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/*****************************************************************************

* fsm.c - Network Control Protocol Finite State Machine 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 <marc@mbsi.ca>

*   Ported to lwIP.

* 97-12-01 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.

*   Original based on BSD fsm.c.

*****************************************************************************/

/*

 * fsm.c - {Link, IP} Control Protocol Finite State Machine.

 *

 * Copyright (c) 1989 Carnegie Mellon 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 Carnegie Mellon 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.

 */

/*

 * TODO:

 * Randomize fsm id on link/init.

 * Deal with variable outgoing MTU.

 */

#include "lwip/opt.h"

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

#include "ppp.h"

#include "pppdebug.h"

#include "fsm.h"

/*************************/

/*** LOCAL DEFINITIONS ***/

/*************************/

#if PPP_DEBUG

static const char *ppperr_strerr[] = {

           "LS_INITIAL",  /* LS_INITIAL  0 */

           "LS_STARTING", /* LS_STARTING 1 */

           "LS_CLOSED",   /* LS_CLOSED   2 */

           "LS_STOPPED",  /* LS_STOPPED  3 */

           "LS_CLOSING",  /* LS_CLOSING  4 */

           "LS_STOPPING", /* LS_STOPPING 5 */

           "LS_REQSENT",  /* LS_REQSENT  6 */

           "LS_ACKRCVD",  /* LS_ACKRCVD  7 */

           "LS_ACKSENT",  /* LS_ACKSENT  8 */

           "LS_OPENED"    /* LS_OPENED   9 */

};

#endif /* PPP_DEBUG */

/************************/

/*** LOCAL DATA TYPES ***/

/************************/

/***********************************/

/*** LOCAL FUNCTION DECLARATIONS ***/

/***********************************/

static void fsm_timeout (void *);

static void fsm_rconfreq (fsm *, u_char, u_char *, int);

static void fsm_rconfack (fsm *, int, u_char *, int);

static void fsm_rconfnakrej (fsm *, int, int, u_char *, int);

static void fsm_rtermreq (fsm *, int, u_char *, int);

static void fsm_rtermack (fsm *);

static void fsm_rcoderej (fsm *, u_char *, int);

static void fsm_sconfreq (fsm *, int);

#define PROTO_NAME(f) ((f)->callbacks->proto_name)

/******************************/

/*** PUBLIC DATA STRUCTURES ***/

/******************************/

/*****************************/

/*** LOCAL DATA STRUCTURES ***/

/*****************************/

int peer_mru[NUM_PPP];

/***********************************/

/*** PUBLIC FUNCTION DEFINITIONS ***/

/***********************************/

/*

 * fsm_init - Initialize fsm.

 *

 * Initialize fsm state.

 */

void

fsm_init(fsm *f)

{

  f->state = LS_INITIAL;

  f->flags = 0;

  f->id = 0;        /* XXX Start with random id? */

  f->timeouttime = FSM_DEFTIMEOUT;

  f->maxconfreqtransmits = FSM_DEFMAXCONFREQS;

  f->maxtermtransmits = FSM_DEFMAXTERMREQS;

  f->maxnakloops = FSM_DEFMAXNAKLOOPS;

  f->term_reason_len = 0;

}

/*

 * fsm_lowerup - The lower layer is up.

 */

void

fsm_lowerup(fsm *f)

{

  int oldState = f->state;

  LWIP_UNUSED_ARG(oldState);

  switch( f->state ) {

    case LS_INITIAL:

      f->state = LS_CLOSED;

      break;

    case LS_STARTING:

      if( f->flags & OPT_SILENT ) {

        f->state = LS_STOPPED;

      } else {

        /* Send an initial configure-request */

        fsm_sconfreq(f, 0);

        f->state = LS_REQSENT;

      }

    break;

    default:

      FSMDEBUG((LOG_INFO, "%s: Up event in state %d (%s)!\n",

          PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

  }

  FSMDEBUG((LOG_INFO, "%s: lowerup state %d (%s) -> %d (%s)\n",

      PROTO_NAME(f), oldState, ppperr_strerr[oldState], f->state, ppperr_strerr[f->state]));

}

/*

 * fsm_lowerdown - The lower layer is down.

