Make the way FSM options are processed easier to read by using structures

instead of u_char *.

The changes are cosmetic except:

  RecvConfigAck() now displays the options that are being ACK'd
  Huge (bogus) options sent from the peer won't cause an infinite loop
  SendIdent and ReceiveIdent are displayed consistenlty with other FSM data
  LCP AUTHPROTO options that aren't understood are NAK'd, not REJ'd

1 files changed, 127 insertions, 29 deletions

diff --git a/usr.sbin/ppp/fsm.c b/usr.sbin/ppp/fsm.c
index d4c89c4..2a108c2 100644
--- a/usr.sbin/ppp/fsm.c
+++ b/usr.sbin/ppp/fsm.c
@@ -170,7 +170,7 @@ static void
 NewState(struct fsm *fp, int new)
 {
   log_Printf(fp->LogLevel, "%s: State change %s --> %s\n",
-	    fp->link->name, State2Nam(fp->state), State2Nam(new));
+             fp->link->name, State2Nam(fp->state), State2Nam(new));
   if (fp->state == ST_STOPPED && fp->StoppedTimer.state == TIMER_RUNNING)
     timer_Stop(&fp->StoppedTimer);
   fp->state = new;
@@ -201,8 +201,8 @@ fsm_Output(struct fsm *fp, u_int code, u_int id, u_char *ptr, int count,
       case CODE_CONFIGACK:
       case CODE_CONFIGREJ:
       case CODE_CONFIGNAK:
-        (*fp->fn->DecodeConfig)(fp, ptr, count, MODE_NOP, NULL);
-        if (count < sizeof(struct fsmconfig))
+        (*fp->fn->DecodeConfig)(fp, ptr, ptr + count, MODE_NOP, NULL);
+        if (count < sizeof(struct fsm_opt_hdr))
           log_Printf(fp->LogLevel, "  [EMPTY]\n");
         break;
     }
@@ -470,16 +470,29 @@ FsmRecvConfigReq(struct fsm *fp, struct fsmheader *lhp, struct mbuf *bp)
   struct fsm_decode dec;
   int plen, flen;
   int ackaction = 0;
+  u_char *cp;
 
+  bp = m_pullup(bp);
   plen = m_length(bp);
   flen = ntohs(lhp->length) - sizeof *lhp;
   if (plen < flen) {
     log_Printf(LogWARN, "%s: FsmRecvConfigReq: plen (%d) < flen (%d)\n",
-	      fp->link->name, plen, flen);
+               fp->link->name, plen, flen);
     m_freem(bp);
     return;
   }
 
+  dec.ackend = dec.ack;
+  dec.nakend = dec.nak;
+  dec.rejend = dec.rej;
+  cp = MBUF_CTOP(bp);
+  (*fp->fn->DecodeConfig)(fp, cp, cp + flen, MODE_REQ, &dec);
+  if (flen < sizeof(struct fsm_opt_hdr))
+    log_Printf(fp->LogLevel, "  [EMPTY]\n");
+
+  if (dec.nakend == dec.nak && dec.rejend == dec.rej)
+    ackaction = 1;
+
   /* Check and process easy case */
   switch (fp->state) {
   case ST_INITIAL:
@@ -511,28 +524,12 @@ FsmRecvConfigReq(struct fsm *fp, struct fsmheader *lhp, struct mbuf *bp)
   case ST_STOPPING:
     m_freem(bp);
     return;
-  case ST_OPENED:
-    (*fp->fn->LayerDown)(fp);
-    break;
-  }
-
-  bp = m_pullup(bp);
-  dec.ackend = dec.ack;
-  dec.nakend = dec.nak;
-  dec.rejend = dec.rej;
-  (*fp->fn->DecodeConfig)(fp, MBUF_CTOP(bp), flen, MODE_REQ, &dec);
-  if (flen < sizeof(struct fsmconfig))
-    log_Printf(fp->LogLevel, "  [EMPTY]\n");
-
-  if (dec.nakend == dec.nak && dec.rejend == dec.rej)
-    ackaction = 1;
-
-  switch (fp->state) {
   case ST_STOPPED:
     FsmInitRestartCounter(fp, FSM_REQ_TIMER);
-    /* Fall through */
-
+    FsmSendConfigReq(fp);
+    break;
   case ST_OPENED:
+    (*fp->fn->LayerDown)(fp);
     FsmSendConfigReq(fp);
     break;
   }
@@ -609,6 +606,26 @@ static void
 FsmRecvConfigAck(struct fsm *fp, struct fsmheader *lhp, struct mbuf *bp)
 /* RCA */
 {
+  struct fsm_decode dec;
+  int plen, flen;
+  u_char *cp;
+
+  plen = m_length(bp);
+  flen = ntohs(lhp->length) - sizeof *lhp;
+  if (plen < flen) {
+    m_freem(bp);
+    return;
+  }
+
+  bp = m_pullup(bp);
+  dec.ackend = dec.ack;
+  dec.nakend = dec.nak;
+  dec.rejend = dec.rej;
+  cp = MBUF_CTOP(bp);
+  (*fp->fn->DecodeConfig)(fp, cp, cp + flen, MODE_ACK, &dec);
+  if (flen < sizeof(struct fsm_opt_hdr))
+    log_Printf(fp->LogLevel, "  [EMPTY]\n");
+
   switch (fp->state) {
     case ST_CLOSED:
     case ST_STOPPED:
@@ -654,6 +671,7 @@ FsmRecvConfigNak(struct fsm *fp, struct fsmheader *lhp, struct mbuf *bp)
 {
   struct fsm_decode dec;
   int plen, flen;
+  u_char *cp;
 
