lib/ext_max_record.c

   1 /*
   2  * Copyright (C) 2001, 2004, 2005 Free Software Foundation
   3  *
   4  * Author: Nikos Mavrogiannopoulos
   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 the code for the Max Record Size TLS extension.
  26  */
  27
  28 #include "gnutls_int.h"
  29 #include "gnutls_errors.h"
  30 #include "gnutls_num.h"
  31 #include <ext_max_record.h>
  32
  33 /*
  34  * In case of a server: if a MAX_RECORD_SIZE extension type is received then it stores
  35  * into the session the new value. The server may use gnutls_get_max_record_size(),
  36  * in order to access it.
  37  *
  38  * In case of a client: If a different max record size (than the default) has
  39  * been specified then it sends the extension.
  40  *
  41  */
  42
  43 int
  44 _gnutls_max_record_recv_params (gnutls_session_t session,
  45                                 const opaque * data, size_t _data_size)
  46 {
  47   ssize_t new_size;
  48   ssize_t data_size = _data_size;
  49
  50   if (session->security_parameters.entity == GNUTLS_SERVER)
  51     {
  52       if (data_size > 0)
  53         {
  54           DECR_LEN (data_size, 1);
  55
  56           new_size = _gnutls_mre_num2record (data[0]);
  57
  58           if (new_size < 0)
  59             {
  60               gnutls_assert ();
  61               return new_size;
  62             }
  63
  64           session->security_parameters.max_record_send_size = new_size;
  65           session->security_parameters.max_record_recv_size = new_size;
  66         }
  67     }
  68   else
  69     {                           /* CLIENT SIDE - we must check if the sent record size is the right one
  70                                  */
  71       if (data_size > 0)
  72         {
  73
  74           if (data_size != 1)
  75             {
  76               gnutls_assert ();
  77               return GNUTLS_E_UNEXPECTED_PACKET_LENGTH;
  78             }
  79
  80           new_size = _gnutls_mre_num2record (data[0]);
  81
  82           if (new_size < 0
  83               || new_size != session->internals.proposed_record_size)
  84             {
  85               gnutls_assert ();
  86               return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
  87             }
  88           else
  89             {
  90               session->security_parameters.max_record_recv_size =
  91                 session->internals.proposed_record_size;
  92             }
  93
  94         }
  95
  96
  97     }
  98
  99   return 0;
 100 }
 101
 102 /* returns data_size or a negative number on failure
 103  */
 104 int
 105 _gnutls_max_record_send_params (gnutls_session_t session, opaque * data,
 106                                 size_t data_size)
 107 {
 108   uint16_t len;
 109   /* this function sends the client extension data (dnsname) */
 110   if (session->security_parameters.entity == GNUTLS_CLIENT)
 111     {
 112
 113       if (session->internals.proposed_record_size != DEFAULT_MAX_RECORD_SIZE)
 114         {
 115           len = 1;
 116           if (data_size < len)
 117             {
 118               gnutls_assert ();
 119               return GNUTLS_E_SHORT_MEMORY_BUFFER;
 120             }
 121
 122           data[0] =
 123             (uint8_t) _gnutls_mre_record2num (session->internals.
 124                                               proposed_record_size);
 125           return len;
 126         }
 127
 128     }
 129   else
 130     {                           /* server side */
 131
 132       if (session->security_parameters.max_record_recv_size !=
 133           DEFAULT_MAX_RECORD_SIZE)
 134         {
 135           len = 1;
 136           if (data_size < len)
 137             {
 138               gnutls_assert ();
 139               return GNUTLS_E_SHORT_MEMORY_BUFFER;
 140             }
 141
 142           data[0] =
 143             (uint8_t)
 144             _gnutls_mre_record2num
 145             (session->security_parameters.max_record_recv_size);
 146           return len;
 147         }
 148
 149
 150     }
 151
 152   return 0;
 153 }
 154
 155 /* Maps numbers to record sizes according to the
 156  * extensions draft.
 157  */
 158 int
 159 _gnutls_mre_num2record (int num)
 160 {
 161   switch (num)
 162     {
 163     case 1:
 164       return 512;
 165     case 2:
 166       return 1024;
 167     case 3:
 168       return 2048;
 169     case 4:
 170       return 4096;
 171     default:
 172       return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
 173     }
 174 }
 175
 176 /* Maps record size to numbers according to the
 177  * extensions draft.
 178  */
 179 int
 180 _gnutls_mre_record2num (uint16_t record_size)
 181 {
 182   switch (record_size)
 183     {
 184     case 512:
 185       return 1;
 186     case 1024:
 187       return 2;
 188     case 2048:
 189       return 3;
 190     case 4096:
 191       return 4;
 192     default:
 193       return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
 194     }
 195
 196 }