#3566: Clean up handling of remote server disconnects.
This changeset does two things: introduces a new RemoteDisconnected exception (that subclasses ConnectionResetError and BadStatusLine) so that a remote server disconnection can be detected by client code (and provides a better error message for debugging purposes), and ensures that the client socket is closed if a ConnectionError happens, so that the automatic re-connection code can work if the application handles the error and continues on. Tests are added that confirm that a connection is re-used or not re-used as appropriate to the various combinations of protocol version and headers. Patch by Martin Panter, reviewed by Demian Brecht. (Tweaked only slightly by me.)
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R David Murray
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@ -175,6 +175,17 @@ The following exceptions are raised as appropriate:
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is received in the HTTP protocol from the server.
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.. exception:: RemoteDisconnected
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A subclass of :exc:`ConnectionResetError` and :exc:`BadStatusLine`. Raised
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by :meth:`HTTPConnection.getresponse` when the attempt to read the response
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results in no data read from the connection, indicating that the remote end
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has closed the connection.
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.. versionadded:: 3.5
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Previously, :exc:`BadStatusLine`\ ``('')`` was raised.
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The constants defined in this module are:
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.. data:: HTTP_PORT
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@ -247,6 +258,11 @@ HTTPConnection Objects
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Note that you must have read the whole response before you can send a new
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request to the server.
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.. versionchanged:: 3.5
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If a :exc:`ConnectionError` or subclass is raised, the
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:class:`HTTPConnection` object will be ready to reconnect when
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a new request is sent.
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.. method:: HTTPConnection.set_debuglevel(level)
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@ -285,7 +301,9 @@ HTTPConnection Objects
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.. method:: HTTPConnection.connect()
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Connect to the server specified when the object was created.
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Connect to the server specified when the object was created. By default,
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this is called automatically when making a request if the client does not
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already have a connection.
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.. method:: HTTPConnection.close()
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@ -20,10 +20,12 @@ request. This diagram details these state transitions:
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| ( putheader() )* endheaders()
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v
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Request-sent
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| response = getresponse()
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v
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Unread-response [Response-headers-read]
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|\_____________________________
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| | getresponse() raises
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| response = getresponse() | ConnectionError
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v v
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Unread-response Idle
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[Response-headers-read]
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|\____________________
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| |
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| response.read() | putrequest()
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@ -83,7 +85,8 @@ __all__ = ["HTTPResponse", "HTTPConnection",
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"UnknownTransferEncoding", "UnimplementedFileMode",
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"IncompleteRead", "InvalidURL", "ImproperConnectionState",
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"CannotSendRequest", "CannotSendHeader", "ResponseNotReady",
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"BadStatusLine", "LineTooLong", "error", "responses"]
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"BadStatusLine", "LineTooLong", "RemoteDisconnected", "error",
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"responses"]
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HTTP_PORT = 80
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HTTPS_PORT = 443
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@ -245,7 +248,8 @@ class HTTPResponse(io.BufferedIOBase):
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if not line:
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# Presumably, the server closed the connection before
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# sending a valid response.
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raise BadStatusLine(line)
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raise RemoteDisconnected("Remote end closed connection without"
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" response")
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try:
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version, status, reason = line.split(None, 2)
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except ValueError:
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@ -1160,7 +1164,11 @@ class HTTPConnection:
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response = self.response_class(self.sock, method=self._method)
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try:
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response.begin()
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try:
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response.begin()
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except ConnectionError:
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self.close()
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raise
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assert response.will_close != _UNKNOWN
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self.__state = _CS_IDLE
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@ -1292,5 +1300,10 @@ class LineTooLong(HTTPException):
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HTTPException.__init__(self, "got more than %d bytes when reading %s"
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% (_MAXLINE, line_type))
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class RemoteDisconnected(ConnectionResetError, BadStatusLine):
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def __init__(self, *pos, **kw):
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BadStatusLine.__init__(self, "")
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ConnectionResetError.__init__(self, *pos, **kw)
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# for backwards compatibility
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error = HTTPException
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@ -107,6 +107,23 @@ class NoEOFBytesIO(io.BytesIO):
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raise AssertionError('caller tried to read past EOF')
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return data
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class FakeSocketHTTPConnection(client.HTTPConnection):
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"""HTTPConnection subclass using FakeSocket; counts connect() calls"""
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def __init__(self, *args):
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self.connections = 0
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super().__init__('example.com')
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self.fake_socket_args = args
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self._create_connection = self.create_connection
