVER_PORT, netif);
1056     dhcp_delete_msg(dhcp);
1057 
1058     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_renew: RENEWING\n"));
1059   } else {
1060     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("dhcp_renew: could not allocate DHCP request\n"));
1061   }
1062   dhcp->tries++;
1063   /* back-off on retries, but to a maximum of 20 seconds */
1064   msecs = dhcp->tries < 10 ? dhcp->tries * 2000 : 20 * 1000;
1065   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
1066   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_renew(): set request timeout %"U16_F" msecs\n", msecs));
1067   return result;
1068 }
1069 
1070 /**
1071  * Rebind with a DHCP server for an existing DHCP lease.
1072  *
1073  * @param netif network interface which must rebind with a DHCP server
1074  */
1075 static err_t
dhcp_rebind(struct netif * netif)1076 dhcp_rebind(struct netif *netif)
1077 {
1078   struct dhcp *dhcp = netif->dhcp;
1079   err_t result;
1080   u16_t msecs;
1081   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_rebind()\n"));
1082   dhcp_set_state(dhcp, DHCP_REBINDING);
1083 
1084   /* create and initialize the DHCP message header */
1085   result = dhcp_create_msg(netif, dhcp, DHCP_REQUEST);
1086   if (result == ERR_OK) {
1087     dhcp_option(dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
1088     dhcp_option_short(dhcp, DHCP_MAX_MSG_LEN(netif));
1089 
1090 #if LWIP_NETIF_HOSTNAME
1091     dhcp_option_hostname(dhcp, netif);
1092 #endif /* LWIP_NETIF_HOSTNAME */
1093 
1094 #if 0
1095     dhcp_option(dhcp, DHCP_OPTION_REQUESTED_IP, 4);
1096     dhcp_option_long(dhcp, ntohl(dhcp->offered_ip_addr.addr));
1097 
1098     dhcp_option(dhcp, DHCP_OPTION_SERVER_ID, 4);
1099     dhcp_option_long(dhcp, ntohl(dhcp->server_ip_addr.addr));
1100 #endif
1101 
1102     dhcp_option_trailer(dhcp);
1103 
1104     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
1105 
1106     /* broadcast to server */
1107     udp_sendto_if(dhcp->pcb, dhcp->p_out, IP_ADDR_BROADCAST, DHCP_SERVER_PORT, netif);
1108     dhcp_delete_msg(dhcp);
1109     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_rebind: REBINDING\n"));
1110   } else {
1111     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("dhcp_rebind: could not allocate DHCP request\n"));
1112   }
1113   dhcp->tries++;
1114   msecs = dhcp->tries < 10 ? dhcp->tries * 1000 : 10 * 1000;
1115   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
1116   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_rebind(): set request timeout %"U16_F" msecs\n", msecs));
1117   return result;
1118 }
1119 
1120 /**
1121  * Enter REBOOTING state to verify an existing lease
1122  *
1123  * @param netif network interface which must reboot
1124  */
1125 static err_t
dhcp_reboot(struct netif * netif)1126 dhcp_reboot(struct netif *netif)
1127 {
1128   struct dhcp *dhcp = netif->dhcp;
1129   err_t result;
1130   u16_t msecs;
1131   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_reboot()\n"));
1132   dhcp_set_state(dhcp, DHCP_REBOOTING);
1133 
1134   /* create and initialize the DHCP message header */
1135   result = dhcp_create_msg(netif, dhcp, DHCP_REQUEST);
1136   if (result == ERR_OK) {
1137     dhcp_option(dhcp, DHCP_OPTION_MAX_MSG_SIZE, DHCP_OPTION_MAX_MSG_SIZE_LEN);
1138     dhcp_option_short(dhcp, 576);
1139 
1140     dhcp_option(dhcp, DHCP_OPTION_REQUESTED_IP, 4);
1141     dhcp_option_long(dhcp, ntohl(ip4_addr_get_u32(&dhcp->offered_ip_addr)));
1142 
1143     dhcp_option_trailer(dhcp);
1144 
1145     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
1146 
1147     /* broadcast to server */
1148     udp_sendto_if(dhcp->pcb, dhcp->p_out, IP_ADDR_BROADCAST, DHCP_SERVER_PORT, netif);
1149     dhcp_delete_msg(dhcp);
1150     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_reboot: REBOOTING\n"));
1151   } else {
1152     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("dhcp_reboot: could not allocate DHCP request\n"));
1153   }
1154   dhcp->tries++;
1155   msecs = dhcp->tries < 10 ? dhcp->tries * 1000 : 10 * 1000;
1156   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
1157   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_reboot(): set request timeout %"U16_F" msecs\n", msecs));
1158   return result;
1159 }
1160 
1161 
1162 /**
1163  * Release a DHCP lease.
