selftests: mptcp: create listeners to receive MPJs

This change updates the "pm_nl_ctl" testing sample with a
"listen" option to bind a MPTCP listening socket to the
provided addr+port. This option is exercised in testing
subflow initiation scenarios in conjunction with userspace
path managers where the MPTCP application does not hold an
active listener to accept requests for new subflows.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Kishen Maloor <kishen.maloor@intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -25,6 +25,9 @@
 #ifndef MPTCP_PM_EVENTS
 #define MPTCP_PM_EVENTS		"mptcp_pm_events"
 #endif
+#ifndef IPPROTO_MPTCP
+#define IPPROTO_MPTCP 262
+#endif
 
 static void syntax(char *argv[])
 {
@@ -41,6 +44,7 @@ static void syntax(char *argv[])
 	fprintf(stderr, "\tdump\n");
 	fprintf(stderr, "\tlimits [<rcv addr max> <subflow max>]\n");
 	fprintf(stderr, "\tevents\n");
+	fprintf(stderr, "\tlisten <local-ip> <local-port>\n");
 	exit(0);
 }
 
@@ -1219,6 +1223,54 @@ int get_set_limits(int fd, int pm_family, int argc, char *argv[])
 	return 0;
 }
 
+int add_listener(int argc, char *argv[])
+{
+	struct sockaddr_storage addr;
+	struct sockaddr_in6 *a6;
+	struct sockaddr_in *a4;
+	u_int16_t family;
+	int enable = 1;
+	int sock;
+	int err;
+
+	if (argc < 4)
+		syntax(argv);
+
+	memset(&addr, 0, sizeof(struct sockaddr_storage));
+	a4 = (struct sockaddr_in *)&addr;
+	a6 = (struct sockaddr_in6 *)&addr;
+
+	if (inet_pton(AF_INET, argv[2], &a4->sin_addr)) {
+		family = AF_INET;
+		a4->sin_family = family;
+		a4->sin_port = htons(atoi(argv[3]));
+	} else if (inet_pton(AF_INET6, argv[2], &a6->sin6_addr)) {
+		family = AF_INET6;
+		a6->sin6_family = family;
+		a6->sin6_port = htons(atoi(argv[3]));
+	} else
+		error(1, errno, "can't parse ip %s", argv[2]);
+
+	sock = socket(family, SOCK_STREAM, IPPROTO_MPTCP);
+	if (sock < 0)
+		error(1, errno, "can't create listener sock\n");
+
+	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(enable))) {
+		close(sock);
+		error(1, errno, "can't set SO_REUSEADDR on listener sock\n");
+	}
+
+	err = bind(sock, (struct sockaddr *)&addr,
+		   ((family == AF_INET) ? sizeof(struct sockaddr_in) :
+		    sizeof(struct sockaddr_in6)));
+
+	if (err == 0 && listen(sock, 30) == 0)
+		pause();
+
+	close(sock);
+	return 0;
+}
+
 int set_flags(int fd, int pm_family, int argc, char *argv[])
 {
 	char data[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
@@ -1375,6 +1427,8 @@ int main(int argc, char *argv[])
 		return set_flags(fd, pm_family, argc, argv);
 	else if (!strcmp(argv[1], "events"))
 		return capture_events(fd, events_mcast_grp);
+	else if (!strcmp(argv[1], "listen"))
+		return add_listener(argc, argv);
 
 	fprintf(stderr, "unknown sub-command: %s", argv[1]);
 	syntax(argv);