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- /*
- * 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:
- * Mechanism to exit() and/or drop DTR.
- * Hold-down on open?
- * Randomize fsm id on link/init.
- * Deal with variable outgoing MTU.
- */
-
- #include <stdio.h>
- #include <sys/types.h>
-
- #include "ppp.h"
- #include "fsm.h"
-
-
- void fsm_timeout(), fsm_rconfreq(), fsm_rconfack(), fsm_rconfnak();
- void fsm_rconfrej(), fsm_rtermreq(), fsm_rtermack(), fsm_rcoderej();
- void fsm_rprotrej(), fsm_rechoreq(), fsm_sconfreq(), fsm_sdata();
-
-
- /*
- * fsm_init - Initialize fsm.
- *
- * Initialize fsm state.
- */
- void fsm_init(f)
- fsm *f;
- {
- f->state = CLOSED;
- f->flags = 0;
- f->id = 0; /* XXX Start with random id? */
- }
-
-
- /*
- * fsm_activeopen - Actively open connection.
- *
- * Set new state, reset desired options and send requests.
- */
- void fsm_activeopen(f)
- fsm *f;
- {
- f->flags &= ~(AOPENDING|POPENDING); /* Clear pending flags */
- if (f->state == REQSENT || /* Already actively open(ing)? */
- f->state == ACKRCVD ||
- f->state == ACKSENT ||
- f->state == OPEN)
- return;
- if (f->state == TERMSENT || /* Closing or */
- !(f->flags & LOWERUP)) { /* lower layer down? */
- f->flags |= AOPENDING; /* Wait for desired event */
- return;
- }
- if (f->callbacks->resetci)
- (*f->callbacks->resetci)(f); /* Reset options */
- fsm_sconfreq(f); /* Send Configure-Request */
- TIMEOUT(fsm_timeout, f, f->timeouttime);
- f->state = REQSENT;
- f->retransmits = 0; /* Reset retransmits count */
- f->nakloops = 0; /* Reset nakloops count */
- }
-
-
- /*
- * fsm_passiveopen - Passively open connection.
- *
- * Set new state and reset desired options.
- */
- void fsm_passiveopen(f)
- fsm *f;
- {
- f->flags &= ~(AOPENDING|POPENDING); /* Clear pending flags */
- if (f->state == LISTEN || /* Already passively open(ing)? */
- f->state == OPEN)
- return;
- if (f->state == REQSENT || /* Active-Opening or */
- f->state == ACKRCVD ||
- f->state == ACKSENT ||
- f->state == TERMSENT || /* closing or */
- !(f->flags & LOWERUP)) { /* lower layer down? */
- f->flags |= POPENDING; /* Wait for desired event */
- return;
- }
- if (f->callbacks->resetci)
- (*f->callbacks->resetci)(f); /* Reset options */
- f->state = LISTEN;
- f->retransmits = 0; /* Reset retransmits count */
- f->nakloops = 0; /* Reset nakloops count */
- }
-
-
- /*
- * fsm_close - Start closing connection.
- *
- * Cancel timeouts and either initiate close or possibly go directly to
- * the CLOSED state.
- */
- void fsm_close(f)
- fsm *f;
- {
- f->flags &= ~(AOPENDING|POPENDING); /* Clear pending flags */
- if (f->state == CLOSED || /* Already CLOSED or Closing? */
- f->state == TERMSENT)
- return;
- if (f->state == REQSENT || /* Timeout pending for Open? */
- f->state == ACKRCVD ||
- f->state == ACKSENT)
- UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
- if (f->state == OPEN && /* Open? */
- f->callbacks->down)
- (*f->callbacks->down)(f); /* Inform upper layers we're down */
- if (f->state == ACKSENT || /* Could peer be OPEN? */
- f->state == OPEN) {
- fsm_sdata(f, TERMREQ, f->reqid = ++f->id, NULL, 0);
- /* Send Terminate-Request */
- TIMEOUT(fsm_timeout, f, f->timeouttime);
- f->state = TERMSENT;
- f->retransmits = 0; /* Reset retransmits count */
- }
- else {
- f->state = CLOSED;
- if (f->callbacks->closed)
- (*f->callbacks->closed)(f); /* Exit/restart/etc. */
- }
- }
-
-
- /*
- * fsm_timeout - Timeout expired.