1164  *
1165  * @param netif network interface which must release its lease
1166  */
1167 err_t
dhcp_release(struct netif * netif)1168 dhcp_release(struct netif *netif)
1169 {
1170   struct dhcp *dhcp = netif->dhcp;
1171   err_t result;
1172   u16_t msecs;
1173   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_release()\n"));
1174 
1175   /* idle DHCP client */
1176   dhcp_set_state(dhcp, DHCP_OFF);
1177   /* clean old DHCP offer */
1178   ip_addr_set_zero(&dhcp->server_ip_addr);
1179   ip_addr_set_zero(&dhcp->offered_ip_addr);
1180   ip_addr_set_zero(&dhcp->offered_sn_mask);
1181   ip_addr_set_zero(&dhcp->offered_gw_addr);
1182 #if LWIP_DHCP_BOOTP_FILE
1183   ip_addr_set_zero(&dhcp->offered_si_addr);
1184 #endif /* LWIP_DHCP_BOOTP_FILE */
1185   dhcp->offered_t0_lease = dhcp->offered_t1_renew = dhcp->offered_t2_rebind = 0;
1186 
1187   /* create and initialize the DHCP message header */
1188   result = dhcp_create_msg(netif, dhcp, DHCP_RELEASE);
1189   if (result == ERR_OK) {
1190     dhcp_option_trailer(dhcp);
1191 
1192     pbuf_realloc(dhcp->p_out, sizeof(struct dhcp_msg) - DHCP_OPTIONS_LEN + dhcp->options_out_len);
1193 
1194     udp_sendto_if(dhcp->pcb, dhcp->p_out, &dhcp->server_ip_addr, DHCP_SERVER_PORT, netif);
1195     dhcp_delete_msg(dhcp);
1196     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_release: RELEASED, DHCP_OFF\n"));
1197   } else {
1198     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("dhcp_release: could not allocate DHCP request\n"));
1199   }
1200   dhcp->tries++;
1201   msecs = dhcp->tries < 10 ? dhcp->tries * 1000 : 10 * 1000;
1202   dhcp->request_timeout = (msecs + DHCP_FINE_TIMER_MSECS - 1) / DHCP_FINE_TIMER_MSECS;
1203   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("dhcp_release(): set request timeout %"U16_F" msecs\n", msecs));
1204   /* bring the interface down */
1205   netif_set_down(netif);
1206   /* remove IP address from interface */
1207   netif_set_ipaddr(netif, IP_ADDR_ANY);
1208   netif_set_gw(netif, IP_ADDR_ANY);
1209   netif_set_netmask(netif, IP_ADDR_ANY);
1210 
1211   return result;
1212 }
1213 
1214 /**
1215  * Remove the DHCP client from the interface.
1216  *
1217  * @param netif The network interface to stop DHCP on
1218  */
1219 void
dhcp_stop(struct netif * netif)1220 dhcp_stop(struct netif *netif)
1221 {
1222   struct dhcp *dhcp;
1223   LWIP_ERROR("dhcp_stop: netif != NULL", (netif != NULL), return;);
1224   dhcp = netif->dhcp;
1225   /* Remove the flag that says this netif is handled by DHCP. */
1226   netif->flags &= ~NETIF_FLAG_DHCP;
1227 
1228   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_stop()\n"));
1229   /* netif is DHCP configured? */
1230   if (dhcp != NULL) {
1231 #if LWIP_DHCP_AUTOIP_COOP
1232     if(dhcp->autoip_coop_state == DHCP_AUTOIP_COOP_STATE_ON) {
1233       autoip_stop(netif);
1234       dhcp->autoip_coop_state = DHCP_AUTOIP_COOP_STATE_OFF;
1235     }
1236 #endif /* LWIP_DHCP_AUTOIP_COOP */
1237 
1238     if (dhcp->pcb != NULL) {
1239       udp_remove(dhcp->pcb);
1240       dhcp->pcb = NULL;
1241     }
1242     LWIP_ASSERT("reply wasn't freed", dhcp->msg_in == NULL);
1243     dhcp_set_state(dhcp, DHCP_OFF);
1244   }
1245 }
1246 
1247 /*
1248  * Set the DHCP state of a DHCP client.
1249  *
1250  * If the state changed, reset the number of tries.
1251  */
1252 static void
dhcp_set_state(struct dhcp * dhcp,u8_t new_state)1253 dhcp_set_state(struct dhcp *dhcp, u8_t new_state)
1254 {
1255   if (new_state != dhcp->state) {
1256     dhcp->state = new_state;
1257     dhcp->tries = 0;
1258     dhcp->request_timeout = 0;
1259   }
1260 }
1261 
1262 /*
1263  * Concatenate an option type and length field to the outgoing
1264  * DHCP message.
