bridge: fdb get support

This patch adds support to lookup a bridge fdb entry
using recently added support in the kernel using RTM_GETNEIGH
(and AF_BRIDGE family).

example:
$bridge fdb get 02:02:00:00:00:03 dev test-dummy0 vlan 1002
02:02:00:00:00:03 dev test-dummy0 vlan 1002 master bridge

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Tested-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David Ahern <dsahern@gmail.com>

bridge/fdb.c

@@ -40,7 +40,9 @@ static void usage(void)
 		"              [ sticky ] [ local | static | dynamic ] [ dst IPADDR ]\n"
 		"              [ vlan VID ] [ port PORT] [ vni VNI ] [ via DEV ]\n"
 		"              [ src_vni VNI ]\n"
-		"       bridge fdb [ show [ br BRDEV ] [ brport DEV ] [ vlan VID ] [ state STATE ] ]\n");
+		"       bridge fdb [ show [ br BRDEV ] [ brport DEV ] [ vlan VID ] [ state STATE ] ]\n"
+		"       bridge fdb get ADDR [ br BRDEV ] { brport |dev }  DEV [ vlan VID ]\n"
+		"              [ vni VNI ]\n");
 	exit(-1);
 }
 
@@ -518,6 +520,113 @@ static int fdb_modify(int cmd, int flags, int argc, char **argv)
 	return 0;
 }
 
+static int fdb_get(int argc, char **argv)
+{
+	struct {
+		struct nlmsghdr	n;
+		struct ndmsg		ndm;
+		char			buf[1024];
+	} req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ndmsg)),
+		.n.nlmsg_flags = NLM_F_REQUEST,
+		.n.nlmsg_type = RTM_GETNEIGH,
+		.ndm.ndm_family = AF_BRIDGE,
+	};
+	char  *d = NULL, *br = NULL;
+	struct nlmsghdr *answer;
+	unsigned long vni = ~0;
+	char abuf[ETH_ALEN];
+	int br_ifindex = 0;
+	char *addr = NULL;
+	short vlan = -1;
+	char *endptr;
+
+	while (argc > 0) {
+		if ((strcmp(*argv, "brport") == 0) || strcmp(*argv, "dev") == 0) {
+			NEXT_ARG();
+			d = *argv;
+		} else if (strcmp(*argv, "br") == 0) {
+			NEXT_ARG();
+			br = *argv;
+		} else if (strcmp(*argv, "dev") == 0) {
+			NEXT_ARG();
+			d = *argv;
+		} else if (strcmp(*argv, "vni") == 0) {
+			NEXT_ARG();
+			vni = strtoul(*argv, &endptr, 0);
+			if ((endptr && *endptr) ||
+			    (vni >> 24) || vni == ULONG_MAX)
+				invarg("invalid VNI\n", *argv);
+		} else if (strcmp(*argv, "self") == 0) {
+			req.ndm.ndm_flags |= NTF_SELF;
+		} else if (matches(*argv, "master") == 0) {
+			req.ndm.ndm_flags |= NTF_MASTER;
+		} else if (matches(*argv, "vlan") == 0) {
+			if (vlan >= 0)
+				duparg2("vlan", *argv);
+			NEXT_ARG();
+			vlan = atoi(*argv);
+		} else {
+			if (strcmp(*argv, "to") == 0)
+				NEXT_ARG();
+
+			if (matches(*argv, "help") == 0)
+				usage();
+			if (addr)
+				duparg2("to", *argv);
+			addr = *argv;
+		}
+		argc--; argv++;
+	}
+
+	if ((d == NULL && br == NULL) || addr == NULL) {
+		fprintf(stderr, "Device or master and address are required arguments.\n");
+		return -1;
+	}
+
+	if (sscanf(addr, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
+		   abuf, abuf+1, abuf+2,
+		   abuf+3, abuf+4, abuf+5) != 6) {
+		fprintf(stderr, "Invalid mac address %s\n", addr);
+		return -1;
+	}
+
+	addattr_l(&req.n, sizeof(req), NDA_LLADDR, abuf, ETH_ALEN);
+
+	if (vlan >= 0)
+		addattr16(&req.n, sizeof(req), NDA_VLAN, vlan);
+
+	if (vni != ~0)
+		addattr32(&req.n, sizeof(req), NDA_VNI, vni);
+
+	if (d) {
+		req.ndm.ndm_ifindex = ll_name_to_index(d);
+		if (!req.ndm.ndm_ifindex) {
+			fprintf(stderr, "Cannot find device \"%s\"\n", d);
+			return -1;
+		}
+	}
+
+	if (br) {
+		br_ifindex = ll_name_to_index(br);
+		if (!br_ifindex) {
+			fprintf(stderr, "Cannot find bridge device \"%s\"\n", br);
+			return -1;
+		}
+		addattr32(&req.n, sizeof(req), NDA_MASTER, br_ifindex);
+	}
+
+	if (rtnl_talk(&rth, &req.n, &answer) < 0)
+		return -2;
+
+	if (print_fdb(answer, stdout) < 0) {
+		fprintf(stderr, "An error :-)\n");
+		return -1;
+	}
+
+	return 0;
+}
+
 int do_fdb(int argc, char **argv)
 {
 	ll_init_map(&rth);
@@ -531,6 +640,8 @@ int do_fdb(int argc, char **argv)
 			return fdb_modify(RTM_NEWNEIGH, NLM_F_CREATE|NLM_F_REPLACE, argc-1, argv+1);
 		if (matches(*argv, "delete") == 0)
 			return fdb_modify(RTM_DELNEIGH, 0, argc-1, argv+1);
+		if (matches(*argv, "get") == 0)
+			return fdb_get(argc-1, argv+1);
 		if (matches(*argv, "show") == 0 ||
 		    matches(*argv, "lst") == 0 ||
 		    matches(*argv, "list") == 0)

man/man8/bridge.8

@@ -92,6 +92,17 @@ bridge \- show / manipulate bridge addresses and devices
 .B state
 .IR STATE " ]"
 
+.ti -8
+.B bridge fdb get
+.I LLADDR " [ "
+.B dev
+.IR DEV " ] [ "
+.B br
+.IR BRDEV " ] [ "
+.B vlan
+.IR VID  " ] ["
+.BR self " ] [ " master " ]"
+
 .ti -8
 .BR "bridge mdb" " { " add " | " del " } "
 .B dev
@@ -550,6 +561,35 @@ With the
 option, the command becomes verbose. It prints out the last updated
 and last used time for each entry.
 
+.SS bridge fdb get - get bridge forwarding entry.
+
+lookup a bridge forwarding table entry.
+
+.TP
+.BI "LLADDR"
+the Ethernet MAC address.
+
+.TP
+.BI dev " DEV"
+the interface to which this address is associated.
+
+.TP
+.BI brport " DEV"
+the bridge port to which this address is associated. same as dev above.
+
+.TP
+.BI br " DEV"
+the bridge to which this address is associated.
+
+.TP
+.B self
+- the address is associated with the port drivers fdb. Usually hardware.
+
+.TP
+.B master
+- the address is associated with master devices fdb. Usually software (default).
+.sp
+
 .SH bridge mdb - multicast group database management
 
 .B mdb