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# -*- test-case-name: twisted.test.test_factories,twisted.internet.test.test_protocol -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Standard implementations of Twisted protocol-related interfaces.
Start here if you are looking to write a new protocol implementation for
Twisted. The Protocol class contains some introductory material.
"""
import random
from typing import Any, Callable, Optional
from zope.interface import implementer
from twisted.internet import defer, error, interfaces
from twisted.internet.interfaces import IAddress, ITransport
from twisted.logger import _loggerFor
from twisted.python import components, failure, log
@implementer(interfaces.IProtocolFactory, interfaces.ILoggingContext)
class Factory:
"""
This is a factory which produces protocols.
By default, buildProtocol will create a protocol of the class given in
self.protocol.
"""
protocol: "Optional[Callable[[], Protocol]]" = None
numPorts = 0
noisy = True
@classmethod
def forProtocol(cls, protocol, *args, **kwargs):
"""
Create a factory for the given protocol.
It sets the C{protocol} attribute and returns the constructed factory
instance.
@param protocol: A L{Protocol} subclass
@param args: Positional arguments for the factory.
@param kwargs: Keyword arguments for the factory.
@return: A L{Factory} instance wired up to C{protocol}.
"""
factory = cls(*args, **kwargs)
factory.protocol = protocol
return factory
def logPrefix(self):
"""
Describe this factory for log messages.
"""
return self.__class__.__name__
def doStart(self):
"""
Make sure startFactory is called.
Users should not call this function themselves!
"""
if not self.numPorts:
if self.noisy:
_loggerFor(self).info("Starting factory {factory!r}", factory=self)
self.startFactory()
self.numPorts = self.numPorts + 1
def doStop(self):
"""
Make sure stopFactory is called.
Users should not call this function themselves!
"""
if self.numPorts == 0:
# This shouldn't happen, but does sometimes and this is better
# than blowing up in assert as we did previously.
return
self.numPorts = self.numPorts - 1
if not self.numPorts:
if self.noisy:
_loggerFor(self).info("Stopping factory {factory!r}", factory=self)
self.stopFactory()
def startFactory(self):
"""
This will be called before I begin listening on a Port or Connector.
It will only be called once, even if the factory is connected
to multiple ports.
This can be used to perform 'unserialization' tasks that
are best put off until things are actually running, such
as connecting to a database, opening files, etcetera.
"""
def stopFactory(self):
"""
This will be called before I stop listening on all Ports/Connectors.
This can be overridden to perform 'shutdown' tasks such as disconnecting
database connections, closing files, etc.
It will be called, for example, before an application shuts down,
if it was connected to a port. User code should not call this function
directly.
"""
def buildProtocol(self, addr: IAddress) -> "Optional[Protocol]":
"""
Create an instance of a subclass of Protocol.
The returned instance will handle input on an incoming server
connection, and an attribute "factory" pointing to the creating
factory.
Alternatively, L{None} may be returned to immediately close the
new connection.
Override this method to alter how Protocol instances get created.
@param addr: an object implementing L{IAddress}
"""
assert self.protocol is not None
p = self.protocol()
p.factory = self
return p
class ClientFactory(Factory):
"""
A Protocol factory for clients.
This can be used together with the various connectXXX methods in
reactors.
"""
def startedConnecting(self, connector):
"""
Called when a connection has been started.
You can call connector.stopConnecting() to stop the connection attempt.
@param connector: a Connector object.
"""
def clientConnectionFailed(self, connector, reason):
"""
Called when a connection has failed to connect.
It may be useful to call connector.connect() - this will reconnect.
@type reason: L{twisted.python.failure.Failure}
"""
def clientConnectionLost(self, connector, reason):
"""
Called when an established connection is lost.
It may be useful to call connector.connect() - this will reconnect.
@type reason: L{twisted.python.failure.Failure}
"""
class _InstanceFactory(ClientFactory):
"""
Factory used by ClientCreator.
@ivar deferred: The L{Deferred} which represents this connection attempt and
which will be fired when it succeeds or fails.
@ivar pending: After a connection attempt succeeds or fails, a delayed call
which will fire the L{Deferred} representing this connection attempt.
