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ppp/pppd/fsm.c

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/*
* fsm.c - {Link, IP} Control Protocol Finite State Machine.
*
* Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The name "Carnegie Mellon University" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For permission or any legal
* details, please contact
* Office of Technology Transfer
* Carnegie Mellon University
* 5000 Forbes Avenue
* Pittsburgh, PA 15213-3890
* (412) 268-4387, fax: (412) 268-7395
* tech-transfer@andrew.cmu.edu
*
* 4. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by Computing Services
* at Carnegie Mellon University (http://www.cmu.edu/computing/)."
*
* CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#define RCSID "$Id: fsm.c,v 1.23 2004/11/13 02:28:15 paulus Exp $"
/*
* TODO:
* Randomize fsm id on link/init.
* Deal with variable outgoing MTU.
*/
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include "pppd.h"
#include "fsm.h"
static const char rcsid[] = RCSID;
static void fsm_timeout __P((void *));
static void fsm_rconfreq __P((fsm *, int, u_char *, int));
static void fsm_rconfack __P((fsm *, int, u_char *, int));
static void fsm_rconfnakrej __P((fsm *, int, int, u_char *, int));
static void fsm_rtermreq __P((fsm *, int, u_char *, int));
static void fsm_rtermack __P((fsm *));
static void fsm_rcoderej __P((fsm *, u_char *, int));
static void fsm_sconfreq __P((fsm *, int));
#define PROTO_NAME(f) ((f)->callbacks->proto_name)
int peer_mru[NUM_PPP];
/*
* fsm_init - Initialize fsm.
*
* Initialize fsm state.
*/
void
fsm_init(f)
fsm *f;
{
f->state = INITIAL;
f->flags = 0;
f->id = 0; /* XXX Start with random id? */
f->timeouttime = DEFTIMEOUT;
f->maxconfreqtransmits = DEFMAXCONFREQS;
f->maxtermtransmits = DEFMAXTERMREQS;
f->maxnakloops = DEFMAXNAKLOOPS;
f->term_reason_len = 0;
}
/*
* fsm_lowerup - The lower layer is up.
*/
void
fsm_lowerup(f)
fsm *f;
{
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(("%s: Up event in state %d!", PROTO_NAME(f), f->state));
}
}
/*
* fsm_lowerdown - The lower layer is down.
*
* Cancel all timeouts and inform upper layers.
*/
void
fsm_lowerdown(f)
fsm *f;
{
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(("%s: Down event in state %d!", PROTO_NAME(f), f->state));
}
}
/*
* fsm_open - Link is allowed to come up.
*/
void
fsm_open(f)
fsm *f;
{
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;
}
}
/*
* terminate_layer - Start process of shutting down the FSM
*
* Cancel any timeout running, notify upper layers we're done, and
* send a terminate-request message as configured.
*/
static void
terminate_layer(f, nextstate)
fsm *f;
int nextstate;
{
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 and send Terminate-Request */
f->retransmits = f->maxtermtransmits;
fsm_sdata(f, TERMREQ, f->reqid = ++f->id,
(u_char *) f->term_reason, f->term_reason_len);
if (f->retransmits == 0) {
/*
* User asked for no terminate requests at all; just close it.
* We've already fired off one Terminate-Request just to be nice
* to the peer, but we're not going to wait for a reply.
*/
f->state = nextstate == CLOSING ? CLOSED : STOPPED;
if( f->callbacks->finished )
(*f->callbacks->finished)(f);
return;
}
TIMEOUT(fsm_timeout, f, f->timeouttime);
--f->retransmits;
f->state = nextstate;
}
/*
* fsm_close - Start closing connection.
*
* Cancel timeouts and either initiate close or possibly go directly to
* the CLOSED state.
*/
void
fsm_close(f, reason)
fsm *f;
char *reason;
{
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:
terminate_layer(f, CLOSING);
break;
}
}
/*
* fsm_timeout - Timeout expired.
*/
static void
fsm_timeout(arg)
void *arg;
{
fsm *f = (fsm *) arg;
switch (f->state) {
case CLOSING:
case STOPPING:
if( f->retransmits <= 0 ){
/*
* We've waited for an ack long enough. Peer probably heard us.
*/
f->state = (f->state == CLOSING)? CLOSED: STOPPED;
if( f->callbacks->finished )
(*f->callbacks->finished)(f);
} else {
/* 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 REQSENT:
case ACKRCVD:
case ACKSENT:
if (f->retransmits <= 0) {
warn("%s: timeout sending Config-Requests\n", PROTO_NAME(f));
f->state = STOPPED;
if( (f->flags & OPT_PASSIVE) == 0 && f->callbacks->finished )
(*f->callbacks->finished)(f);
} else {
/* Retransmit the configure-request */
if (f->callbacks->retransmit)
(*f->callbacks->retransmit)(f);
fsm_sconfreq(f, 1); /* Re-send Configure-Request */
if( f->state == ACKRCVD )
f->state = REQSENT;
}
break;
default:
FSMDEBUG(("%s: Timeout event in state %d!", PROTO_NAME(f), f->state));
}
}
/*
* fsm_input - Input packet.
