lib/algorithms/protocols.c

   1 /*
   2  * Copyright (C) 2011-2012 Free Software Foundation, Inc.
   3  *
   4  * Author: Nikos Mavrogiannopoulos
   5  *
   6  * This file is part of GnuTLS.
   7  *
   8  * The GnuTLS is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public License
  10  * as published by the Free Software Foundation; either version 3 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program.  If not, see <http://www.gnu.org/licenses/>
  20  *
  21  */
  22
  23 #include <gnutls_int.h>
  24 #include <algorithms.h>
  25 #include <gnutls_errors.h>
  26 #include <x509/common.h>
  27
  28
  29 /* TLS Versions */
  30
  31 typedef struct
  32 {
  33   const char *name;
  34   gnutls_protocol_t id;         /* gnutls internal version number */
  35   int major;                    /* defined by the protocol */
  36   int minor;                    /* defined by the protocol */
  37   transport_t transport;        /* Type of transport, stream or datagram */
  38   int supported;                /* 0 not supported, > 0 is supported */
  39 } gnutls_version_entry;
  40
  41 static const gnutls_version_entry sup_versions[] = {
  42   {"SSL3.0", GNUTLS_SSL3, 3, 0, GNUTLS_STREAM, 1},
  43   {"TLS1.0", GNUTLS_TLS1, 3, 1, GNUTLS_STREAM, 1},
  44   {"TLS1.1", GNUTLS_TLS1_1, 3, 2, GNUTLS_STREAM, 1},
  45   {"TLS1.2", GNUTLS_TLS1_2, 3, 3, GNUTLS_STREAM, 1},
  46   {"DTLS1.0", GNUTLS_DTLS1_0, 254, 255, GNUTLS_DGRAM, 1}, /* 1.1 over datagram */
  47   {0, 0, 0, 0, 0}
  48 };
  49
  50 #define GNUTLS_VERSION_LOOP(b) \
  51         const gnutls_version_entry *p; \
  52                 for(p = sup_versions; p->name != NULL; p++) { b ; }
  53
  54 #define GNUTLS_VERSION_ALG_LOOP(a) \
  55         GNUTLS_VERSION_LOOP( if(p->id == version) { a; break; })
  56
  57 /* Return the priority of the provided version number */
  58 int
  59 _gnutls_version_priority (gnutls_session_t session, gnutls_protocol_t version)
  60 {
  61   unsigned int i;
  62
  63   for (i = 0; i < session->internals.priorities.protocol.algorithms; i++)
  64     {
  65       if (session->internals.priorities.protocol.priority[i] == version)
  66         return i;
  67     }
  68   return -1;
  69 }
  70
  71 /* Returns the lowest TLS version number in the priorities.
  72  */
  73 gnutls_protocol_t
  74 _gnutls_version_lowest (gnutls_session_t session)
  75 {
  76   unsigned int i, min = 0xff;
  77   gnutls_protocol_t cur_prot;
  78
  79   for (i = 0; i < session->internals.priorities.protocol.algorithms; i++)
  80     {
  81       cur_prot = session->internals.priorities.protocol.priority[i];
  82
  83       if (cur_prot < min && _gnutls_version_is_supported(session, cur_prot))
  84         min = cur_prot;
  85     }
  86
  87   if (min == 0xff)
  88     return GNUTLS_VERSION_UNKNOWN;      /* unknown version */
  89
  90   return min;
  91 }
  92
  93 /* Returns the maximum version in the priorities
  94  */
  95 gnutls_protocol_t
  96 _gnutls_version_max (gnutls_session_t session)
  97 {
  98   unsigned int i, max = 0x00;
  99   gnutls_protocol_t cur_prot;
 100
 101   for (i = 0; i < session->internals.priorities.protocol.algorithms; i++)
 102     {
 103       cur_prot = session->internals.priorities.protocol.priority[i];
 104
 105       if (cur_prot > max && _gnutls_version_is_supported(session, cur_prot))
 106         max = cur_prot;
 107     }
 108
 109   if (max == 0x00)
 110     return GNUTLS_VERSION_UNKNOWN;      /* unknown version */
 111
 112   return max;
 113 }
 114
 115
 116 /**
 117  * gnutls_protocol_get_name:
 118  * @version: is a (gnutls) version number
 119  *
 120  * Convert a #gnutls_protocol_t value to a string.
 121  *
 122  * Returns: a string that contains the name of the specified TLS
 123  *   version (e.g., "TLS1.0"), or %NULL.
 124  **/
 125 const char *
 126 gnutls_protocol_get_name (gnutls_protocol_t version)
 127 {
 128   const char *ret = NULL;
 129
 130   /* avoid prefix */
 131   GNUTLS_VERSION_ALG_LOOP (ret = p->name);
 132   return ret;
 133 }
 134
 135 /**
 136  * gnutls_protocol_get_id:
 137  * @name: is a protocol name
 138  *
 139  * The names are compared in a case insensitive way.