"""
noisy = False
pending = None
def __init__(self, reactor, instance, deferred):
self.reactor = reactor
self.instance = instance
self.deferred = deferred
def __repr__(self) -> str:
return f"<ClientCreator factory: {self.instance!r}>"
def buildProtocol(self, addr):
"""
Return the pre-constructed protocol instance and arrange to fire the
waiting L{Deferred} to indicate success establishing the connection.
"""
self.pending = self.reactor.callLater(
0, self.fire, self.deferred.callback, self.instance
)
self.deferred = None
return self.instance
def clientConnectionFailed(self, connector, reason):
"""
Arrange to fire the waiting L{Deferred} with the given failure to
indicate the connection could not be established.
"""
self.pending = self.reactor.callLater(
0, self.fire, self.deferred.errback, reason
)
self.deferred = None
def fire(self, func, value):
"""
Clear C{self.pending} to avoid a reference cycle and then invoke func
with the value.
"""
self.pending = None
func(value)
class ClientCreator:
"""
Client connections that do not require a factory.
The various connect* methods create a protocol instance using the given
protocol class and arguments, and connect it, returning a Deferred of the
resulting protocol instance.
Useful for cases when we don't really need a factory. Mainly this
is when there is no shared state between protocol instances, and no need
to reconnect.
The C{connectTCP}, C{connectUNIX}, and C{connectSSL} methods each return a
L{Deferred} which will fire with an instance of the protocol class passed to
L{ClientCreator.__init__}. These Deferred can be cancelled to abort the
connection attempt (in a very unlikely case, cancelling the Deferred may not
prevent the protocol from being instantiated and connected to a transport;
if this happens, it will be disconnected immediately afterwards and the
Deferred will still errback with L{CancelledError}).
"""
def __init__(self, reactor, protocolClass, *args, **kwargs):
self.reactor = reactor
self.protocolClass = protocolClass
self.args = args
self.kwargs = kwargs
def _connect(self, method, *args, **kwargs):
"""
Initiate a connection attempt.
@param method: A callable which will actually start the connection
attempt. For example, C{reactor.connectTCP}.
@param args: Positional arguments to pass to C{method}, excluding the
factory.
@param kwargs: Keyword arguments to pass to C{method}.
@return: A L{Deferred} which fires with an instance of the protocol
class passed to this L{ClientCreator}'s initializer or fails if the
connection cannot be set up for some reason.
"""
def cancelConnect(deferred):
connector.disconnect()
if f.pending is not None:
f.pending.cancel()
d = defer.Deferred(cancelConnect)
f = _InstanceFactory(
self.reactor, self.protocolClass(*self.args, **self.kwargs), d
)
connector = method(factory=f, *args, **kwargs)
return d
def connectTCP(self, host, port, timeout=30, bindAddress=None):
"""
Connect to a TCP server.
The parameters are all the same as to L{IReactorTCP.connectTCP} except
that the factory parameter is omitted.
@return: A L{Deferred} which fires with an instance of the protocol
class passed to this L{ClientCreator}'s initializer or fails if the
connection cannot be set up for some reason.
"""
return self._connect(
self.reactor.connectTCP,
host,
port,
timeout=timeout,
bindAddress=bindAddress,
)
def connectUNIX(self, address, timeout=30, checkPID=False):
"""
Connect to a Unix socket.
The parameters are all the same as to L{IReactorUNIX.connectUNIX} except
that the factory parameter is omitted.
@return: A L{Deferred} which fires with an instance of the protocol
class passed to this L{ClientCreator}'s initializer or fails if the
connection cannot be set up for some reason.
"""
return self._connect(
self.reactor.connectUNIX, address, timeout=timeout, checkPID=checkPID
)
def connectSSL(self, host, port, contextFactory, timeout=30, bindAddress=None):
"""
Connect to an SSL server.
The parameters are all the same as to L{IReactorSSL.connectSSL} except
that the factory parameter is omitted.
@return: A L{Deferred} which fires with an instance of the protocol
class passed to this L{ClientCreator}'s initializer or fails if the
connection cannot be set up for some reason.
"""
return self._connect(
self.reactor.connectSSL,
host,
port,
contextFactory=contextFactory,
timeout=timeout,
bindAddress=bindAddress,
)
class ReconnectingClientFactory(ClientFactory):
"""
Factory which auto-reconnects clients with an exponential back-off.
Note that clients should call my resetDelay method after they have
connected successfully.
@ivar maxDelay: Maximum number of seconds between connection attempts.
