inet_hashtables: Add inet_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: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: KOVACS Krisztian <hidden@sch.bme.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index bb619d8..3522bbc 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -16,6 +16,7 @@
 
 
 #include <linux/interrupt.h>
+#include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/list.h>
 #include <linux/slab.h>
@@ -28,6 +29,7 @@
 #include <net/inet_connection_sock.h>
 #include <net/inet_sock.h>
 #include <net/sock.h>
+#include <net/route.h>
 #include <net/tcp_states.h>
 #include <net/netns/hash.h>
 
@@ -371,6 +373,18 @@
 	return sk;
 }
 
+static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
+					     struct sk_buff *skb,
+					     const __be16 sport,
+					     const __be16 dport)
+{
+	const struct iphdr *iph = ip_hdr(skb);
+
+	return __inet_lookup(dev_net(skb->dst->dev), hashinfo,
+			     iph->saddr, sport,
+			     iph->daddr, dport, inet_iif(skb));
+}
+
 extern int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 		struct sock *sk, u32 port_offset,
 		int (*check_established)(struct inet_timewait_death_row *,