chap.c

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/*** WARNING - THIS HAS NEVER BEEN FINISHED ***/
/*****************************************************************************
* chap.c - Network Challenge Handshake Authentication Protocol program file.
*
* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
* portions Copyright (c) 1997 by Global Election Systems Inc.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice and the following disclaimer are included verbatim in any 
* distributions. No written agreement, license, or royalty fee is required
* for any of the authorized uses.
*
* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *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 CONTRIBUTORS 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.
*
******************************************************************************
* REVISION HISTORY
*
* 03-01-01 Marc Boucher <[e-mail]>
*   Ported to lwIP.
* 97-12-04 Guy Lancaster <[e-mail]>, Global Election Systems Inc.
*	Original based on BSD chap.c.
*****************************************************************************/
/*
 * chap.c - Challenge Handshake Authentication Protocol.
 *
 * Copyright (c) 1993 The Australian National University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the Australian National University.  The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Copyright (c) 1991 Gregory M. Christy.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Gregory M. Christy.  The name of the author may not be used to
 * endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include "ppp.h"
#if PPP_SUPPORT > 0
#include "magic.h"

#if CHAP_SUPPORT > 0

#include "randm.h"
#include "auth.h"
#include "md5.h"
#include "chap.h"
#include "chpms.h"
#include "pppdebug.h"


/*************************/
/*** LOCAL DEFINITIONS ***/
/*************************/


/************************/
/*** LOCAL DATA TYPES ***/
/************************/


/***********************************/
/*** LOCAL FUNCTION DECLARATIONS ***/
/***********************************/
/*
 * Protocol entry points.
 */
static void ChapInit (int);
static void ChapLowerUp (int);
static void ChapLowerDown (int);
static void ChapInput (int, u_char *, int);
static void ChapProtocolReject (int);
static int  ChapPrintPkt (u_char *, int,
			      void (*) (void *, char *, ...), void *);

static void ChapChallengeTimeout (void *);
static void ChapResponseTimeout (void *);
static void ChapReceiveChallenge (chap_state *, u_char *, int, int);
static void ChapRechallenge (void *);
static void ChapReceiveResponse (chap_state *, u_char *, int, int);
static void ChapReceiveSuccess(chap_state *cstate, u_char *inp, u_char id, int len);
static void ChapReceiveFailure(chap_state *cstate, u_char *inp, u_char id, int len);
static void ChapSendStatus (chap_state *, int);
static void ChapSendChallenge (chap_state *);
static void ChapSendResponse (chap_state *);
static void ChapGenChallenge (chap_state *);


/******************************/
/*** PUBLIC DATA STRUCTURES ***/
/******************************/
chap_state chap[NUM_PPP];		/* CHAP state; one for each unit */

struct protent chap_protent = {
    PPP_CHAP,
    ChapInit,
    ChapInput,
    ChapProtocolReject,
    ChapLowerUp,
    ChapLowerDown,
    NULL,
    NULL,
#if 0
    ChapPrintPkt,
    NULL,
#endif
    1,
    "CHAP",
#if 0
    NULL,
    NULL,
    NULL
#endif
};



/*****************************/
/*** LOCAL DATA STRUCTURES ***/
/*****************************/
static char *ChapCodenames[] = {
	"Challenge", "Response", "Success", "Failure"
};



/***********************************/
/*** PUBLIC FUNCTION DEFINITIONS ***/
/***********************************/
/*
 * ChapAuthWithPeer - Authenticate us with our peer (start client).
 *
 */
void ChapAuthWithPeer(int unit, char *our_name, int digest)
{
	chap_state *cstate = &chap[unit];
	
	cstate->resp_name = our_name;
	cstate->resp_type = digest;
	
	if (cstate->clientstate == CHAPCS_INITIAL ||
			cstate->clientstate == CHAPCS_PENDING) {
		/* lower layer isn't up - wait until later */
		cstate->clientstate = CHAPCS_PENDING;
		return;
	}
	
