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/* cookie generation/verification routines.
* Copyright (C) 1997 Angelos D. Keromytis.
* Copyright (C) 1998-2002 D. Hugh Redelmeier.
* Copyright (C) 2009 Andreas Steffen - Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program 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 General Public License
* for more details.
*/
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <freeswan.h>
#include <library.h>
#include <crypto/rngs/rng.h>
#include "constants.h"
#include "defs.h"
#include "cookie.h"
const u_char zero_cookie[COOKIE_SIZE]; /* guaranteed 0 */
/* Generate a cookie.
* First argument is true if we're to create an Initiator cookie.
* Length SHOULD be a multiple of sizeof(u_int32_t).
*/
void get_cookie(bool initiator, u_int8_t *cookie, int length, ip_address *addr)
{
hasher_t *hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1);
u_char buffer[HASH_SIZE_SHA1];
do {
if (initiator)
{
rng_t *rng;
rng = lib->crypto->create_rng(lib->crypto, RNG_STRONG);
rng->get_bytes(rng, length, cookie);
rng->destroy(rng);
}
else /* Responder cookie */
{
chunk_t addr_chunk, secret_chunk, counter_chunk;
size_t addr_len;
static u_int32_t counter = 0;
unsigned char addr_buf[
sizeof(union {struct in_addr A; struct in6_addr B;})];
addr_len = addrbytesof(addr, addr_buf, sizeof(addr_buf));
addr_chunk = chunk_create(addr_buf, addr_len);
secret_chunk = chunk_create(secret_of_the_day, HASH_SIZE_SHA1);
counter++;
counter_chunk = chunk_create((void *) &counter, sizeof(counter));
hasher->get_hash(hasher, addr_chunk, NULL);
hasher->get_hash(hasher, secret_chunk, NULL);
hasher->get_hash(hasher, counter_chunk, buffer);
memcpy(cookie, buffer, length);
}
} while (is_zero_cookie(cookie)); /* probably never loops */
hasher->destroy(hasher);
}
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