 *

 * Cancel all timeouts and inform upper layers.

 */

void

fsm_lowerdown(fsm *f)

{

  int oldState = f->state;

  LWIP_UNUSED_ARG(oldState);

  switch( f->state ) {

    case LS_CLOSED:

      f->state = LS_INITIAL;

      break;

    case LS_STOPPED:

      f->state = LS_STARTING;

      if( f->callbacks->starting ) {

        (*f->callbacks->starting)(f);

      }

      break;

    case LS_CLOSING:

      f->state = LS_INITIAL;

      UNTIMEOUT(fsm_timeout, f);  /* Cancel timeout */

      break;

    case LS_STOPPING:

    case LS_REQSENT:

    case LS_ACKRCVD:

    case LS_ACKSENT:

      f->state = LS_STARTING;

      UNTIMEOUT(fsm_timeout, f);  /* Cancel timeout */

      break;

    case LS_OPENED:

      if( f->callbacks->down ) {

        (*f->callbacks->down)(f);

      }

      f->state = LS_STARTING;

      break;

    default:

      FSMDEBUG((LOG_INFO, "%s: Down event in state %d (%s)!\n",

          PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

  }

  FSMDEBUG((LOG_INFO, "%s: lowerdown state %d (%s) -> %d (%s)\n",

      PROTO_NAME(f), oldState, ppperr_strerr[oldState], f->state, ppperr_strerr[f->state]));

}

/*

 * fsm_open - Link is allowed to come up.

 */

void

fsm_open(fsm *f)

{

  int oldState = f->state;

  LWIP_UNUSED_ARG(oldState);

  switch( f->state ) {

    case LS_INITIAL:

      f->state = LS_STARTING;

      if( f->callbacks->starting ) {

        (*f->callbacks->starting)(f);

      }

      break;

    case LS_CLOSED:

      if( f->flags & OPT_SILENT ) {

        f->state = LS_STOPPED;

      } else {

        /* Send an initial configure-request */

        fsm_sconfreq(f, 0);

        f->state = LS_REQSENT;

      }

      break;

    case LS_CLOSING:

      f->state = LS_STOPPING;

      /* fall through */

    case LS_STOPPED:

    case LS_OPENED:

      if( f->flags & OPT_RESTART ) {

        fsm_lowerdown(f);

        fsm_lowerup(f);

      }

      break;

  }

  FSMDEBUG((LOG_INFO, "%s: open state %d (%s) -> %d (%s)\n",

      PROTO_NAME(f), oldState, ppperr_strerr[oldState], f->state, ppperr_strerr[f->state]));

}

/*

 * fsm_close - Start closing connection.

 *

 * Cancel timeouts and either initiate close or possibly go directly to

 * the LS_CLOSED state.

 */

void

fsm_close(fsm *f, char *reason)

{

  int oldState = f->state;

  LWIP_UNUSED_ARG(oldState);

  f->term_reason = reason;

  f->term_reason_len = (reason == NULL? 0: strlen(reason));

  switch( f->state ) {

    case LS_STARTING:

      f->state = LS_INITIAL;

      break;

    case LS_STOPPED:

      f->state = LS_CLOSED;

      break;

    case LS_STOPPING:

      f->state = LS_CLOSING;

      break;

    case LS_REQSENT:

    case LS_ACKRCVD:

    case LS_ACKSENT:

    case LS_OPENED:

      if( f->state != LS_OPENED ) {

        UNTIMEOUT(fsm_timeout, f);  /* Cancel timeout */

      } else if( f->callbacks->down ) {

        (*f->callbacks->down)(f);  /* Inform upper layers we're down */

      }

      /* Init restart counter, send Terminate-Request */

      f->retransmits = f->maxtermtransmits;

      fsm_sdata(f, TERMREQ, f->reqid = ++f->id,

            (u_char *) f->term_reason, f->term_reason_len);

      TIMEOUT(fsm_timeout, f, f->timeouttime);

      --f->retransmits;

      f->state = LS_CLOSING;

      break;

  }

  FSMDEBUG((LOG_INFO, "%s: close reason=%s state %d (%s) -> %d (%s)\n",

      PROTO_NAME(f), reason, oldState, ppperr_strerr[oldState], f->state, ppperr_strerr[f->state]));

}

/*

 * fsm_sdata - Send some data.