1265  *
1266  */
1267 static void
dhcp_option(struct dhcp * dhcp,u8_t option_type,u8_t option_len)1268 dhcp_option(struct dhcp *dhcp, u8_t option_type, u8_t option_len)
1269 {
1270   LWIP_ASSERT("dhcp_option: dhcp->options_out_len + 2 + option_len <= DHCP_OPTIONS_LEN", dhcp->options_out_len + 2U + option_len <= DHCP_OPTIONS_LEN);
1271   dhcp->msg_out->options[dhcp->options_out_len++] = option_type;
1272   dhcp->msg_out->options[dhcp->options_out_len++] = option_len;
1273 }
1274 /*
1275  * Concatenate a single byte to the outgoing DHCP message.
1276  *
1277  */
1278 static void
dhcp_option_byte(struct dhcp * dhcp,u8_t value)1279 dhcp_option_byte(struct dhcp *dhcp, u8_t value)
1280 {
1281   LWIP_ASSERT("dhcp_option_byte: dhcp->options_out_len < DHCP_OPTIONS_LEN", dhcp->options_out_len < DHCP_OPTIONS_LEN);
1282   dhcp->msg_out->options[dhcp->options_out_len++] = value;
1283 }
1284 
1285 static void
dhcp_option_short(struct dhcp * dhcp,u16_t value)1286 dhcp_option_short(struct dhcp *dhcp, u16_t value)
1287 {
1288   LWIP_ASSERT("dhcp_option_short: dhcp->options_out_len + 2 <= DHCP_OPTIONS_LEN", dhcp->options_out_len + 2U <= DHCP_OPTIONS_LEN);
1289   dhcp->msg_out->options[dhcp->options_out_len++] = (u8_t)((value & 0xff00U) >> 8);
1290   dhcp->msg_out->options[dhcp->options_out_len++] = (u8_t) (value & 0x00ffU);
1291 }
1292 
1293 static void
dhcp_option_long(struct dhcp * dhcp,u32_t value)1294 dhcp_option_long(struct dhcp *dhcp, u32_t value)
1295 {
1296   LWIP_ASSERT("dhcp_option_long: dhcp->options_out_len + 4 <= DHCP_OPTIONS_LEN", dhcp->options_out_len + 4U <= DHCP_OPTIONS_LEN);
1297   dhcp->msg_out->options[dhcp->options_out_len++] = (u8_t)((value & 0xff000000UL) >> 24);
1298   dhcp->msg_out->options[dhcp->options_out_len++] = (u8_t)((value & 0x00ff0000UL) >> 16);
1299   dhcp->msg_out->options[dhcp->options_out_len++] = (u8_t)((value & 0x0000ff00UL) >> 8);
1300   dhcp->msg_out->options[dhcp->options_out_len++] = (u8_t)((value & 0x000000ffUL));
1301 }
1302 
1303 #if LWIP_NETIF_HOSTNAME
1304 static void
dhcp_option_hostname(struct dhcp * dhcp,struct netif * netif)1305 dhcp_option_hostname(struct dhcp *dhcp, struct netif *netif)
1306 {
1307   if (netif->hostname != NULL) {
1308     size_t namelen = strlen(netif->hostname);
1309     if (namelen > 0) {
1310       u8_t len;
1311       const char *p = netif->hostname;
1312       /* Shrink len to available bytes (need 2 bytes for OPTION_HOSTNAME
1313          and 1 byte for trailer) */
1314       size_t available = DHCP_OPTIONS_LEN - dhcp->options_out_len - 3;
1315       LWIP_ASSERT("DHCP: hostname is too long!", namelen <= available);
1316       len = LWIP_MIN(namelen, available);
1317       dhcp_option(dhcp, DHCP_OPTION_HOSTNAME, len);
1318       while (len--) {
1319         dhcp_option_byte(dhcp, *p++);
1320       }
1321     }
1322   }
1323 }
1324 #endif /* LWIP_NETIF_HOSTNAME */
1325 
1326 /**
1327  * Extract the DHCP message and the DHCP options.
1328  *
1329  * Extract the DHCP message and the DHCP options, each into a contiguous
1330  * piece of memory. As a DHCP message is variable sized by its options,
1331  * and also allows overriding some fields for options, the easy approach
1332  * is to first unfold the options into a conitguous piece of memory, and
1333  * use that further on.
