#!/usr/bin/env python
"""
Utility functions to create server sockets able to listen on both
IPv4 and IPv6.
"""
__author__ = "Giampaolo Rodola' <g.rodola [AT] gmail [DOT] com>"
__license__ = "MIT"
import os
import sys
import socket
import select
import contextlib
_reuse_addr = os.name == 'posix' and sys.platform != 'cygwin'
def has_dual_stack(sock=None):
"""Return True if kernel allows creating a socket which is able to
listen for both IPv4 and IPv6 connections.
If *sock* is provided the check is made against it.
"""
try:
if sock is not None:
return not sock.getsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY)
else:
sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
with contextlib.closing(sock):
if not sock.getsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY):
return True
sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, False)
return True
except (socket.error, AttributeError):
return False
def create_server_sock(address, reuse_addr=_reuse_addr, queue_size=5,
dual_stack=has_dual_stack()):
"""Convenience function which creates a TCP server bound to
*address* and return the socket object.
Internally it takes care of choosing the right address family
(IPv4 or IPv6) depending on the host specified in *address*.
If *host* is an empty string or None all interfaces are assumed.
If dual stack is supported by kernel the socket will be able to
listen for both IPv4 and IPv6 connections.
The returned socket can be used to accept() new connections as in:
>>> server = create_server_sock((None, 8000))
>>> while True:
... sock, addr = server.accept()
... # handle new sock connection
"""
AF_INET6_ = getattr(socket, "AF_INET6", 0)
host, port = address
if host == "":
# http://mail.python.org/pipermail/python-ideas/2013-March/019937.html
host = None
if host is None and dual_stack:
host = "::"
err = None
info = socket.getaddrinfo(host, port, socket.AF_UNSPEC, socket.SOCK_STREAM,
0, socket.AI_PASSIVE)
if not dual_stack:
# in case AF_INET6 are listed first we want AF_INET as the default
info.sort(key=lambda x: x[0] == socket.AF_INET, reverse=True)
for res in info:
af, socktype, proto, canonname, sa = res
sock = None
try:
sock = socket.socket(af, socktype, proto)
if reuse_addr:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
if af == AF_INET6_ and dual_stack:
if sock.getsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY):
sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY,
False)
sock.bind(sa)
sock.listen(queue_size)
return sock
except socket.error as _:
err = _
if sock is not None:
sock.close()
if err is not None:
raise err
else:
raise socket.error("getaddrinfo returns an empty list")
class MultipleSocketsListener:
"""Listen on multiple addresses specified as a list of
(host, port) tuples.
Useful to listen on both IPv4 and IPv6 on those systems where
a dual stack is not supported natively (Windows and many UNIXes).
The returned instance is a socket-like object which can be used to
accept() new connections, as with a common socket.
Calls like settimeout() and setsockopt() will be applied to all
sockets.
Callks like gettimeout() or getsockopt() will refer to the first
socket in the list.
"""
def __init__(self, addresses, reuse_addr=_reuse_addr, queue_size=5):
self._socks = []
self._sockmap = {}
if hasattr(select, 'poll'):
self._pollster = select.poll()
else:
self._pollster = None
try:
for addr in addresses:
sock = create_server_sock(addr, reuse_addr, queue_size,
dual_stack=False)
fd = sock.fileno()
if self._pollster is not None:
self._pollster.register(fd, select.POLLIN)
self._socks.append(sock)
self._sockmap[fd] = sock
except Exception:
self.close()
raise
def __enter__(self):
return self
def __exit__(self, *args):
self.close()
def _poll(self):
"""Return the first readable fd."""
timeout = self.gettimeout()
if self._pollster is None:
ret = select.select(self._sockmap.keys(), [], [], timeout)
if timeout and ret == ([], [], []):
raise socket.timeout('timed out')
else:
if timeout != None:
timeout *= 1000
ret = self._pollster.poll(timeout)
if timeout and ret == []:
raise socket.timeout('timed out')
try:
return ret[0][0]
except IndexError:
# non-blocking socket
pass
def _multicall(self, name, *args, **kwargs):
for sock in self._socks:
meth = getattr(sock, name)
meth(*args, **kwargs)
def accept(self):
"""Accept a connection from the first socket which is ready
to do so.
"""
fd = self._poll()
sock = self._sockmap[fd] if fd else self._socks[0]
return sock.accept()
def filenos(self):
"""Return sockets's file descriptors as a list of integers.
This is useful with select().
"""
return list(self._sockmap.keys())
def getsockname(self):
"""Return first registered socket's own address."""
return self._socks[0].getsockname()
def getsockopt(self):
"""Return first registered socket's options."""
return self._socks[0].getsockopt()
def gettimeout(self):
"""Return first registered socket's timeout."""
return self._socks[0].gettimeout()
def settimeout(self, timeout):
"""Set timeout for all registered sockets."""
self._multicall('settimeout', timeout)
def setblocking(self, flag):
"""Set non/blocking mode for all registered sockets."""
self._multicall('setblocking', flag)
def setsockopt(self, level, optname, value):
"""Set option for all registered sockets."""
self._multicall('setsockopt', level, optname, value)
def shutdown(self, how):
"""Shut down all registered sockets."""
self._multicall('shutdown', how)
def close(self):
"""Close all registered sockets."""
