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connect.py
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# Copyright (C) 2008 AG Projects. See LICENSE for details
"""Establish MSRP connection.
This module provides means to obtain a connected and bound MSRPTransport
instance. It uniformly handles 4 different configurations you may find your
client engaged in:
1. Calling endpoint, not using a relay (ConnectorDirect)
2. Answering endpoint, not using a relay (AcceptorDirect)
3. Calling endpoint, using a relay (ConnectorRelay)
4. Answering endpoint, using a relay (AcceptorRelay)
The answering endpoint may skip using the relay if sure that it's accessible
directly. The calling endpoint is unlikely to need the relay.
Once you have an instance of the right class (use the convenience functions
get_connector() and get_acceptor() to get one), the procedure to establish the
connection is the same:
full_local_path = connector.prepare()
try:
... put full_local_path in SDP 'a:path' attribute
... get full_remote_path from remote's 'a:path: attribute
... (the order of the above steps is reversed if you're the
... answering party, but that does not affect connector's usage)
msrptransport = connector.complete(full_remote_path)
finally:
connector.cleanup()
To customize connection's parameters, create a new protocol.URI object and pass
it to prepare() function, e.g.
local_uri = protocol.URI(use_tls=False, port=5000)
connector.prepare(local_uri)
prepare() may update local_uri in place with the actual connection parameters
used (e.g. if you specified port=0). 'port' attribute of local_uri is currently
only respected by AcceptorDirect.
"""
from __future__ import with_statement
import random
from twisted.internet.address import IPv4Address
from application.system import default_host_ip
from eventlet.twistedutil.protocol import GreenClientCreator, SpawnFactory
from eventlet.coros import event
from eventlet.api import timeout
from eventlet.proc import spawn_greenlet
from msrplib import protocol, MSRPError
from msrplib.transport import MSRPTransport, MSRPTransactionError, MSRPBadRequest
from msrplib.digest import process_www_authenticate
__all__ = ['MSRPRelaySettings',
'MSRPTimeout',
'MSRPConnectTimeout',
'MSRPRelayConnectTimeout',
'MSRPIncomingConnectTimeout',
'MSRPBindSessionTimeout',
'MSRPRelayAuthError',
'MSRPAuthTimeout',
'get_connector',
'get_acceptor']
class MSRPRelaySettings(protocol.ConnectInfo):
use_tls = True
def __init__(self, domain, username, password, host=None, port=None, use_tls=None, credentials=None):
protocol.ConnectInfo.__init__(self, host, use_tls=use_tls, port=port, credentials=credentials)
self.domain = domain
self.username = username
self.password = password
def __str__(self):
result = "MSRPRelay %s://%s" % (self.scheme, self.host or self.domain)
if self.port:
result += ':%s' % self.port
return result
def __repr__(self):
params = [self.domain, self.username, self.password, self.host, self.port]
if params[-1] is None:
del params[-1]
if params[-1] is None:
del params[-1]
return '%s(%s)' % (type(self).__name__, ', '.join(repr(x) for x in params))
@property
def uri_domain(self):
return protocol.URI(host=self.domain, port=self.port, use_tls=self.use_tls, session_id='')
class TimeoutMixin(object):
@classmethod
def timeout(cls):
return timeout(cls.seconds, cls)
class MSRPTimeout(MSRPError, TimeoutMixin):
seconds = 10
class MSRPConnectTimeout(MSRPTimeout):
pass
class MSRPRelayConnectTimeout(MSRPTimeout):
pass
class MSRPIncomingConnectTimeout(MSRPTimeout):
pass
class MSRPBindSessionTimeout(MSRPTimeout):
pass
class MSRPRelayAuthError(MSRPTransactionError):
pass
class MSRPAuthTimeout(MSRPTransactionError, TimeoutMixin):
code = 408
comment = 'No response to AUTH request'
seconds = 30
class ConnectBase(object):
MSRPTransportClass = MSRPTransport
SRVConnectorClass = None
def __init__(self, traffic_logger=None, state_logger=None, MSRPTransportClass=None):
if MSRPTransportClass is not None:
self.MSRPTransportClass = MSRPTransportClass
self.traffic_logger = traffic_logger
self.state_logger = state_logger
def generate_local_uri(self, port=0):
return protocol.URI(port=port)
def _connect(self, local_uri, remote_uri):
if self.state_logger:
self.state_logger.report_connecting(remote_uri)
creator = GreenClientCreator(gtransport_class=self.MSRPTransportClass, local_uri=local_uri,
traffic_logger=self.traffic_logger, state_logger=self.state_logger)
connectFuncName = 'connect' + remote_uri.protocol_name
connectFuncArgs = remote_uri.protocolArgs
if remote_uri.host:
args = (remote_uri.host, remote_uri.port or 2855) + connectFuncArgs
msrp = getattr(creator, connectFuncName)(*args)
else:
if not remote_uri.domain:
raise ValueError("remote_uri must have either 'host' or 'domain'")
msrp = creator.connectSRV(remote_uri.scheme, remote_uri.domain,
connectFuncName=connectFuncName,
connectFuncArgs=connectFuncArgs,
ConnectorClass=self.SRVConnectorClass)
if self.state_logger:
self.state_logger.report_connected(msrp)
return msrp
def cleanup(self):
pass
class ConnectorDirect(ConnectBase):
BOGUS_LOCAL_PORT = 12345
def prepare(self, local_uri=None):
if local_uri is None:
local_uri = self.generate_local_uri(self.BOGUS_LOCAL_PORT)
self.local_uri = local_uri
return [self.local_uri]
def getHost(self):
return IPv4Address('TCP', default_host_ip, 0)
def complete(self, full_remote_path):
with MSRPConnectTimeout.timeout():
msrp = self._connect(self.local_uri, full_remote_path[0])
# can't do the following, because local_uri was already used in the INVITE
#msrp.local_uri.port = msrp.getHost().port
try:
with MSRPBindSessionTimeout.timeout():
msrp.bind(full_remote_path)
except:
spawn_greenlet(msrp.loseConnection)
raise
return msrp
class AcceptorDirect(ConnectBase):
def _listen(self, local_uri, handler):