 *

 * Used for all packets sent to our peer by this module.

 */

void

fsm_sdata( fsm *f, u_char code, u_char id, u_char *data, int datalen)

{

  u_char *outp;

  int outlen;

  /* Adjust length to be smaller than MTU */

  outp = outpacket_buf[f->unit];

  if (datalen > peer_mru[f->unit] - (int)HEADERLEN) {

    datalen = peer_mru[f->unit] - HEADERLEN;

  }

  if (datalen && data != outp + PPP_HDRLEN + HEADERLEN) {

    BCOPY(data, outp + PPP_HDRLEN + HEADERLEN, datalen);

  }

  outlen = datalen + HEADERLEN;

  MAKEHEADER(outp, f->protocol);

  PUTCHAR(code, outp);

  PUTCHAR(id, outp);

  PUTSHORT(outlen, outp);

  pppWrite(f->unit, outpacket_buf[f->unit], outlen + PPP_HDRLEN);

  FSMDEBUG((LOG_INFO, "fsm_sdata(%s): Sent code %d,%d,%d.\n",

        PROTO_NAME(f), code, id, outlen));

}

/*

 * fsm_input - Input packet.

 */

void

fsm_input(fsm *f, u_char *inpacket, int l)

{

  u_char *inp = inpacket;

  u_char code, id;

  int len;

  /*

  * Parse header (code, id and length).

  * If packet too short, drop it.

  */

  if (l < HEADERLEN) {

    FSMDEBUG((LOG_WARNING, "fsm_input(%x): Rcvd short header.\n",

          f->protocol));

    return;

  }

  GETCHAR(code, inp);

  GETCHAR(id, inp);

  GETSHORT(len, inp);

  if (len < HEADERLEN) {

    FSMDEBUG((LOG_INFO, "fsm_input(%x): Rcvd illegal length.\n",

        f->protocol));

    return;

  }

  if (len > l) {

    FSMDEBUG((LOG_INFO, "fsm_input(%x): Rcvd short packet.\n",

        f->protocol));

    return;

  }

  len -= HEADERLEN;    /* subtract header length */

  if( f->state == LS_INITIAL || f->state == LS_STARTING ) {

    FSMDEBUG((LOG_INFO, "fsm_input(%x): Rcvd packet in state %d (%s).\n",

        f->protocol, f->state, ppperr_strerr[f->state]));

    return;

  }

  FSMDEBUG((LOG_INFO, "fsm_input(%s):%d,%d,%d\n", PROTO_NAME(f), code, id, l));

  /*

   * Action depends on code.

   */

  switch (code) {

    case CONFREQ:

      fsm_rconfreq(f, id, inp, len);

      break;

    case CONFACK:

      fsm_rconfack(f, id, inp, len);

      break;

    case CONFNAK:

    case CONFREJ:

      fsm_rconfnakrej(f, code, id, inp, len);

      break;

    case TERMREQ:

      fsm_rtermreq(f, id, inp, len);

      break;

    case TERMACK:

      fsm_rtermack(f);

      break;

    case CODEREJ:

      fsm_rcoderej(f, inp, len);

      break;

    default:

      if( !f->callbacks->extcode ||

          !(*f->callbacks->extcode)(f, code, id, inp, len) ) {

        fsm_sdata(f, CODEREJ, ++f->id, inpacket, len + HEADERLEN);

      }

      break;

  }

}

/*

 * fsm_protreject - Peer doesn't speak this protocol.

