summaryrefslogtreecommitdiffstats
path: root/epan/asn1.c
blob: c47bed701b7efd96add9d2132a29e443ff1f8acf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
/* asn1.c
 * Common routines for ASN.1
 * 2007  Anders Broman
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"

#include <glib.h>

#include <string.h>
#include <stdlib.h>
#include <math.h>

#include <epan/packet.h>

#include "asn1.h"

void asn1_ctx_init(asn1_ctx_t *actx, asn1_enc_e encoding, bool aligned, packet_info *pinfo) {
  memset(actx, '\0', sizeof(*actx));
  actx->signature = ASN1_CTX_SIGNATURE;
  actx->encoding = encoding;
  actx->aligned = aligned;
  actx->pinfo = pinfo;
}

bool asn1_ctx_check_signature(asn1_ctx_t *actx) {
  return actx && (actx->signature == ASN1_CTX_SIGNATURE);
}

void asn1_ctx_clean_external(asn1_ctx_t *actx) {
  memset(&actx->external, '\0', sizeof(actx->external));
  actx->external.hf_index = -1;
  actx->external.encoding = -1;
}

void asn1_ctx_clean_epdv(asn1_ctx_t *actx) {
  memset(&actx->embedded_pdv, '\0', sizeof(actx->embedded_pdv));
  actx->embedded_pdv.hf_index = -1;
  actx->embedded_pdv.identification = -1;
}


/*--- stack/parameters ---*/

void asn1_stack_frame_push(asn1_ctx_t *actx, const gchar *name) {
  asn1_stack_frame_t *frame;

  frame = wmem_new0(actx->pinfo->pool, asn1_stack_frame_t);
  frame->name = name;
  frame->next = actx->stack;
  actx->stack = frame;
}

void asn1_stack_frame_pop(asn1_ctx_t *actx, const gchar *name) {
  DISSECTOR_ASSERT(actx->stack);
  DISSECTOR_ASSERT(!strcmp(actx->stack->name, name));
  actx->stack = actx->stack->next;
}

void asn1_stack_frame_check(asn1_ctx_t *actx, const gchar *name, const asn1_par_def_t *par_def) {
  const asn1_par_def_t *pd = par_def;
  asn1_par_t *par;

  DISSECTOR_ASSERT(actx->stack);
  DISSECTOR_ASSERT(!strcmp(actx->stack->name, name));

  par = actx->stack->par;
  while (pd->name) {
    DISSECTOR_ASSERT(par);
    DISSECTOR_ASSERT((pd->ptype == ASN1_PAR_IRR) || (par->ptype == pd->ptype));
    par->name = pd->name;
    pd++;
    par = par->next;
  }
  DISSECTOR_ASSERT(!par);
}

static asn1_par_t *get_par_by_name(asn1_ctx_t *actx, const gchar *name) {
  asn1_par_t *par = NULL;

  DISSECTOR_ASSERT(actx->stack);
  par = actx->stack->par;
  while (par) {
    if (!strcmp(par->name, name))
      return par;
    par = par->next;
  }
  return par;
}

static asn1_par_t *push_new_par(asn1_ctx_t *actx) {
  asn1_par_t *par, **pp;

  DISSECTOR_ASSERT(actx->stack);

  par = wmem_new0(actx->pinfo->pool, asn1_par_t);

  pp = &(actx->stack->par);
  while (*pp)
    pp = &((*pp)->next);
  *pp = par;

  return par;
}

void asn1_param_push_boolean(asn1_ctx_t *actx, bool value) {
  asn1_par_t *par;

  par = push_new_par(actx);
  par->ptype = ASN1_PAR_BOOLEAN;
  par->value.v_boolean = value;
}

void asn1_param_push_integer(asn1_ctx_t *actx, gint32 value) {
  asn1_par_t *par;

  par = push_new_par(actx);
  par->ptype = ASN1_PAR_INTEGER;
  par->value.v_integer = value;
}

bool asn1_param_get_boolean(asn1_ctx_t *actx, const gchar *name) {
  asn1_par_t *par = NULL;

  par = get_par_by_name(actx, name);
  DISSECTOR_ASSERT(par);
  return par->value.v_boolean;
}

gint32 asn1_param_get_integer(asn1_ctx_t *actx, const gchar *name) {
  asn1_par_t *par = NULL;

  par = get_par_by_name(actx, name);
  DISSECTOR_ASSERT(par);
  return par->value.v_integer;
}


