Current File : //lib/python3/dist-packages/twisted/test/test_tcp_internals.py
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Whitebox tests for TCP APIs.
"""
import errno
import os
import socket
try:
import resource
except ImportError:
resource = None # type: ignore[assignment]
from unittest import skipIf
from twisted.internet import interfaces, reactor
from twisted.internet.defer import gatherResults, maybeDeferred
from twisted.internet.protocol import Protocol, ServerFactory
from twisted.internet.tcp import (
_ACCEPT_ERRORS,
EAGAIN,
ECONNABORTED,
EINPROGRESS,
EMFILE,
ENFILE,
ENOBUFS,
ENOMEM,
EPERM,
EWOULDBLOCK,
Port,
)
from twisted.python import log
from twisted.python.runtime import platform
from twisted.trial.unittest import TestCase
@skipIf(
not interfaces.IReactorFDSet.providedBy(reactor),
"This test only applies to reactors that implement IReactorFDset",
)
class PlatformAssumptionsTests(TestCase):
"""
Test assumptions about platform behaviors.
"""
socketLimit = 8192
def setUp(self):
self.openSockets = []
if resource is not None:
# On some buggy platforms we might leak FDs, and the test will
# fail creating the initial two sockets we *do* want to
# succeed. So, we make the soft limit the current number of fds
# plus two more (for the two sockets we want to succeed). If we've
# leaked too many fds for that to work, there's nothing we can
# do.
from twisted.internet.process import _listOpenFDs
newLimit = len(_listOpenFDs()) + 2
self.originalFileLimit = resource.getrlimit(resource.RLIMIT_NOFILE)
resource.setrlimit(
resource.RLIMIT_NOFILE, (newLimit, self.originalFileLimit[1])
)
self.socketLimit = newLimit + 100
def tearDown(self):
while self.openSockets:
self.openSockets.pop().close()
if resource is not None:
# `macOS` implicitly lowers the hard limit in the setrlimit call
# above. Retrieve the new hard limit to pass in to this
# setrlimit call, so that it doesn't give us a permission denied
# error.
currentHardLimit = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
newSoftLimit = min(self.originalFileLimit[0], currentHardLimit)
resource.setrlimit(resource.RLIMIT_NOFILE, (newSoftLimit, currentHardLimit))
def socket(self):
"""
Create and return a new socket object, also tracking it so it can be
closed in the test tear down.
"""
s = socket.socket()
self.openSockets.append(s)
return s
@skipIf(
platform.getType() == "win32",
"Windows requires an unacceptably large amount of resources to "
"provoke this behavior in the naive manner.",
)
def test_acceptOutOfFiles(self):
"""
Test that the platform accept(2) call fails with either L{EMFILE} or
L{ENOBUFS} when there are too many file descriptors open.
"""
# Make a server to which to connect
port = self.socket()
port.bind(("127.0.0.1", 0))
serverPortNumber = port.getsockname()[1]
port.listen(5)
# Make a client to use to connect to the server
client = self.socket()
client.setblocking(False)
# Use up all the rest of the file descriptors.
for i in range(self.socketLimit):
try:
self.socket()
except OSError as e:
if e.args[0] in (EMFILE, ENOBUFS):
# The desired state has been achieved.
break
else:
# Some unexpected error occurred.
raise
else:
self.fail("Could provoke neither EMFILE nor ENOBUFS from platform.")
# Non-blocking connect is supposed to fail, but this is not true
# everywhere (e.g. freeBSD)
self.assertIn(
client.connect_ex(("127.0.0.1", serverPortNumber)), (0, EINPROGRESS)
)
# Make sure that the accept call fails in the way we expect.
exc = self.assertRaises(socket.error, port.accept)
self.assertIn(exc.args[0], (EMFILE, ENOBUFS))
@skipIf(
not interfaces.IReactorFDSet.providedBy(reactor),
"This test only applies to reactors that implement IReactorFDset",
)
class SelectReactorTests(TestCase):
"""
Tests for select-specific failure conditions.
"""
def setUp(self):
self.ports = []
self.messages = []
log.addObserver(self.messages.append)
def tearDown(self):
log.removeObserver(self.messages.append)
return gatherResults([maybeDeferred(p.stopListening) for p in self.ports])
def port(self, portNumber, factory, interface):
"""
Create, start, and return a new L{Port}, also tracking it so it can
be stopped in the test tear down.
"""
p = Port(portNumber, factory, interface=interface)
p.startListening()
self.ports.append(p)
return p
def _acceptFailureTest(self, socketErrorNumber):
"""
Test behavior in the face of an exception from C{accept(2)}.
On any exception which indicates the platform is unable or unwilling
to allocate further resources to us, the existing port should remain
listening, a message should be logged, and the exception should not
propagate outward from doRead.
@param socketErrorNumber: The errno to simulate from accept.
"""
class FakeSocket:
"""
Pretend to be a socket in an overloaded system.
"""
def accept(self):
raise OSError(socketErrorNumber, os.strerror(socketErrorNumber))
factory = ServerFactory()
port = self.port(0, factory, interface="127.0.0.1")
self.patch(port, "socket", FakeSocket())
port.doRead()
expectedFormat = "Could not accept new connection ({acceptError})"
expectedErrorCode = errno.errorcode[socketErrorNumber]
matchingMessages = [
(
msg.get("log_format") == expectedFormat
and msg.get("acceptError") == expectedErrorCode
)
for msg in self.messages
]
self.assertGreater(
len(matchingMessages),
0,
"Log event for failed accept not found in " "%r" % (self.messages,),
)
def test_tooManyFilesFromAccept(self):
"""
C{accept(2)} can fail with C{EMFILE} when there are too many open file
descriptors in the process. Test that this doesn't negatively impact
any other existing connections.