- */
- void fsm_timeout(f)
- fsm *f;
- {
- switch (f->state) {
- case REQSENT:
- case ACKRCVD:
- case ACKSENT:
- if (f->flags & POPENDING) { /* Go passive? */
- f->state = CLOSED; /* Pretend for a moment... */
- fsm_passiveopen(f);
- return;
- }
- if (f->callbacks->retransmit) /* If there is a retransmit rtn? */
- (*f->callbacks->retransmit)(f);
- fsm_sconfreq(f); /* Send Configure-Request */
- TIMEOUT(fsm_timeout, f, f->timeouttime);
- f->state = REQSENT;
- ++f->retransmits;
- f->nakloops = 0;
- break;
-
- case TERMSENT:
- if (f->flags & POPENDING) { /* Go passive? */
- f->state = CLOSED; /* Pretend for a moment... */
- fsm_passiveopen(f);
- return;
- }
- if (++f->retransmits > f->maxtermtransmits) {
- /*
- * We've waited for an ack long enough. Peer probably heard us.
- */
- f->state = CLOSED;
- if (f->callbacks->closed)
- (*f->callbacks->closed)(f); /* Exit/restart/etc. */
- return;
- }
- if (f->callbacks->retransmit) /* If there is a retransmit rtn? */
- (*f->callbacks->retransmit)(f);
- fsm_sdata(f, TERMREQ, f->reqid = ++f->id, NULL, 0);
- /* Send Terminate-Request */
- TIMEOUT(fsm_timeout, f, f->timeouttime);
- ++f->retransmits;
- }
- }
-
-
- /*
- * fsm_lowerup - The lower layer is up.
- *
- * Start Active or Passive Open if pending.
- */
- void fsm_lowerup(f)
- fsm *f;
- {
- f->flags |= LOWERUP;
- if (f->flags & AOPENDING) /* Attempting Active-Open? */
- fsm_activeopen(f); /* Try it now */
- else if (f->flags & POPENDING) /* Attempting Passive-Open? */
- fsm_passiveopen(f); /* Try it now */
- }
-
-
- /*
- * fsm_lowerdown - The lower layer is down.
- *
- * Cancel all timeouts and inform upper layers.
- */
- void fsm_lowerdown(f)
- fsm *f;
- {
- #if 0 /* XXX */
- f->flags &= ~(LOWERUP|AOPENDING|POPENDING);
- /* Clear pending flags */
- #endif
- f->flags &= ~LOWERUP;
- if (f->state == REQSENT || /* Timeout pending? */
- f->state == ACKRCVD ||
- f->state == ACKSENT ||
- f->state == TERMSENT)
- UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
- if (f->state == OPEN && /* OPEN? */
- f->callbacks->down)
- (*f->callbacks->down)(f); /* Inform upper layers */
- f->state = CLOSED;
- if (f->callbacks->closed)
- (*f->callbacks->closed)(f); /* Exit/restart/etc. */
- }
-
-
- /*
- * fsm_protreject - Peer doesn't speak this protocol.
- *
- * Pretend that the lower layer went down.
- */
- void fsm_protreject(f)
- fsm *f;
- {
- fsm_lowerdown(f);
- }
-
-
- /*
- * fsm_input - Input packet.
- */
- void fsm_input(f, inpacket, l)
- fsm *f;
- PACKET *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 = PACKET_DATA(inpacket);
- if (l < HEADERLEN) {
- FSMDEBUG((stderr, "ppp: fsm_input(%x): Rcvd short header.\n",
- f->protocol));
- goto freepacket;
- }
- GETCHAR(code, inp);
- GETCHAR(id, inp);
- GETSHORT(len, inp);
- if (len < HEADERLEN) {
- FSMDEBUG((stderr, "ppp: fsm_input(%x): Rcvd illegal length.\n",
- f->protocol));
- goto freepacket;
- }
- if (len > l) {
- FSMDEBUG((stderr, "ppp: fsm_input(%x): Rcvd short packet.\n",
- f->protocol));
- goto freepacket;
- }
- len -= HEADERLEN;
-
- /*
- * Action depends on code.