/*--- ROSE ---*/

void rose_ctx_init(rose_ctx_t *rctx) {
  memset(rctx, '\0', sizeof(*rctx));
  rctx->signature = ROSE_CTX_SIGNATURE;
}

bool rose_ctx_check_signature(rose_ctx_t *rctx) {
  return rctx && (rctx->signature == ROSE_CTX_SIGNATURE);
}

void rose_ctx_clean_data(rose_ctx_t *rctx) {
  memset(&rctx->d, '\0', sizeof(rctx->d));
  rctx->d.code = -1;
}

asn1_ctx_t *get_asn1_ctx(void *ptr) {
  asn1_ctx_t *actx = (asn1_ctx_t*)ptr;

  if (!asn1_ctx_check_signature(actx))
    actx = NULL;

  return actx;
}

rose_ctx_t *get_rose_ctx(void *ptr) {
  rose_ctx_t *rctx = (rose_ctx_t*)ptr;
  asn1_ctx_t *actx = (asn1_ctx_t*)ptr;

  if (!asn1_ctx_check_signature(actx))
    actx = NULL;

  if (actx)
    rctx = actx->rose_ctx;

  if (!rose_ctx_check_signature(rctx))
    rctx = NULL;

  return rctx;
}

/** Only tested for BER */
double asn1_get_real(const guint8 *real_ptr, gint len) {
  guint8 octet;
  const guint8 *p;
  guint8 *buf;
  double val = 0;

  /* 8.5.2    If the real value is the value zero,
   *          there shall be no contents octets in the encoding.
   */
  if (len < 1) return val;

  octet = real_ptr[0];
  p = real_ptr + 1;
  len -= 1;
  if (octet & 0x80) {  /* binary encoding */
    int i;
    bool Eneg;
    gint8 S; /* Sign */
    guint8 B; /* Base */
    guint8 F; /* scaling Factor */
    gint32 E = 0; /* Exponent (supported max 3 octets/24 bit) */
    guint64 N = 0; /* N (supported max 8 octets/64 bit) */

    guint8 lenE, lenN;

    if(octet & 0x40) S = -1; else S = 1;
    switch(octet & 0x30) {
      case 0x00: B = 2; break;
      case 0x10: B = 8; break;
      case 0x20: B = 16; break;
      case 0x30: /* Reserved */
      default:
        /* TODO Add some warning in tree about reserved value for Base */
        return 0;
    }
    F = (octet & 0x0c) >> 2;

    /* 8.5.6.4 Exponent length */
    lenE = (octet & 0x3) + 1;

    /* we can't handle exponents > 24 bits */
    /* TODO Next octet(s) define length of exponent */
    DISSECTOR_ASSERT(lenE != 4);

    /* Ensure the buffer len and its content are coherent */
    DISSECTOR_ASSERT(lenE < len - 1);

    Eneg = ((*p) & 0x80) ? TRUE : FALSE;
    for (i = 0; i < lenE; i++) {
      if(Eneg) {
        /* 2's complement: inverse bits */
        E = (E<<8) | ((guint8) ~(*p));
      } else {
        E = (E<<8) | *p;
      }
      p++;
    }
    if(Eneg) {
      /* 2's complement: ... and add 1 (and make negative of course) */
      E = -(E + 1);
    }

    lenN = len - lenE;

    /* we can't handle integers > 64 bits */
    DISSECTOR_ASSERT(lenN <= 8);

    for (i=0; i<lenN; i++) {
      N = (N<<8) | *p;
      p++;
    }
    val = (double) S * N * pow(2, F) * pow(B, E);
  } else if (octet & 0x40) {  /* SpecialRealValue */
    switch (octet & 0x3F) {
      case 0x00: val = HUGE_VAL; break;
      case 0x01: val = -HUGE_VAL; break;
    }
  } else {  /* decimal encoding */
    buf = g_strndup(p, len);
    val = g_ascii_strtod(buf, NULL);
    g_free(buf);
  }

  return val;
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local Variables:
 * c-basic-offset: 2
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * ex: set shiftwidth=2 tabstop=8 expandtab:
 * :indentSize=2:tabSize=8:noTabs=true:
 */