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# -*- test-case-name: twisted.test.test_loopback -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Testing support for protocols -- loopback between client and server.
"""
# system imports
import tempfile
from zope.interface import implementer
from twisted.internet import defer, interfaces, main, protocol
from twisted.internet.interfaces import IAddress
from twisted.internet.task import deferLater
# Twisted Imports
from twisted.protocols import policies
from twisted.python import failure
class _LoopbackQueue:
"""
Trivial wrapper around a list to give it an interface like a queue, which
the addition of also sending notifications by way of a Deferred whenever
the list has something added to it.
"""
_notificationDeferred = None
disconnect = False
def __init__(self):
self._queue = []
def put(self, v):
self._queue.append(v)
if self._notificationDeferred is not None:
d, self._notificationDeferred = self._notificationDeferred, None
d.callback(None)
def __nonzero__(self):
return bool(self._queue)
__bool__ = __nonzero__
def get(self):
return self._queue.pop(0)
@implementer(IAddress)
class _LoopbackAddress:
pass
@implementer(interfaces.ITransport, interfaces.IConsumer)
class _LoopbackTransport:
disconnecting = False
producer = None
# ITransport
def __init__(self, q):
self.q = q
def write(self, data):
if not isinstance(data, bytes):
raise TypeError("Can only write bytes to ITransport")
self.q.put(data)
def writeSequence(self, iovec):
self.q.put(b"".join(iovec))
def loseConnection(self):
self.q.disconnect = True
self.q.put(None)
def abortConnection(self):
"""
Abort the connection. Same as L{loseConnection}.
"""
self.loseConnection()
def getPeer(self):
return _LoopbackAddress()
def getHost(self):
return _LoopbackAddress()
# IConsumer
def registerProducer(self, producer, streaming):
assert self.producer is None
self.producer = producer
self.streamingProducer = streaming
self._pollProducer()
def unregisterProducer(self):
assert self.producer is not None
self.producer = None
def _pollProducer(self):
if self.producer is not None and not self.streamingProducer:
self.producer.resumeProducing()
def identityPumpPolicy(queue, target):
"""
L{identityPumpPolicy} is a policy which delivers each chunk of data written
to the given queue as-is to the target.
This isn't a particularly realistic policy.
@see: L{loopbackAsync}
"""
while queue:
bytes = queue.get()
if bytes is None:
break
target.dataReceived(bytes)
def collapsingPumpPolicy(queue, target):
"""
L{collapsingPumpPolicy} is a policy which collapses all outstanding chunks
into a single string and delivers it to the target.
@see: L{loopbackAsync}
"""
bytes = []
while queue:
chunk = queue.get()
if chunk is None:
break
bytes.append(chunk)
if bytes:
target.dataReceived(b"".join(bytes))
def loopbackAsync(server, client, pumpPolicy=identityPumpPolicy):
"""
Establish a connection between C{server} and C{client} then transfer data
between them until the connection is closed. This is often useful for
testing a protocol.
@param server: The protocol instance representing the server-side of this
connection.
@param client: The protocol instance representing the client-side of this
connection.
@param pumpPolicy: When either C{server} or C{client} writes to its
transport, the string passed in is added to a queue of data for the
other protocol. Eventually, C{pumpPolicy} will be called with one such
queue and the corresponding protocol object. The pump policy callable
is responsible for emptying the queue and passing the strings it
contains to the given protocol's C{dataReceived} method. The signature
of C{pumpPolicy} is C{(queue, protocol)}. C{queue} is an object with a
C{get} method which will return the next string written to the
transport, or L{None} if the transport has been disconnected, and which
evaluates to C{True} if and only if there are more items to be
retrieved via C{get}.
@return: A L{Deferred} which fires when the connection has been closed and
both sides have received notification of this.
"""
serverToClient = _LoopbackQueue()
clientToServer = _LoopbackQueue()
server.makeConnection(_LoopbackTransport(serverToClient))
client.makeConnection(_LoopbackTransport(clientToServer))
return _loopbackAsyncBody(
server, serverToClient, client, clientToServer, pumpPolicy
)
def _loopbackAsyncBody(server, serverToClient, client, clientToServer, pumpPolicy):
"""
Transfer bytes from the output queue of each protocol to the input of the other.
@param server: The protocol instance representing the server-side of this
connection.
@param serverToClient: The L{_LoopbackQueue} holding the server's output.
@param client: The protocol instance representing the client-side of this
connection.
@param clientToServer: The L{_LoopbackQueue} holding the client's output.
@param pumpPolicy: See L{loopbackAsync}.
@return: A L{Deferred} which fires when the connection has been closed and
both sides have received notification of this.
