From 402059e4a46a764632eba8a669f5b012f173ee7b Mon Sep 17 00:00:00 2001
From: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue, 1 May 2018 17:05:05 +0200
Subject: [PATCH] Fix behavior of recv() in the CLOSING state.

The behavior wasn't tested correctly: in some test cases, the connection
had already moved to the CLOSED state, where the close code and reason
are already known.

Refactor half_close_connection_{local,remote} to allow multiple runs of
the event loop while remaining in the CLOSING state. Refactor affected
tests accordingly.

I verified that all tests in the CLOSING state were behaving is intended
by inserting debug statements in recv/send/ping/pong and running:

$ PYTHONASYNCIODEBUG=1 python -m unittest -v websockets.test_protocol.{Client,Server}Tests.test_{recv,send,ping,pong}_on_closing_connection_{local,remote}

Fix #317, #327, #350, #357.

Signed-off-by: Joseph Kogut <joseph.kogut@gmail.com>
---
 websockets/protocol.py      | 10 ++---
 websockets/test_protocol.py | 78 +++++++++++++++++++++++++++++--------
 2 files changed, 66 insertions(+), 22 deletions(-)

diff --git a/websockets/protocol.py b/websockets/protocol.py
index f8121a1..7583fe9 100644
--- a/websockets/protocol.py
+++ b/websockets/protocol.py
@@ -303,7 +303,7 @@ class WebSocketCommonProtocol(asyncio.StreamReaderProtocol):
         # Don't yield from self.ensure_open() here because messages could be
         # received before the closing frame even if the connection is closing.
 
-        # Wait for a message until the connection is closed
+        # Wait for a message until the connection is closed.
         next_message = asyncio_ensure_future(
             self.messages.get(), loop=self.loop)
         try:
@@ -315,15 +315,15 @@ class WebSocketCommonProtocol(asyncio.StreamReaderProtocol):
             next_message.cancel()
             raise
 
-        # Now there's no need to yield from self.ensure_open(). Either a
-        # message was received or the connection was closed.
-
         if next_message in done:
             return next_message.result()
         else:
             next_message.cancel()
             if not self.legacy_recv:
-                raise ConnectionClosed(self.close_code, self.close_reason)
+                assert self.state in [State.CLOSING, State.CLOSED]
+                # Wait until the connection is closed to raise
+                # ConnectionClosed with the correct code and reason.
+                yield from self.ensure_open()
 
     @asyncio.coroutine
     def send(self, data):
diff --git a/websockets/test_protocol.py b/websockets/test_protocol.py
index 70348fb..bfd4e3b 100644
--- a/websockets/test_protocol.py
+++ b/websockets/test_protocol.py
@@ -105,7 +105,7 @@ class CommonTests:
         self.loop.call_soon(self.loop.stop)
         self.loop.run_forever()
 
-    def make_drain_slow(self, delay=3 * MS):
+    def make_drain_slow(self, delay=MS):
         # Process connection_made in order to initialize self.protocol.writer.
         self.run_loop_once()
 
@@ -174,6 +174,8 @@ class CommonTests:
         # Empty the outgoing data stream so we can make assertions later on.
         self.assertOneFrameSent(True, OP_CLOSE, close_frame_data)
 
+        assert self.protocol.state is State.CLOSED
+
     def half_close_connection_local(self, code=1000, reason='close'):
         """
         Start a closing handshake but do not complete it.
@@ -181,31 +183,56 @@ class CommonTests:
         The main difference with `close_connection` is that the connection is
         left in the CLOSING state until the event loop runs again.
 
+        The current implementation returns a task that must be awaited or
+        cancelled, else asyncio complains about destroying a pending task.
+
         """
         close_frame_data = serialize_close(code, reason)
-        # Trigger the closing handshake from the local side.
-        self.ensure_future(self.protocol.close(code, reason))
+        # Trigger the closing handshake from the local endpoint.
+        close_task = self.ensure_future(self.protocol.close(code, reason))
         self.run_loop_once()    # wait_for executes
         self.run_loop_once()    # write_frame executes
         # Empty the outgoing data stream so we can make assertions later on.
         self.assertOneFrameSent(True, OP_CLOSE, close_frame_data)
-        # Prepare the response to the closing handshake from the remote side.
-        self.loop.call_soon(
-            self.receive_frame, Frame(True, OP_CLOSE, close_frame_data))
-        self.loop.call_soon(self.receive_eof_if_client)
+
+        assert self.protocol.state is State.CLOSING
+
+        # Complete the closing sequence at 1ms intervals so the test can run
+        # at each point even it goes back to the event loop several times.
+        self.loop.call_later(
+            MS, self.receive_frame, Frame(True, OP_CLOSE, close_frame_data))
+        self.loop.call_later(2 * MS, self.receive_eof_if_client)
+
+        # This task must be awaited or cancelled by the caller.
+        return close_task
 
     def half_close_connection_remote(self, code=1000, reason='close'):
         """
-        Receive a closing handshake.
+        Receive a closing handshake but do not complete it.
 
