extmod/modlwip: Make socket.connect raise ETIMEDOUT on non-zero timeout.

If the socket timeout is 0 then a failed socket.connect() raises
EINPROGRESS (which is what the lwIP bindings already did), but if the
socket timeout is non-zero then a failed socket.connect() should raise
ETIMEDOUT.  The latter is fixed in this commit.

A test is added for these timeout cases.

Signed-off-by: Damien George <damien@micropython.org>

extmod/modlwip.c

@@ -326,6 +326,10 @@ typedef struct _lwip_socket_obj_t {
     int8_t state;
 } lwip_socket_obj_t;
 
+static inline bool socket_is_timedout(lwip_socket_obj_t *socket, mp_uint_t ticks_start) {
+    return socket->timeout != -1 && (mp_uint_t)(mp_hal_ticks_ms() - ticks_start) >= socket->timeout;
+}
+
 static inline void poll_sockets(void) {
     mp_event_wait_ms(1);
 }
@@ -1130,21 +1134,21 @@ static mp_obj_t lwip_socket_connect(mp_obj_t self_in, mp_obj_t addr_in) {
             MICROPY_PY_LWIP_EXIT
 
             // And now we wait...
-            if (socket->timeout != -1) {
-                for (mp_uint_t retries = socket->timeout / 100; retries--;) {
-                    mp_hal_delay_ms(100);
-                    if (socket->state != STATE_CONNECTING) {
-                        break;
+            mp_uint_t ticks_start = mp_hal_ticks_ms();
+            for (;;) {
+                poll_sockets();
+                if (socket->state != STATE_CONNECTING) {
+                    break;
+                }
+                if (socket_is_timedout(socket, ticks_start)) {
+                    if (socket->timeout == 0) {
+                        mp_raise_OSError(MP_EINPROGRESS);
+                    } else {
+                        mp_raise_OSError(MP_ETIMEDOUT);
                     }
                 }
-                if (socket->state == STATE_CONNECTING) {
-                    mp_raise_OSError(MP_EINPROGRESS);
-                }
-            } else {
-                while (socket->state == STATE_CONNECTING) {
-                    poll_sockets();
-                }
             }
+
             if (socket->state == STATE_CONNECTED) {
                 err = ERR_OK;
             } else {

tests/net_hosted/connect_timeout.py

@@ -0,0 +1,24 @@
+# Test that socket.connect() on a socket with timeout raises EINPROGRESS or ETIMEDOUT appropriately.
+
+import errno
+import socket
+
+
+def test(peer_addr, timeout, expected_exc):
+    s = socket.socket()
+    s.settimeout(timeout)
+    try:
+        s.connect(peer_addr)
+        print("OK")
+    except OSError as er:
+        print(er.args[0] in expected_exc)
+    s.close()
+
+
+if __name__ == "__main__":
+    # This test needs an address that doesn't respond to TCP connections.
+    # 1.1.1.1:8000 seem to reliably timeout, so use that.
+    addr = socket.getaddrinfo("1.1.1.1", 8000)[0][-1]
+
+    test(addr, 0, (errno.EINPROGRESS,))
+    test(addr, 1, (errno.ETIMEDOUT, "timed out"))  # CPython uses a string instead of errno