release/src/router/rp-l2tp/auth.c

   1 /***********************************************************************
   2 *
   3 * auth.c
   4 *
   5 * Code for doing CHAP-style authentication
   6 *
   7 * Copyright (C) 2002 by Roaring Penguin Software Inc.
   8 *
   9 * This software may be distributed under the terms of the GNU General
  10 * Public License, Version 2, or (at your option) any later version.
  11 *
  12 * LIC: GPL
  13 *
  14 ***********************************************************************/
  15
  16 static char const RCSID[] =
  17 "$Id: auth.c,v 1.1.48.1 2005/08/08 12:05:25 honor Exp $";
  18
  19 #include "l2tp.h"
  20 #include "md5.h"
  21 #include <string.h>
  22
  23 /**********************************************************************
  24 * %FUNCTION: auth_gen_response
  25 * %ARGUMENTS:
  26 *  msg_type -- message type
  27 *  secret -- secret to use
  28 *  challenge -- challenge received from peer
  29 *  chal_len -- length of challenge
  30 *  buf -- buffer in which to place 16-byte response
  31 * %RETURNS:
  32 *  Nothing
  33 * %DESCRIPTION:
  34 *  Computes a response for the challenge using "secret"
  35 ***********************************************************************/
  36 void
  37 l2tp_auth_gen_response(uint16_t msg_type,
  38                   char const *secret,
  39                   unsigned char const *challenge,
  40                   size_t chal_len,
  41                   unsigned char buf[16])
  42 {
  43     struct MD5Context ctx;
  44     unsigned char id = (unsigned char) msg_type;
  45
  46     MD5Init(&ctx);
  47     MD5Update(&ctx, &id, 1);
  48     MD5Update(&ctx, (unsigned char *) secret, strlen(secret));
  49     MD5Update(&ctx, challenge, chal_len);
  50     MD5Final(buf, &ctx);
  51     DBG(l2tp_db(DBG_AUTH, "auth_gen_response(secret=%s) -> %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n", secret,
  52            buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6], buf[7],
  53            buf[8], buf[9], buf[10], buf[11], buf[12], buf[13], buf[14], buf[15]));
  54 }