tipc: make node number calculation reproducible

The 32-bit node number, aka node hash or node address, is calculated
based on the 128-bit node identity when it is not set explicitly by
the user. In future commits we will need to perform this hash operation
on peer nodes while feeling safe that we obtain the same result.

We do this by interpreting the initial hash as a network byte order
number. Whenever we need to use the number locally on a node
we must therefore translate it to host byte order to obtain an
architecure independent result.

Furthermore, given the context where we use this number, we must not
allow it to be zero unless the node identity also is zero. Hence, in
the rare cases when the xor-ed hash value may end up as zero we replace
it with a fix number, knowing that the code anyway is capable of
handling hash collisions.

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/net/tipc/addr.c b/net/tipc/addr.c
index 0f1eaed1bd1b..abe29d1aa23a 100644
--- a/net/tipc/addr.c
+++ b/net/tipc/addr.c
@@ -55,12 +55,11 @@ bool tipc_in_scope(bool legacy_format, u32 domain, u32 addr)
 void tipc_set_node_id(struct net *net, u8 *id)
 {
 	struct tipc_net *tn = tipc_net(net);
-	u32 *tmp = (u32 *)id;
 
 	memcpy(tn->node_id, id, NODE_ID_LEN);
 	tipc_nodeid2string(tn->node_id_string, id);
-	tn->trial_addr = tmp[0] ^ tmp[1] ^ tmp[2] ^ tmp[3];
-	pr_info("Own node identity %s, cluster identity %u\n",
+	tn->trial_addr = hash128to32(id);
+	pr_info("Node identity %s, cluster identity %u\n",
 		tipc_own_id_string(net), tn->net_id);
 }
 
@@ -76,7 +75,7 @@ void tipc_set_node_addr(struct net *net, u32 addr)
 	}
 	tn->trial_addr = addr;
 	tn->addr_trial_end = jiffies;
-	pr_info("32-bit node address hash set to %x\n", addr);
+	pr_info("Node number set to %u\n", addr);
 }
 
 char *tipc_nodeid2string(char *str, u8 *id)