tipc: Introduce node signature field in neighbor discovery message

Adds support for the new "node signature" in neighbor discovery messages,
which is a 16 bit identifier chosen randomly when TIPC is initialized.
This field makes it possible for nodes receiving a neighbor discovery
message to detect if multiple neighboring nodes are using the same network
address (i.e. <Z.C.N>), even when the messages are arriving on different
interfaces.

This first phase of node signature support creates the signature,
incorporates it into outgoing neighbor discovery messages, and tracks
the signature used by valid neighbors. An upcoming patch builds on this
foundation to implement the improved duplicate neighbor detection checking.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/net/tipc/msg.h b/net/tipc/msg.h
index 7b0cda1..2ec13b7 100644
--- a/net/tipc/msg.h
+++ b/net/tipc/msg.h
@@ -517,6 +517,16 @@ static inline void msg_set_seq_gap(struct tipc_msg *m, u32 n)
 	msg_set_bits(m, 1, 16, 0x1fff, n);
 }
 
+static inline u32 msg_node_sig(struct tipc_msg *m)
+{
+	return msg_bits(m, 1, 0, 0xffff);
+}
+
+static inline void msg_set_node_sig(struct tipc_msg *m, u32 n)
+{
+	msg_set_bits(m, 1, 0, 0xffff, n);
+}
+
 
 /*
  * Word 2