bpo-27456: Simplify sock type checks (#4922)

Recent sock.type fix (see bug 32331) makes sock.type checks simpler
in asyncio.

Lib/asyncio/base_events.py

@@ -82,26 +82,6 @@ def _set_reuseport(sock):
                              'SO_REUSEPORT defined but not implemented.')
 
 
-def _is_stream_socket(sock_type):
-    if hasattr(socket, 'SOCK_NONBLOCK'):
-        # Linux's socket.type is a bitmask that can include extra info
-        # about socket (like SOCK_NONBLOCK bit), therefore we can't do simple
-        # `sock_type == socket.SOCK_STREAM`, see
-        # https://github.com/torvalds/linux/blob/v4.13/include/linux/net.h#L77
-        # for more details.
-        return (sock_type & 0xF) == socket.SOCK_STREAM
-    else:
-        return sock_type == socket.SOCK_STREAM
-
-
-def _is_dgram_socket(sock_type):
-    if hasattr(socket, 'SOCK_NONBLOCK'):
-        # See the comment in `_is_stream_socket`.
-        return (sock_type & 0xF) == socket.SOCK_DGRAM
-    else:
-        return sock_type == socket.SOCK_DGRAM
-
-
 def _ipaddr_info(host, port, family, type, proto):
     # Try to skip getaddrinfo if "host" is already an IP. Users might have
     # handled name resolution in their own code and pass in resolved IPs.
@@ -112,9 +92,9 @@ def _ipaddr_info(host, port, family, type, proto):
             host is None:
         return None
 
-    if _is_stream_socket(type):
+    if type == socket.SOCK_STREAM:
         proto = socket.IPPROTO_TCP
-    elif _is_dgram_socket(type):
+    elif type == socket.SOCK_DGRAM:
         proto = socket.IPPROTO_UDP
     else:
         return None
@@ -759,7 +739,7 @@ class BaseEventLoop(events.AbstractEventLoop):
             if sock is None:
                 raise ValueError(
                     'host and port was not specified and no sock specified')
-            if not _is_stream_socket(sock.type):
+            if sock.type != socket.SOCK_STREAM:
                 # We allow AF_INET, AF_INET6, AF_UNIX as long as they
                 # are SOCK_STREAM.
                 # We support passing AF_UNIX sockets even though we have
@@ -809,7 +789,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                                        allow_broadcast=None, sock=None):
         """Create datagram connection."""
         if sock is not None:
-            if not _is_dgram_socket(sock.type):
+            if sock.type != socket.SOCK_DGRAM:
                 raise ValueError(
                     f'A UDP Socket was expected, got {sock!r}')
             if (local_addr or remote_addr or
@@ -1037,7 +1017,7 @@ class BaseEventLoop(events.AbstractEventLoop):
         else:
             if sock is None:
                 raise ValueError('Neither host/port nor sock were specified')
-            if not _is_stream_socket(sock.type):
+            if sock.type != socket.SOCK_STREAM:
                 raise ValueError(f'A Stream Socket was expected, got {sock!r}')
             sockets = [sock]
 
@@ -1060,7 +1040,7 @@ class BaseEventLoop(events.AbstractEventLoop):
         This method is a coroutine.  When completed, the coroutine
         returns a (transport, protocol) pair.
         """
-        if not _is_stream_socket(sock.type):
+        if sock.type != socket.SOCK_STREAM:
             raise ValueError(f'A Stream Socket was expected, got {sock!r}')
 
         transport, protocol = await self._create_connection_transport(

Lib/asyncio/selector_events.py

@@ -41,7 +41,7 @@ def _test_selector_event(selector, fd, event):
 if hasattr(socket, 'TCP_NODELAY'):
     def _set_nodelay(sock):
         if (sock.family in {socket.AF_INET, socket.AF_INET6} and
-                base_events._is_stream_socket(sock.type) and
+                sock.type == socket.SOCK_STREAM and
                 sock.proto == socket.IPPROTO_TCP):
             sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
 else:

Lib/asyncio/unix_events.py

@@ -222,7 +222,7 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
             if sock is None:
                 raise ValueError('no path and sock were specified')
             if (sock.family != socket.AF_UNIX or
-                    not base_events._is_stream_socket(sock.type)):
+                    sock.type != socket.SOCK_STREAM):
                 raise ValueError(
                     f'A UNIX Domain Stream Socket was expected, got {sock!r}')
             sock.setblocking(False)
@@ -276,7 +276,7 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
                     'path was not specified, and no sock specified')
 
             if (sock.family != socket.AF_UNIX or
-                    not base_events._is_stream_socket(sock.type)):
+                    sock.type != socket.SOCK_STREAM):
                 raise ValueError(
                     f'A UNIX Domain Stream Socket was expected, got {sock!r}')