BadVPN – Rev 1
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/*
* chap-md5.c - New CHAP/MD5 implementation.
*
* Copyright (c) 2003 Paul Mackerras. 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. The name(s) of the authors of this software must not be used to
* endorse or promote products derived from this software without
* prior written permission.
*
* 3. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by Paul Mackerras
* <paulus@samba.org>".
*
* THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT && CHAP_SUPPORT /* don't build if not configured for use in lwipopts.h */
#if 0 /* UNUSED */
#include <stdlib.h>
#include <string.h>
#endif /* UNUSED */
#include "netif/ppp/ppp_impl.h"
#include "netif/ppp/chap-new.h"
#include "netif/ppp/chap-md5.h"
#include "netif/ppp/magic.h"
#include "netif/ppp/pppcrypt.h"
#define MD5_HASH_SIZE 16
#define MD5_MIN_CHALLENGE 17
#define MD5_MAX_CHALLENGE 24
#define MD5_MIN_MAX_POWER_OF_TWO_CHALLENGE 3 /* 2^3-1 = 7, 17+7 = 24 */
#if PPP_SERVER
static void chap_md5_generate_challenge(ppp_pcb *pcb, unsigned char *cp) {
int clen;
LWIP_UNUSED_ARG(pcb);
clen = MD5_MIN_CHALLENGE + magic_pow(MD5_MIN_MAX_POWER_OF_TWO_CHALLENGE);
*cp++ = clen;
magic_random_bytes(cp, clen);
}
static int chap_md5_verify_response(ppp_pcb *pcb, int id, const char *name,
const unsigned char *secret, int secret_len,
const unsigned char *challenge, const unsigned char *response,
char *message, int message_space) {
lwip_md5_context ctx;
unsigned char idbyte = id;
unsigned char hash[MD5_HASH_SIZE];
int challenge_len, response_len;
LWIP_UNUSED_ARG(name);
LWIP_UNUSED_ARG(pcb);
challenge_len = *challenge++;
response_len = *response++;
if (response_len == MD5_HASH_SIZE) {
/* Generate hash of ID, secret, challenge */
lwip_md5_init(&ctx);
lwip_md5_starts(&ctx);
lwip_md5_update(&ctx, &idbyte, 1);
lwip_md5_update(&ctx, secret, secret_len);
lwip_md5_update(&ctx, challenge, challenge_len);
lwip_md5_finish(&ctx, hash);
lwip_md5_free(&ctx);
/* Test if our hash matches the peer's response */
if (memcmp(hash, response, MD5_HASH_SIZE) == 0) {
ppp_slprintf(message, message_space, "Access granted");
return 1;
}
}
ppp_slprintf(message, message_space, "Access denied");
return 0;
}
#endif /* PPP_SERVER */
static void chap_md5_make_response(ppp_pcb *pcb, unsigned char *response, int id, const char *our_name,
const unsigned char *challenge, const char *secret, int secret_len,
unsigned char *private_) {
lwip_md5_context ctx;
unsigned char idbyte = id;
int challenge_len = *challenge++;
LWIP_UNUSED_ARG(our_name);
LWIP_UNUSED_ARG(private_);
LWIP_UNUSED_ARG(pcb);
lwip_md5_init(&ctx);
lwip_md5_starts(&ctx);
lwip_md5_update(&ctx, &idbyte, 1);
lwip_md5_update(&ctx, (const u_char *)secret, secret_len);
lwip_md5_update(&ctx, challenge, challenge_len);
lwip_md5_finish(&ctx, &response[1]);
lwip_md5_free(&ctx);
response[0] = MD5_HASH_SIZE;
}
const struct chap_digest_type md5_digest = {
CHAP_MD5, /* code */
#if PPP_SERVER
chap_md5_generate_challenge,
chap_md5_verify_response,
#endif /* PPP_SERVER */
chap_md5_make_response,
NULL, /* check_success */
NULL, /* handle_failure */
};
#endif /* PPP_SUPPORT && CHAP_SUPPORT */