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def connect(self):
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"""Count the number of times connect() is invoked"""
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self.connections += 1
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return super().connect()
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def create_connection(self, *pos, **kw):
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return FakeSocket(*self.fake_socket_args)
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class HeaderTests(TestCase):
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def test_auto_headers(self):
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# Some headers are added automatically, but should not be added by
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@ -777,7 +794,7 @@ class BasicTest(TestCase):
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response = self # Avoid garbage collector closing the socket
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client.HTTPResponse.__init__(self, *pos, **kw)
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conn.response_class = Response
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conn.sock = FakeSocket('') # Emulate server dropping connection
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conn.sock = FakeSocket('Invalid status line')
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conn.request('GET', '/')
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self.assertRaises(client.BadStatusLine, conn.getresponse)
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self.assertTrue(response.closed)
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@ -1174,6 +1191,78 @@ class TimeoutTest(TestCase):
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httpConn.close()
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class PersistenceTest(TestCase):
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def test_reuse_reconnect(self):
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# Should reuse or reconnect depending on header from server
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tests = (
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('1.0', '', False),
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('1.0', 'Connection: keep-alive\r\n', True),
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('1.1', '', True),
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('1.1', 'Connection: close\r\n', False),
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('1.0', 'Connection: keep-ALIVE\r\n', True),
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('1.1', 'Connection: cloSE\r\n', False),
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)
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for version, header, reuse in tests:
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with self.subTest(version=version, header=header):
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msg = (
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'HTTP/{} 200 OK\r\n'
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'{}'
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'Content-Length: 12\r\n'
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'\r\n'
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'Dummy body\r\n'
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).format(version, header)
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conn = FakeSocketHTTPConnection(msg)
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self.assertIsNone(conn.sock)
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conn.request('GET', '/open-connection')
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with conn.getresponse() as response:
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self.assertEqual(conn.sock is None, not reuse)
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response.read()
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self.assertEqual(conn.sock is None, not reuse)
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self.assertEqual(conn.connections, 1)
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conn.request('GET', '/subsequent-request')
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self.assertEqual(conn.connections, 1 if reuse else 2)
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def test_disconnected(self):
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def make_reset_reader(text):
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"""Return BufferedReader that raises ECONNRESET at EOF"""
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stream = io.BytesIO(text)
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def readinto(buffer):
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size = io.BytesIO.readinto(stream, buffer)
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if size == 0:
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raise ConnectionResetError()
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return size
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stream.readinto = readinto
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return io.BufferedReader(stream)
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tests = (
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(io.BytesIO, client.RemoteDisconnected),
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(make_reset_reader, ConnectionResetError),
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)
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for stream_factory, exception in tests:
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with self.subTest(exception=exception):
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conn = FakeSocketHTTPConnection(b'', stream_factory)
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conn.request('GET', '/eof-response')
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self.assertRaises(exception, conn.getresponse)
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self.assertIsNone(conn.sock)
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# HTTPConnection.connect() should be automatically invoked
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conn.request('GET', '/reconnect')
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self.assertEqual(conn.connections, 2)
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def test_100_close(self):
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conn = FakeSocketHTTPConnection(
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b'HTTP/1.1 100 Continue\r\n'
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b'\r\n'
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# Missing final response
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)
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conn.request('GET', '/', headers={'Expect': '100-continue'})
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self.assertRaises(client.RemoteDisconnected, conn.getresponse)
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self.assertIsNone(conn.sock)
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conn.request('GET', '/reconnect')
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self.assertEqual(conn.connections, 2)
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class HTTPSTest(TestCase):
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def setUp(self):
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@ -1513,6 +1602,7 @@ class TunnelTests(TestCase):
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@support.reap_threads
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def test_main(verbose=None):
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support.run_unittest(HeaderTests, OfflineTest, BasicTest, TimeoutTest,
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PersistenceTest,
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HTTPSTest, RequestBodyTest, SourceAddressTest,
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HTTPResponseTest, ExtendedReadTest,
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ExtendedReadTestChunked, TunnelTests)
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@ -1128,7 +1128,7 @@ class Transport:
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if i or e.errno not in (errno.ECONNRESET, errno.ECONNABORTED,
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errno.EPIPE):
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raise
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except http.client.BadStatusLine: #close after we sent request
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except http.client.RemoteDisconnected:
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if i:
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raise
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