tipc: support binding to specific ip address when activating UDP bearer

INADDR_ANY is hard-coded when activating UDP bearer. So, we could not
bind to a specific IP address even with replicast mode using - given
remote ip address instead of using multicast ip address.

In this commit, we fixed it by checking and switch to use appropriate
local ip address.

before:
$netstat -plu
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address
udp        0      0 **0.0.0.0:6118**            0.0.0.0:*

after:
$netstat -plu
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address
udp        0      0 **10.0.0.2:6118**           0.0.0.0:*
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Hoang Le <hoang.h.le@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/udp_media.c

@@ -650,6 +650,7 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 	struct udp_tunnel_sock_cfg tuncfg = {NULL};
 	struct nlattr *opts[TIPC_NLA_UDP_MAX + 1];
 	u8 node_id[NODE_ID_LEN] = {0,};
+	int rmcast = 0;
 
 	ub = kzalloc(sizeof(*ub), GFP_ATOMIC);
 	if (!ub)
@@ -680,6 +681,9 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 	if (err)
 		goto err;
 
+	/* Checking remote ip address */
+	rmcast = tipc_udp_is_mcast_addr(&remote);
+
 	/* Autoconfigure own node identity if needed */
 	if (!tipc_own_id(net)) {
 		memcpy(node_id, local.ipv6.in6_u.u6_addr8, 16);
@@ -705,7 +709,12 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 			goto err;
 		}
 		udp_conf.family = AF_INET;
+
+		/* Switch to use ANY to receive packets from group */
+		if (rmcast)
 			udp_conf.local_ip.s_addr = htonl(INADDR_ANY);
+		else
+			udp_conf.local_ip.s_addr = local.ipv4.s_addr;
 		udp_conf.use_udp_checksums = false;
 		ub->ifindex = dev->ifindex;
 		if (tipc_mtu_bad(dev, sizeof(struct iphdr) +
@@ -719,7 +728,10 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 		udp_conf.family = AF_INET6;
 		udp_conf.use_udp6_tx_checksums = true;
 		udp_conf.use_udp6_rx_checksums = true;
+		if (rmcast)
 			udp_conf.local_ip6 = in6addr_any;
+		else
+			udp_conf.local_ip6 = local.ipv6;
 		b->mtu = 1280;
 #endif
 	} else {
@@ -741,7 +753,7 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 	 * is used if it's a multicast address.
 	 */
 	memcpy(&b->bcast_addr.value, &remote, sizeof(remote));
-	if (tipc_udp_is_mcast_addr(&remote))
+	if (rmcast)
 		err = enable_mcast(ub, &remote);
 	else
 		err = tipc_udp_rcast_add(b, &remote);