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/* $OpenBSD: cookie.c,v 1.16 2014/01/23 01:04:28 deraadt Exp $ */
/* $EOM: cookie.c,v 1.21 1999/08/05 15:00:04 niklas Exp $ */
/*
* Copyright (c) 1998, 1999 Niklas Hallqvist. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This code was written under funding by Ericsson Radio Systems.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <string.h>
#include "cookie.h"
#include "exchange.h"
#include "hash.h"
#include "transport.h"
#include "util.h"
#define COOKIE_SECRET_SIZE 16
/*
* Generate an anti-clogging token (a protection against an attacker forcing
* us to keep state for a flood of connection requests) a.k.a. a cookie
* at BUF, LEN bytes long. The cookie will be generated by hashing of
* information found, among otherplaces, in transport T and exchange
* EXCHANGE.
*/
void
cookie_gen(struct transport *t, struct exchange *exchange, u_int8_t *buf,
size_t len)
{
struct hash *hash = hash_get(HASH_SHA1);
u_int8_t tmpsecret[COOKIE_SECRET_SIZE];
struct sockaddr *name;
hash->Init(hash->ctx);
(*t->vtbl->get_dst)(t, &name);
hash->Update(hash->ctx, (u_int8_t *)name, SA_LEN(name));
(*t->vtbl->get_src)(t, &name);
hash->Update(hash->ctx, (u_int8_t *)name, SA_LEN(name));
if (exchange->initiator == 0)
hash->Update(hash->ctx, exchange->cookies +
ISAKMP_HDR_ICOOKIE_OFF, ISAKMP_HDR_ICOOKIE_LEN);
arc4random_buf(tmpsecret, COOKIE_SECRET_SIZE);
hash->Update(hash->ctx, tmpsecret, COOKIE_SECRET_SIZE);
hash->Final(hash->digest, hash->ctx);
memcpy(buf, hash->digest, len);
}
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