#!/usr/bin/env python
#
# Copyright 2011 Facebook
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Miscellaneous network utility code."""
from __future__ import absolute_import, division, print_function, with_statement
import errno
import os
import re
import socket
import ssl
import stat
from tornado.concurrent import dummy_executor, run_on_executor
from tornado.ioloop import IOLoop
from tornado.platform.auto import set_close_exec
from tornado.util import Configurable
[docs]def bind_sockets(port, address=None, family=socket.AF_UNSPEC, backlog=128, flags=None):
"""Creates listening sockets bound to the given port and address.
Returns a list of socket objects (multiple sockets are returned if
the given address maps to multiple IP addresses, which is most common
for mixed IPv4 and IPv6 use).
Address may be either an IP address or hostname. If it's a hostname,
the server will listen on all IP addresses associated with the
name. Address may be an empty string or None to listen on all
available interfaces. Family may be set to either `socket.AF_INET`
or `socket.AF_INET6` to restrict to IPv4 or IPv6 addresses, otherwise
both will be used if available.
The ``backlog`` argument has the same meaning as for
`socket.listen() <socket.socket.listen>`.
``flags`` is a bitmask of AI_* flags to `~socket.getaddrinfo`, like
``socket.AI_PASSIVE | socket.AI_NUMERICHOST``.
"""
sockets = []
if address == "":
address = None
if not socket.has_ipv6 and family == socket.AF_UNSPEC:
# Python can be compiled with --disable-ipv6, which causes
# operations on AF_INET6 sockets to fail, but does not
# automatically exclude those results from getaddrinfo
# results.
# http://bugs.python.org/issue16208
family = socket.AF_INET
if flags is None:
flags = socket.AI_PASSIVE
for res in set(socket.getaddrinfo(address, port, family, socket.SOCK_STREAM,
0, flags)):
af, socktype, proto, canonname, sockaddr = res
try:
sock = socket.socket(af, socktype, proto)
except socket.error as e:
if e.args[0] == errno.EAFNOSUPPORT:
continue
raise
set_close_exec(sock.fileno())
if os.name != 'nt':
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
if af == socket.AF_INET6:
# On linux, ipv6 sockets accept ipv4 too by default,
# but this makes it impossible to bind to both
# 0.0.0.0 in ipv4 and :: in ipv6. On other systems,
# separate sockets *must* be used to listen for both ipv4
# and ipv6. For consistency, always disable ipv4 on our
# ipv6 sockets and use a separate ipv4 socket when needed.
#
# Python 2.x on windows doesn't have IPPROTO_IPV6.
if hasattr(socket, "IPPROTO_IPV6"):
sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 1)
sock.setblocking(0)
sock.bind(sockaddr)
sock.listen(backlog)
sockets.append(sock)
return sockets
if hasattr(socket, 'AF_UNIX'):
[docs] def bind_unix_socket(file, mode=0o600, backlog=128):
"""Creates a listening unix socket.
If a socket with the given name already exists, it will be deleted.
If any other file with that name exists, an exception will be
raised.
Returns a socket object (not a list of socket objects like
`bind_sockets`)
"""
sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
set_close_exec(sock.fileno())
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.setblocking(0)
try:
st = os.stat(file)
except OSError as err:
if err.errno != errno.ENOENT:
raise
else:
if stat.S_ISSOCK(st.st_mode):
os.remove(file)
else:
raise ValueError("File %s exists and is not a socket", file)
sock.bind(file)
os.chmod(file, mode)
sock.listen(backlog)
return sock
[docs]def add_accept_handler(sock, callback, io_loop=None):
"""Adds an `.IOLoop` event handler to accept new connections on ``sock``.
When a connection is accepted, ``callback(connection, address)`` will
be run (``connection`` is a socket object, and ``address`` is the
address of the other end of the connection). Note that this signature
is different from the ``callback(fd, events)`` signature used for
`.IOLoop` handlers.
"""
if io_loop is None:
io_loop = IOLoop.current()
def accept_handler(fd, events):
while True:
try:
connection, address = sock.accept()
except socket.error as e:
# EWOULDBLOCK and EAGAIN indicate we have accepted every
# connection that is available.
if e.args[0] in (errno.EWOULDBLOCK, errno.EAGAIN):
return
# ECONNABORTED indicates that there was a connection
# but it was closed while still in the accept queue.
# (observed on FreeBSD).
if e.args[0] == errno.ECONNABORTED:
continue
raise
callback(connection, address)
io_loop.add_handler(sock.fileno(), accept_handler, IOLoop.READ)
[docs]def is_valid_ip(ip):
"""Returns true if the given string is a well-formed IP address.
Supports IPv4 and IPv6.
"""
try:
res = socket.getaddrinfo(ip, 0, socket.AF_UNSPEC,
socket.SOCK_STREAM,
0, socket.AI_NUMERICHOST)
return bool(res)
except socket.gaierror as e:
if e.args[0] == socket.EAI_NONAME:
return False
raise
return True
[docs]class Resolver(Configurable):
"""Configurable asynchronous DNS resolver interface.
