Prohibit DNS lookups in UDP.sendto()

See issue #91.

Author: 1st1

tests/test_udp.py

@@ -167,6 +167,23 @@ def test_create_datagram_endpoint_wrong_sock(self):
                                         'A UDP Socket was expected'):
                 self.loop.run_until_complete(coro)
 
+    def test_udp_sendto_dns(self):
+        coro = self.loop.create_datagram_endpoint(
+            asyncio.DatagramProtocol,
+            local_addr=('127.0.0.1', 0),
+            family=socket.AF_INET)
+
+        s_transport, server = self.loop.run_until_complete(coro)
+
+        with self.assertRaisesRegex(ValueError, 'DNS lookup'):
+            s_transport.sendto(b'aaaa', ('example.com', 80))
+
+        with self.assertRaisesRegex(ValueError, 'socket family mismatch'):
+            s_transport.sendto(b'aaaa', ('::1', 80))
+
+        s_transport.close()
+        self.loop.run_until_complete(asyncio.sleep(0.01, loop=self.loop))
+
 
 class Test_AIO_UDP(_TestUDP, tb.AIOTestCase):
     pass

uvloop/handles/udp.pyx

@@ -139,6 +139,19 @@ cdef class UDPTransport(UVBaseTransport):
             raise ValueError(
                 'Invalid address: must be None or {}'.format(self.address))
 
+        if addr is not None:
+            addrinfo = __static_getaddrinfo_pyaddr(
+                addr[0], addr[1],
+                uv.AF_UNSPEC, self.sock.type, self.sock.proto, 0)
+            if addrinfo is None:
+                raise ValueError(
+                    'UDP.sendto(): address {!r} requires a DNS lookup'.format(
+                        addr))
+            if addrinfo[0] != self.sock.family:
+                raise ValueError(
+                    'UDP.sendto(): {!r} socket family mismatch'.format(
+                        addr))
+
         if self._conn_lost and self._address:
             if self._conn_lost >= LOG_THRESHOLD_FOR_CONNLOST_WRITES:
                 aio_logger.warning('socket.send() raised exception.')