"""
def pump(source, q, target):
sent = False
if q:
pumpPolicy(q, target)
sent = True
if sent and not q:
# A write buffer has now been emptied. Give any producer on that
# side an opportunity to produce more data.
source.transport._pollProducer()
return sent
while 1:
disconnect = clientSent = serverSent = False
# Deliver the data which has been written.
serverSent = pump(server, serverToClient, client)
clientSent = pump(client, clientToServer, server)
if not clientSent and not serverSent:
# Neither side wrote any data. Wait for some new data to be added
# before trying to do anything further.
d = defer.Deferred()
clientToServer._notificationDeferred = d
serverToClient._notificationDeferred = d
d.addCallback(
_loopbackAsyncContinue,
server,
serverToClient,
client,
clientToServer,
pumpPolicy,
)
return d
if serverToClient.disconnect:
# The server wants to drop the connection. Flush any remaining
# data it has.
disconnect = True
pump(server, serverToClient, client)
elif clientToServer.disconnect:
# The client wants to drop the connection. Flush any remaining
# data it has.
disconnect = True
pump(client, clientToServer, server)
if disconnect:
# Someone wanted to disconnect, so okay, the connection is gone.
server.connectionLost(failure.Failure(main.CONNECTION_DONE))
client.connectionLost(failure.Failure(main.CONNECTION_DONE))
return defer.succeed(None)
def _loopbackAsyncContinue(
ignored, server, serverToClient, client, clientToServer, pumpPolicy
):
# Clear the Deferred from each message queue, since it has already fired
# and cannot be used again.
clientToServer._notificationDeferred = None
serverToClient._notificationDeferred = None
# Schedule some more byte-pushing to happen. This isn't done
# synchronously because no actual transport can re-enter dataReceived as
# a result of calling write, and doing this synchronously could result
# in that.
from twisted.internet import reactor
return deferLater(
reactor,
0,
_loopbackAsyncBody,
server,
serverToClient,
client,
clientToServer,
pumpPolicy,
)
@implementer(interfaces.ITransport, interfaces.IConsumer)
class LoopbackRelay:
buffer = b""
shouldLose = 0
disconnecting = 0
producer = None
def __init__(self, target, logFile=None):
self.target = target
self.logFile = logFile
def write(self, data):
self.buffer = self.buffer + data
if self.logFile:
self.logFile.write("loopback writing %s\n" % repr(data))
def writeSequence(self, iovec):
self.write(b"".join(iovec))
def clearBuffer(self):
if self.shouldLose == -1:
return
if self.producer:
self.producer.resumeProducing()
if self.buffer:
if self.logFile:
self.logFile.write("loopback receiving %s\n" % repr(self.buffer))
buffer = self.buffer
self.buffer = b""
self.target.dataReceived(buffer)
if self.shouldLose == 1:
self.shouldLose = -1
self.target.connectionLost(failure.Failure(main.CONNECTION_DONE))
def loseConnection(self):
if self.shouldLose != -1:
self.shouldLose = 1
def getHost(self):
return "loopback"
def getPeer(self):
return "loopback"
def registerProducer(self, producer, streaming):
self.producer = producer
def unregisterProducer(self):
self.producer = None
def logPrefix(self):
return f"Loopback({self.target.__class__.__name__!r})"
class LoopbackClientFactory(protocol.ClientFactory):
def __init__(self, protocol):
self.disconnected = 0
self.deferred = defer.Deferred()
self.protocol = protocol
def buildProtocol(self, addr):
return self.protocol
def clientConnectionLost(self, connector, reason):
self.disconnected = 1
self.deferred.callback(None)
class _FireOnClose(policies.ProtocolWrapper):
def __init__(self, protocol, factory):
policies.ProtocolWrapper.__init__(self, protocol, factory)
self.deferred = defer.Deferred()
def connectionLost(self, reason):
policies.ProtocolWrapper.connectionLost(self, reason)
self.deferred.callback(None)
def loopbackTCP(server, client, port=0, noisy=True):
"""Run session between server and client protocol instances over TCP."""
from twisted.internet import reactor
f = policies.WrappingFactory(protocol.Factory())
serverWrapper = _FireOnClose(f, server)
f.noisy = noisy
f.buildProtocol = lambda addr: serverWrapper
serverPort = reactor.listenTCP(port, f, interface="127.0.0.1")
clientF = LoopbackClientFactory(client)
clientF.noisy = noisy
reactor.connectTCP("127.0.0.1", serverPort.getHost().port, clientF)
d = clientF.deferred
d.addCallback(lambda x: serverWrapper.deferred)
d.addCallback(lambda x: serverPort.stopListening())
return d
def loopbackUNIX(server, client, noisy=True):
"""Run session between server and client protocol instances over UNIX socket."""
path = tempfile.mktemp()
from twisted.internet import reactor
f = policies.WrappingFactory(protocol.Factory())
serverWrapper = _FireOnClose(f, server)
f.noisy = noisy
f.buildProtocol = lambda addr: serverWrapper
serverPort = reactor.listenUNIX(path, f)
clientF = LoopbackClientFactory(client)
clientF.noisy = noisy
reactor.connectUNIX(path, clientF)
d = clientF.deferred
d.addCallback(lambda x: serverWrapper.deferred)
d.addCallback(lambda x: serverPort.stopListening())
return d