- */
- switch (code) {
- case CONFREQ:
- FSMDEBUG((stderr, "ppp: fsm_rconfreq(%x): Rcvd id %d.\n",
- f->protocol, id));
-
- if (f->state == TERMSENT)
- goto freepacket;
- if (f->state == CLOSED) {
- fsm_sdata(f, TERMACK, id, NULL, 0);
- goto freepacket;
- }
- if (f->state == OPEN &&
- f->callbacks->down)
- (*f->callbacks->down)(f); /* Inform upper layers */
- if (f->state == OPEN ||
- f->state == LISTEN) {
- /* XXX Possibly need hold-down on OPEN? */
- fsm_sconfreq(f); /* Send Configure-Request */
- TIMEOUT(fsm_timeout, f, f->timeouttime);
- }
- if (f->callbacks->reqci) /* Check CI */
- code = (*f->callbacks->reqci)(f, inp, &len);
- else if (len)
- code = CONFREJ; /* Reject all CI */
-
- inp = PACKET_DATA(inpacket); /* Reset to header */
- PUTCHAR(code, inp);
- PUTCHAR(id, inp);
- len += HEADERLEN;
- PUTSHORT(len, inp);
- OUTPUT(f->unit, inpacket, len, f->protocol);
-
- if (code == CONFACK) {
- if (f->state == ACKRCVD) {
- UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
- if (f->callbacks->up)
- (*f->callbacks->up)(f); /* Inform upper layers */
- f->state = OPEN;
- }
- else
- f->state = ACKSENT;
- }
- else {
- if (f->state != ACKRCVD)
- f->state = REQSENT;
- }
- return;
-
- case CONFACK:
- fsm_rconfack(f, inp, id, len);
- break;
-
- case CONFNAK:
- fsm_rconfnak(f, inp, id, len);
- break;
-
- case CONFREJ:
- fsm_rconfrej(f, inp, id, len);
- break;
-
- case TERMREQ:
- fsm_rtermreq(f, id);
- break;
-
- case TERMACK:
- fsm_rtermack(f);
- break;
-
- case CODEREJ:
- fsm_rcoderej(f, inp, len);
- break;
-
- case PROTREJ:
- fsm_rprotrej(f, inp, len);
- break;
-
- case ECHOREQ:
- FSMDEBUG((stderr, "ppp: fsm_rechoreq(%x): Rcvd id %d.\n",
- f->protocol, id));
-
- switch (f->state) {
- case CLOSED:
- case LISTEN:
- fsm_sdata(f, TERMACK, id, NULL, 0);
- break;
-
- case OPEN:
- inp = PACKET_DATA(inpacket); /* Reset to header */
- PUTCHAR(ECHOREP, inp);
- PUTCHAR(id, inp);
- len += HEADERLEN;
- PUTSHORT(len, inp);
- OUTPUT(f->unit, inpacket, len, f->protocol);
- return;
- }
- break;
-
- case ECHOREP:
- case DISCREQ:
- /* XXX Deliver to ECHOREQ sender? */
- break;
-
- default:
- fsm_sdata(f, CODEREJ, ++f->id, PACKET_DATA(inpacket), len + HEADERLEN);
- break;
- }
-
- freepacket:
- PACKET_FREE(inpacket);
- }
-
-
- /*
- * fsm_rconfack - Receive Configure-Ack.
- */
- void fsm_rconfack(f, inp, id, len)
- fsm *f;
- u_char *inp;
- u_char id;
- int len;
- {
- FSMDEBUG((stderr, "ppp: fsm_rconfack(%x): Rcvd id %d.\n",
- f->protocol, id));
-
- switch (f->state) {
- case LISTEN:
- case CLOSED:
- fsm_sdata(f, TERMACK, id, NULL, 0);
- break;
-
- case ACKRCVD:
- case REQSENT:
- if (id != f->reqid) /* Expected id? */
- break; /* Nope, toss... */
- if (f->callbacks->ackci &&
- (*f->callbacks->ackci)(f, inp, len)) /* Good ack? */
- f->state = ACKRCVD;
- else
- f->state = REQSENT; /* Wait for timeout to retransmit */
- break;
-
- case ACKSENT:
- if (id != f->reqid) /* Expected id? */
- break; /* Nope, toss... */
- if (f->callbacks->ackci &&
- (*f->callbacks->ackci)(f, inp, len)) { /* Good ack? */
- UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
- if (f->callbacks->up)
- (*f->callbacks->up)(f); /* Inform upper layers */
- f->state = OPEN;
- }
- else
- f->state = REQSENT; /* Wait for timeout to retransmit */
- break;
-
- case OPEN:
- if (f->callbacks->down)
- (*f->callbacks->down)(f); /* Inform upper layers */
- f->state = CLOSED; /* Only for a moment... */
- fsm_activeopen(f); /* Restart */
- break;
- }
- }
-
-
- /*
- * fsm_rconfnak - Receive Configure-Nak.