*/
void
fsm_input(f, inpacket, l)
fsm *f;
u_char *inpacket;
int l;
{
u_char *inp;
u_char code, id;
int len;
/*
* Parse header (code, id and length).
* If packet too short, drop it.
*/
inp = inpacket;
if (l < HEADERLEN) {
FSMDEBUG(("fsm_input(%x): Rcvd short header.", f->protocol));
return;
}
GETCHAR(code, inp);
GETCHAR(id, inp);
GETSHORT(len, inp);
if (len < HEADERLEN) {
FSMDEBUG(("fsm_input(%x): Rcvd illegal length.", f->protocol));
return;
}
if (len > l) {
FSMDEBUG(("fsm_input(%x): Rcvd short packet.", f->protocol));
return;
}
len -= HEADERLEN; /* subtract header length */
if( f->state == INITIAL || f->state == STARTING ){
FSMDEBUG(("fsm_input(%x): Rcvd packet in state %d.",
f->protocol, f->state));
return;
}
/*
* 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_rconfreq - Receive Configure-Request.
*/
static void
fsm_rconfreq(f, id, inp, len)
fsm *f;
u_char id;
u_char *inp;
int len;
{
int code, reject_if_disagree;
switch( f->state ){
case CLOSED:
/* Go away, we're closed */
fsm_sdata(f, TERMACK, id, NULL, 0);
return;
case CLOSING:
case STOPPING:
return;
case 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 */
f->state = REQSENT;
break;
case STOPPED:
/* Negotiation started by our peer */
fsm_sconfreq(f, 0); /* Send initial Configure-Request */
f->state = 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, code, id, inp, len);
if (code == CONFACK) {
if (f->state == ACKRCVD) {
UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
f->state = OPENED;
if (f->callbacks->up)
(*f->callbacks->up)(f); /* Inform upper layers */
} else
f->state = ACKSENT;
f->nakloops = 0;
} else {
/* we sent CONFNAK or CONFREJ */
if (f->state != ACKRCVD)
f->state = REQSENT;
if( code == CONFNAK )
++f->nakloops;
}
}
/*
* fsm_rconfack - Receive Configure-Ack.
*/
static void
fsm_rconfack(f, id, inp, len)
fsm *f;
int id;
u_char *inp;
int len;
{
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 */
error("Received bad configure-ack: %P", inp, len);
return;
}
f->seen_ack = 1;
f->rnakloops = 0;
switch (f->state) {
case CLOSED:
case STOPPED:
fsm_sdata(f, TERMACK, id, NULL, 0);
break;
case REQSENT:
f->state = ACKRCVD;
f->retransmits = f->maxconfreqtransmits;
break;
case ACKRCVD:
/* Huh? an extra valid Ack? oh well... */
UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
fsm_sconfreq(f, 0);
f->state = REQSENT;
break;
case ACKSENT:
UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
f->state = OPENED;
f->retransmits = f->maxconfreqtransmits;
if (f->callbacks->up)
(*f->callbacks->up)(f); /* Inform upper layers */
break;
case 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 */
f->state = REQSENT;
break;
}
}
/*
* fsm_rconfnakrej - Receive Configure-Nak or Configure-Reject.
*/
static void
fsm_rconfnakrej(f, code, id, inp, len)
fsm *f;
int code, id;
u_char *inp;
int len;
{
int ret;
int treat_as_reject;
if (id != f->reqid || f->seen_ack) /* Expected id? */
return; /* Nope, toss... */
if (code == CONFNAK) {
++f->rnakloops;
treat_as_reject = (f->rnakloops >= f->maxnakloops);
if (f->callbacks->nakci == NULL
|| !(ret = f->callbacks->nakci(f, inp, len, treat_as_reject))) {
error("Received bad configure-nak: %P", inp, len);
return;
}
} else {
f->rnakloops = 0;
if (f->callbacks->rejci == NULL
|| !(ret = f->callbacks->rejci(f, inp, len))) {
error("Received bad configure-rej: %P", inp, len);
return;
}
}
f->seen_ack = 1;
switch (f->state) {
case CLOSED:
case STOPPED:
fsm_sdata(f, TERMACK, id, NULL, 0);
break;
case REQSENT:
case ACKSENT:
/* They didn't agree to what we wanted - try another request */
UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
if (ret < 0)
f->state = STOPPED; /* kludge for stopping CCP */
else
fsm_sconfreq(f, 0); /* Send Configure-Request */
break;
case ACKRCVD:
/* Got a Nak/reject when we had already had an Ack?? oh well... */
UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
fsm_sconfreq(f, 0);
f->state = REQSENT;
break;
case 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 */
f->state = REQSENT;
break;
}
}
/*
* fsm_rtermreq - Receive Terminate-Req.
