From 39d1bb46c68ac628ff2e59d7dd94db058be134e8 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sat, 7 Dec 2002 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2002-12-07

---
 ip/icmp.c | 10 +++++-----
 ip/ip.c   |  6 +++++-
 ip/ip.h   |  2 +-
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/ip/icmp.c b/ip/icmp.c
index 026ca674303d819c1131acb26a290f8a3e57e4ed..302669c7661babba8aa5066b8642d10c5d021bdb 100644
--- a/ip/icmp.c
+++ b/ip/icmp.c
@@ -216,7 +216,7 @@ icmpttlexceeded(Fs *f, uchar *ia, Block *bp)
 }
 
 static void
-icmpunreachable(Fs *f, Block *bp, int code)
+icmpunreachable(Fs *f, Block *bp, int code, int seq)
 {
 	Block	*nbp;
 	Icmp	*p, *np;
@@ -247,7 +247,7 @@ icmpunreachable(Fs *f, Block *bp, int code)
 	np->code = code;
 	np->proto = IP_ICMPPROTO;
 	hnputs(np->icmpid, 0);
-	hnputs(np->seq, 0);
+	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);
@@ -256,13 +256,13 @@ icmpunreachable(Fs *f, Block *bp, int code)
 extern void
 icmpnoconv(Fs *f, Block *bp)
 {
-	icmpunreachable(f, bp, 3);
+	icmpunreachable(f, bp, 3, 0);
 }
 
 extern void
-icmpcantfrag(Fs *f, Block *bp)
+icmpcantfrag(Fs *f, Block *bp, int mtu)
 {
-	icmpunreachable(f, bp, 4);
+	icmpunreachable(f, bp, 4, mtu);
 }
 
 static void
diff --git a/ip/ip.c b/ip/ip.c
index 5c486619af40c783e5c2e5881ae4484fa526b45b..c260b0fe8ab51491fad3b1c18f7ff320d84a3043 100644
--- a/ip/ip.c
+++ b/ip/ip.c
@@ -317,7 +317,7 @@ if((eh->frag[0] & (IP_DF>>8)) && !gating) print("%V: DF set\n", eh->dst);
 	if(eh->frag[0] & (IP_DF>>8)){
 		ip->stats[FragFails]++;
 		ip->stats[OutDiscards]++;
-		icmpcantfrag(f, bp);
+		icmpcantfrag(f, bp, medialen);
 		netlog(f, Logip, "%V: eh->frag[0] & (IP_DF>>8)\n", eh->dst);
 		goto raise;
 	}
@@ -528,6 +528,10 @@ ipiput4(Fs *f, Ipifc *ifc, Block *bp)
 		h = (Ip4hdr*)(bp->rp);
 	}
 
+	/* don't let any frag info go up the stack */
+	h->frag[0] = 0;
+	h->frag[1] = 0;
+
 	proto = h->proto;
 	p = Fsrcvpcol(f, proto);
 	if(p != nil && p->rcv != nil) {
diff --git a/ip/ip.h b/ip/ip.h
index f20092a8c4eecb2cddfa769ef4f7ea7574dc6758..8863df5e9b4963d1e59b1299748a39b302004a07 100644
--- a/ip/ip.h
+++ b/ip/ip.h
@@ -614,7 +614,7 @@ extern long	ipgateread6(Fs *f, char *cp, ulong offset, int n);
 extern void	iprouting(Fs*, int);
 extern void	closeifcconv(Ifcconv*);
 extern void	icmpnoconv(Fs*, Block*);
-extern void	icmpcantfrag(Fs*, Block*);
+extern void	icmpcantfrag(Fs*, Block*, int);
 extern void	icmpttlexceeded(Fs*, uchar*, Block*);
 extern ushort	ipcsum(uchar*);
 extern void	ipiput4(Fs*, Ipifc*, Block*);