/*****************************************************************************
* 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;