By default, a blocking implementation is used (which simply calls
`socket.getaddrinfo`). An alternative implementation can be
chosen with the `Resolver.configure <.Configurable.configure>`
class method::
Resolver.configure('tornado.netutil.ThreadedResolver')
The implementations of this interface included with Tornado are
* `tornado.netutil.BlockingResolver`
* `tornado.netutil.ThreadedResolver`
* `tornado.netutil.OverrideResolver`
* `tornado.platform.twisted.TwistedResolver`
* `tornado.platform.caresresolver.CaresResolver`
"""
@classmethod
def configurable_base(cls):
return Resolver
@classmethod
def configurable_default(cls):
return BlockingResolver
[docs] def resolve(self, host, port, family=socket.AF_UNSPEC, callback=None):
"""Resolves an address.
The ``host`` argument is a string which may be a hostname or a
literal IP address.
Returns a `.Future` whose result is a list of (family,
address) pairs, where address is a tuple suitable to pass to
`socket.connect <socket.socket.connect>` (i.e. a ``(host,
port)`` pair for IPv4; additional fields may be present for
IPv6). If a ``callback`` is passed, it will be run with the
result as an argument when it is complete.
"""
raise NotImplementedError()
[docs] def close(self):
"""Closes the `Resolver`, freeing any resources used.
.. versionadded:: 3.1
"""
pass
[docs]class ExecutorResolver(Resolver):
"""Resolver implementation using a `concurrent.futures.Executor`.
Use this instead of `ThreadedResolver` when you require additional
control over the executor being used.
The executor will be shut down when the resolver is closed unless
``close_resolver=False``; use this if you want to reuse the same
executor elsewhere.
"""
def initialize(self, io_loop=None, executor=None, close_executor=True):
self.io_loop = io_loop or IOLoop.current()
if executor is not None:
self.executor = executor
self.close_executor = close_executor
else:
self.executor = dummy_executor
self.close_executor = False
def close(self):
if self.close_executor:
self.executor.shutdown()
self.executor = None
@run_on_executor
def resolve(self, host, port, family=socket.AF_UNSPEC):
# On Solaris, getaddrinfo fails if the given port is not found
# in /etc/services and no socket type is given, so we must pass
# one here. The socket type used here doesn't seem to actually
# matter (we discard the one we get back in the results),
# so the addresses we return should still be usable with SOCK_DGRAM.
addrinfo = socket.getaddrinfo(host, port, family, socket.SOCK_STREAM)
results = []
for family, socktype, proto, canonname, address in addrinfo:
results.append((family, address))
return results
[docs]class BlockingResolver(ExecutorResolver):
"""Default `Resolver` implementation, using `socket.getaddrinfo`.
The `.IOLoop` will be blocked during the resolution, although the
callback will not be run until the next `.IOLoop` iteration.
"""
def initialize(self, io_loop=None):
super(BlockingResolver, self).initialize(io_loop=io_loop)
[docs]class ThreadedResolver(ExecutorResolver):
"""Multithreaded non-blocking `Resolver` implementation.
Requires the `concurrent.futures` package to be installed
(available in the standard library since Python 3.2,
installable with ``pip install futures`` in older versions).
The thread pool size can be configured with::
Resolver.configure('tornado.netutil.ThreadedResolver',
num_threads=10)
.. versionchanged:: 3.1
All ``ThreadedResolvers`` share a single thread pool, whose
size is set by the first one to be created.
"""
_threadpool = None
_threadpool_pid = None
def initialize(self, io_loop=None, num_threads=10):
threadpool = ThreadedResolver._create_threadpool(num_threads)
super(ThreadedResolver, self).initialize(
io_loop=io_loop, executor=threadpool, close_executor=False)
@classmethod
def _create_threadpool(cls, num_threads):
pid = os.getpid()
if cls._threadpool_pid != pid:
# Threads cannot survive after a fork, so if our pid isn't what it
# was when we created the pool then delete it.
cls._threadpool = None
if cls._threadpool is None:
from concurrent.futures import ThreadPoolExecutor
cls._threadpool = ThreadPoolExecutor(num_threads)
cls._threadpool_pid = pid
return cls._threadpool
[docs]class OverrideResolver(Resolver):
"""Wraps a resolver with a mapping of overrides.
This can be used to make local DNS changes (e.g. for testing)
without modifying system-wide settings.
The mapping can contain either host strings or host-port pairs.
"""
def initialize(self, resolver, mapping):
self.resolver = resolver
self.mapping = mapping
def close(self):
self.resolver.close()
def resolve(self, host, port, *args, **kwargs):
if (host, port) in self.mapping:
host, port = self.mapping[(host, port)]
elif host in self.mapping:
host = self.mapping[host]
return self.resolver.resolve(host, port, *args, **kwargs)
# These are the keyword arguments to ssl.wrap_socket that must be translated
# to their SSLContext equivalents (the other arguments are still passed
# to SSLContext.wrap_socket).
_SSL_CONTEXT_KEYWORDS = frozenset(['ssl_version', 'certfile', 'keyfile',
'cert_reqs', 'ca_certs', 'ciphers'])
[docs]def ssl_options_to_context(ssl_options):
"""Try to convert an ``ssl_options`` dictionary to an
`~ssl.SSLContext` object.