1334  *
1335  */
1336 static err_t
dhcp_parse_reply(struct dhcp * dhcp,struct pbuf * p)1337 dhcp_parse_reply(struct dhcp *dhcp, struct pbuf *p)
1338 {
1339   u8_t *options;
1340   u16_t offset;
1341   u16_t offset_max;
1342   u16_t options_idx;
1343   u16_t options_idx_max;
1344   struct pbuf *q;
1345   int parse_file_as_options = 0;
1346   int parse_sname_as_options = 0;
1347 
1348   /* clear received options */
1349   dhcp_clear_all_options(dhcp);
1350   /* check that beginning of dhcp_msg (up to and including chaddr) is in first pbuf */
1351   if (p->len < DHCP_SNAME_OFS) {
1352     return ERR_BUF;
1353   }
1354   dhcp->msg_in = (struct dhcp_msg *)p->payload;
1355 #if LWIP_DHCP_BOOTP_FILE
1356   /* clear boot file name */
1357   dhcp->boot_file_name[0] = 0;
1358 #endif /* LWIP_DHCP_BOOTP_FILE */
1359 
1360   /* parse options */
1361 
1362   /* start with options field */
1363   options_idx = DHCP_OPTIONS_OFS;
1364   /* parse options to the end of the received packet */
1365   options_idx_max = p->tot_len;
1366 again:
1367   q = p;
1368   while((q != NULL) && (options_idx >= q->len)) {
1369     options_idx -= q->len;
1370     options_idx_max -= q->len;
1371     q = q->next;
1372   }
1373   if (q == NULL) {
1374     return ERR_BUF;
1375   }
1376   offset = options_idx;
1377   offset_max = options_idx_max;
1378   options = (u8_t*)q->payload;
1379   /* at least 1 byte to read and no end marker, then at least 3 bytes to read? */
1380   while((q != NULL) && (options[offset] != DHCP_OPTION_END) && (offset < offset_max)) {
1381     u8_t op = options[offset];
1382     u8_t len;
1383     u8_t decode_len = 0;
1384     int decode_idx = -1;
1385     u16_t val_offset = offset + 2;
1386     /* len byte might be in the next pbuf */
1387     if (offset + 1 < q->len) {
1388       len = options[offset + 1];
1389     } else {
1390       len = (q->next != NULL ? ((u8_t*)q->next->payload)[0] : 0);
1391     }
1392     /* LWIP_DEBUGF(DHCP_DEBUG, ("msg_offset=%"U16_F", q->len=%"U16_F, msg_offset, q->len)); */
1393     decode_len = len;
1394     switch(op) {
1395       /* case(DHCP_OPTION_END): handled above */
1396       case(DHCP_OPTION_PAD):
1397         /* special option: no len encoded */
1398         decode_len = len = 0;
1399         /* will be increased below */
1400         offset--;
1401         break;
1402       case(DHCP_OPTION_SUBNET_MASK):
1403         LWIP_ERROR("len == 4", len == 4, return ERR_VAL;);
1404         decode_idx = DHCP_OPTION_IDX_SUBNET_MASK;
1405         break;
1406       case(DHCP_OPTION_ROUTER):
1407         decode_len = 4; /* only copy the first given router */
1408         LWIP_ERROR("len >= decode_len", len >= decode_len, return ERR_VAL;);
1409         decode_idx = DHCP_OPTION_IDX_ROUTER;
1410         break;
1411       case(DHCP_OPTION_DNS_SERVER):
1412         /* special case: there might be more than one server */
1413         LWIP_ERROR("len % 4 == 0", len % 4 == 0, return ERR_VAL;);
1414         /* limit number of DNS servers */
1415         decode_len = LWIP_MIN(len, 4 * DNS_MAX_SERVERS);
1416         LWIP_ERROR("len >= decode_len", len >= decode_len, return ERR_VAL;);
1417         decode_idx = DHCP_OPTION_IDX_DNS_SERVER;
1418         break;
1419       case(DHCP_OPTION_LEASE_TIME):
1420         LWIP_ERROR("len == 4", len == 4, return ERR_VAL;);
1421         decode_idx = DHCP_OPTION_IDX_LEASE_TIME;
1422         break;
1423       case(DHCP_OPTION_OVERLOAD):
1424         LWIP_ERROR("len == 1", len == 1, return ERR_VAL;);
1425         decode_idx = DHCP_OPTION_IDX_OVERLOAD;
1426         break;
1427       case(DHCP_OPTION_MESSAGE_TYPE):
1428         LWIP_ERROR("len == 1", len == 1, return ERR_VAL;);
1429         decode_idx = DHCP_OPTION_IDX_MSG_TYPE;
1430         break;
1431       case(DHCP_OPTION_SERVER_ID):
1432         LWIP_ERROR("len == 4", len == 4, return ERR_VAL;);