 *

 * Treat this as a catastrophic error (RXJ-).

 */

void

fsm_protreject(fsm *f)

{

  switch( f->state ) {

    case LS_CLOSING:

      UNTIMEOUT(fsm_timeout, f);  /* Cancel timeout */

      /* fall through */

    case LS_CLOSED:

      f->state = LS_CLOSED;

      if( f->callbacks->finished ) {

        (*f->callbacks->finished)(f);

      }

      break;

    case LS_STOPPING:

    case LS_REQSENT:

    case LS_ACKRCVD:

    case LS_ACKSENT:

      UNTIMEOUT(fsm_timeout, f);  /* Cancel timeout */

      /* fall through */

    case LS_STOPPED:

      f->state = LS_STOPPED;

      if( f->callbacks->finished ) {

        (*f->callbacks->finished)(f);

      }

      break;

    case LS_OPENED:

      if( f->callbacks->down ) {

        (*f->callbacks->down)(f);

      }

      /* Init restart counter, send Terminate-Request */

      f->retransmits = f->maxtermtransmits;

      fsm_sdata(f, TERMREQ, f->reqid = ++f->id,

            (u_char *) f->term_reason, f->term_reason_len);

      TIMEOUT(fsm_timeout, f, f->timeouttime);

      --f->retransmits;

      f->state = LS_STOPPING;

      break;

    default:

      FSMDEBUG((LOG_INFO, "%s: Protocol-reject event in state %d (%s)!\n",

            PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

    }

}

/**********************************/

/*** LOCAL FUNCTION DEFINITIONS ***/

/**********************************/

/*

 * fsm_timeout - Timeout expired.

 */

static void

fsm_timeout(void *arg)

{

  fsm *f = (fsm *) arg;

  switch (f->state) {

    case LS_CLOSING:

    case LS_STOPPING:

      if( f->retransmits <= 0 ) {

        FSMDEBUG((LOG_WARNING, "%s: timeout sending Terminate-Request state=%d (%s)\n",

             PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

        /*

         * We've waited for an ack long enough.  Peer probably heard us.

         */

        f->state = (f->state == LS_CLOSING)? LS_CLOSED: LS_STOPPED;

        if( f->callbacks->finished ) {

          (*f->callbacks->finished)(f);

        }

      } else {

        FSMDEBUG((LOG_WARNING, "%s: timeout resending Terminate-Requests state=%d (%s)\n",

             PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

        /* Send Terminate-Request */

        fsm_sdata(f, TERMREQ, f->reqid = ++f->id,

            (u_char *) f->term_reason, f->term_reason_len);

        TIMEOUT(fsm_timeout, f, f->timeouttime);

        --f->retransmits;

      }

      break;

    case LS_REQSENT:

    case LS_ACKRCVD:

    case LS_ACKSENT:

      if (f->retransmits <= 0) {

        FSMDEBUG((LOG_WARNING, "%s: timeout sending Config-Requests state=%d (%s)\n",

         PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

        f->state = LS_STOPPED;

        if( (f->flags & OPT_PASSIVE) == 0 && f->callbacks->finished ) {

          (*f->callbacks->finished)(f);

        }

      } else {

        FSMDEBUG((LOG_WARNING, "%s: timeout resending Config-Request state=%d (%s)\n",

         PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

        /* Retransmit the configure-request */

        if (f->callbacks->retransmit) {

          (*f->callbacks->retransmit)(f);

        }

        fsm_sconfreq(f, 1);    /* Re-send Configure-Request */

        if( f->state == LS_ACKRCVD ) {

          f->state = LS_REQSENT;

        }

      }

      break;

    default:

      FSMDEBUG((LOG_INFO, "%s: Timeout event in state %d (%s)!\n",

          PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

  }

}

/*

 * fsm_rconfreq - Receive Configure-Request.

