bridge: mdb: add support for source address

This patch adds the user-space control and dump of mdb entry source
address. When setting the new MDBA_SET_ENTRY_ATTRS nested attribute is
used and inside is added MDBE_ATTR_SOURCE based on the address family.
When dumping we look for MDBA_MDB_EATTR_SOURCE and if present we add the
"src x.x.x.x" output. The source address will be always shown as it's
needed to match the entry to modify it from user-space.

Example:
 $ bridge mdb add dev bridge port ens13 grp 239.0.0.1 src 1.2.3.4 permanent vid 100
 $ bridge mdb show
 dev bridge port ens13 grp 239.0.0.1 src 1.2.3.4 permanent vid 100

Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David Ahern <dsahern@gmail.com>

bridge/mdb.c

@@ -31,7 +31,7 @@ static unsigned int filter_index, filter_vlan;
 static void usage(void)
 {
 	fprintf(stderr,
-		"Usage: bridge mdb { add | del } dev DEV port PORT grp GROUP [permanent | temp] [vid VID]\n"
+		"Usage: bridge mdb { add | del } dev DEV port PORT grp GROUP [src SOURCE] [permanent | temp] [vid VID]\n"
 		"       bridge mdb {show} [ dev DEV ] [ vid VID ]\n");
 	exit(-1);
 }
@@ -118,16 +118,16 @@ static void br_print_router_ports(FILE *f, struct rtattr *attr,
 static void print_mdb_entry(FILE *f, int ifindex, const struct br_mdb_entry *e,
 			    struct nlmsghdr *n, struct rtattr **tb)
 {
+	const void *grp, *src;
 	SPRINT_BUF(abuf);
 	const char *dev;
-	const void *src;
 	int af;
 
 	if (filter_vlan && e->vid != filter_vlan)
 		return;
 
 	af = e->addr.proto == htons(ETH_P_IP) ? AF_INET : AF_INET6;
-	src = af == AF_INET ? (const void *)&e->addr.u.ip4 :
+	grp = af == AF_INET ? (const void *)&e->addr.u.ip4 :
 			      (const void *)&e->addr.u.ip6;
 	dev = ll_index_to_name(ifindex);
 
@@ -140,8 +140,13 @@ static void print_mdb_entry(FILE *f, int ifindex, const struct br_mdb_entry *e,
 
 	print_color_string(PRINT_ANY, ifa_family_color(af),
 			    "grp", " grp %s",
-			    inet_ntop(af, src, abuf, sizeof(abuf)));
+			    inet_ntop(af, grp, abuf, sizeof(abuf)));
-
+	if (tb && tb[MDBA_MDB_EATTR_SOURCE]) {
+		src = (const void *)RTA_DATA(tb[MDBA_MDB_EATTR_SOURCE]);
+		print_color_string(PRINT_ANY, ifa_family_color(af),
+				   "src", " src %s",
+				   inet_ntop(af, src, abuf, sizeof(abuf)));
+	}
 	print_string(PRINT_ANY, "state", " %s",
 			   (e->state & MDB_PERMANENT) ? "permanent" : "temp");
 
@@ -378,8 +383,8 @@ static int mdb_modify(int cmd, int flags, int argc, char **argv)
 		.n.nlmsg_type = cmd,
 		.bpm.family = PF_BRIDGE,
 	};
+	char *d = NULL, *p = NULL, *grp = NULL, *src = NULL;
 	struct br_mdb_entry entry = {};
-	char *d = NULL, *p = NULL, *grp = NULL;
 	short vid = 0;
 
 	while (argc > 0) {
@@ -400,6 +405,9 @@ static int mdb_modify(int cmd, int flags, int argc, char **argv)
 		} else if (strcmp(*argv, "vid") == 0) {
 			NEXT_ARG();
 			vid = atoi(*argv);
+		} else if (strcmp(*argv, "src") == 0) {
+			NEXT_ARG();
+			src = *argv;
 		} else {
 			if (matches(*argv, "help") == 0)
 				usage();
@@ -431,6 +439,24 @@ static int mdb_modify(int cmd, int flags, int argc, char **argv)
 
 	entry.vid = vid;
 	addattr_l(&req.n, sizeof(req), MDBA_SET_ENTRY, &entry, sizeof(entry));
+	if (src) {
+		struct rtattr *nest = addattr_nest(&req.n, sizeof(req),
+						   MDBA_SET_ENTRY_ATTRS);
+		struct in6_addr src_ip6;
+		__be32 src_ip4;
+
+		nest->rta_type |= NLA_F_NESTED;
+		if (!inet_pton(AF_INET, src, &src_ip4)) {
+			if (!inet_pton(AF_INET6, src, &src_ip6)) {
+				fprintf(stderr, "Invalid source address \"%s\"\n", src);
+				return -1;
+			}
+			addattr_l(&req.n, sizeof(req), MDBE_ATTR_SOURCE, &src_ip6, sizeof(src_ip6));
+		} else {
+			addattr32(&req.n, sizeof(req), MDBE_ATTR_SOURCE, src_ip4);
+		}
+		addattr_nest_end(&req.n, nest);
+	}
 
 	if (rtnl_talk(&rth, &req.n, NULL) < 0)
 		return -1;

man/man8/bridge.8

@@ -116,6 +116,8 @@ bridge \- show / manipulate bridge addresses and devices
 .I PORT
 .B grp
 .IR GROUP " [ "
+.B src
+.IR SOURCE " ] [ "
 .BR permanent " | " temp " ] [ "
 .B vid
 .IR VID " ] "
@@ -694,6 +696,12 @@ the port.
 - the mdb entry is temporary (default)
 .sp
 
+.TP
+.BI src " SOURCE"
+optional source IP address of a sender for this multicast group. If IGMPv3 for IPv4, or
+MLDv2 for IPv6 respectively, are enabled it will be included in the lookup when
+forwarding multicast traffic.
+
 .TP
 .BI vid " VID"
 the VLAN ID which is known to have members of this multicast group.