- */
- void fsm_rconfnak(f, inp, id, len)
- fsm *f;
- u_char *inp;
- u_char id;
- int len;
- {
- FSMDEBUG((stderr, "ppp: fsm_rconfnak(%x): Rcvd id %d.\n",
- f->protocol, id));
-
- switch (f->state) {
- case LISTEN:
- case CLOSED:
- fsm_sdata(f, TERMACK, id, NULL, 0);
- break;
-
- case REQSENT:
- case ACKSENT:
- if (id != f->reqid) /* Expected id? */
- break; /* Nope, toss... */
- if (++f->nakloops > f->maxnakloops) {
- FSMDEBUG((stderr,
- "ppp: fsm_rconfnak(%x): Possible CONFNAK loop!\n",
- f->protocol));
- break; /* Break the loop */
- }
- UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
- if (f->callbacks->nakci)
- (*f->callbacks->nakci)(f, inp, len);
- fsm_sconfreq(f); /* Send Configure-Request */
- TIMEOUT(fsm_timeout, f, f->timeouttime);
- ++f->retransmits;
- break;
-
- case ACKRCVD:
- f->state = REQSENT; /* Wait for timeout to retransmit */
- break;
-
- case OPEN:
- if (f->callbacks->down)
- (*f->callbacks->down)(f); /* Inform upper layers */
- f->state = CLOSED; /* Only for a moment... */
- fsm_activeopen(f); /* Restart */
- break;
- }
- }
-
-
- /*
- * fsm_rconfrej - Receive Configure-Rej.
- */
- void fsm_rconfrej(f, inp, id, len)
- fsm *f;
- u_char *inp;
- u_char id;
- int len;
- {
- FSMDEBUG((stderr, "ppp: fsm_rconfrej(%x): Rcvd id %d.\n",
- f->protocol, id));
-
- switch (f->state) {
- case LISTEN:
- case CLOSED:
- fsm_sdata(f, TERMACK, id, NULL, 0);
- break;
-
- case REQSENT:
- case ACKSENT:
- if (id != f->reqid) /* Expected id? */
- break; /* Nope, toss... */
- if (++f->nakloops > f->maxnakloops)
- break; /* Break the loop */
- UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
- if (f->callbacks->rejci)
- (*f->callbacks->rejci)(f, inp, len);
- fsm_sconfreq(f); /* Send Configure-Request */
- TIMEOUT(fsm_timeout, f, f->timeouttime);
- ++f->retransmits;
- break;
-
- case ACKRCVD:
- f->state = REQSENT; /* Wait for timeout to retransmit */
- break;
-
- case OPEN:
- f->state = CLOSED; /* Only for a moment... */
- fsm_activeopen(f); /* Restart */
- break;
- }
- }
-
-
- /*
- * fsm_rtermreq - Receive Terminate-Req.
- */
- void fsm_rtermreq(f, id)
- fsm *f;
- u_char id;
- {
- FSMDEBUG((stderr, "ppp: fsm_rtermreq(%x): Rcvd id %d.\n",
- f->protocol, id));
-
- fsm_sdata(f, TERMACK, id, NULL, 0);
- switch (f->state) {
- case ACKRCVD:
- case ACKSENT:
- f->state = REQSENT; /* Start over but keep trying */
- break;
-
- case OPEN:
- if (f->callbacks->down)
- (*f->callbacks->down)(f); /* Inform upper layers */
- f->state = CLOSED;
- if (f->callbacks->closed)
- (*f->callbacks->closed)(f); /* Exit/restart/etc. */
- break;
- }
- }
-
-
- /*
- * fsm_rtermack - Receive Terminate-Ack.
