lib/gnutls_supplemental.c

   1 /*
   2  * Copyright (C) 2007, 2008, 2010 Free Software Foundation, Inc.
   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, size_t data_size);
  55 typedef int (*supp_send_func) (gnutls_session_t session, gnutls_buffer * buf);
  56
  57 typedef struct
  58 {
  59   const char *name;
  60   gnutls_supplemental_data_format_type_t type;
  61   supp_recv_func supp_recv_func;
  62   supp_send_func supp_send_func;
  63 } gnutls_supplemental_entry;
  64
  65 gnutls_supplemental_entry _gnutls_supplemental[] = {
  66   {0, 0, 0, 0}
  67 };
  68
  69 const char *
  70 gnutls_supplemental_get_name (gnutls_supplemental_data_format_type_t type)
  71 {
  72   gnutls_supplemental_entry *p;
  73
  74   for (p = _gnutls_supplemental; p->name != NULL; p++)
  75     if (p->type == type)
  76       return p->name;
  77
  78   return NULL;
  79 }
  80
  81 static supp_recv_func
  82 get_supp_func_recv (gnutls_supplemental_data_format_type_t type)
  83 {
  84   gnutls_supplemental_entry *p;
  85
  86   for (p = _gnutls_supplemental; p->name != NULL; p++)
  87     if (p->type == type)
  88       return p->supp_recv_func;
  89
  90   return NULL;
  91 }
  92
  93 int
  94 _gnutls_gen_supplemental (gnutls_session_t session, gnutls_buffer * buf)
  95 {
  96   gnutls_supplemental_entry *p;
  97   int ret;
  98
  99   /* Make room for 3 byte length field. */
 100   ret = _gnutls_buffer_append (buf, "\0\0\0", 3);
 101   if (ret < 0)
 102     {
 103       gnutls_assert ();
 104       return ret;
 105     }
 106
 107   for (p = _gnutls_supplemental; p->name; p++)
 108     {
 109       supp_send_func supp_send = p->supp_send_func;
 110       size_t sizepos = buf->length;
 111
 112       /* Make room for supplement type and length byte length field. */
 113       ret = _gnutls_buffer_append (buf, "\0\0\0\0", 4);
 114       if (ret < 0)
 115         {
 116           gnutls_assert ();
 117           return ret;
 118         }
 119
 120       ret = supp_send (session, buf);
 121       if (ret < 0)
 122         {
 123           gnutls_assert ();
 124           return ret;
 125         }
 126
 127       /* If data were added, store type+length, otherwise reset. */
 128       if (buf->length > sizepos + 4)
 129         {
 130           buf->data[sizepos] = 0;
 131           buf->data[sizepos + 1] = p->type;
 132           buf->data[sizepos + 2] = ((buf->length - sizepos - 4) >> 8) & 0xFF;
 133           buf->data[sizepos + 3] = (buf->length - sizepos - 4) & 0xFF;
 134         }
 135       else
 136         buf->length -= 4;
 137     }
 138
 139   buf->data[0] = ((buf->length - 3) >> 16) & 0xFF;
 140   buf->data[1] = ((buf->length - 3) >> 8) & 0xFF;
 141   buf->data[2] = (buf->length - 3) & 0xFF;
 142
 143   _gnutls_debug_log ("EXT[%p]: Sending %d bytes of supplemental data\n",
 144                      session, (int) buf->length);
 145
 146   return buf->length;
 147 }
 148
 149 int
 150 _gnutls_parse_supplemental (gnutls_session_t session,
 151                             const uint8_t * data, int datalen)
 152 {
 153   const opaque *p = data;
 154   ssize_t dsize = datalen;
 155   size_t total_size;
 156
 157   DECR_LEN (dsize, 3);
 158   total_size = _gnutls_read_uint24 (p);
 159   p += 3;
 160
 161   if (dsize != (ssize_t) total_size)
 162     {
 163       gnutls_assert ();
 164       return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
 165     }
 166
 167   do
 168     {
 169       uint16_t supp_data_type;
 170       uint16_t supp_data_length;
 171       supp_recv_func recv_func;
 172
 173       DECR_LEN (dsize, 2);
 174       supp_data_type = _gnutls_read_uint16 (p);
 175       p += 2;
 176
 177       DECR_LEN (dsize, 2);
 178       supp_data_length = _gnutls_read_uint16 (p);
 179       p += 2;
 180
 181       _gnutls_debug_log ("EXT[%p]: Got supplemental type=%02x length=%d\n",
 182                          session, supp_data_type, supp_data_length);
 183
 184       recv_func = get_supp_func_recv (supp_data_type);
 185       if (recv_func)
 186         {
 187           int ret = recv_func (session, p, supp_data_length);
 188           if (ret < 0)
 189             {
 190               gnutls_assert ();
 191               return ret;
 192             }
 193         }
 194       else
 195         {
 196           gnutls_assert ();
 197           return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
 198         }
 199
 200       DECR_LEN (dsize, supp_data_length);
 201       p += supp_data_length;
 202     }
 203   while (dsize > 0);
 204
 205   return 0;
 206 }