self._multicall('close')
self._socks = []
self._sockmap.clear()
# ===================================================================
# --- tests
# ===================================================================
if __name__ == '__main__':
import unittest
import threading
import contextlib
import errno
import time
try:
from test.support import find_unused_port # PY3
except ImportError:
from test.test_support import find_unused_port # PY2
class TestCase(unittest.TestCase):
def echo_server(self, sock):
def run():
with contextlib.closing(sock):
conn, _ = sock.accept()
with contextlib.closing(conn) as conn:
msg = conn.recv(1024)
if not msg:
return
conn.sendall(msg)
t = threading.Thread(target=run)
t.start()
time.sleep(.1)
def test_create_server_sock(self):
port = find_unused_port()
sock = create_server_sock((None, port))
with contextlib.closing(sock):
self.assertEqual(sock.getsockname()[1], port)
self.assertEqual(sock.type, socket.SOCK_STREAM)
if has_dual_stack():
self.assertEqual(sock.family, socket.AF_INET6)
else:
self.assertEqual(sock.family, socket.AF_INET)
self.echo_server(sock)
cl = socket.create_connection(('localhost', port), timeout=2)
with contextlib.closing(cl):
cl.sendall(b'foo')
self.assertEqual(cl.recv(1024), b'foo')
def test_has_dual_stack(self):
# IPv4 sockets are not supposed to support dual stack
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
with contextlib.closing(sock):
sock.bind(("", 0))
self.assertFalse(has_dual_stack(sock=sock))
def test_dual_stack(self):
sock = create_server_sock((None, 0))
with contextlib.closing(sock):
self.echo_server(sock)
port = sock.getsockname()[1]
cl = socket.create_connection(("127.0.0.1", port), timeout=2)
with contextlib.closing(cl):
cl.sendall(b'foo')
self.assertEqual(cl.recv(1024), b'foo')
sock = create_server_sock((None, 0))
with contextlib.closing(sock):
self.echo_server(sock)
port = sock.getsockname()[1]
if has_dual_stack():
self.assertTrue(has_dual_stack(sock=sock))
cl = socket.create_connection(("::1", port), timeout=2)
with contextlib.closing(cl):
cl.sendall(b'foo')
self.assertEqual(cl.recv(1024), b'foo')
else:
self.assertFalse(has_dual_stack(sock=sock))
try:
socket.create_connection(("::1", port))
except socket.error as err:
if os.name == 'nt':
code = errno.WSAECONNREFUSED
else:
code = errno.ECONNREFUSED
self.assertEqual(err.errno, code)
else:
self.fail('exception not raised')
# just stop server
cl = socket.create_connection(("127.0.0.1", port), timeout=2)
with contextlib.closing(sock):
cl.sendall(b'foo')
cl.recv(1024)
if hasattr(unittest, 'skip'): # PY >= 2.7
unittest.skip('dual stack cannot be tested as not '
'supported')
# --- multiple listener tests
def test_mlistener(self):
port = find_unused_port()
# v4
sock = MultipleSocketsListener([('127.0.0.1', port), ('::1', port)])
with contextlib.closing(sock):
self.echo_server(sock)
port = sock.getsockname()[1]
cl = socket.create_connection(("127.0.0.1", port), timeout=2)
with contextlib.closing(cl):
cl.sendall(b'foo')
self.assertEqual(cl.recv(1024), b'foo')
# v6
sock = MultipleSocketsListener([('127.0.0.1', port), ('::1', port)])
with contextlib.closing(sock):
self.echo_server(sock)
port = sock.getsockname()[1]
cl = socket.create_connection(("::1", port), timeout=2)
with contextlib.closing(cl):
cl.sendall(b'foo')
self.assertEqual(cl.recv(1024), b'foo')
def test_mlistener_timeout(self):
sock = MultipleSocketsListener([('127.0.0.1', 0), ('::1', 0)])
sock.settimeout(.01)
self.assertRaises(socket.timeout, sock.accept)
def test_mlistener_nonblocking(self):
sock = MultipleSocketsListener([('127.0.0.1', 0), ('::1', 0)])
sock.setblocking(False)
try:
sock.accept()
except socket.error as err:
if os.name == 'nt':
code = errno.WSAEWOULDBLOCK
else:
code = errno.EAGAIN
self.assertEqual(err.errno, code)
else:
self.fail('exception not raised')
def test_mlistener_ctx_manager(self):
with MultipleSocketsListener([("0.0.0.0", 0), ("::", 0)]) as msl:
pass
self.assertEqual(msl._socks, [])
self.assertEqual(msl._sockmap, {})
test_suite = unittest.TestSuite()
test_suite.addTest(unittest.makeSuite(TestCase))
unittest.TextTestRunner(verbosity=2).run(test_suite)
Diff to Previous Revision
--- revision 2 2013-03-29 03:22:48
+++ revision 3 2013-03-29 12:16:50
@@ -170,27 +170,35 @@
return list(self._sockmap.keys())
def getsockname(self):
+ """Return first registered socket's own address."""
return self._socks[0].getsockname()
def getsockopt(self):
+ """Return first registered socket's options."""
return self._socks[0].getsockopt()
def gettimeout(self):
+ """Return first registered socket's timeout."""
return self._socks[0].gettimeout()
def settimeout(self, timeout):
+ """Set timeout for all registered sockets."""
self._multicall('settimeout', timeout)
- def setblocking(self, arg):
- self._multicall('setblocking', arg)
+ def setblocking(self, flag):
+ """Set non/blocking mode for all registered sockets."""
+ self._multicall('setblocking', flag)
def setsockopt(self, level, optname, value):
+ """Set option for all registered sockets."""
self._multicall('setsockopt', level, optname, value)
def shutdown(self, how):
+ """Shut down all registered sockets."""
self._multicall('shutdown', how)
def close(self):
+ """Close all registered sockets."""
self._multicall('close')
self._socks = []
self._sockmap.clear()