@ivar initialDelay: Delay for the first reconnection attempt.
@ivar factor: A multiplicitive factor by which the delay grows
@ivar jitter: Percentage of randomness to introduce into the delay length
to prevent stampeding.
@ivar clock: The clock used to schedule reconnection. It's mainly useful to
be parametrized in tests. If the factory is serialized, this attribute
will not be serialized, and the default value (the reactor) will be
restored when deserialized.
@type clock: L{IReactorTime}
@ivar maxRetries: Maximum number of consecutive unsuccessful connection
attempts, after which no further connection attempts will be made. If
this is not explicitly set, no maximum is applied.
"""
maxDelay = 3600
initialDelay = 1.0
# Note: These highly sensitive factors have been precisely measured by
# the National Institute of Science and Technology. Take extreme care
# in altering them, or you may damage your Internet!
# (Seriously: <http://physics.nist.gov/cuu/Constants/index.html>)
factor = 2.7182818284590451 # (math.e)
# Phi = 1.6180339887498948 # (Phi is acceptable for use as a
# factor if e is too large for your application.)
# This is the value of the molar Planck constant times c, joule
# meter/mole. The value is attributable to
# https://physics.nist.gov/cgi-bin/cuu/Value?nahc|search_for=molar+planck+constant+times+c
jitter = 0.119626565582
delay = initialDelay
retries = 0
maxRetries = None
_callID = None
connector = None
clock = None
continueTrying = 1
def clientConnectionFailed(self, connector, reason):
if self.continueTrying:
self.connector = connector
self.retry()
def clientConnectionLost(self, connector, unused_reason):
if self.continueTrying:
self.connector = connector
self.retry()
def retry(self, connector=None):
"""
Have this connector connect again, after a suitable delay.
"""
if not self.continueTrying:
if self.noisy:
log.msg(f"Abandoning {connector} on explicit request")
return
if connector is None:
if self.connector is None:
raise ValueError("no connector to retry")
else:
connector = self.connector
self.retries += 1
if self.maxRetries is not None and (self.retries > self.maxRetries):
if self.noisy:
log.msg("Abandoning %s after %d retries." % (connector, self.retries))
return
self.delay = min(self.delay * self.factor, self.maxDelay)
if self.jitter:
self.delay = random.normalvariate(self.delay, self.delay * self.jitter)
if self.noisy:
log.msg(
"%s will retry in %d seconds"
% (
connector,
self.delay,
)
)
def reconnector():
self._callID = None
connector.connect()
if self.clock is None:
from twisted.internet import reactor
self.clock = reactor
self._callID = self.clock.callLater(self.delay, reconnector)
def stopTrying(self):
"""
Put a stop to any attempt to reconnect in progress.
"""
# ??? Is this function really stopFactory?
if self._callID:
self._callID.cancel()
self._callID = None
self.continueTrying = 0
if self.connector:
try:
self.connector.stopConnecting()
except error.NotConnectingError:
pass
def resetDelay(self):
"""
Call this method after a successful connection: it resets the delay and
the retry counter.
"""
self.delay = self.initialDelay
self.retries = 0
self._callID = None
self.continueTrying = 1
def __getstate__(self):
"""
Remove all of the state which is mutated by connection attempts and
failures, returning just the state which describes how reconnections
should be attempted. This will make the unserialized instance
behave just as this one did when it was first instantiated.
"""
state = self.__dict__.copy()
for key in [
"connector",
"retries",
"delay",
"continueTrying",
"_callID",
"clock",
]:
if key in state:
del state[key]
return state
class ServerFactory(Factory):
"""
Subclass this to indicate that your protocol.Factory is only usable for servers.
"""
class BaseProtocol:
"""
This is the abstract superclass of all protocols.
Some methods have helpful default implementations here so that they can
easily be shared, but otherwise the direct subclasses of this class are more
interesting, L{Protocol} and L{ProcessProtocol}.
"""
connected = 0
transport: Optional[ITransport] = None
def makeConnection(self, transport):
"""
Make a connection to a transport and a server.
This sets the 'transport' attribute of this Protocol, and calls the
connectionMade() callback.
"""
self.connected = 1
self.transport = transport
self.connectionMade()
def connectionMade(self):
"""
Called when a connection is made.