	/*
	 * We get here as a result of LCP coming up.
	 * So even if CHAP was open before, we will 
	 * have to re-authenticate ourselves.
	 */
	cstate->clientstate = CHAPCS_LISTEN;
}


/*
 * ChapAuthPeer - Authenticate our peer (start server).
 */
void ChapAuthPeer(int unit, char *our_name, int digest)
{
	chap_state *cstate = &chap[unit];
	
	cstate->chal_name = our_name;
	cstate->chal_type = digest;
	
	if (cstate->serverstate == CHAPSS_INITIAL ||
			cstate->serverstate == CHAPSS_PENDING) {
		/* lower layer isn't up - wait until later */
		cstate->serverstate = CHAPSS_PENDING;
		return;
	}
	
	ChapGenChallenge(cstate);
	ChapSendChallenge(cstate);		/* crank it up dude! */
	cstate->serverstate = CHAPSS_INITIAL_CHAL;
}




/**********************************/
/*** LOCAL FUNCTION DEFINITIONS ***/
/**********************************/
/*
 * ChapInit - Initialize a CHAP unit.
 */
static void ChapInit(int unit)
{
	chap_state *cstate = &chap[unit];
	
	BZERO(cstate, sizeof(*cstate));
	cstate->unit = unit;
	cstate->clientstate = CHAPCS_INITIAL;
	cstate->serverstate = CHAPSS_INITIAL;
	cstate->timeouttime = CHAP_DEFTIMEOUT;
	cstate->max_transmits = CHAP_DEFTRANSMITS;
	/* random number generator is initialized in magic_init */
}


/*
 * ChapChallengeTimeout - Timeout expired on sending challenge.
 */
static void ChapChallengeTimeout(void *arg)
{
	chap_state *cstate = (chap_state *) arg;
	
	/* if we aren't sending challenges, don't worry.  then again we */
	/* probably shouldn't be here either */
	if (cstate->serverstate != CHAPSS_INITIAL_CHAL &&
			cstate->serverstate != CHAPSS_RECHALLENGE)
		return;
	
	if (cstate->chal_transmits >= cstate->max_transmits) {
		/* give up on peer */
		CHAPDEBUG((LOG_ERR, "Peer failed to respond to CHAP challenge\n"));
		cstate->serverstate = CHAPSS_BADAUTH;
		auth_peer_fail(cstate->unit, PPP_CHAP);
		return;
	}
	
	ChapSendChallenge(cstate);		/* Re-send challenge */
}


/*
 * ChapResponseTimeout - Timeout expired on sending response.
 */
static void ChapResponseTimeout(void *arg)
{
	chap_state *cstate = (chap_state *) arg;
	
	/* if we aren't sending a response, don't worry. */
	if (cstate->clientstate != CHAPCS_RESPONSE)
		return;
	
	ChapSendResponse(cstate);		/* re-send response */
}


/*
 * ChapRechallenge - Time to challenge the peer again.
 */
static void ChapRechallenge(void *arg)
{
	chap_state *cstate = (chap_state *) arg;
	
	/* if we aren't sending a response, don't worry. */
	if (cstate->serverstate != CHAPSS_OPEN)
		return;
	
	ChapGenChallenge(cstate);
	ChapSendChallenge(cstate);
	cstate->serverstate = CHAPSS_RECHALLENGE;
}


/*
 * ChapLowerUp - The lower layer is up.
 *
 * Start up if we have pending requests.
 */
static void ChapLowerUp(int unit)
{
	chap_state *cstate = &chap[unit];
	
	if (cstate->clientstate == CHAPCS_INITIAL)
		cstate->clientstate = CHAPCS_CLOSED;
	else if (cstate->clientstate == CHAPCS_PENDING)
		cstate->clientstate = CHAPCS_LISTEN;
	
	if (cstate->serverstate == CHAPSS_INITIAL)
		cstate->serverstate = CHAPSS_CLOSED;
	else if (cstate->serverstate == CHAPSS_PENDING) {
		ChapGenChallenge(cstate);
		ChapSendChallenge(cstate);
		cstate->serverstate = CHAPSS_INITIAL_CHAL;
	}
}