         The main difference with `close_connection` is that the connection is
         left in the CLOSING state until the event loop runs again.
 
         """
+        # On the server side, websockets completes the closing handshake and
+        # closes the TCP connection immediately. Yield to the event loop after
+        # sending the close frame to run the test while the connection is in
+        # the CLOSING state.
+        if not self.protocol.is_client:
+            self.make_drain_slow()
+
         close_frame_data = serialize_close(code, reason)
-        # Trigger the closing handshake from the remote side.
+        # Trigger the closing handshake from the remote endpoint.
         self.receive_frame(Frame(True, OP_CLOSE, close_frame_data))
-        self.receive_eof_if_client()
+        self.run_loop_once()    # read_frame executes
+        # Empty the outgoing data stream so we can make assertions later on.
+        self.assertOneFrameSent(True, OP_CLOSE, close_frame_data)
+
+        assert self.protocol.state is State.CLOSING
+
+        # Complete the closing sequence at 1ms intervals so the test can run
+        # at each point even it goes back to the event loop several times.
+        self.loop.call_later(2 * MS, self.receive_eof_if_client)
 
     def process_invalid_frames(self):
         """
@@ -335,11 +362,13 @@ class CommonTests:
         self.assertEqual(data, b'tea')
 
     def test_recv_on_closing_connection_local(self):
-        self.half_close_connection_local()
+        close_task = self.half_close_connection_local()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.recv())
 
+        self.loop.run_until_complete(close_task)    # cleanup
+
     def test_recv_on_closing_connection_remote(self):
         self.half_close_connection_remote()
 
@@ -421,24 +450,29 @@ class CommonTests:
         self.assertNoFrameSent()
 
     def test_send_on_closing_connection_local(self):
-        self.half_close_connection_local()
+        close_task = self.half_close_connection_local()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.send('foobar'))
+
         self.assertNoFrameSent()
 
+        self.loop.run_until_complete(close_task)    # cleanup
+
     def test_send_on_closing_connection_remote(self):
         self.half_close_connection_remote()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.send('foobar'))
-        self.assertOneFrameSent(True, OP_CLOSE, serialize_close(1000, 'close'))
+
+        self.assertNoFrameSent()
 
     def test_send_on_closed_connection(self):
         self.close_connection()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.send('foobar'))
+
         self.assertNoFrameSent()
 
     # Test the ping coroutine.
@@ -466,24 +500,29 @@ class CommonTests:
         self.assertNoFrameSent()
 
     def test_ping_on_closing_connection_local(self):
-        self.half_close_connection_local()
+        close_task = self.half_close_connection_local()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.ping())
+
         self.assertNoFrameSent()
 
+        self.loop.run_until_complete(close_task)    # cleanup
+
     def test_ping_on_closing_connection_remote(self):
         self.half_close_connection_remote()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.ping())
-        self.assertOneFrameSent(True, OP_CLOSE, serialize_close(1000, 'close'))
+
+        self.assertNoFrameSent()
 
     def test_ping_on_closed_connection(self):
         self.close_connection()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.ping())
+
         self.assertNoFrameSent()
 
     # Test the pong coroutine.
@@ -506,24 +545,29 @@ class CommonTests:
         self.assertNoFrameSent()
 
     def test_pong_on_closing_connection_local(self):
-        self.half_close_connection_local()
+        close_task = self.half_close_connection_local()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.pong())
+
         self.assertNoFrameSent()
 
+        self.loop.run_until_complete(close_task)    # cleanup
+
     def test_pong_on_closing_connection_remote(self):
         self.half_close_connection_remote()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.pong())
-        self.assertOneFrameSent(True, OP_CLOSE, serialize_close(1000, 'close'))
+
+        self.assertNoFrameSent()
 
     def test_pong_on_closed_connection(self):
         self.close_connection()
 
         with self.assertRaises(ConnectionClosed):
             self.loop.run_until_complete(self.protocol.pong())
+
         self.assertNoFrameSent()
 
     # Test the protocol's logic for acknowledging pings with pongs.
-- 
2.17.0