The ``ssl_options`` dictionary contains keywords to be passed to
`ssl.wrap_socket`. In Python 3.2+, `ssl.SSLContext` objects can
be used instead. This function converts the dict form to its
`~ssl.SSLContext` equivalent, and may be used when a component which
accepts both forms needs to upgrade to the `~ssl.SSLContext` version
to use features like SNI or NPN.
"""
if isinstance(ssl_options, dict):
assert all(k in _SSL_CONTEXT_KEYWORDS for k in ssl_options), ssl_options
if (not hasattr(ssl, 'SSLContext') or
isinstance(ssl_options, ssl.SSLContext)):
return ssl_options
context = ssl.SSLContext(
ssl_options.get('ssl_version', ssl.PROTOCOL_SSLv23))
if 'certfile' in ssl_options:
context.load_cert_chain(ssl_options['certfile'], ssl_options.get('keyfile', None))
if 'cert_reqs' in ssl_options:
context.verify_mode = ssl_options['cert_reqs']
if 'ca_certs' in ssl_options:
context.load_verify_locations(ssl_options['ca_certs'])
if 'ciphers' in ssl_options:
context.set_ciphers(ssl_options['ciphers'])
return context
[docs]def ssl_wrap_socket(socket, ssl_options, server_hostname=None, **kwargs):
"""Returns an ``ssl.SSLSocket`` wrapping the given socket.
``ssl_options`` may be either a dictionary (as accepted by
`ssl_options_to_context`) or an `ssl.SSLContext` object.
Additional keyword arguments are passed to ``wrap_socket``
(either the `~ssl.SSLContext` method or the `ssl` module function
as appropriate).
"""
context = ssl_options_to_context(ssl_options)
if hasattr(ssl, 'SSLContext') and isinstance(context, ssl.SSLContext):
if server_hostname is not None and getattr(ssl, 'HAS_SNI'):
# Python doesn't have server-side SNI support so we can't
# really unittest this, but it can be manually tested with
# python3.2 -m tornado.httpclient https://sni.velox.ch
return context.wrap_socket(socket, server_hostname=server_hostname,
**kwargs)
else:
return context.wrap_socket(socket, **kwargs)
else:
return ssl.wrap_socket(socket, **dict(context, **kwargs))
if hasattr(ssl, 'match_hostname') and hasattr(ssl, 'CertificateError'): # python 3.2+
ssl_match_hostname = ssl.match_hostname
SSLCertificateError = ssl.CertificateError
else:
# match_hostname was added to the standard library ssl module in python 3.2.
# The following code was backported for older releases and copied from
# https://bitbucket.org/brandon/backports.ssl_match_hostname
class SSLCertificateError(ValueError):
pass
def _dnsname_to_pat(dn, max_wildcards=1):
pats = []
for frag in dn.split(r'.'):
if frag.count('*') > max_wildcards:
# Issue #17980: avoid denials of service by refusing more
# than one wildcard per fragment. A survery of established
# policy among SSL implementations showed it to be a
# reasonable choice.
raise SSLCertificateError(
"too many wildcards in certificate DNS name: " + repr(dn))
if frag == '*':
# When '*' is a fragment by itself, it matches a non-empty dotless
# fragment.
pats.append('[^.]+')
else:
# Otherwise, '*' matches any dotless fragment.
frag = re.escape(frag)
pats.append(frag.replace(r'\*', '[^.]*'))
return re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE)
def ssl_match_hostname(cert, hostname):
"""Verify that *cert* (in decoded format as returned by
SSLSocket.getpeercert()) matches the *hostname*. RFC 2818 rules
are mostly followed, but IP addresses are not accepted for *hostname*.
CertificateError is raised on failure. On success, the function
returns nothing.
"""
if not cert:
raise ValueError("empty or no certificate")
dnsnames = []
san = cert.get('subjectAltName', ())
for key, value in san:
if key == 'DNS':
if _dnsname_to_pat(value).match(hostname):
return
dnsnames.append(value)
if not dnsnames:
# The subject is only checked when there is no dNSName entry
# in subjectAltName
for sub in cert.get('subject', ()):
for key, value in sub:
# XXX according to RFC 2818, the most specific Common Name
# must be used.
if key == 'commonName':
if _dnsname_to_pat(value).match(hostname):
return
dnsnames.append(value)
if len(dnsnames) > 1:
raise SSLCertificateError("hostname %r "
"doesn't match either of %s"
% (hostname, ', '.join(map(repr, dnsnames))))
elif len(dnsnames) == 1:
raise SSLCertificateError("hostname %r "
"doesn't match %r"
% (hostname, dnsnames[0]))
else:
raise SSLCertificateError("no appropriate commonName or "
"subjectAltName fields were found")