devip: tcpmssclamp() to minimum of source and destination interface MTU

We used to only clamp to the MTU of the destination interface,
but this is wrong. We have to clamp to the minimum of both
source and destination.

For this, we change the gating argument type of ipoput4()
and ipoput6() from int to Ipifc* to pass the source interface.

1 files changed, 14 insertions, 14 deletions

diff --git a/sys/src/9/ip/icmp.c b/sys/src/9/ip/icmp.c
index 526540af3..c4168605b 100644
--- a/sys/src/9/ip/icmp.c
+++ b/sys/src/9/ip/icmp.c
@@ -185,7 +185,7 @@ icmpkick(void *x, Block *bp)
 	memset(p->cksum, 0, sizeof(p->cksum));
 	hnputs(p->cksum, ptclcsum(bp, ICMP_IPSIZE, blocklen(bp) - ICMP_IPSIZE));
 	ipriv->stats[OutMsgs]++;
-	ipoput4(c->p->f, bp, 0, c->ttl, c->tos, nil);
+	ipoput4(c->p->f, bp, nil, c->ttl, c->tos, nil);
 }
 
 static int
@@ -240,7 +240,7 @@ icmpttlexceeded(Fs *f, Ipifc *ifc, Block *bp)
 	hnputs(np->seq, 0);
 	memset(np->cksum, 0, sizeof(np->cksum));
 	hnputs(np->cksum, ptclcsum(nbp, ICMP_IPSIZE, blocklen(nbp) - ICMP_IPSIZE));
-	ipoput4(f, nbp, 0, MAXTTL, DFLTTOS, nil);
+	ipoput4(f, nbp, nil, MAXTTL, DFLTTOS, nil);
 }
 
 static void
@@ -280,7 +280,7 @@ icmpunreachable(Fs *f, Ipifc *ifc, Block *bp, int code, int seq)
 	hnputs(np->seq, seq);
 	memset(np->cksum, 0, sizeof(np->cksum));
 	hnputs(np->cksum, ptclcsum(nbp, ICMP_IPSIZE, blocklen(nbp) - ICMP_IPSIZE));
-	ipoput4(f, nbp, 0, MAXTTL, DFLTTOS, nil);
+	ipoput4(f, nbp, nil, MAXTTL, DFLTTOS, nil);
 }
 
 void
@@ -302,7 +302,7 @@ icmpcantfrag(Fs *f, Block *bp, int mtu)
 }
 
 static void
-goticmpkt(Proto *icmp, Block *bp)
+goticmpkt(Proto *icmp, Block *bp, Ipifc *ifc)
 {
 	uchar	dst[IPaddrlen], src[IPaddrlen];
 	ushort	recid;
@@ -331,7 +331,7 @@ goticmpkt(Proto *icmp, Block *bp)
 			q = nil;
 		qunlock(icmp);
 
-		ipoput4(icmp->f, bp, 1, hop - 1, p->tos, q);
+		ipoput4(icmp->f, bp, ifc, hop - 1, p->tos, q);
 		return;
 	}
 	for(c = icmp->conv; (s = *c) != nil; c++){
@@ -386,7 +386,7 @@ static char *unreachcode[] =
 };
 
 static void
-icmpiput(Proto *icmp, Ipifc*, Block *bp)
+icmpiput(Proto *icmp, Ipifc *ifc, Block *bp)
 {
 	int	n;
 	Icmp	*p;
@@ -426,14 +426,14 @@ icmpiput(Proto *icmp, Ipifc*, Block *bp)
 		if(r == nil)
 			goto raise;
 		ipriv->out[EchoReply]++;
-		ipoput4(icmp->f, r, 0, MAXTTL, DFLTTOS, nil);
+		ipoput4(icmp->f, r, nil, MAXTTL, DFLTTOS, nil);
 		break;
 	case TimeExceed:
 		if(p->code == 0){
 			snprint(msg = m2, sizeof m2, "ttl exceeded at %V", p->src);
 			goto Advise;
 		}
-		goticmpkt(icmp, bp);
+		goticmpkt(icmp, bp, ifc);
 		break;
 	case Unreachable:
 		if(p->code >= nelem(unreachcode)) {
@@ -455,14 +455,14 @@ icmpiput(Proto *icmp, Ipifc*, Block *bp)
 			pr = Fsrcvpcolx(icmp->f, p->proto);
 			if(pr != nil && pr->advise != nil) {
 				netlog(icmp->f, Logicmp, "advising %s!%V -> %V: %s\n", pr->name, p->src, p->dst, msg);
-				(*pr->advise)(pr, bp, msg);
+				(*pr->advise)(pr, bp, ifc, msg);
 				return;
 			}
 		}
 		bp->rp -= ICMP_IPSIZE+ICMP_HDRSIZE;
 		/* wet floor */
 	default:
-		goticmpkt(icmp, bp);
+		goticmpkt(icmp, bp, ifc);
 		break;
 	}
 	return;
@@ -479,7 +479,7 @@ raise:
  * and send the advice to ip4.
  */
 void
-icmpproxyadvice(Fs *f, Block *bp, uchar *ip4)
+icmpproxyadvice(Fs *f, Block *bp, Ipifc *ifc, uchar *ip4)
 {
 	Icmp	*p;
 	int	hop;
@@ -509,14 +509,14 @@ icmpproxyadvice(Fs *f, Block *bp, uchar *ip4)
 	memset(p->cksum, 0, sizeof(p->cksum));
 	hnputs(p->cksum, ptclcsum(bp, ICMP_IPSIZE, blocklen(bp) - ICMP_IPSIZE));
 
-	ipoput4(f, bp, 1, hop - 1, p->tos, nil);
+	ipoput4(f, bp, ifc, hop - 1, p->tos, nil);
 	return;
 drop:
 	freeblist(bp);
 }
 
 static void
-icmpadvise(Proto *icmp, Block *bp, char *msg)
+icmpadvise(Proto *icmp, Block *bp, Ipifc *ifc, char *msg)
 {
 	uchar	dst[IPaddrlen], src[IPaddrlen];
 	ushort	recid;
@@ -543,7 +543,7 @@ icmpadvise(Proto *icmp, Block *bp, char *msg)
 		hnputs_csum(p->icmpid, q->forward.rport, p->cksum);
 		qunlock(icmp);
 
-		icmpproxyadvice(icmp->f, bp, p->src);
+		icmpproxyadvice(icmp->f, bp, ifc, p->src);
 		return;
 	}
 	for(c = icmp->conv; (s = *c) != nil; c++){