C{EMFILE} mainly occurs on Linux when the open file rlimit is
encountered.
"""
return self._acceptFailureTest(EMFILE)
def test_noBufferSpaceFromAccept(self):
"""
Similar to L{test_tooManyFilesFromAccept}, but test the case where
C{accept(2)} fails with C{ENOBUFS}.
This mainly occurs on Windows and FreeBSD, but may be possible on
Linux and other platforms as well.
"""
return self._acceptFailureTest(ENOBUFS)
def test_connectionAbortedFromAccept(self):
"""
Similar to L{test_tooManyFilesFromAccept}, but test the case where
C{accept(2)} fails with C{ECONNABORTED}.
It is not clear whether this is actually possible for TCP
connections on modern versions of Linux.
"""
return self._acceptFailureTest(ECONNABORTED)
@skipIf(platform.getType() == "win32", "Windows accept(2) cannot generate ENFILE")
def test_noFilesFromAccept(self):
"""
Similar to L{test_tooManyFilesFromAccept}, but test the case where
C{accept(2)} fails with C{ENFILE}.
This can occur on Linux when the system has exhausted (!) its supply
of inodes.
"""
return self._acceptFailureTest(ENFILE)
@skipIf(platform.getType() == "win32", "Windows accept(2) cannot generate ENOMEM")
def test_noMemoryFromAccept(self):
"""
Similar to L{test_tooManyFilesFromAccept}, but test the case where
C{accept(2)} fails with C{ENOMEM}.
On Linux at least, this can sensibly occur, even in a Python program
(which eats memory like no ones business), when memory has become
fragmented or low memory has been filled (d_alloc calls
kmem_cache_alloc calls kmalloc - kmalloc only allocates out of low
memory).
"""
return self._acceptFailureTest(ENOMEM)
@skipIf(
os.environ.get("INFRASTRUCTURE") == "AZUREPIPELINES",
"Hangs on Azure Pipelines due to firewall",
)
def test_acceptScaling(self):
"""
L{tcp.Port.doRead} increases the number of consecutive
C{accept} calls it performs if all of the previous C{accept}
calls succeed; otherwise, it reduces the number to the amount
of successful calls.
"""
factory = ServerFactory()
factory.protocol = Protocol
port = self.port(0, factory, interface="127.0.0.1")
self.addCleanup(port.stopListening)
clients = []
def closeAll():
for client in clients:
client.close()
self.addCleanup(closeAll)
def connect():
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client.connect(("127.0.0.1", port.getHost().port))
return client
clients.append(connect())
port.numberAccepts = 1
port.doRead()
self.assertGreater(port.numberAccepts, 1)
clients.append(connect())
port.doRead()
# There was only one outstanding client connection, so only
# one accept(2) was possible.
self.assertEqual(port.numberAccepts, 1)
port.doRead()
# There were no outstanding client connections, so only one
# accept should be tried next.
self.assertEqual(port.numberAccepts, 1)
@skipIf(platform.getType() == "win32", "Windows accept(2) cannot generate EPERM")
def test_permissionFailure(self):
"""
C{accept(2)} returning C{EPERM} is treated as a transient
failure and the call retried no more than the maximum number
of consecutive C{accept(2)} calls.
"""
maximumNumberOfAccepts = 123
acceptCalls = [0]
class FakeSocketWithAcceptLimit:
"""
Pretend to be a socket in an overloaded system whose
C{accept} method can only be called
C{maximumNumberOfAccepts} times.
"""
def accept(oself):
acceptCalls[0] += 1
if acceptCalls[0] > maximumNumberOfAccepts:
self.fail("Maximum number of accept calls exceeded.")
raise OSError(EPERM, os.strerror(EPERM))
# Verify that FakeSocketWithAcceptLimit.accept() fails the
# test if the number of accept calls exceeds the maximum.
for _ in range(maximumNumberOfAccepts):
self.assertRaises(socket.error, FakeSocketWithAcceptLimit().accept)
self.assertRaises(self.failureException, FakeSocketWithAcceptLimit().accept)
acceptCalls = [0]
factory = ServerFactory()
port = self.port(0, factory, interface="127.0.0.1")
port.numberAccepts = 123
self.patch(port, "socket", FakeSocketWithAcceptLimit())
# This should not loop infinitely.
port.doRead()
# This is scaled down to 1 because no accept(2)s returned
# successfully.
self.assertEquals(port.numberAccepts, 1)
def test_unknownSocketErrorRaise(self):
"""
A C{socket.error} raised by C{accept(2)} whose C{errno} is
unknown to the recovery logic is logged.
"""
knownErrors = list(_ACCEPT_ERRORS)
knownErrors.extend([EAGAIN, EPERM, EWOULDBLOCK])
# Windows has object()s stubs for some errnos.
unknownAcceptError = (
max(error for error in knownErrors if isinstance(error, int)) + 1
)
class FakeSocketWithUnknownAcceptError:
"""
Pretend to be a socket in an overloaded system whose
C{accept} method can only be called
C{maximumNumberOfAccepts} times.
"""
def accept(oself):
raise OSError(unknownAcceptError, "unknown socket error message")
factory = ServerFactory()
port = self.port(0, factory, interface="127.0.0.1")
self.patch(port, "socket", FakeSocketWithUnknownAcceptError())
port.doRead()
failures = self.flushLoggedErrors(socket.error)
self.assertEqual(1, len(failures))
self.assertEqual(failures[0].value.args[0], unknownAcceptError)
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