1433         decode_idx = DHCP_OPTION_IDX_SERVER_ID;
1434         break;
1435       case(DHCP_OPTION_T1):
1436         LWIP_ERROR("len == 4", len == 4, return ERR_VAL;);
1437         decode_idx = DHCP_OPTION_IDX_T1;
1438         break;
1439       case(DHCP_OPTION_T2):
1440         LWIP_ERROR("len == 4", len == 4, return ERR_VAL;);
1441         decode_idx = DHCP_OPTION_IDX_T2;
1442         break;
1443       default:
1444         decode_len = 0;
1445         LWIP_DEBUGF(DHCP_DEBUG, ("skipping option %"U16_F" in options\n", op));
1446         break;
1447     }
1448     offset += len + 2;
1449     if (decode_len > 0) {
1450       u32_t value = 0;
1451       u16_t copy_len;
1452 decode_next:
1453       LWIP_ASSERT("check decode_idx", decode_idx >= 0 && decode_idx < DHCP_OPTION_IDX_MAX);
1454       if (!dhcp_option_given(dhcp, decode_idx)) {
1455         copy_len = LWIP_MIN(decode_len, 4);
1456         pbuf_copy_partial(q, &value, copy_len, val_offset);
1457         if (decode_len > 4) {
1458           /* decode more than one u32_t */
1459           LWIP_ERROR("decode_len % 4 == 0", decode_len % 4 == 0, return ERR_VAL;);
1460           dhcp_got_option(dhcp, decode_idx);
1461           dhcp_set_option_value(dhcp, decode_idx, htonl(value));
1462           decode_len -= 4;
1463           val_offset += 4;
1464           decode_idx++;
1465           goto decode_next;
1466         } else if (decode_len == 4) {
1467           value = ntohl(value);
1468         } else {
1469           LWIP_ERROR("invalid decode_len", decode_len == 1, return ERR_VAL;);
1470           value = ((u8_t*)&value)[0];
1471         }
1472         dhcp_got_option(dhcp, decode_idx);
1473         dhcp_set_option_value(dhcp, decode_idx, value);
1474       }
1475     }
1476     if (offset >= q->len) {
1477       offset -= q->len;
1478       offset_max -= q->len;
1479       if ((offset < offset_max) && offset_max) {
1480         q = q->next;
1481         LWIP_ASSERT("next pbuf was null", q);
1482         options = (u8_t*)q->payload;
1483       } else {
1484         // We've run out of bytes, probably no end marker. Don't proceed.
1485         break;
1486       }
1487     }
1488   }
1489   /* is this an overloaded message? */
1490   if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_OVERLOAD)) {
1491     u32_t overload = dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_OVERLOAD);
1492     dhcp_clear_option(dhcp, DHCP_OPTION_IDX_OVERLOAD);
1493     if (overload == DHCP_OVERLOAD_FILE) {
1494       parse_file_as_options = 1;
1495       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("overloaded file field\n"));
1496     } else if (overload == DHCP_OVERLOAD_SNAME) {
1497       parse_sname_as_options = 1;
1498       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("overloaded sname field\n"));
1499     } else if (overload == DHCP_OVERLOAD_SNAME_FILE) {
1500       parse_sname_as_options = 1;
1501       parse_file_as_options = 1;
1502       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("overloaded sname and file field\n"));
1503     } else {
1504       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("invalid overload option: %d\n", (int)overload));
1505     }
1506 #if LWIP_DHCP_BOOTP_FILE
1507     if (!parse_file_as_options) {
1508       /* only do this for ACK messages */
1509       if (dhcp_option_given(dhcp, DHCP_OPTION_IDX_MSG_TYPE) &&
1510         (dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_MSG_TYPE) == DHCP_ACK))
1511       /* copy bootp file name, don't care for sname (server hostname) */
1512       pbuf_copy_partial(p, dhcp->boot_file_name, DHCP_FILE_LEN-1, DHCP_FILE_OFS);
1513       /* make sure the string is really NULL-terminated */
1514       dhcp->boot_file_name[DHCP_FILE_LEN-1] = 0;
1515     }
1516 #endif /* LWIP_DHCP_BOOTP_FILE */
1517   }
