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, 3 insertions, 0 deletions

diff --git a/net/tipc/discover.c b/net/tipc/discover.c
index a00e5f811569..7ae1b4c33aeb 100644
--- a/net/tipc/discover.c
+++ b/net/tipc/discover.c
@@ -82,6 +82,7 @@ static struct sk_buff *tipc_disc_init_msg(u32 type,
                 msg = buf_msg(buf);
                 tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain);
                 msg_set_non_seq(msg, 1);
+                msg_set_node_sig(msg, tipc_random);
                 msg_set_dest_domain(msg, dest_domain);
                 msg_set_bc_netid(msg, tipc_net_id);
                 b_ptr->media->addr2msg(&b_ptr->addr, msg_media_addr(msg));
@@ -128,6 +129,7 @@ void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
         u32 orig = msg_prevnode(msg);
         u32 net_id = msg_bc_netid(msg);
         u32 type = msg_type(msg);
+        u32 signature = msg_node_sig(msg);
         int link_fully_up;
 
         media_addr.broadcast = 1;
@@ -197,6 +199,7 @@ void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
         }
 
         /* Accept discovery message & send response, if necessary */
+        n_ptr->signature = signature;
         link_fully_up = link_working_working(link);
 
         if ((type == DSC_REQ_MSG) && !link_fully_up && !b_ptr->blocked) {