   plen = m_length(bp);
   flen = ntohs(lhp->length) - sizeof *lhp;
@@ -687,8 +705,9 @@ FsmRecvConfigNak(struct fsm *fp, struct fsmheader *lhp, struct mbuf *bp)
   dec.ackend = dec.ack;
   dec.nakend = dec.nak;
   dec.rejend = dec.rej;
-  (*fp->fn->DecodeConfig)(fp, MBUF_CTOP(bp), flen, MODE_NAK, &dec);
-  if (flen < sizeof(struct fsmconfig))
+  cp = MBUF_CTOP(bp);
+  (*fp->fn->DecodeConfig)(fp, cp, cp + flen, MODE_NAK, &dec);
+  if (flen < sizeof(struct fsm_opt_hdr))
     log_Printf(fp->LogLevel, "  [EMPTY]\n");
 
   switch (fp->state) {
@@ -782,6 +801,7 @@ FsmRecvConfigRej(struct fsm *fp, struct fsmheader *lhp, struct mbuf *bp)
 {
   struct fsm_decode dec;
   int plen, flen;
+  u_char *cp;
 
   plen = m_length(bp);
   flen = ntohs(lhp->length) - sizeof *lhp;
@@ -817,8 +837,9 @@ FsmRecvConfigRej(struct fsm *fp, struct fsmheader *lhp, struct mbuf *bp)
   dec.ackend = dec.ack;
   dec.nakend = dec.nak;
   dec.rejend = dec.rej;
-  (*fp->fn->DecodeConfig)(fp, MBUF_CTOP(bp), flen, MODE_REJ, &dec);
-  if (flen < sizeof(struct fsmconfig))
+  cp = MBUF_CTOP(bp);
+  (*fp->fn->DecodeConfig)(fp, cp, cp + flen, MODE_REJ, &dec);
+  if (flen < sizeof(struct fsm_opt_hdr))
     log_Printf(fp->LogLevel, "  [EMPTY]\n");
 
   switch (fp->state) {
@@ -1052,12 +1073,12 @@ fsm_Input(struct fsm *fp, struct mbuf *bp)
   if (lh.id != fp->reqid && codep->check_reqid &&
       Enabled(fp->bundle, OPT_IDCHECK)) {
     log_Printf(fp->LogLevel, "%s: Recv%s(%d), dropped (expected %d)\n",
-	      fp->link->name, codep->name, lh.id, fp->reqid);
+               fp->link->name, codep->name, lh.id, fp->reqid);
     return;
   }
 
   log_Printf(fp->LogLevel, "%s: Recv%s(%d) state = %s\n",
-	    fp->link->name, codep->name, lh.id, State2Nam(fp->state));
+             fp->link->name, codep->name, lh.id, State2Nam(fp->state));
 
   if (codep->inc_reqid && (lh.id == fp->reqid ||
       (!Enabled(fp->bundle, OPT_IDCHECK) && codep->check_reqid)))
@@ -1106,3 +1127,80 @@ fsm2initial(struct fsm *fp)
   if (fp->state > ST_INITIAL)
     fsm_Close(fp);
 }
+
+struct fsm_opt *
+fsm_readopt(u_char **cp)
+{
+  struct fsm_opt *o = (struct fsm_opt *)*cp;
+
+  if (o->hdr.len < sizeof(struct fsm_opt_hdr)) {
+    log_Printf(LogERROR, "Bad option length %d (out of phase?)\n", o->hdr.len);
+    return NULL;
+  }
+
+  *cp += o->hdr.len;
+
+  if (o->hdr.len > sizeof(struct fsm_opt)) {
+    o->hdr.len = sizeof(struct fsm_opt);
+    log_Printf(LogERROR, "Warning: Truncating option length to %d\n",
+               o->hdr.len);
+  }
+
+  return o;
+}
+
+static int
+fsm_opt(u_char *opt, int optlen, const struct fsm_opt *o)
+{
+  int cplen = o->hdr.len;
+
+  if (optlen < sizeof(struct fsm_opt_hdr))
+    optlen = 0;
+
+  if (cplen > optlen) {
+    log_Printf(LogERROR, "Can't REJ length %d - trunating to %d\n",
+      cplen, optlen);
+    cplen = optlen;
+  }
+  memcpy(opt, o, cplen);
+  if (cplen)
+    opt[1] = cplen;
+
+  return cplen;
+}
+
+void
+fsm_rej(struct fsm_decode *dec, const struct fsm_opt *o)
+{
+  if (!dec)
+    return;
+  dec->rejend += fsm_opt(dec->rejend, FSM_OPTLEN - (dec->rejend - dec->rej), o);
+}
+
+void
+fsm_ack(struct fsm_decode *dec, const struct fsm_opt *o)
+{
+  if (!dec)
+    return;
+  dec->ackend += fsm_opt(dec->ackend, FSM_OPTLEN - (dec->ackend - dec->ack), o);
+}
+
+void
+fsm_nak(struct fsm_decode *dec, const struct fsm_opt *o)
+{
+  if (!dec)
+    return;
+  dec->nakend += fsm_opt(dec->nakend, FSM_OPTLEN - (dec->nakend - dec->nak), o);
+}
+
+void
+fsm_opt_normalise(struct fsm_decode *dec)
+{
+  if (dec->rejend != dec->rej) {
+    /* rejects are preferred */
+    dec->ackend = dec->ack;
+    dec->nakend = dec->nak;
+  } else if (dec->nakend != dec->nak)
+    /* then NAKs */
+    dec->ackend = dec->ack;
+}