diff mbox

sit: Clean up DF code by copying from IPIP

Message ID 20091109184201.GA9493@gondor.apana.org.au
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Herbert Xu Nov. 9, 2009, 6:42 p.m. UTC 
Hi Dave:

This can go into net-next since it doesn't really alter the
behaviour in any significant way.

sit: Clean up DF code by copying from IPIP

This patch rearranges the SIT DF bit handling using the new IPIP
DF code.  The only externally visible effect should be the case where
PMTU is enabled and the MTU is exactly 1280 bytes.  In this case
the previous code would send packets out with DF off while the new
code would set the DF bit.  This is inline with RFC 4213.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>


Thanks,

Comments

David Miller Nov. 11, 2009, 6:33 a.m. UTC | #1 
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Mon, 9 Nov 2009 13:42:01 -0500

> sit: Clean up DF code by copying from IPIP
> 
> This patch rearranges the SIT DF bit handling using the new IPIP
> DF code.  The only externally visible effect should be the case where
> PMTU is enabled and the MTU is exactly 1280 bytes.  In this case
> the previous code would send packets out with DF off while the new
> code would set the DF bit.  This is inline with RFC 4213.
> 
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Applied to net-next-2.6
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diff mbox

Patch

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index dbd19a7..97739ee 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -559,6 +559,7 @@  static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 	struct iphdr  *tiph = &tunnel->parms.iph;
 	struct ipv6hdr *iph6 = ipv6_hdr(skb);
 	u8     tos = tunnel->parms.iph.tos;
+	__be16 df = tiph->frag_off;
 	struct rtable *rt;     			/* Route to the other host */
 	struct net_device *tdev;			/* Device to other host */
 	struct iphdr  *iph;			/* Our new IP header */
@@ -648,25 +649,28 @@  static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 		goto tx_error;
 	}
 
-	if (tiph->frag_off)
+	if (df) {
 		mtu = dst_mtu(&rt->u.dst) - sizeof(struct iphdr);
-	else
-		mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
 
-	if (mtu < 68) {
-		stats->collisions++;
-		ip_rt_put(rt);
-		goto tx_error;
-	}
-	if (mtu < IPV6_MIN_MTU)
-		mtu = IPV6_MIN_MTU;
-	if (tunnel->parms.iph.daddr && skb_dst(skb))
-		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
+		if (mtu < 68) {
+			stats->collisions++;
+			ip_rt_put(rt);
+			goto tx_error;
+		}
 
-	if (skb->len > mtu) {
-		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
-		ip_rt_put(rt);
-		goto tx_error;
+		if (mtu < IPV6_MIN_MTU) {
+			mtu = IPV6_MIN_MTU;
+			df = 0;
+		}
+
+		if (tunnel->parms.iph.daddr && skb_dst(skb))
+			skb_dst(skb)->ops->update_pmtu(skb_dst(skb), mtu);
+
+		if (skb->len > mtu) {
+			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, dev);
+			ip_rt_put(rt);
+			goto tx_error;
+		}
 	}
 
 	if (tunnel->err_count > 0) {
@@ -714,11 +718,7 @@  static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 	iph 			=	ip_hdr(skb);
 	iph->version		=	4;
 	iph->ihl		=	sizeof(struct iphdr)>>2;
-	if (mtu > IPV6_MIN_MTU)
-		iph->frag_off	=	tiph->frag_off;
-	else
-		iph->frag_off	=	0;
-
+	iph->frag_off		=	df;
 	iph->protocol		=	IPPROTO_IPV6;
 	iph->tos		=	INET_ECN_encapsulate(tos, ipv6_get_dsfield(iph6));
 	iph->daddr		=	rt->rt_dst;