1518   if (parse_file_as_options) {
1519     /* if both are overloaded, parse file first and then sname (RFC 2131 ch. 4.1) */
1520     parse_file_as_options = 0;
1521     options_idx = DHCP_FILE_OFS;
1522     options_idx_max = DHCP_FILE_OFS + DHCP_FILE_LEN;
1523     goto again;
1524   } else if (parse_sname_as_options) {
1525     parse_sname_as_options = 0;
1526     options_idx = DHCP_SNAME_OFS;
1527     options_idx_max = DHCP_SNAME_OFS + DHCP_SNAME_LEN;
1528     goto again;
1529   }
1530   return ERR_OK;
1531 }
1532 
1533 /**
1534  * If an incoming DHCP message is in response to us, then trigger the state machine
1535  */
1536 static void
dhcp_recv(void * arg,struct udp_pcb * pcb,struct pbuf * p,ip_addr_t * addr,u16_t port)1537 dhcp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *addr, u16_t port)
1538 {
1539   struct netif *netif = (struct netif *)arg;
1540   struct dhcp *dhcp = netif->dhcp;
1541   struct dhcp_msg *reply_msg = (struct dhcp_msg *)p->payload;
1542   u8_t msg_type;
1543   u8_t i;
1544   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_recv(pbuf = %p) from DHCP server %"U16_F".%"U16_F".%"U16_F".%"U16_F" port %"U16_F"\n", (void*)p,
1545     ip4_addr1_16(addr), ip4_addr2_16(addr), ip4_addr3_16(addr), ip4_addr4_16(addr), port));
1546   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("pbuf->len = %"U16_F"\n", p->len));
1547   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("pbuf->tot_len = %"U16_F"\n", p->tot_len));
1548   /* prevent warnings about unused arguments */
1549   LWIP_UNUSED_ARG(pcb);
1550   LWIP_UNUSED_ARG(addr);
1551   LWIP_UNUSED_ARG(port);
1552 
1553   LWIP_ASSERT("reply wasn't freed", dhcp->msg_in == NULL);
1554 
1555   if (p->len < DHCP_MIN_REPLY_LEN) {
1556     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("DHCP reply message or pbuf too short\n"));
1557     goto free_pbuf_and_return;
1558   }
1559 
1560   if (reply_msg->op != DHCP_BOOTREPLY) {
1561     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("not a DHCP reply message, but type %"U16_F"\n", (u16_t)reply_msg->op));
1562     goto free_pbuf_and_return;
1563   }
1564   /* iterate through hardware address and match against DHCP message */
1565   for (i = 0; i < netif->hwaddr_len; i++) {
1566     if (netif->hwaddr[i] != reply_msg->chaddr[i]) {
1567       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
1568         ("netif->hwaddr[%"U16_F"]==%02"X16_F" != reply_msg->chaddr[%"U16_F"]==%02"X16_F"\n",
1569         (u16_t)i, (u16_t)netif->hwaddr[i], (u16_t)i, (u16_t)reply_msg->chaddr[i]));
1570       goto free_pbuf_and_return;
1571     }
1572   }
1573   /* match transaction ID against what we expected */
1574   if (ntohl(reply_msg->xid) != dhcp->xid) {
1575     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING,
1576       ("transaction id mismatch reply_msg->xid(%"X32_F")!=dhcp->xid(%"X32_F")\n",ntohl(reply_msg->xid),dhcp->xid));
1577     goto free_pbuf_and_return;
1578   }
1579   /* option fields could be unfold? */
1580   if (dhcp_parse_reply(dhcp, p) != ERR_OK) {
1581     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
1582       ("problem unfolding DHCP message - too short on memory?\n"));
1583     goto free_pbuf_and_return;
1584   }
1585 
1586   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("searching DHCP_OPTION_MESSAGE_TYPE\n"));
1587   /* obtain pointer to DHCP message type */
1588   if (!dhcp_option_given(dhcp, DHCP_OPTION_IDX_MSG_TYPE)) {
1589     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("DHCP_OPTION_MESSAGE_TYPE option not found\n"));
1590     goto free_pbuf_and_return;
1591   }
1592 
1593   /* read DHCP message type */
1594   msg_type = (u8_t)dhcp_get_option_value(dhcp, DHCP_OPTION_IDX_MSG_TYPE);
1595   /* message type is DHCP ACK? */
1596   if (msg_type == DHCP_ACK) {
1597     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("DHCP_ACK received\n"));
1598     /* in requesting state? */
1599     if (dhcp->state == DHCP_REQUESTING) {
1600       dhcp_handle_ack(netif);
1601 #if DHCP_DOES_ARP_CHECK
1602       /* check if the acknowledged lease address is already in use */
1603       dhcp_check(netif);
1604 #else
1605       /* bind interface to the acknowledged lease address */
1606       dhcp_bind(netif);
1607 #endif
1608     }
1609     /* already bound to the given lease address? */
1610     else if ((dhcp->state == DHCP_REBOOTING) || (dhcp->state == DHCP_REBINDING) || (dhcp->state == DHCP_RENEWING)) {
1611       dhcp_bind(netif);
1612     }
1613   }
1614   /* received a DHCP_NAK in appropriate state? */
1615   else if ((msg_type == DHCP_NAK) &&
1616     ((dhcp->state == DHCP_REBOOTING) || (dhcp->state == DHCP_REQUESTING) ||
1617      (dhcp->state == DHCP_REBINDING) || (dhcp->state == DHCP_RENEWING  ))) {
1618     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("DHCP_NAK received\n"));
1619     dhcp_handle_nak(netif);
1620   }
1621   /* received a DHCP_OFFER in DHCP_SELECTING state? */
1622   else if ((msg_type == DHCP_OFFER) && (dhcp->state == DHCP_SELECTING)) {
1623     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("DHCP_OFFER received in DHCP_SELECTING state\n"));
1624     dhcp->request_timeout = 0;
1625     /* remember offered lease */
1626     dhcp_handle_offer(netif);
1627   }
1628 free_pbuf_and_return:
1629   dhcp->msg_in = NULL;
1630   pbuf_free(p);
1631 }
1632 
1633 /**
1634  * Create a DHCP request, fill in common headers
1635  *
1636  * @param netif the netif under DHCP control
1637  * @param dhcp dhcp control struct
1638  * @param message_type message type of the request
1639  */
1640 static err_t
dhcp_create_msg(struct netif * netif,struct dhcp * dhcp,u8_t message_type)1641 dhcp_create_msg(struct netif *netif, struct dhcp *dhcp, u8_t message_type)
1642 {
1643   u16_t i;
1644 #ifndef DHCP_GLOBAL_XID
1645   /** default global transaction identifier starting value (easy to match
1646    *  with a packet analyser). We simply increment for each new request.
1647    *  Predefine DHCP_GLOBAL_XID to a better value or a function call to generate one
1648    *  at runtime, any supporting function prototypes can be defined in DHCP_GLOBAL_XID_HEADER */
1649 #if DHCP_CREATE_RAND_XID && defined(LWIP_RAND)
1650   static u32_t xid;
1651 #else /* DHCP_CREATE_RAND_XID && defined(LWIP_RAND) */
1652   static u32_t xid = 0xABCD0000;
1653 #endif /* DHCP_CREATE_RAND_XID && defined(LWIP_RAND) */
1654 #else
1655   if (!xid_initialised) {
1656     xid = DHCP_GLOBAL_XID;
1657     xid_initialised = !xid_initialised;
1658   }
1659 #endif
1660   LWIP_ERROR("dhcp_create_msg: netif != NULL", (netif != NULL), return ERR_ARG;);
1661   LWIP_ERROR("dhcp_create_msg: dhcp != NULL", (dhcp != NULL), return ERR_VAL;);
1662   LWIP_ASSERT("dhcp_create_msg: dhcp->p_out == NULL", dhcp->p_out == NULL);
1663   LWIP_ASSERT("dhcp_create_msg: dhcp->msg_out == NULL", dhcp->msg_out == NULL);
1664   dhcp->p_out = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct dhcp_msg), PBUF_RAM);
1665   if (dhcp->p_out == NULL) {
1666     LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS,
1667       ("dhcp_create_msg(): could not allocate pbuf\n"));
1668     return ERR_MEM;
1669   }
1670   LWIP_ASSERT("dhcp_create_msg: check that first pbuf can hold struct dhcp_msg",
1671            (dhcp->p_out->len >= sizeof(struct dhcp_msg)));
1672 
1673   /* reuse transaction identifier in retransmissions */
1674   if (dhcp->tries == 0) {
1675 #if DHCP_CREATE_RAND_XID && defined(LWIP_RAND)
1676     xid = LWIP_RAND();
1677 #else /* DHCP_CREATE_RAND_XID && defined(LWIP_RAND) */
1678     xid++;
1679 #endif /* DHCP_CREATE_RAND_XID && defined(LWIP_RAND) */
1680   }
1681   dhcp->xid = xid;
