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
  53 typedef int (*supp_recv_func) (gnutls_session_t session,
  54                                const opaque *data,
  55                                size_t data_size);
  56 typedef int (*supp_send_func) (gnutls_session_t session,
  57                                gnutls_buffer *buf);
  58
  59 typedef struct
  60 {
  61   const char *name;
  62   gnutls_supplemental_data_format_type_t type;
  63   supp_recv_func supp_recv_func;
  64   supp_send_func supp_send_func;
  65 } gnutls_supplemental_entry;
  66
  67 gnutls_supplemental_entry _gnutls_supplemental[] = {
  68   { 0, 0, 0, 0 }
  69 };
  70
  71 const char *
  72 gnutls_supplemental_get_name (gnutls_supplemental_data_format_type_t type)
  73 {
  74   gnutls_supplemental_entry *p;
  75
  76   for(p = _gnutls_supplemental; p->name != NULL; p++)
  77     if(p->type == type)
  78       return p->name;
  79
  80   return NULL;
  81 }
  82
  83 static supp_recv_func
  84 get_supp_func_recv (gnutls_supplemental_data_format_type_t type)
  85 {
  86   gnutls_supplemental_entry *p;
  87
  88   for(p = _gnutls_supplemental; p->name != NULL; p++)
  89     if(p->type == type)
  90       return p->supp_recv_func;
  91
  92   return NULL;
  93 }
  94
  95 int
  96 _gnutls_gen_supplemental (gnutls_session_t session, gnutls_buffer *buf)
  97 {
  98   gnutls_supplemental_entry *p;
  99   int ret;
 100
 101   /* Make room for 3 byte length field. */
 102   ret = _gnutls_buffer_append (buf, "\0\0\0", 3);
 103   if (ret < 0)
 104     {
 105       gnutls_assert ();
 106       return ret;
 107     }
 108
 109   for(p = _gnutls_supplemental; p->name; p++)
 110     {
 111       supp_send_func supp_send = p->supp_send_func;
 112       size_t sizepos = buf->length;
 113       int ret;
 114
 115       /* Make room for supplement type and length byte length field. */
 116       ret = _gnutls_buffer_append (buf, "\0\0\0\0", 4);
 117       if (ret < 0)
 118         {
 119           gnutls_assert ();
 120           return ret;
 121         }
 122
 123       ret = supp_send (session, buf);
 124       if (ret < 0)
 125         {
 126           gnutls_assert ();
 127           return ret;
 128         }
 129
 130       /* If data were added, store type+length, otherwise reset. */
 131       if (buf->length > sizepos + 4)
 132         {
 133           buf->data[sizepos] = 0;
 134           buf->data[sizepos + 1] = p->type;
 135           buf->data[sizepos + 2] = ((buf->length - sizepos - 4) >> 8) & 0xFF;
 136           buf->data[sizepos + 3] = (buf->length - sizepos -4) & 0xFF;
 137         }
 138       else
 139         buf->length -= 4;
 140     }
 141
 142   buf->data[0] = ((buf->length - 3) >> 16) & 0xFF;
 143   buf->data[1] = ((buf->length - 3) >> 8) & 0xFF;
 144   buf->data[2] = (buf->length - 3) & 0xFF;
 145
 146   _gnutls_debug_log ("EXT[%x]: Sending %d bytes of supplemental data\n",
 147                      session, buf->length);
 148
 149   return buf->length;
 150 }
 151
 152 int
 153 _gnutls_parse_supplemental (gnutls_session_t session,
 154                             const uint8_t * data,
 155                             int datalen)
 156 {
 157   const opaque *p = data;
 158   ssize_t dsize = datalen;
 159   size_t total_size;
 160
 161   DECR_LEN (dsize, 3);
 162   total_size = _gnutls_read_uint24 (p);
 163   p += 3;
 164
 165   if (dsize != total_size)
 166     {
 167       gnutls_assert();
 168       return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
 169     }
 170
 171   do
 172     {
 173       uint16_t supp_data_type;
 174       uint16_t supp_data_length;
 175       supp_recv_func recv_func;
 176
 177       DECR_LEN (dsize, 2);
 178       supp_data_type = _gnutls_read_uint16 (p);
 179       p += 2;
 180
 181       DECR_LEN (dsize, 2);
 182       supp_data_length = _gnutls_read_uint16 (p);
 183       p += 2;
 184
 185       _gnutls_debug_log ("EXT[%x]: Got supplemental type=%02x length=%d\n",
 186                          session, supp_data_type, supp_data_length);
 187
 188       recv_func = get_supp_func_recv (supp_data_type);
 189       if (recv_func)
 190         {
 191           int ret = recv_func (session, p, supp_data_length);
 192           if (ret < 0)
 193             {
 194               gnutls_assert ();
 195               return ret;
 196             }
 197         }
 198       else
 199         {
 200           gnutls_assert ();
 201           return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
 202         }
 203
 204       DECR_LEN (dsize, supp_data_length);
 205       p += supp_data_length;
 206     }
 207   while (dsize > 0);
 208
 209   return 0;
 210 }