[PATCH net-next 2/8] udp: Add udp6_lib_lookup_skb and udp4_lib_lookup_skb

[Tom Herbert]

Add externally visible functions to lookup a UDP socket by skb. This
will be used for GRO in UDP sockets. These functions also check
if skb->dst is set, and if it is not skb->dev is used to get dev_net.
This allows calling lookup functions before dst has been set on the
skbuff.

Signed-off-by: Tom Herbert <t...@herbertland.com>
---
 include/net/udp.h |  4 ++++
 net/ipv4/udp.c    | 13 +++++++++++++
 net/ipv6/udp.c    | 13 +++++++++++++
 3 files changed, 30 insertions(+)

diff --git a/include/net/udp.h b/include/net/udp.h
index d870ec1..e2e3803 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -260,6 +260,8 @@ struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, 
__be16 sport,
 struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
                               __be32 daddr, __be16 dport, int dif,
                               struct udp_table *tbl, struct sk_buff *skb);
+struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
+                                __be16 sport, __be16 dport);
 struct sock *udp6_lib_lookup(struct net *net,
                             const struct in6_addr *saddr, __be16 sport,
                             const struct in6_addr *daddr, __be16 dport,
@@ -269,6 +271,8 @@ struct sock *__udp6_lib_lookup(struct net *net,
                               const struct in6_addr *daddr, __be16 dport,
                               int dif, struct udp_table *tbl,
                               struct sk_buff *skb);
+struct sock *udp6_lib_lookup_skb(struct sk_buff *skb,
+                                __be16 sport, __be16 dport);
 
 /*
  *     SNMP statistics for UDP and UDP-Lite
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 355bdb2..b39c566 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -604,6 +604,19 @@ static inline struct sock *__udp4_lib_lookup_skb(struct 
sk_buff *skb,
                                 udptable, skb);
 }
 
+struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
+                                __be16 sport, __be16 dport)
+{
+       const struct iphdr *iph = ip_hdr(skb);
+       const struct net_device *dev =
+           skb_dst(skb) ? skb_dst(skb)->dev : skb->dev;
+
+       return __udp4_lib_lookup(dev_net(dev), iph->saddr, sport,
+                                iph->daddr, dport, inet_iif(skb),
+                                &udp_table, skb);
+}
+EXPORT_SYMBOL_GPL(udp4_lib_lookup_skb);
+
 /* Must be called under rcu_read_lock().
  * Does increment socket refcount.
  */
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 78a7dfd..33a58eb 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -326,6 +326,19 @@ static struct sock *__udp6_lib_lookup_skb(struct sk_buff 
*skb,
                                 udptable, skb);
 }
 
+struct sock *udp6_lib_lookup_skb(struct sk_buff *skb,
+                                __be16 sport, __be16 dport)
+{
+       const struct ipv6hdr *iph = ipv6_hdr(skb);
+       const struct net_device *dev =
+           skb_dst(skb) ? skb_dst(skb)->dev : skb->dev;
+
+       return __udp6_lib_lookup(dev_net(dev), &iph->saddr, sport,
+                                &iph->daddr, dport, inet6_iif(skb),
+                                &udp_table, skb);
+}
+EXPORT_SYMBOL_GPL(udp6_lib_lookup_skb);
+
 /* Must be called under rcu_read_lock().
  * Does increment socket refcount.
  */
-- 
2.8.0.rc2