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/* session.c --- Data integrity/privacy protection of DIGEST-MD5.
* Copyright (C) 2002-2025 Simon Josefsson
*
* This file is part of GNU SASL Library.
*
* GNU SASL Library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* GNU SASL Library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with GNU SASL Library; if not, see
* <https://www.gnu.org/licenses/>.
*
*/
#include <config.h>
/* Get specification. */
#include "session.h"
/* Get malloc, free. */
#include <stdlib.h>
/* Get memcpy, strdup, strlen. */
#include <string.h>
/* Get gc_hmac_md5. */
#include <gc.h>
#define MD5LEN 16
#define SASL_INTEGRITY_PREFIX_LENGTH 4
#define MAC_DATA_LEN 4
#define MAC_HMAC_LEN 10
#define MAC_MSG_TYPE "\x00\x01"
#define MAC_MSG_TYPE_LEN 2
#define MAC_SEQNUM_LEN 4
int
digest_md5_encode (const char *input, size_t input_len,
char **output, size_t *output_len,
digest_md5_qop qop,
unsigned long sendseqnum, char key[DIGEST_MD5_LENGTH])
{
int res;
if (qop & DIGEST_MD5_QOP_AUTH_CONF)
{
return -1;
}
else if (qop & DIGEST_MD5_QOP_AUTH_INT)
{
char *seqnumin;
char hash[GC_MD5_DIGEST_SIZE];
size_t len;
seqnumin = malloc (MAC_SEQNUM_LEN + input_len);
if (seqnumin == NULL)
return -1;
seqnumin[0] = (sendseqnum >> 24) & 0xFF;
seqnumin[1] = (sendseqnum >> 16) & 0xFF;
seqnumin[2] = (sendseqnum >> 8) & 0xFF;
seqnumin[3] = sendseqnum & 0xFF;
memcpy (seqnumin + MAC_SEQNUM_LEN, input, input_len);
res = gc_hmac_md5 (key, MD5LEN,
seqnumin, MAC_SEQNUM_LEN + input_len, hash);
free (seqnumin);
if (res)
return -1;
*output_len = MAC_DATA_LEN + input_len + MAC_HMAC_LEN +
MAC_MSG_TYPE_LEN + MAC_SEQNUM_LEN;
*output = malloc (*output_len);
if (!*output)
return -1;
len = MAC_DATA_LEN;
memcpy (*output + len, input, input_len);
len += input_len;
memcpy (*output + len, hash, MAC_HMAC_LEN);
len += MAC_HMAC_LEN;
memcpy (*output + len, MAC_MSG_TYPE, MAC_MSG_TYPE_LEN);
len += MAC_MSG_TYPE_LEN;
(*output + len)[0] = (sendseqnum >> 24) & 0xFF;
(*output + len)[1] = (sendseqnum >> 16) & 0xFF;
(*output + len)[2] = (sendseqnum >> 8) & 0xFF;
(*output + len)[3] = sendseqnum & 0xFF;
len += MAC_SEQNUM_LEN;
(*output)[0] = ((len - MAC_DATA_LEN) >> 24) & 0xFF;
(*output)[1] = ((len - MAC_DATA_LEN) >> 16) & 0xFF;
(*output)[2] = ((len - MAC_DATA_LEN) >> 8) & 0xFF;
(*output)[3] = (len - MAC_DATA_LEN) & 0xFF;
}
else
{
*output_len = input_len;
*output = malloc (input_len);
if (!*output)
return -1;
memcpy (*output, input, input_len);
}
return 0;
}
#define C2I(buf) ((buf[3] & 0xFF) | \
((buf[2] & 0xFF) << 8) | \
((buf[1] & 0xFF) << 16) | \
((buf[0] & 0xFF) << 24))
int
digest_md5_decode (const char *input, size_t input_len,
char **output, size_t *output_len,
digest_md5_qop qop,
unsigned long readseqnum, char key[DIGEST_MD5_LENGTH])
{
if (qop & DIGEST_MD5_QOP_AUTH_CONF)
{
return -1;
}
else if (qop & DIGEST_MD5_QOP_AUTH_INT)
{
char *seqnumin;
char hash[GC_MD5_DIGEST_SIZE];
unsigned long len;
char tmpbuf[SASL_INTEGRITY_PREFIX_LENGTH];
int res;
if (input_len < SASL_INTEGRITY_PREFIX_LENGTH)
return -2;
len = C2I (input);
if (input_len < SASL_INTEGRITY_PREFIX_LENGTH + len)
return -2;
len -= MAC_HMAC_LEN + MAC_MSG_TYPE_LEN + MAC_SEQNUM_LEN;
seqnumin = malloc (SASL_INTEGRITY_PREFIX_LENGTH + len);
if (seqnumin == NULL)
return -1;
tmpbuf[0] = (readseqnum >> 24) & 0xFF;
tmpbuf[1] = (readseqnum >> 16) & 0xFF;
tmpbuf[2] = (readseqnum >> 8) & 0xFF;
tmpbuf[3] = readseqnum & 0xFF;
memcpy (seqnumin, tmpbuf, SASL_INTEGRITY_PREFIX_LENGTH);
memcpy (seqnumin + SASL_INTEGRITY_PREFIX_LENGTH,
input + MAC_DATA_LEN, len);
res = gc_hmac_md5 (key, MD5LEN, seqnumin, MAC_SEQNUM_LEN + len, hash);
free (seqnumin);
if (res)
return -1;
if (memcmp
(hash,
input + input_len - MAC_SEQNUM_LEN - MAC_MSG_TYPE_LEN -
MAC_HMAC_LEN, MAC_HMAC_LEN) == 0
&& memcmp (MAC_MSG_TYPE,
input + input_len - MAC_SEQNUM_LEN - MAC_MSG_TYPE_LEN,
MAC_MSG_TYPE_LEN) == 0
&& memcmp (tmpbuf, input + input_len - MAC_SEQNUM_LEN,
MAC_SEQNUM_LEN) == 0)
{
*output_len = len;
*output = malloc (*output_len);
if (!*output)
return -1;
memcpy (*output, input + MAC_DATA_LEN, len);
}
else
return -1;
}
else
{
*output_len = input_len;
*output = malloc (input_len);
if (!*output)
return -1;
memcpy (*output, input, input_len);
}
return 0;
}
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