tests: net: socket: tcp: Add another test case for asynchronous connect

Verify that if the application triggers asynchronous connect with
non-blocking sockets, and starts to monitor the socket with poll()
immediately but with POLLIN only set, the poll() is still able to
report an error if the connection fails. As no POLLOUT is monitored, the
application won't know when the connection is done in case of success,
but it should still be notified in case of errors.

To achieve this, modify the existing test case to allow to specify what
events should be monitored by poll(). Additionally monitor the time
spent in poll() - an error should cause poll() to exit immediately,
not after the specified timeout.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

tests/net/socket/tcp/src/main.c

@@ -2288,14 +2288,16 @@ ZTEST(net_socket_tcp, test_connect_and_wait_for_v4_select)
  * make sure poll() returns proper error for the closed
  * connection.
  */
-ZTEST(net_socket_tcp, test_connect_and_wait_for_v4_poll)
+void test_connect_and_wait_for_v4_poll_common(uint16_t events)
 {
 	struct sockaddr_in addr = { 0 };
 	struct zsock_pollfd fds[1];
 	struct in_addr v4addr;
 	int fd, flags, ret, optval;
 	bool closed = false;
 	socklen_t optlen = sizeof(optval);
+	int64_t start_time, time_diff;
+	int timeout_ms = 1000;
 
 	fd = zsock_socket(AF_INET, SOCK_STREAM, 0);
 
@@ -2318,14 +2320,24 @@ ZTEST(net_socket_tcp, test_connect_and_wait_for_v4_poll)
 	while (1) {
 		memset(fds, 0, sizeof(fds));
 		fds[0].fd = fd;
-		fds[0].events = ZSOCK_POLLOUT;
+		fds[0].events = events;
 
-		/* Check if the connection is there, this should timeout */
-		ret = zsock_poll(fds, 1, 10);
+		/* Peer should reject the connection with RST as port is closed.
+		 * Connection error should be notified as soon as it happens,
+		 * not after a timeout. Otherwise, blocking poll() would never
+		 * recover.
+		 */
+		start_time = k_uptime_get();
+
+		ret = zsock_poll(fds, 1, timeout_ms);
 		if (ret < 0) {
 			break;
 		}
 
+		time_diff = k_uptime_get() - start_time;
+
+		zassert(time_diff < timeout_ms, "poll() should quit before a timeout");
+
 		if (fds[0].revents > 0) {
 			if (fds[0].revents & ZSOCK_POLLERR) {
 				closed = true;
@@ -2349,6 +2361,16 @@ ZTEST(net_socket_tcp, test_connect_and_wait_for_v4_poll)
 	zassert_equal(ret, 0, "close failed, %d", errno);
 }
 
+ZTEST(net_socket_tcp, test_connect_and_wait_for_v4_poll_pollout)
+{
+	test_connect_and_wait_for_v4_poll_common(ZSOCK_POLLOUT);
+}
+
+ZTEST(net_socket_tcp, test_connect_and_wait_for_v4_poll_pollin)
+{
+	test_connect_and_wait_for_v4_poll_common(ZSOCK_POLLIN);
+}
+
 ZTEST(net_socket_tcp, test_so_keepalive_opt)
 {
 	struct sockaddr_in bind_addr4;