chap.c

lwip-1.4.0

/*** 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 "lwip/opt.h"

#if PPP_SUPPORT  /* don't build if not configured for use in lwipopts.h */

#if CHAP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#include "ppp.h"
#include "pppdebug.h"

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

#include <string.h>

#if 0 /* UNUSED */
/*
 * Command-line options.
 */
static option_t chap_option_list[] = {
    { "chap-restart", o_int, &chap[0].timeouttime,
      "Set timeout for CHAP" },
    { "chap-max-challenge", o_int, &chap[0].max_transmits,
      "Set max #xmits for challenge" },
    { "chap-interval", o_int, &chap[0].chal_interval,
      "Set interval for rechallenge" },
#ifdef MSLANMAN
    { "ms-lanman", o_bool, &ms_lanman,
      "Use LanMan passwd when using MS-CHAP", 1 },
#endif
    { NULL }
};
#endif /* UNUSED */

/*
 * 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);
#if PPP_ADDITIONAL_CALLBACKS
static int  ChapPrintPkt (u_char *, int, void (*) (void *, char *, ...), void *);
#endif

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

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

static void ChapChallengeTimeout (void *);
static void ChapResponseTimeout (void *);
static void ChapReceiveChallenge (chap_state *, u_char *, u_char, 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 *);

/*
 * 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 */
}


/*
 * ChapAuthWithPeer - Authenticate us with our peer (start client).
 *
 */
void
ChapAuthWithPeer(int unit, char *our_name, u_char 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, u_char 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;
}


/*
 * 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); /* lwip: just sets the PPP error code on this unit to PPPERR_AUTHFAIL */
  }
  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, u_char 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;
  }

  GETCHAR(rchallenge_len, inp);
  len -= sizeof (u_char) + rchallenge_len;  /* now name field length */
  if (len < 0) {
    CHAPDEBUG(LOG_INFO, ("ChapReceiveChallenge: rcvd short packet.\n"));
    return;
  }
  rchallenge = inp;
  INCPTR(rchallenge_len, inp);

  if (len >= (int)sizeof(rhostname)) {