- */
- void fsm_rtermack(f)
- fsm *f;
- {
- FSMDEBUG((stderr, "ppp: fsm_rtermack(%x).\n", f->protocol));
-
- switch (f->state) {
- case OPEN:
- if (f->callbacks->down)
- (*f->callbacks->down)(f); /* Inform upper layers */
- f->state = CLOSED;
- if (f->callbacks->closed)
- (*f->callbacks->closed)(f); /* Exit/restart/etc. */
- break;
-
- case TERMSENT:
- UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
- f->state = CLOSED;
- if (f->callbacks->closed)
- (*f->callbacks->closed)(f); /* Exit/restart/etc. */
- break;
- }
- }
-
-
- /*
- * fsm_rcoderej - Receive an Code-Reject.
- */
- void fsm_rcoderej(f, inp, len)
- fsm *f;
- u_char *inp;
- int len;
- {
- u_char code;
-
- FSMDEBUG((stderr, "ppp: fsm_rcoderej(%x).\n", f->protocol));
-
- if (len < sizeof (u_char)) {
- FSMDEBUG((stderr,
- "ppp: fsm_rcoderej: Rcvd short Code-Reject packet!\n"));
- return;
- }
- GETCHAR(code, inp);
- FSMDEBUG((stderr,
- "ppp: fsm_rcoderej: Rcvd Code-Reject for code %d!\n",
- code));
- }
-
-
- /*
- * fsm_rprotrej - Receive an Protocol-Reject.
- *
- * Figure out which protocol is rejected and inform it.
- */
- void fsm_rprotrej(f, inp, len)
- fsm *f;
- u_char *inp;
- int len;
- {
- u_short prot;
-
- FSMDEBUG((stderr, "ppp: fsm_rprotrej.\n"));
-
- if (len < sizeof (u_short)) {
- FSMDEBUG((stderr,
- "ppp: fsm_rprotrej: Rcvd short Protocol-Reject packet!\n"));
- return;
- }
- if (f->protocol != LCP) { /* Only valid for LCP */
- FSMDEBUG((stderr,
- "ppp: fsm_rprotrej: Rcvd non-LCP Protocol-Reject!\n"));
- return;
- }
-
- GETSHORT(prot, inp);
-
- FSMDEBUG((stderr,
- "ppp: fsm_rprotrej: Rcvd Protocol-Reject packet for %x!\n",
- prot));
- DEMUXPROTREJ(f->unit, prot); /* Inform protocol */
- }
-
-
- /*
- * fsm_sconfreq - Send a Configure-Request.
- */
- void fsm_sconfreq(f)
- fsm *f;
- {
- PACKET *outpacket;
- u_char *outp;
- int outlen;
-
- outlen = HEADERLEN + (f->callbacks->cilen ? (*f->callbacks->cilen)(f) : 0);
- /* XXX Adjust outlen to MTU */
- outpacket = PACKET_ALLOC(outlen);
- outp = PACKET_DATA(outpacket);
-
- PUTCHAR(CONFREQ, outp);
- PUTCHAR(f->reqid = ++f->id, outp);
- PUTSHORT(outlen, outp);
- if (f->callbacks->cilen && f->callbacks->addci)
- (*f->callbacks->addci)(f, outp);
- OUTPUT(f->unit, outpacket, outlen, f->protocol);
-
- FSMDEBUG((stderr, "ppp: fsm_sconfreq(%x): Sent id %d.\n",
- f->protocol, f->reqid));
- }
-
-
- /*
- * fsm_sdata - Send some data.
- *
- * Used for Terminate-Request, Terminate-Ack, Code-Reject, Protocol-Reject,
- * Echo-Request, and Discard-Request.
- */
- void fsm_sdata(f, code, id, data, datalen)
- fsm *f;
- u_char code, id;
- u_char *data;
- int datalen;
- {
- PACKET *outpacket;
- u_char *outp;
- int outlen;
-
- /* Adjust length to be smaller than MTU */
- if (datalen > MTU - HEADERLEN)
- datalen = MTU - HEADERLEN;
- outlen = datalen + HEADERLEN;
- outpacket = PACKET_ALLOC(outlen);
- outp = PACKET_DATA(outpacket);
-
- PUTCHAR(code, outp);
- PUTCHAR(id, outp);
- PUTSHORT(outlen, outp);
- if (datalen)
- BCOPY(data, outp, datalen);
- OUTPUT(f->unit, outpacket, outlen, f->protocol);
-
- FSMDEBUG((stderr, "ppp: fsm_sdata(%x): Sent code %d, id %d.\n",
- f->protocol, code, id));
- }
-