selftests: mptcp: add token for dump_addr

The command dump_addr() of pm_nl_ctl can be used like this in in-kernel PM:

        pm_nl_ctl dump

This patch adds token argument for it to support userspace PM:

        pm_nl_ctl dump token $token

If 'token $token' is passed to dump_addr(), copy it into the kernel
netlink.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -1127,8 +1127,16 @@ int dump_addrs(int fd, int pm_family, int argc, char *argv[])
 		  1024];
 	pid_t pid = getpid();
 	struct nlmsghdr *nh;
+	u_int32_t token = 0;
+	struct rtattr *rta;
 	int off = 0;
 
+	if (argc != 2 && argc != 4)
+		syntax(argv);
+
+	if (argc == 4 && !strcmp(argv[2], "token"))
+		token = strtoul(argv[3], NULL, 10);
+
 	memset(data, 0, sizeof(data));
 	nh = (void *)data;
 	off = init_genl_req(data, pm_family, MPTCP_PM_CMD_GET_ADDR,
@@ -1138,6 +1146,15 @@ int dump_addrs(int fd, int pm_family, int argc, char *argv[])
 	nh->nlmsg_pid = pid;
 	nh->nlmsg_len = off;
 
+	/* token */
+	if (token) {
+		rta = (void *)(data + off);
+		rta->rta_type = MPTCP_PM_ATTR_TOKEN;
+		rta->rta_len = RTA_LENGTH(4);
+		memcpy(RTA_DATA(rta), &token, 4);
+		off += NLMSG_ALIGN(rta->rta_len);
+	}
+
 	print_addrs(nh, pm_family, do_nl_req(fd, nh, off, sizeof(data)));
 	return 0;
 }