inet: Add udplib_lookup_skb() helpers

To be able to use the cached socket reference in the skb during input
processing we add a new set of lookup functions that receive the skb on
their argument list.
Signed-off-by: KOVACS Krisztian <hidden@sch.bme.hu>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp.c

@@ -302,6 +302,17 @@ static struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
 	return result;
 }
 
+static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
+						 __be16 sport, __be16 dport,
+						 struct hlist_head udptable[])
+{
+	const struct iphdr *iph = ip_hdr(skb);
+
+	return __udp4_lib_lookup(dev_net(skb->dst->dev), iph->saddr, sport,
+				 iph->daddr, dport, inet_iif(skb),
+				 udptable);
+}
+
 struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 			     __be32 daddr, __be16 dport, int dif)
 {
@@ -1208,8 +1219,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[],
 		return __udp4_lib_mcast_deliver(net, skb, uh,
 				saddr, daddr, udptable);
 
-	sk = __udp4_lib_lookup(net, saddr, uh->source, daddr,
-			uh->dest, inet_iif(skb), udptable);
+	sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
 
 	if (sk != NULL) {
 		int ret = udp_queue_rcv_skb(sk, skb);

net/ipv6/udp.c

@@ -107,6 +107,17 @@ static struct sock *__udp6_lib_lookup(struct net *net,
 	return result;
 }
 
+static struct sock *__udp6_lib_lookup_skb(struct sk_buff *skb,
+					  __be16 sport, __be16 dport,
+					  struct hlist_head udptable[])
+{
+	struct ipv6hdr *iph = ipv6_hdr(skb);
+
+	return __udp6_lib_lookup(dev_net(skb->dst->dev), &iph->saddr, sport,
+				 &iph->daddr, dport, inet6_iif(skb),
+				 udptable);
+}
+
 /*
  * 	This should be easy, if there is something there we
  * 	return it, otherwise we block.
@@ -488,8 +499,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[],
 	 * check socket cache ... must talk to Alan about his plans
 	 * for sock caches... i'll skip this for now.
 	 */
-	sk = __udp6_lib_lookup(net, saddr, uh->source,
-			       daddr, uh->dest, inet6_iif(skb), udptable);
+	sk = __udp6_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
 
 	if (sk == NULL) {
 		if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))