lib/gnutls_supplemental.c

   1 /*
   2  * Copyright (C) 2007 Free Software Foundation
   3  *
   4  * Author: Simon Josefsson
   5  *
   6  * This file is part of GNUTLS.
   7  *
   8  * The GNUTLS library 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 2.1 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
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  21  * USA
  22  *
  23  */
  24
  25 /* This file contains support functions for 'TLS Handshake Message for
  26  * Supplemental Data' (RFC 4680).
  27  *
  28  * The idea here is simple.  gnutls_handshake() in gnuts_handshake.c
  29  * will call _gnutls_gen_supplemental and _gnutls_parse_supplemental
  30  * when some extension requested that supplemental data be sent or
  31  * received.  Extension request this by setting the flags
  32  * do_recv_supplemental or do_send_supplemental in the session.
  33  *
  34  * The functions in this file iterate through the _gnutls_supplemental
  35  * array, and calls the send/recv functions for each respective data
  36  * type.
  37  *
  38  * The receive function of each data type is responsible for decoding
  39  * its own data.  If the extension did not expect to receive
  40  * supplemental data, it should return GNUTLS_E_UNEXPECTED_PACKET.
  41  * Otherwise, it just parse the data as normal.
  42  *
  43  * The send function needs to append the 2-byte data format type, and
  44  * append the 2-byte length of its data, and the data.  If it doesn't
  45  * want to send any data, it is fine to return without doing anything.
  46  */
  47
  48 #include "gnutls_int.h"
  49 #include "gnutls_supplemental.h"
  50 #include "gnutls_errors.h"
  51 #include "gnutls_num.h"
  52 #include "ext_authz.h"
  53
  54 typedef int (*supp_recv_func) (gnutls_session_t session,
  55                                const opaque *data,
  56                                size_t data_size);
  57 typedef int (*supp_send_func) (gnutls_session_t session,
  58                                gnutls_buffer *buf);
  59
  60 typedef struct
  61 {
  62   const char *name;
  63   gnutls_supplemental_data_format_type_t type;
  64   supp_recv_func supp_recv_func;
  65   supp_send_func supp_send_func;
  66 } gnutls_supplemental_entry;
  67
  68 gnutls_supplemental_entry _gnutls_supplemental[] = {
  69   { "authz_data",
  70     GNUTLS_SUPPLEMENTAL_AUTHZ_DATA,
  71     _gnutls_authz_supp_recv_params,
  72     _gnutls_authz_supp_send_params },
  73   { 0, 0, 0, 0 }
  74 };
  75
  76 const char *
  77 gnutls_supplemental_get_name (gnutls_supplemental_data_format_type_t type)
  78 {
  79   gnutls_supplemental_entry *p;
  80
  81   for(p = _gnutls_supplemental; p->name != NULL; p++)
  82     if(p->type == type)
  83       return p->name;
  84
  85   return NULL;
  86 }
  87
  88 static supp_recv_func
  89 get_supp_func_recv (gnutls_supplemental_data_format_type_t type)
  90 {
  91   gnutls_supplemental_entry *p;
  92
  93   for(p = _gnutls_supplemental; p->name != NULL; p++)
  94     if(p->type == type)
  95       return p->supp_recv_func;
  96
  97   return NULL;
  98 }
  99
 100 int
 101 _gnutls_gen_supplemental (gnutls_session_t session, gnutls_buffer *buf)
 102 {
 103   gnutls_supplemental_entry *p;
 104   int ret;
 105
 106   /* Make room for 3 byte length field. */
 107   ret = _gnutls_buffer_append (buf, "\0\0\0", 3);
 108   if (ret < 0)
 109     {
 110       gnutls_assert ();
 111       return ret;
 112     }
 113
 114   for(p = _gnutls_supplemental; p->name; p++)
 115     {
 116       supp_send_func supp_send = p->supp_send_func;
 117       size_t sizepos = buf->length;
 118       int ret;
 119
 120       /* Make room for supplement type and length byte length field. */
 121       ret = _gnutls_buffer_append (buf, "\0\0\0\0", 4);
 122       if (ret < 0)
 123         {
 124           gnutls_assert ();
 125           return ret;
 126         }
 127
 128       ret = supp_send (session, buf);
 129       if (ret < 0)
 130         {
 131           gnutls_assert ();
 132           return ret;
 133         }
 134
 135       /* If data were added, store type+length, otherwise reset. */
 136       if (buf->length > sizepos + 4)
 137         {
 138           buf->data[sizepos] = 0;
 139           buf->data[sizepos + 1] = p->type;
 140           buf->data[sizepos + 2] = ((buf->length - sizepos - 4) >> 8) & 0xFF;
 141           buf->data[sizepos + 3] = (buf->length - sizepos -4) & 0xFF;
 142         }
 143       else
 144         buf->length -= 4;
 145     }
 146
 147   buf->data[0] = ((buf->length - 3) >> 16) & 0xFF;
 148   buf->data[1] = ((buf->length - 3) >> 8) & 0xFF;
 149   buf->data[2] = (buf->length - 3) & 0xFF;
 150
 151   _gnutls_debug_log ("EXT[%x]: Sending %d bytes of supplemental data\n",
 152                      session, buf->length);
 153
 154   return buf->length;
 155 }
 156
 157 int
 158 _gnutls_parse_supplemental (gnutls_session_t session,
 159                             const uint8_t * data,
 160                             int datalen)
 161 {
 162   const opaque *p = data;
 163   ssize_t dsize = datalen;
 164   size_t total_size;
 165
 166   DECR_LEN (dsize, 3);
 167   total_size = _gnutls_read_uint24 (p);
 168   p += 3;
 169
 170   if (dsize != total_size)
 171     {
 172       gnutls_assert();
 173       return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
 174     }
 175
 176   do
 177     {
 178       uint16_t supp_data_type;
 179       uint16_t supp_data_length;
 180       supp_recv_func recv_func;
 181
 182       DECR_LEN (dsize, 2);
 183       supp_data_type = _gnutls_read_uint16 (p);
 184       p += 2;
 185
 186       DECR_LEN (dsize, 2);
 187       supp_data_length = _gnutls_read_uint16 (p);
 188       p += 2;
 189
 190       _gnutls_debug_log ("EXT[%x]: Got supplemental type=%02x length=%d\n",
 191                          session, supp_data_type, supp_data_length);
 192
 193       recv_func = get_supp_func_recv (supp_data_type);
 194       if (recv_func)
 195         {
 196           int ret = recv_func (session, p, supp_data_length);
 197           if (ret < 0)
 198             {
 199               gnutls_assert ();
 200               return ret;
 201             }
 202         }
 203       else
 204         {
 205           gnutls_assert ();
 206           return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
 207         }
 208
 209       DECR_LEN (dsize, supp_data_length);
 210       p += supp_data_length;
 211     }
 212   while (dsize > 0);
 213
 214   return 0;
 215 }