Skip unavailable interfaces during socket bind (#1028)

bdraco · web-flow · commit aa59998182ce · 2021-11-13T09:08:43.000-06:00
- We already skip these when adding multicast members.
  Apply the same logic to the socket bind call
diff --git a/tests/utils/test_net.py b/tests/utils/test_net.py
@@ -3,7 +3,7 @@
 
 
 """Unit tests for zeroconf._utils.net."""
-from unittest.mock import Mock, patch
+from unittest.mock import MagicMock, Mock, patch
 
 import errno
 import ifaddr
@@ -198,3 +198,26 @@ def test_add_multicast_member():
     # No error should return True
     with patch("socket.socket.setsockopt"):
         assert netutils.add_multicast_member(sock, interface) is True
+
+
+def test_bind_raises_skips_address():
+    """Test bind failing in new_socket returns None on EADDRNOTAVAIL."""
+    err = errno.EADDRNOTAVAIL
+
+    def _mock_socket(*args, **kwargs):
+        sock = MagicMock()
+        sock.bind = MagicMock(side_effect=OSError(err, "Error: {}".format(err)))
+        return sock
+
+    with patch("socket.socket", _mock_socket):
+        assert netutils.new_socket(("0.0.0.0", 0)) is None
+
+    err = errno.EAGAIN
+    with pytest.raises(OSError), patch("socket.socket", _mock_socket):
+        netutils.new_socket(("0.0.0.0", 0))
+
+
+def test_new_respond_socket_new_socket_returns_none():
+    """Test new_respond_socket returns None if new_socket returns None."""
+    with patch.object(netutils, "new_socket", return_value=None):
+        assert netutils.new_respond_socket(("0.0.0.0", 0)) is None
diff --git a/zeroconf/_utils/net.py b/zeroconf/_utils/net.py
@@ -218,7 +218,7 @@ def new_socket(
     port: int = _MDNS_PORT,
     ip_version: IPVersion = IPVersion.V4Only,
     apple_p2p: bool = False,
-) -> socket.socket:
+) -> Optional[socket.socket]:
     log.debug(
         'Creating new socket with port %s, ip_version %s, apple_p2p %s and bind_addr %r',
         port,
@@ -243,7 +243,17 @@ def new_socket(
         # https://opensource.apple.com/source/xnu/xnu-4570.41.2/bsd/sys/socket.h
         s.setsockopt(socket.SOL_SOCKET, 0x1104, 1)
 
-    s.bind((bind_addr[0], port, *bind_addr[1:]))
+    bind_tup = (bind_addr[0], port, *bind_addr[1:])
+    try:
+        s.bind(bind_tup)
+    except OSError as ex:
+        if ex.errno == errno.EADDRNOTAVAIL:
+            log.warning(
+                'Address not available when binding to %s, ' 'it is expected to happen on some systems',
+                bind_tup,
+            )
+            return None
+        raise
     log.debug('Created socket %s', s)
     return s
 
@@ -323,6 +333,8 @@ def new_respond_socket(
         apple_p2p=apple_p2p,
         bind_addr=cast(Tuple[Tuple[str, int, int], int], interface)[0] if is_v6 else (cast(str, interface),),
     )
+    if not respond_socket:
+        return None
     log.debug('Configuring socket %s with multicast interface %s', respond_socket, interface)
     if is_v6:
         iface_bin = struct.pack('@I', cast(int, interface[1]))
