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Record the current connection attempt in a future and allow cancellation

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It does not make sense to have competing connection attempts, as the
XMLStream class is not designed for this. On slow and unpredictable
networks, it means we could have two c2s connections opened, leading to
mayhem.
This commit is contained in:
mathieui 2017-11-23 00:00:37 +01:00
parent 80b9cd43b1
commit eab8c265f4
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GPG key ID: C59F84CEEFD616E3
1 changed files with 20 additions and 4 deletions
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24
slixmpp/xmlstream/xmlstream.py
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@ -204,6 +204,9 @@ class XMLStream(asyncio.BaseProtocol):
#: We use an ID prefix to ensure that all ID values are unique.
self._id_prefix = '%s-' % uuid.uuid4()
# Current connection attempt (Future)
self._current_connection_attempt = None
#: A list of DNS results that have not yet been tried.
self.dns_answers = None
@ -265,6 +268,7 @@ class XMLStream(asyncio.BaseProtocol):
localhost
"""
self.cancel_connection_attempt()
if host and port:
self.address = (host, int(port))
try:
@ -281,7 +285,7 @@ class XMLStream(asyncio.BaseProtocol):
self.disable_starttls = disable_starttls
self.event("connecting")
asyncio.async(self._connect_routine())
self._current_connection_attempt = asyncio.async(self._connect_routine())
@asyncio.coroutine
def _connect_routine(self):
@ -310,6 +314,7 @@ class XMLStream(asyncio.BaseProtocol):
self.address[1],
ssl=ssl_context,
server_hostname=self.default_domain if self.use_ssl else None)
self.connect_loop_wait = 0
except Socket.gaierror as e:
self.event('connection_failed',
'No DNS record available for %s' % self.default_domain)
@ -317,9 +322,7 @@ class XMLStream(asyncio.BaseProtocol):
log.debug('Connection failed: %s', e)
self.event("connection_failed", e)
self.connect_loop_wait = self.connect_loop_wait * 2 + 1
asyncio.async(self._connect_routine())
else:
self.connect_loop_wait = 0
self._current_connection_attempt = asyncio.async(self._connect_routine())
def process(self, *, forever=True, timeout=None):
"""Process all the available XMPP events (receiving or sending data on the
@ -431,6 +434,17 @@ class XMLStream(asyncio.BaseProtocol):
self.transport = None
self.socket = None
def cancel_connection_attempt(self):
"""
Immediatly cancel the current create_connection() Future.
This is useful when a client using slixmpp tries to connect
on flaky networks, where sometimes a connection just gets lost
and it needs to reconnect while the attempt is still ongoing.
"""
if self._current_connection_attempt:
self._current_connection_attempt.cancel()
self._current_connection_attempt = None
def disconnect(self, wait=2.0):
"""Close the XML stream and wait for an acknowldgement from the server for
at most `wait` seconds. After the given number of seconds has
@ -444,6 +458,7 @@ class XMLStream(asyncio.BaseProtocol):
:param wait: Time to wait for a response from the server.
"""
self.cancel_connection_attempt()
if self.transport:
self.send_raw(self.stream_footer)
self.schedule('Disconnect wait', wait,
@ -453,6 +468,7 @@ class XMLStream(asyncio.BaseProtocol):
"""
Forcibly close the connection
"""
self.cancel_connection_attempt()
if self.transport:
self.transport.close()
self.transport.abort()