lib/gs2/gs2parser.c

   1 /* gs2parser.h --- GS2 parser.
   2  * Copyright (C) 2006  Simon Josefsson
   3  *
   4  * This file is part of GNU SASL Library.
   5  *
   6  * GNU SASL Library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public License
   8  * as published by the Free Software Foundation; either version 2.1 of
   9  * the License, or (at your option) any later version.
  10  *
  11  * GNU SASL Library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with GNU SASL Library; if not, write to the Free
  18  * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  19  * Boston, MA 02110-1301, USA.
  20  *
  21  */
  22
  23 #include "gs2parser.h"
  24
  25 int
  26 gs2_parser (const char *token, size_t toklen, struct gs2_token *out)
  27 {
  28   uint32_t ctxlen;
  29
  30   /* Packets shorter than 4 octets are invalid. */
  31   if (toklen < 4)
  32     return 1;
  33
  34   ctxlen = token[0] << 24 | token[1] << 16 | token[2] << 8 | token[3];
  35
  36   /* If the length field is longer than the entire packet size, minus
  37      4 octets, the packet is invalid. */
  38   if (ctxlen > toklen - 4)
  39     return 1;
  40
  41   out->context_length = ctxlen;
  42   out->context_token = token + 4;
  43
  44   out->wrap_length = toklen - ctxlen - 4;
  45   out->wrap_token = out->wrap_length > 0 ? token + 4 + out->wrap_length : NULL;
  46
  47   return 0;
  48 }