*/
static void
fsm_rtermreq(f, id, p, len)
fsm *f;
int id;
u_char *p;
int len;
{
switch (f->state) {
case ACKRCVD:
case ACKSENT:
f->state = REQSENT; /* Start over but keep trying */
break;
case OPENED:
if (len > 0) {
info("%s terminated by peer (%0.*v)", PROTO_NAME(f), len, p);
} else
info("%s terminated by peer", PROTO_NAME(f));
f->retransmits = 0;
f->state = STOPPING;
if (f->callbacks->down)
(*f->callbacks->down)(f); /* Inform upper layers */
TIMEOUT(fsm_timeout, f, f->timeouttime);
break;
}
fsm_sdata(f, TERMACK, id, NULL, 0);
}
/*
* fsm_rtermack - Receive Terminate-Ack.
*/
static void
fsm_rtermack(f)
fsm *f;
{
switch (f->state) {
case CLOSING:
UNTIMEOUT(fsm_timeout, f);
f->state = CLOSED;
if( f->callbacks->finished )
(*f->callbacks->finished)(f);
break;
case STOPPING:
UNTIMEOUT(fsm_timeout, f);
f->state = STOPPED;
if( f->callbacks->finished )
(*f->callbacks->finished)(f);
break;
case ACKRCVD:
f->state = REQSENT;
break;
case OPENED:
if (f->callbacks->down)
(*f->callbacks->down)(f); /* Inform upper layers */
fsm_sconfreq(f, 0);
f->state = REQSENT;
break;
}
}
/*
* fsm_rcoderej - Receive an Code-Reject.
*/
static void
fsm_rcoderej(f, inp, len)
fsm *f;
u_char *inp;
int len;
{
u_char code, id;
if (len < HEADERLEN) {
FSMDEBUG(("fsm_rcoderej: Rcvd short Code-Reject packet!"));
return;
}
GETCHAR(code, inp);
GETCHAR(id, inp);
warn("%s: Rcvd Code-Reject for code %d, id %d", PROTO_NAME(f), code, id);
if( f->state == ACKRCVD )
f->state = REQSENT;
}
/*
* fsm_protreject - Peer doesn't speak this protocol.
*
* Treat this as a catastrophic error (RXJ-).
*/
void
fsm_protreject(f)
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:
case REQSENT:
case ACKRCVD:
case ACKSENT:
UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
/* fall through */
case STOPPED:
f->state = STOPPED;
if( f->callbacks->finished )
(*f->callbacks->finished)(f);
break;
case OPENED:
terminate_layer(f, STOPPING);
break;
default:
FSMDEBUG(("%s: Protocol-reject event in state %d!",
PROTO_NAME(f), f->state));
}
}
/*
* fsm_sconfreq - Send a Configure-Request.
*/
static void
fsm_sconfreq(f, retransmit)
fsm *f;
int retransmit;
{
u_char *outp;
int cilen;
if( f->state != REQSENT && f->state != ACKRCVD && f->state != ACKSENT ){
/* Not currently negotiating - reset options */
if( f->callbacks->resetci )
(*f->callbacks->resetci)(f);
f->nakloops = 0;
f->rnakloops = 0;
}
if( !retransmit ){
/* New request - reset retransmission counter, use new ID */
f->retransmits = f->maxconfreqtransmits;
f->reqid = ++f->id;
}
f->seen_ack = 0;
/*
* Make up the request packet
*/
outp = outpacket_buf + PPP_HDRLEN + HEADERLEN;
if( f->callbacks->cilen && f->callbacks->addci ){
cilen = (*f->callbacks->cilen)(f);
if( cilen > peer_mru[f->unit] - HEADERLEN )
cilen = peer_mru[f->unit] - HEADERLEN;
if (f->callbacks->addci)
(*f->callbacks->addci)(f, outp, &cilen);
} else
cilen = 0;
/* send the request to our peer */
fsm_sdata(f, CONFREQ, f->reqid, outp, cilen);
/* start the retransmit timer */
--f->retransmits;
TIMEOUT(fsm_timeout, f, f->timeouttime);
}
/*
* fsm_sdata - Send some data.
*
* Used for all packets sent to our peer by this module.
*/
void
fsm_sdata(f, code, id, data, datalen)
fsm *f;
u_char code, id;
u_char *data;
int datalen;
{
u_char *outp;
int outlen;
/* Adjust length to be smaller than MTU */
outp = outpacket_buf;
if (datalen > peer_mru[f->unit] - 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);
output(f->unit, outpacket_buf, outlen + PPP_HDRLEN);
}
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