1682   LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE,
1683               ("transaction id xid(%"X32_F")\n", xid));
1684 
1685   dhcp->msg_out = (struct dhcp_msg *)dhcp->p_out->payload;
1686 
1687   dhcp->msg_out->op = DHCP_BOOTREQUEST;
1688   /* TODO: make link layer independent */
1689   dhcp->msg_out->htype = DHCP_HTYPE_ETH;
1690   dhcp->msg_out->hlen = netif->hwaddr_len;
1691   dhcp->msg_out->hops = 0;
1692   dhcp->msg_out->xid = htonl(dhcp->xid);
1693   dhcp->msg_out->secs = 0;
1694   /* we don't need the broadcast flag since we can receive unicast traffic
1695      before being fully configured! */
1696   dhcp->msg_out->flags = 0;
1697   ip_addr_set_zero(&dhcp->msg_out->ciaddr);
1698   /* set ciaddr to netif->ip_addr based on message_type and state */
1699   if ((message_type == DHCP_INFORM) || (message_type == DHCP_DECLINE) ||
1700       ((message_type == DHCP_REQUEST) && /* DHCP_BOUND not used for sending! */
1701        ((dhcp->state==DHCP_RENEWING) || dhcp->state==DHCP_REBINDING))) {
1702     ip_addr_copy(dhcp->msg_out->ciaddr, netif->ip_addr);
1703   }
1704   ip_addr_set_zero(&dhcp->msg_out->yiaddr);
1705   ip_addr_set_zero(&dhcp->msg_out->siaddr);
1706   ip_addr_set_zero(&dhcp->msg_out->giaddr);
1707   for (i = 0; i < DHCP_CHADDR_LEN; i++) {
1708     /* copy netif hardware address, pad with zeroes */
1709     dhcp->msg_out->chaddr[i] = (i < netif->hwaddr_len) ? netif->hwaddr[i] : 0/* pad byte*/;
1710   }
1711   for (i = 0; i < DHCP_SNAME_LEN; i++) {
1712     dhcp->msg_out->sname[i] = 0;
1713   }
1714   for (i = 0; i < DHCP_FILE_LEN; i++) {
1715     dhcp->msg_out->file[i] = 0;
1716   }
1717   dhcp->msg_out->cookie = PP_HTONL(DHCP_MAGIC_COOKIE);
1718   dhcp->options_out_len = 0;
1719   /* fill options field with an incrementing array (for debugging purposes) */
1720   for (i = 0; i < DHCP_OPTIONS_LEN; i++) {
1721     dhcp->msg_out->options[i] = (u8_t)i; /* for debugging only, no matter if truncated */
1722   }
1723   /* Add option MESSAGE_TYPE */
1724   dhcp_option(dhcp, DHCP_OPTION_MESSAGE_TYPE, DHCP_OPTION_MESSAGE_TYPE_LEN);
1725   dhcp_option_byte(dhcp, message_type);
1726   return ERR_OK;
1727 }
1728 
1729 /**
1730  * Free previously allocated memory used to send a DHCP request.
1731  *
1732  * @param dhcp the dhcp struct to free the request from
1733  */
1734 static void
dhcp_delete_msg(struct dhcp * dhcp)1735 dhcp_delete_msg(struct dhcp *dhcp)
1736 {
1737   LWIP_ERROR("dhcp_delete_msg: dhcp != NULL", (dhcp != NULL), return;);
1738   LWIP_ASSERT("dhcp_delete_msg: dhcp->p_out != NULL", dhcp->p_out != NULL);
1739   LWIP_ASSERT("dhcp_delete_msg: dhcp->msg_out != NULL", dhcp->msg_out != NULL);
1740   if (dhcp->p_out != NULL) {
1741     pbuf_free(dhcp->p_out);
1742   }
1743   dhcp->p_out = NULL;
1744   dhcp->msg_out = NULL;
1745 }
1746 
1747 /**
1748  * Add a DHCP message trailer
1749  *
1750  * Adds the END option to the DHCP message, and if
1751  * necessary, up to three padding bytes.
1752  *
1753  * @param dhcp DHCP state structure
1754  */
1755 static void
dhcp_option_trailer(struct dhcp * dhcp)1756 dhcp_option_trailer(struct dhcp *dhcp)
1757 {
1758   LWIP_ERROR("dhcp_option_trailer: dhcp != NULL", (dhcp != NULL), return;);
1759   LWIP_ASSERT("dhcp_option_trailer: dhcp->msg_out != NULL\n", dhcp->msg_out != NULL);
1760   LWIP_ASSERT("dhcp_option_trailer: dhcp->options_out_len < DHCP_OPTIONS_LEN\n", dhcp->options_out_len < DHCP_OPTIONS_LEN);
1761   dhcp->msg_out->options[dhcp->options_out_len++] = DHCP_OPTION_END;
1762   /* packet is too small, or not 4 byte aligned? */
1763   while (((dhcp->options_out_len < DHCP_MIN_OPTIONS_LEN) || (dhcp->options_out_len & 3)) &&
1764          (dhcp->options_out_len < DHCP_OPTIONS_LEN)) {
1765     /* add a fill/padding byte */
1766     dhcp->msg_out->options[dhcp->options_out_len++] = 0;
1767   }
1768 }
1769 
1770 #endif /* LWIP_DHCP */
1771