/*
 * ChapLowerDown - The lower layer is down.
 *
 * Cancel all timeouts.
 */
static void ChapLowerDown(int unit)
{
	chap_state *cstate = &chap[unit];
	
	/* Timeout(s) pending?  Cancel if so. */
	if (cstate->serverstate == CHAPSS_INITIAL_CHAL ||
			cstate->serverstate == CHAPSS_RECHALLENGE)
		UNTIMEOUT(ChapChallengeTimeout, cstate);
	else if (cstate->serverstate == CHAPSS_OPEN
			&& cstate->chal_interval != 0)
		UNTIMEOUT(ChapRechallenge, cstate);
	if (cstate->clientstate == CHAPCS_RESPONSE)
		UNTIMEOUT(ChapResponseTimeout, cstate);
	
	cstate->clientstate = CHAPCS_INITIAL;
	cstate->serverstate = CHAPSS_INITIAL;
}


/*
 * ChapProtocolReject - Peer doesn't grok CHAP.
 */
static void ChapProtocolReject(int unit)
{
	chap_state *cstate = &chap[unit];
	
	if (cstate->serverstate != CHAPSS_INITIAL &&
			cstate->serverstate != CHAPSS_CLOSED)
		auth_peer_fail(unit, PPP_CHAP);
	if (cstate->clientstate != CHAPCS_INITIAL &&
			cstate->clientstate != CHAPCS_CLOSED)
		auth_withpeer_fail(unit, PPP_CHAP);
	ChapLowerDown(unit);		/* shutdown chap */
}


/*
 * ChapInput - Input CHAP packet.
 */
static void ChapInput(int unit, u_char *inpacket, int packet_len)
{
	chap_state *cstate = &chap[unit];
	u_char *inp;
	u_char code, id;
	int len;
	
	/*
	 * Parse header (code, id and length).
	 * If packet too short, drop it.
	 */
	inp = inpacket;
	if (packet_len < CHAP_HEADERLEN) {
		CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short header.\n"));
		return;
	}
	GETCHAR(code, inp);
	GETCHAR(id, inp);
	GETSHORT(len, inp);
	if (len < CHAP_HEADERLEN) {
		CHAPDEBUG((LOG_INFO, "ChapInput: rcvd illegal length.\n"));
		return;
	}
	if (len > packet_len) {
		CHAPDEBUG((LOG_INFO, "ChapInput: rcvd short packet.\n"));
		return;
	}
	len -= CHAP_HEADERLEN;
	
	/*
	 * Action depends on code (as in fact it usually does :-).
	 */
	switch (code) {
	case CHAP_CHALLENGE:
		ChapReceiveChallenge(cstate, inp, id, len);
		break;
	
	case CHAP_RESPONSE:
		ChapReceiveResponse(cstate, inp, id, len);
		break;
	
	case CHAP_FAILURE:
		ChapReceiveFailure(cstate, inp, id, len);
		break;
	
	case CHAP_SUCCESS:
		ChapReceiveSuccess(cstate, inp, id, len);
		break;
	
	default:				/* Need code reject? */
		CHAPDEBUG((LOG_WARNING, "Unknown CHAP code (%d) received.\n", code));
		break;
	}
}


/*
 * ChapReceiveChallenge - Receive Challenge and send Response.
 */
static void ChapReceiveChallenge(chap_state *cstate, u_char *inp, int id, int len)
{
	int rchallenge_len;
	u_char *rchallenge;
	int secret_len;
	char secret[MAXSECRETLEN];
	char rhostname[256];
	MD5_CTX mdContext;
	u_char hash[MD5_SIGNATURE_SIZE];
	
	CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: Rcvd id %d.\n", id));
	if (cstate->clientstate == CHAPCS_CLOSED ||
		cstate->clientstate == CHAPCS_PENDING) {
		CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: in state %d\n",
			   cstate->clientstate));
		return;
	}
	
	if (len < 2) {
		CHAPDEBUG((LOG_INFO, "ChapReceiveChallenge: rcvd short packet.\n"));
		return;