This may be considered the initializer of the protocol, because
it is called when the connection is completed. For clients,
this is called once the connection to the server has been
established; for servers, this is called after an accept() call
stops blocking and a socket has been received. If you need to
send any greeting or initial message, do it here.
"""
connectionDone = failure.Failure(error.ConnectionDone())
connectionDone.cleanFailure()
@implementer(interfaces.IProtocol, interfaces.ILoggingContext)
class Protocol(BaseProtocol):
"""
This is the base class for streaming connection-oriented protocols.
If you are going to write a new connection-oriented protocol for Twisted,
start here. Any protocol implementation, either client or server, should
be a subclass of this class.
The API is quite simple. Implement L{dataReceived} to handle both
event-based and synchronous input; output can be sent through the
'transport' attribute, which is to be an instance that implements
L{twisted.internet.interfaces.ITransport}. Override C{connectionLost} to be
notified when the connection ends.
Some subclasses exist already to help you write common types of protocols:
see the L{twisted.protocols.basic} module for a few of them.
"""
factory: Optional[Factory] = None
def logPrefix(self):
"""
Return a prefix matching the class name, to identify log messages
related to this protocol instance.
"""
return self.__class__.__name__
def dataReceived(self, data: bytes) -> None:
"""
Called whenever data is received.
Use this method to translate to a higher-level message. Usually, some
callback will be made upon the receipt of each complete protocol
message.
@param data: a string of indeterminate length. Please keep in mind
that you will probably need to buffer some data, as partial
(or multiple) protocol messages may be received! I recommend
that unit tests for protocols call through to this method with
differing chunk sizes, down to one byte at a time.
"""
def connectionLost(self, reason: failure.Failure = connectionDone) -> None:
"""
Called when the connection is shut down.
Clear any circular references here, and any external references
to this Protocol. The connection has been closed.
@type reason: L{twisted.python.failure.Failure}
"""
@implementer(interfaces.IConsumer)
class ProtocolToConsumerAdapter(components.Adapter):
def write(self, data: bytes) -> None:
self.original.dataReceived(data)
def registerProducer(self, producer, streaming):
pass
def unregisterProducer(self):
pass
components.registerAdapter(
ProtocolToConsumerAdapter, interfaces.IProtocol, interfaces.IConsumer
)
@implementer(interfaces.IProtocol)
class ConsumerToProtocolAdapter(components.Adapter):
def dataReceived(self, data: bytes) -> None:
self.original.write(data)
def connectionLost(self, reason: failure.Failure) -> None:
pass
def makeConnection(self, transport):
pass
def connectionMade(self):
pass
components.registerAdapter(
ConsumerToProtocolAdapter, interfaces.IConsumer, interfaces.IProtocol
)
@implementer(interfaces.IProcessProtocol)
class ProcessProtocol(BaseProtocol):
"""
Base process protocol implementation which does simple dispatching for
stdin, stdout, and stderr file descriptors.
"""
transport: Optional[interfaces.IProcessTransport] = None
def childDataReceived(self, childFD: int, data: bytes) -> None:
if childFD == 1:
self.outReceived(data)
elif childFD == 2:
self.errReceived(data)
def outReceived(self, data: bytes) -> None:
"""
Some data was received from stdout.
"""
def errReceived(self, data: bytes) -> None:
"""
Some data was received from stderr.
"""
def childConnectionLost(self, childFD: int) -> None:
if childFD == 0:
self.inConnectionLost()
elif childFD == 1:
self.outConnectionLost()
elif childFD == 2:
self.errConnectionLost()
def inConnectionLost(self):
"""
This will be called when stdin is closed.
"""
def outConnectionLost(self):
"""
This will be called when stdout is closed.
"""
def errConnectionLost(self):
"""
This will be called when stderr is closed.
"""
def processExited(self, reason: failure.Failure) -> None:
"""
This will be called when the subprocess exits.
@type reason: L{twisted.python.failure.Failure}
"""
def processEnded(self, reason: failure.Failure) -> None:
"""
Called when the child process exits and all file descriptors
associated with it have been closed.
@type reason: L{twisted.python.failure.Failure}
"""
class AbstractDatagramProtocol:
"""
Abstract protocol for datagram-oriented transports, e.g. IP, ICMP, ARP,
UDP.
"""
transport = None
numPorts = 0
noisy = True
def __getstate__(self):
d = self.__dict__.copy()
d["transport"] = None
return d
def doStart(self):
"""
Make sure startProtocol is called.