 */

static void

fsm_rconfreq(fsm *f, u_char id, u_char *inp, int len)

{

  int code, reject_if_disagree;

  FSMDEBUG((LOG_INFO, "fsm_rconfreq(%s): Rcvd id %d state=%d (%s)\n",

        PROTO_NAME(f), id, f->state, ppperr_strerr[f->state]));

  switch( f->state ) {

    case LS_CLOSED:

      /* Go away, we're closed */

      fsm_sdata(f, TERMACK, id, NULL, 0);

      return;

    case LS_CLOSING:

    case LS_STOPPING:

      return;

    case LS_OPENED:

      /* Go down and restart negotiation */

      if( f->callbacks->down ) {

        (*f->callbacks->down)(f);  /* Inform upper layers */

      }

      fsm_sconfreq(f, 0);    /* Send initial Configure-Request */

      break;

    case LS_STOPPED:

      /* Negotiation started by our peer */

      fsm_sconfreq(f, 0);    /* Send initial Configure-Request */

      f->state = LS_REQSENT;

      break;

  }

  /*

  * Pass the requested configuration options

  * to protocol-specific code for checking.

  */

  if (f->callbacks->reqci) {    /* Check CI */

    reject_if_disagree = (f->nakloops >= f->maxnakloops);

    code = (*f->callbacks->reqci)(f, inp, &len, reject_if_disagree);

  } else if (len) {

    code = CONFREJ;      /* Reject all CI */

  } else {

    code = CONFACK;

  }

  /* send the Ack, Nak or Rej to the peer */

  fsm_sdata(f, (u_char)code, id, inp, len);

  if (code == CONFACK) {

    if (f->state == LS_ACKRCVD) {

      UNTIMEOUT(fsm_timeout, f);  /* Cancel timeout */

      f->state = LS_OPENED;

      if (f->callbacks->up) {

        (*f->callbacks->up)(f);  /* Inform upper layers */

      }

    } else {

      f->state = LS_ACKSENT;

    }

    f->nakloops = 0;

  } else {

    /* we sent CONFACK or CONFREJ */

    if (f->state != LS_ACKRCVD) {

      f->state = LS_REQSENT;

    }

    if( code == CONFNAK ) {

      ++f->nakloops;

    }

  }

}

/*

 * fsm_rconfack - Receive Configure-Ack.

 */

static void

fsm_rconfack(fsm *f, int id, u_char *inp, int len)

{

  FSMDEBUG((LOG_INFO, "fsm_rconfack(%s): Rcvd id %d state=%d (%s)\n",

        PROTO_NAME(f), id, f->state, ppperr_strerr[f->state]));

  if (id != f->reqid || f->seen_ack) {   /* Expected id? */

    return; /* Nope, toss... */

  }

  if( !(f->callbacks->ackci? (*f->callbacks->ackci)(f, inp, len): (len == 0)) ) {

    /* Ack is bad - ignore it */

    FSMDEBUG((LOG_INFO, "%s: received bad Ack (length %d)\n",

          PROTO_NAME(f), len));

    return;

  }

  f->seen_ack = 1;

  switch (f->state) {

    case LS_CLOSED:

    case LS_STOPPED:

      fsm_sdata(f, TERMACK, (u_char)id, NULL, 0);

      break;

    case LS_REQSENT:

      f->state = LS_ACKRCVD;

      f->retransmits = f->maxconfreqtransmits;

      break;

    case LS_ACKRCVD:

      /* Huh? an extra valid Ack? oh well... */

      UNTIMEOUT(fsm_timeout, f);  /* Cancel timeout */

      fsm_sconfreq(f, 0);

      f->state = LS_REQSENT;

      break;

    case LS_ACKSENT:

      UNTIMEOUT(fsm_timeout, f);  /* Cancel timeout */

      f->state = LS_OPENED;

      f->retransmits = f->maxconfreqtransmits;

      if (f->callbacks->up) {

        (*f->callbacks->up)(f);  /* Inform upper layers */

      }

      break;

    case LS_OPENED: