fsm.c

FreeRTOS is a portable, open source, mini Real Time Kernel - a free to download and royalty free RTO

/*****************************************************************************
* 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 <[e-mail]>
*   Ported to lwIP.
* 97-12-01 Guy Lancaster <[e-mail]>, 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 "ppp.h"
#if PPP_SUPPORT > 0
#include "fsm.h"
#include "pppdebug.h"


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


/************************/
/*** 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 = 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;

	switch( f->state ){
	case INITIAL:
		f->state = CLOSED;
		break;
	
	case STARTING:
		if( f->flags & OPT_SILENT )
			f->state = STOPPED;
		else {
			/* Send an initial configure-request */
			fsm_sconfreq(f, 0);
			f->state = REQSENT;
		}
	break;
	
	default:
		FSMDEBUG((LOG_INFO, "%s: Up event in state %d!\n",
				PROTO_NAME(f), f->state));
	}
	
	FSMDEBUG((LOG_INFO, "%s: lowerup state %d -> %d\n",
			PROTO_NAME(f), oldState, 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;
	
	switch( f->state ){
	case CLOSED:
		f->state = INITIAL;
		break;
	
	case STOPPED:
		f->state = STARTING;
		if( f->callbacks->starting )
			(*f->callbacks->starting)(f);
		break;
	
	case CLOSING:
		f->state = INITIAL;
		UNTIMEOUT(fsm_timeout, f);	/* Cancel timeout */
		break;
	
	case STOPPING:
	case REQSENT:
	case ACKRCVD:
	case ACKSENT:
		f->state = STARTING;
		UNTIMEOUT(fsm_timeout, f);	/* Cancel timeout */
		break;
	
	case OPENED:
		if( f->callbacks->down )
			(*f->callbacks->down)(f);
		f->state = STARTING;
		break;
	
	default:
		FSMDEBUG((LOG_INFO, "%s: Down event in state %d!\n",
				PROTO_NAME(f), f->state));
	}
	
	FSMDEBUG((LOG_INFO, "%s: lowerdown state %d -> %d\n",
			PROTO_NAME(f), oldState, f->state));
}


/*
 * fsm_open - Link is allowed to come up.
 */
void fsm_open(fsm *f)
{
	int oldState = f->state;
	
	switch( f->state ){
		case INITIAL:
			f->state = STARTING;
			if( f->callbacks->starting )
				(*f->callbacks->starting)(f);
			break;
		
		case CLOSED:
		if( f->flags & OPT_SILENT )
			f->state = STOPPED;
		else {
			/* Send an initial configure-request */
			fsm_sconfreq(f, 0);
			f->state = REQSENT;
		}
		break;
	
	case CLOSING:
		f->state = STOPPING;
		/* fall through */
	case STOPPED:
	case OPENED:
		if( f->flags & OPT_RESTART ){
			fsm_lowerdown(f);
			fsm_lowerup(f);
		}
		break;
	}
	
	FSMDEBUG((LOG_INFO, "%s: open state %d -> %d\n",
			PROTO_NAME(f), oldState, f->state));
}


/*
 * fsm_close - Start closing connection.
 *
 * Cancel timeouts and either initiate close or possibly go directly to
 * the CLOSED state.
 */
void fsm_close(fsm *f, char *reason)
{
	int oldState = f->state;
	
	f->term_reason = reason;
	f->term_reason_len = (reason == NULL? 0: strlen(reason));
	switch( f->state ){
	case STARTING:
		f->state = INITIAL;
		break;
	case STOPPED:
		f->state = CLOSED;
		break;
	case STOPPING:
		f->state = CLOSING;
		break;
	
	case REQSENT:
	case ACKRCVD:
	case ACKSENT:
	case OPENED:
		if( f->state != 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 = CLOSING;
		break;
	}
	
	FSMDEBUG((LOG_INFO, "%s: close reason=%s state %d -> %d\n",
			PROTO_NAME(f), reason, oldState, 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 == INITIAL || f->state == STARTING ){
		FSMDEBUG((LOG_INFO, "fsm_input(%x): Rcvd packet in state %d.\n",
				f->protocol, 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 CLOSING:
		UNTIMEOUT(fsm_timeout, f);	/* Cancel timeout */
		/* fall through */
	case CLOSED:
		f->state = CLOSED;
		if( f->callbacks->finished )
			(*f->callbacks->finished)(f);
		break;
	
	case STOPPING: