add an overridable socket_factory to dns.quic._sync for #1059

dns/quic/_sync.py

@@ -21,6 +21,9 @@
  UnexpectedEOF,
 )
 
+# Function used to create a socket. Can be overridden if needed in special
+# situations.
+socket_factory = socket.socket
 
 class SyncQuicStream(BaseQuicStream):
  def __init__(self, connection, stream_id):
@@ -75,7 +78,7 @@ def __exit__(self, exc_type, exc_val, exc_tb):
 class SyncQuicConnection(BaseQuicConnection):
  def __init__(self, connection, address, port, source, source_port, manager):
  super().__init__(connection, address, port, source, source_port, manager)
- self._socket = socket.socket(self._af, socket.SOCK_DGRAM, 0)
+ self._socket = socket_factory(self._af, socket.SOCK_DGRAM, 0)
  if self._source is not None:
  try:
  self._socket.bind(