 140  *
 141  * Returns: an id of the specified protocol, or
 142  * %GNUTLS_VERSION_UNKNOWN on error.
 143  **/
 144 gnutls_protocol_t
 145 gnutls_protocol_get_id (const char *name)
 146 {
 147   gnutls_protocol_t ret = GNUTLS_VERSION_UNKNOWN;
 148
 149   GNUTLS_VERSION_LOOP (
 150     if (strcasecmp (p->name, name) == 0)
 151       {
 152         ret = p->id;
 153         break;
 154       }
 155   );
 156
 157   return ret;
 158 }
 159
 160 /**
 161  * gnutls_protocol_list:
 162  *
 163  * Get a list of supported protocols, e.g. SSL 3.0, TLS 1.0 etc.
 164  *
 165  * This function is not thread safe.
 166  *
 167  * Returns: a (0)-terminated list of #gnutls_protocol_t integers
 168  * indicating the available protocols.
 169  *
 170  **/
 171 const gnutls_protocol_t *
 172 gnutls_protocol_list (void)
 173 {
 174 static gnutls_protocol_t supported_protocols[MAX_ALGOS] = {0};
 175
 176   if (supported_protocols[0] == 0)
 177     {
 178       int i = 0;
 179
 180       GNUTLS_VERSION_LOOP (supported_protocols[i++]=p->id);
 181       supported_protocols[i++]=0;
 182     }
 183
 184   return supported_protocols;
 185 }
 186
 187 int
 188 _gnutls_version_get_minor (gnutls_protocol_t version)
 189 {
 190   int ret = -1;
 191
 192   GNUTLS_VERSION_ALG_LOOP (ret = p->minor);
 193   return ret;
 194 }
 195
 196 /* Returns a version number given the major and minor numbers.
 197  */
 198 gnutls_protocol_t
 199 _gnutls_version_get (int major, int minor)
 200 {
 201   int ret = -1;
 202
 203   GNUTLS_VERSION_LOOP (if ((p->major == major) && (p->minor == minor))
 204                        ret = p->id);
 205   return ret;
 206 }
 207
 208 int
 209 _gnutls_version_get_major (gnutls_protocol_t version)
 210 {
 211   int ret = -1;
 212
 213   GNUTLS_VERSION_ALG_LOOP (ret = p->major);
 214   return ret;
 215 }
 216
 217 /* Version Functions */
 218
 219 int
 220 _gnutls_version_is_supported (gnutls_session_t session,
 221                               const gnutls_protocol_t version)
 222 {
 223   int ret = 0;
 224
 225   GNUTLS_VERSION_ALG_LOOP (ret = p->supported && p->transport == session->internals.transport);
 226
 227   if (ret == 0)
 228     return 0;
 229
 230   if (_gnutls_version_priority (session, version) < 0)
 231     return 0;                   /* disabled by the user */
 232   else
 233     return 1;
 234 }
 235
 236
 237 /* This function determines if the version specified has a
 238    cipher-suite selected PRF hash function instead of the old
 239    hardcoded MD5+SHA1. */
 240 int
 241 _gnutls_version_has_selectable_prf (gnutls_protocol_t version)
 242 {
 243   switch (version)
 244     {
 245     case GNUTLS_DTLS1_0:
 246     case GNUTLS_TLS1_1:
 247     case GNUTLS_TLS1_0:
 248     case GNUTLS_SSL3:
 249       return 0;
 250     default:
 251       return 1;
 252     }
 253 }
 254
 255 /* This function determines if the version specified has selectable
 256    signature/hash functions for certificate authentification. */
 257 int
 258 _gnutls_version_has_selectable_sighash (gnutls_protocol_t version)
 259 {
 260   switch (version)
 261     {
 262     case GNUTLS_DTLS1_0:
 263     case GNUTLS_TLS1_1:
 264     case GNUTLS_TLS1_0:
 265     case GNUTLS_SSL3:
 266       return 0;
 267     default:
 268       return 1;
 269     }
 270 }
 271
 272 /* This function determines if the version specified has support for
 273    TLS extensions. */
 274 int
 275 _gnutls_version_has_extensions (gnutls_protocol_t version)
 276 {
 277   switch (version)
 278     {
 279     case GNUTLS_SSL3:
 280       return 0;
 281     default:
 282       /* Versions after TLS 1.0 are required to handle extensions.
 283        * SSL 3.0 also required extensions to be ignored, but
 284        * some earlier draft didn't.
 285        */
 286       return 1;
 287     }
 288 }
 289
 290 /* This function determines if the version specified has explicit IVs
 291    (for CBC attack prevention). */
 292 int
 293 _gnutls_version_has_explicit_iv (gnutls_protocol_t version)
 294 {
 295   switch (version)
 296     {
 297     case GNUTLS_TLS1_0:
 298     case GNUTLS_SSL3:
 299       return 0;
 300     default:
 301       /* All versions after TLS 1.1 have explicit IV */
 302       return 1;
 303     }
 304 }
 305