1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis */
2 /* SPDX-License-Identifier: Unlicense */
3 #include "tomcrypt_private.h"
4 #include <stdarg.h>
5 
6 /**
7    @file ssh_encode_sequence_multi.c
8    SSH data type representation as per RFC4251, Russ Williams
9 */
10 
11 #ifdef LTC_SSH
12 
13 /**
14   Encode a SSH sequence using a VA list
15   @param out    [out] Destination for data
16   @param outlen [in/out] Length of buffer and resulting length of output
17   @remark <...> is of the form <type, data> (int, <int,ulong32,ulong64>) except for string&name-list <type, data, size> (int, void*, unsigned long)
18   @return CRYPT_OK on success
19 */
ssh_encode_sequence_multi(unsigned char * out,unsigned long * outlen,...)20 int ssh_encode_sequence_multi(unsigned char *out, unsigned long *outlen, ...)
21 {
22    int           err;
23    va_list       args;
24    ulong32       size;
25    ssh_data_type type;
26    void          *vdata;
27    const char    *sdata;
28    int           idata;
29    ulong32       u32data;
30    ulong64       u64data;
31 
32    LTC_ARGCHK(out    != NULL);
33    LTC_ARGCHK(outlen != NULL);
34 
35    /* Check values and calculate output size */
36    size = 0;
37    va_start(args, outlen);
38    while ((type = (ssh_data_type)va_arg(args, int)) != LTC_SSHDATA_EOL) {
39       switch (type) {
40          case LTC_SSHDATA_BYTE:
41          case LTC_SSHDATA_BOOLEAN: /* Both stored as 1 byte */
42             LTC_UNUSED_PARAM( va_arg(args, int) );
43             size++;
44             break;
45          case LTC_SSHDATA_UINT32:
46             LTC_UNUSED_PARAM( va_arg(args, ulong32) );
47             size += 4;
48             break;
49          case LTC_SSHDATA_UINT64:
50             LTC_UNUSED_PARAM( va_arg(args, ulong64) );
51             size += 8;
52             break;
53          case LTC_SSHDATA_STRING:
54          case LTC_SSHDATA_NAMELIST:
55             LTC_UNUSED_PARAM( va_arg(args, char*) );
56             size += va_arg(args, unsigned long);
57             size += 4;
58             break;
59          case LTC_SSHDATA_MPINT:
60             vdata = va_arg(args, void*);
61             /* Calculate size */
62             size += 4;
63             if (mp_iszero(vdata) != LTC_MP_YES) {
64                size += mp_unsigned_bin_size(vdata);
65                if ((mp_count_bits(vdata) & 7) == 0) size++; /* Zero padding if high bit set */
66             }
67             break;
68 
69          case LTC_SSHDATA_EOL: /* Should never get here */
70 	 default:
71             err = CRYPT_INVALID_ARG;
72             goto error;
73       }
74    }
75    va_end(args);
76 
77    /* Check we have sufficient space */
78    if (*outlen < size) {
79       *outlen = size;
80       err = CRYPT_BUFFER_OVERFLOW;
81       goto errornoargs;
82    }
83    *outlen = size;
84 
85    /* Encode values into buffer */
86    va_start(args, outlen);
87    while ((type = (ssh_data_type)va_arg(args, int)) != LTC_SSHDATA_EOL) {
88       switch (type) {
89          case LTC_SSHDATA_BYTE:
90             idata = va_arg(args, int);
91 
92             *out++ = (unsigned char)(idata & 255);
93             break;
94          case LTC_SSHDATA_BOOLEAN:
95             idata = va_arg(args, int);
96 
97             /*
98                The value 0 represents FALSE, and the value 1 represents TRUE.  All non-zero values MUST be
99                interpreted as TRUE; however, applications MUST NOT store values other than 0 and 1.
100              */
101             *out++ = (idata)?1:0;
102             break;
103          case LTC_SSHDATA_UINT32:
104             u32data = va_arg(args, ulong32);
105             STORE32H(u32data, out);
106             out += 4;
107             break;
108          case LTC_SSHDATA_UINT64:
109             u64data = va_arg(args, ulong64);
110             STORE64H(u64data, out);
111             out += 8;
112             break;
113          case LTC_SSHDATA_STRING:
114          case LTC_SSHDATA_NAMELIST:
115             sdata = va_arg(args, char*);
116             size = va_arg(args, unsigned long);
117             STORE32H(size, out);
118             out += 4;
119             XMEMCPY(out, sdata, size);
120             out += size;
121             break;
122          case LTC_SSHDATA_MPINT:
123             vdata = va_arg(args, void*);
124             if (mp_iszero(vdata) == LTC_MP_YES) {
125                STORE32H(0, out);
126                out += 4;
127             } else {
128                size = mp_unsigned_bin_size(vdata);
129                if ((mp_count_bits(vdata) & 7) == 0) {
130                   /* Zero padding if high bit set */
131                   STORE32H(size+1, out);
132                   out += 4;
133                   *out++ = 0;
134                } else {
135                   STORE32H(size, out);
136                   out += 4;
137                }
138                if ((err = mp_to_unsigned_bin(vdata, out)) != CRYPT_OK) {
139                   err = CRYPT_ERROR;
140                   goto error;
141                }
142                out += size;
143             }
144             break;
145 
146          case LTC_SSHDATA_EOL: /* Should never get here */
147 	 default:
148             err = CRYPT_INVALID_ARG;
149             goto error;
150       }
151    }
152    err = CRYPT_OK;
153 
154 error:
155    va_end(args);
156 errornoargs:
157    return err;
158 }
159 
160 #endif
161