selftests: mptcp: add the id argument for set_flags

This patch added the id argument for setting the address flags in
pm_nl_ctl.

Usage:

    pm_nl_ctl set id 1 flags backup
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/mptcp/pm_nl_ctl.c

@@ -28,7 +28,7 @@ static void syntax(char *argv[])
 	fprintf(stderr, "\tadd [flags signal|subflow|backup|fullmesh] [id <nr>] [dev <name>] <ip>\n");
 	fprintf(stderr, "\tdel <id> [<ip>]\n");
 	fprintf(stderr, "\tget <id>\n");
-	fprintf(stderr, "\tset <ip> [flags backup|nobackup|fullmesh|nofullmesh] [port <nr>]\n");
+	fprintf(stderr, "\tset [<ip>] [id <nr>] flags [no]backup|[no]fullmesh [port <nr>]\n");
 	fprintf(stderr, "\tflush\n");
 	fprintf(stderr, "\tdump\n");
 	fprintf(stderr, "\tlimits [<rcv addr max> <subflow max>]\n");
@@ -657,8 +657,10 @@ int set_flags(int fd, int pm_family, int argc, char *argv[])
 	u_int32_t flags = 0;
 	u_int16_t family;
 	int nest_start;
+	int use_id = 0;
+	u_int8_t id;
 	int off = 0;
-	int arg;
+	int arg = 2;
 
 	memset(data, 0, sizeof(data));
 	nh = (void *)data;
@@ -674,18 +676,30 @@ int set_flags(int fd, int pm_family, int argc, char *argv[])
 	nest->rta_len = RTA_LENGTH(0);
 	off += NLMSG_ALIGN(nest->rta_len);
 
+	if (!strcmp(argv[arg], "id")) {
+		if (++arg >= argc)
+			error(1, 0, " missing id value");
+
+		use_id = 1;
+		id = atoi(argv[arg]);
+		rta = (void *)(data + off);
+		rta->rta_type = MPTCP_PM_ADDR_ATTR_ID;
+		rta->rta_len = RTA_LENGTH(1);
+		memcpy(RTA_DATA(rta), &id, 1);
+		off += NLMSG_ALIGN(rta->rta_len);
+	} else {
 		/* addr data */
 		rta = (void *)(data + off);
-	if (inet_pton(AF_INET, argv[2], RTA_DATA(rta))) {
+		if (inet_pton(AF_INET, argv[arg], RTA_DATA(rta))) {
 			family = AF_INET;
 			rta->rta_type = MPTCP_PM_ADDR_ATTR_ADDR4;
 			rta->rta_len = RTA_LENGTH(4);
-	} else if (inet_pton(AF_INET6, argv[2], RTA_DATA(rta))) {
+		} else if (inet_pton(AF_INET6, argv[arg], RTA_DATA(rta))) {
 			family = AF_INET6;
 			rta->rta_type = MPTCP_PM_ADDR_ATTR_ADDR6;
 			rta->rta_len = RTA_LENGTH(16);
 		} else {
-		error(1, errno, "can't parse ip %s", argv[2]);
+			error(1, errno, "can't parse ip %s", argv[arg]);
 		}
 		off += NLMSG_ALIGN(rta->rta_len);
 
@@ -695,8 +709,12 @@ int set_flags(int fd, int pm_family, int argc, char *argv[])
 		rta->rta_len = RTA_LENGTH(2);
 		memcpy(RTA_DATA(rta), &family, 2);
 		off += NLMSG_ALIGN(rta->rta_len);
+	}
 
-	for (arg = 3; arg < argc; arg++) {
+	if (++arg >= argc)
+		error(1, 0, " missing flags keyword");
+
+	for (; arg < argc; arg++) {
 		if (!strcmp(argv[arg], "flags")) {
 			char *tok, *str;
 
@@ -724,6 +742,9 @@ int set_flags(int fd, int pm_family, int argc, char *argv[])
 		} else if (!strcmp(argv[arg], "port")) {
 			u_int16_t port;
 
+			if (use_id)
+				error(1, 0, " port can't be used with id");
+
 			if (++arg >= argc)
 				error(1, 0, " missing port value");