tipc: introduce replicast as transport option for multicast

TIPC multicast messages are currently carried over a reliable
'broadcast link', making use of the underlying media's ability to
transport packets as L2 broadcast or IP multicast to all nodes in
the cluster.

When the used bearer is lacking that ability, we can instead emulate
the broadcast service by replicating and sending the packets over as
many unicast links as needed to reach all identified destinations.
We now introduce a new TIPC link-level 'replicast' service that does
this.

Reviewed-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 8 deletions

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index d2f353934f82..93b6ae3154c9 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -740,32 +740,43 @@ static int tipc_sendmcast(struct  socket *sock, struct tipc_name_seq *seq,
 	struct tipc_msg *hdr = &tsk->phdr;
 	struct net *net = sock_net(sk);
 	int mtu = tipc_bcast_get_mtu(net);
+	u32 domain = addr_domain(net, TIPC_CLUSTER_SCOPE);
 	struct sk_buff_head pkts;
+	struct tipc_nlist dsts;
 	int rc;
 
+	/* Block or return if any destination link is congested */
 	rc = tipc_wait_for_cond(sock, &timeout, !tsk->cong_link_cnt);
 	if (unlikely(rc))
 		return rc;
 
+	/* Lookup destination nodes */
+	tipc_nlist_init(&dsts, tipc_own_addr(net));
+	tipc_nametbl_lookup_dst_nodes(net, seq->type, seq->lower,
+				      seq->upper, domain, &dsts);
+	if (!dsts.local && !dsts.remote)
+		return -EHOSTUNREACH;
+
+	/* Build message header */
 	msg_set_type(hdr, TIPC_MCAST_MSG);
+	msg_set_hdr_sz(hdr, MCAST_H_SIZE);
 	msg_set_lookup_scope(hdr, TIPC_CLUSTER_SCOPE);
 	msg_set_destport(hdr, 0);
 	msg_set_destnode(hdr, 0);
 	msg_set_nametype(hdr, seq->type);
 	msg_set_namelower(hdr, seq->lower);
 	msg_set_nameupper(hdr, seq->upper);
-	msg_set_hdr_sz(hdr, MCAST_H_SIZE);
 
+	/* Build message as chain of buffers */
 	skb_queue_head_init(&pkts);
 	rc = tipc_msg_build(hdr, msg, 0, dlen, mtu, &pkts);
-	if (unlikely(rc != dlen))
-		return rc;
 
-	rc = tipc_bcast_xmit(net, &pkts);
-	if (unlikely(rc == -ELINKCONG)) {
-		tsk->cong_link_cnt = 1;
-		rc = 0;
-	}
+	/* Send message if build was successful */
+	if (unlikely(rc == dlen))
+		rc = tipc_mcast_xmit(net, &pkts, &dsts,
+				     &tsk->cong_link_cnt);
+
+	tipc_nlist_purge(&dsts);
 
 	return rc ? rc : dlen;
 }