This will be called by makeConnection(), users should not call it.
"""
if not self.numPorts:
if self.noisy:
log.msg("Starting protocol %s" % self)
self.startProtocol()
self.numPorts = self.numPorts + 1
def doStop(self):
"""
Make sure stopProtocol is called.
This will be called by the port, users should not call it.
"""
assert self.numPorts > 0
self.numPorts = self.numPorts - 1
self.transport = None
if not self.numPorts:
if self.noisy:
log.msg("Stopping protocol %s" % self)
self.stopProtocol()
def startProtocol(self):
"""
Called when a transport is connected to this protocol.
Will only be called once, even if multiple ports are connected.
"""
def stopProtocol(self):
"""
Called when the transport is disconnected.
Will only be called once, after all ports are disconnected.
"""
def makeConnection(self, transport):
"""
Make a connection to a transport and a server.
This sets the 'transport' attribute of this DatagramProtocol, and calls the
doStart() callback.
"""
assert self.transport == None
self.transport = transport
self.doStart()
def datagramReceived(self, datagram: bytes, addr: Any) -> None:
"""
Called when a datagram is received.
@param datagram: the bytes received from the transport.
@param addr: tuple of source of datagram.
"""
@implementer(interfaces.ILoggingContext)
class DatagramProtocol(AbstractDatagramProtocol):
"""
Protocol for datagram-oriented transport, e.g. UDP.
@type transport: L{None} or
L{IUDPTransport<twisted.internet.interfaces.IUDPTransport>} provider
@ivar transport: The transport with which this protocol is associated,
if it is associated with one.
"""
def logPrefix(self):
"""
Return a prefix matching the class name, to identify log messages
related to this protocol instance.
"""
return self.__class__.__name__
def connectionRefused(self):
"""
Called due to error from write in connected mode.
Note this is a result of ICMP message generated by *previous*
write.
"""
class ConnectedDatagramProtocol(DatagramProtocol):
"""
Protocol for connected datagram-oriented transport.
No longer necessary for UDP.
"""
def datagramReceived(self, datagram):
"""
Called when a datagram is received.
@param datagram: the string received from the transport.
"""
def connectionFailed(self, failure: failure.Failure) -> None:
"""
Called if connecting failed.
Usually this will be due to a DNS lookup failure.
"""
@implementer(interfaces.ITransport)
class FileWrapper:
"""
A wrapper around a file-like object to make it behave as a Transport.
This doesn't actually stream the file to the attached protocol,
and is thus useful mainly as a utility for debugging protocols.
"""
closed = 0
disconnecting = 0
producer = None
streamingProducer = 0
def __init__(self, file):
self.file = file
def write(self, data: bytes) -> None:
try:
self.file.write(data)
except BaseException:
self.handleException()
def _checkProducer(self):
# Cheating; this is called at "idle" times to allow producers to be
# found and dealt with
if self.producer:
self.producer.resumeProducing()
def registerProducer(self, producer, streaming):
"""
From abstract.FileDescriptor
"""
self.producer = producer
self.streamingProducer = streaming
if not streaming:
producer.resumeProducing()
def unregisterProducer(self):
self.producer = None
def stopConsuming(self):
self.unregisterProducer()
self.loseConnection()
def writeSequence(self, iovec):
self.write(b"".join(iovec))
def loseConnection(self):
self.closed = 1
try:
self.file.close()
except OSError:
self.handleException()
def getPeer(self):
# FIXME: https://twistedmatrix.com/trac/ticket/7820
# According to ITransport, this should return an IAddress!
return "file", "file"
def getHost(self):
# FIXME: https://twistedmatrix.com/trac/ticket/7820
# According to ITransport, this should return an IAddress!
return "file"
def handleException(self):
pass
def resumeProducing(self):
# Never sends data anyways
pass
def pauseProducing(self):
# Never sends data anyways
pass
def stopProducing(self):
self.loseConnection()
__all__ = [
"Factory",
"ClientFactory",
"ReconnectingClientFactory",
"connectionDone",
"Protocol",
"ProcessProtocol",
"FileWrapper",
"ServerFactory",
"AbstractDatagramProtocol",
"DatagramProtocol",
"ConnectedDatagramProtocol",
"ClientCreator",
]