# QQQ use ip from local_uri as binding interface?
from twisted.internet import reactor
factory = SpawnFactory(handler, self.MSRPTransportClass, local_uri,
traffic_logger=self.traffic_logger, state_logger=self.state_logger)
listenFuncName = 'listen' + local_uri.protocol_name
listenFuncArgs = (local_uri.port or 0, factory) + local_uri.protocolArgs
port = getattr(reactor, listenFuncName)(*listenFuncArgs)
if self.state_logger:
self.state_logger.report_listen(local_uri, port)
return local_uri, port
def prepare(self, local_uri=None):
"""Start listening for an incoming MSRP connection using port and
use_tls from local_uri if provided.
Return full local path, suitable to put in SDP a:path attribute.
Note, that `local_uri' may be updated in place.
"""
if local_uri is None:
local_uri = self.generate_local_uri()
self.transport_event = event()
local_uri, self.listener = self._listen(local_uri, self.transport_event.send)
# QQQ update local_uri.host as well?
local_uri.port = self.listener.getHost().port
self.local_uri = local_uri
return [local_uri]
def getHost(self):
return self.listener.getHost()
def _accept(self):
msrp = self.transport_event.wait()
if self.state_logger:
self.state_logger.report_accepted(msrp, self.local_uri)
return msrp
def complete(self, full_remote_path):
"""Accept an incoming MSRP connection and bind it.
Return MSRPTransport instance.
"""
try:
with MSRPIncomingConnectTimeout.timeout():
msrp = self._accept()
finally:
self.cleanup()
try:
with MSRPBindSessionTimeout.timeout():
msrp.accept_binding(full_remote_path)
except:
spawn_greenlet(msrp.loseConnection)
raise
return msrp
def cleanup(self):
if self.listener is not None:
self.listener.stopListening()
self.listener = None
self.transport_event = None
def _deliver_chunk(msrp, chunk):
msrp.write(chunk.encode())
with MSRPAuthTimeout.timeout():
response = msrp.read_chunk()
if response.method is not None:
raise MSRPBadRequest
if response.transaction_id!=chunk.transaction_id:
raise MSRPBadRequest
return response
class RelayConnectBase(ConnectBase):
def __init__(self, relay, **kwargs):
self.relay = relay
ConnectBase.__init__(self, **kwargs)
def _relay_connect(self, local_uri):
conn = self._connect(local_uri, self.relay)
try:
local_uri.port = conn.getHost().port
msrpdata = protocol.MSRPData(method="AUTH", transaction_id='%x' % random.getrandbits(64))
msrpdata.add_header(protocol.ToPathHeader([self.relay.uri_domain]))
msrpdata.add_header(protocol.FromPathHeader([local_uri]))
response = _deliver_chunk(conn, msrpdata)
if response.code == 401:
www_authenticate = response.headers["WWW-Authenticate"]
auth, rsp_auth = process_www_authenticate(self.relay.username, self.relay.password, "AUTH",
str(self.relay.uri_domain), **www_authenticate.decoded)
msrpdata.transaction_id = '%x' % random.getrandbits(64)
msrpdata.add_header(protocol.AuthorizationHeader(auth))
response = _deliver_chunk(conn, msrpdata)
if response.code != 200:
raise MSRPRelayAuthError(comment=response.comment, code=response.code)
conn.set_local_path(list(response.headers["Use-Path"].decoded))
if self.state_logger:
self.state_logger.report_session_reserved(conn)
except:
spawn_greenlet(conn.loseConnection)
raise
return conn
def _relay_connect_timeout(self, local_uri):
with MSRPRelayConnectTimeout.timeout():
return self._relay_connect(local_uri)
def prepare(self, local_uri=None):
if local_uri is None:
local_uri = self.generate_local_uri()
self.msrp = self._relay_connect_timeout(local_uri)
return self.msrp.full_local_path
def getHost(self):
return self.msrp.getHost()
def cleanup(self):
if self.msrp is not None:
self.msrp.loseConnection()
self.msrp = None
class ConnectorRelay(RelayConnectBase):
def complete(self, full_remote_path):
try:
with MSRPBindSessionTimeout.timeout():
self.msrp.bind(full_remote_path)
return self.msrp
except:
spawn_greenlet(self.msrp.loseConnection)
raise
finally:
self.msrp = None
class AcceptorRelay(RelayConnectBase):
def complete(self, full_remote_path):
try:
with MSRPBindSessionTimeout.timeout():
self.msrp.accept_binding(full_remote_path)
return self.msrp
except:
spawn_greenlet(self.msrp.loseConnection)
raise
finally:
self.msrp = None
def get_connector(relay, **kwargs):
if relay is None:
return ConnectorDirect(**kwargs)
return ConnectorRelay(relay, **kwargs)
def get_acceptor(relay, **kwargs):
if relay is None:
return AcceptorDirect(**kwargs)
return AcceptorRelay(relay, **kwargs)

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