net: introduce skb_flow_dissect()

We use at least two flow dissectors in network stack, with known
limitations and code duplication.

Introduce skb_flow_dissect() to factorize this, highly inspired from
existing dissector from __skb_get_rxhash()

Note : We extensively use skb_header_pointer(), this permits us to not
touch skb at all.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/net/flow_keys.h b/include/net/flow_keys.h
new file mode 100644
index 000000000000..e4cb28526563
--- /dev/null
+++ b/include/net/flow_keys.h
@@ -0,0 +1,15 @@
+#ifndef _NET_FLOW_KEYS_H
+#define _NET_FLOW_KEYS_H
+
+struct flow_keys {
+        __be32 src;
+        __be32 dst;
+        union {
+                __be32 ports;
+                __be16 port16[2];
+        };
+        u8 ip_proto;
+};
+
+extern bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow);
+#endif