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# -*- coding: utf-8 -*-
# Copyright 2019 The Matrix.org Foundation C.I.C.
#
# 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.
import logging
import re
from urllib.request import getproxies_environment, proxy_bypass_environment
from zope.interface import implementer
from twisted.internet import defer
from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
from twisted.python.failure import Failure
from twisted.web.client import URI, BrowserLikePolicyForHTTPS, _AgentBase
from twisted.web.error import SchemeNotSupported
from twisted.web.iweb import IAgent
from synapse.http.connectproxyclient import HTTPConnectProxyEndpoint
logger = logging.getLogger(__name__)
_VALID_URI = re.compile(br"\A[\x21-\x7e]+\Z")
@implementer(IAgent)
class ProxyAgent(_AgentBase):
"""An Agent implementation which will use an HTTP proxy if one was requested
Args:
reactor: twisted reactor to place outgoing
connections.
proxy_reactor: twisted reactor to use for connections to the proxy server
reactor might have some blacklisting applied (i.e. for DNS queries),
but we need unblocked access to the proxy.
contextFactory (IPolicyForHTTPS): A factory for TLS contexts, to control the
verification parameters of OpenSSL. The default is to use a
`BrowserLikePolicyForHTTPS`, so unless you have special
requirements you can leave this as-is.
connectTimeout (Optional[float]): The amount of time that this Agent will wait
for the peer to accept a connection, in seconds. If 'None',
HostnameEndpoint's default (30s) will be used.
This is used for connections to both proxies and destination servers.
bindAddress (bytes): The local address for client sockets to bind to.
pool (HTTPConnectionPool|None): connection pool to be used. If None, a
non-persistent pool instance will be created.
use_proxy (bool): Whether proxy settings should be discovered and used
from conventional environment variables.
"""
def __init__(
self,
reactor,
proxy_reactor=None,
contextFactory=BrowserLikePolicyForHTTPS(),
connectTimeout=None,
bindAddress=None,
pool=None,
use_proxy=False,
):
_AgentBase.__init__(self, reactor, pool)
if proxy_reactor is None:
self.proxy_reactor = reactor
else:
self.proxy_reactor = proxy_reactor
self._endpoint_kwargs = {}
if connectTimeout is not None:
self._endpoint_kwargs["timeout"] = connectTimeout
if bindAddress is not None:
self._endpoint_kwargs["bindAddress"] = bindAddress
http_proxy = None
https_proxy = None
no_proxy = None
if use_proxy:
proxies = getproxies_environment()
http_proxy = proxies["http"].encode() if "http" in proxies else None
https_proxy = proxies["https"].encode() if "https" in proxies else None
no_proxy = proxies["no"] if "no" in proxies else None
self.http_proxy_endpoint = _http_proxy_endpoint(
http_proxy, self.proxy_reactor, **self._endpoint_kwargs
)
self.https_proxy_endpoint = _http_proxy_endpoint(
https_proxy, self.proxy_reactor, **self._endpoint_kwargs
)
self.no_proxy = no_proxy
self._policy_for_https = contextFactory
self._reactor = reactor
def request(self, method, uri, headers=None, bodyProducer=None):
"""
Issue a request to the server indicated by the given uri.
Supports `http` and `https` schemes.
An existing connection from the connection pool may be used or a new one may be
created.
See also: twisted.web.iweb.IAgent.request
Args:
method (bytes): The request method to use, such as `GET`, `POST`, etc
uri (bytes): The location of the resource to request.
headers (Headers|None): Extra headers to send with the request
bodyProducer (IBodyProducer|None): An object which can generate bytes to
make up the body of this request (for example, the properly encoded
contents of a file for a file upload). Or, None if the request is to
have no body.
Returns:
Deferred[IResponse]: completes when the header of the response has
been received (regardless of the response status code).
Can fail with:
SchemeNotSupported: if the uri is not http or https
twisted.internet.error.TimeoutError if the server we are connecting
to (proxy or destination) does not accept a connection before
connectTimeout.
... other things too.
"""
uri = uri.strip()
if not _VALID_URI.match(uri):
raise ValueError("Invalid URI {!r}".format(uri))
parsed_uri = URI.fromBytes(uri)
pool_key = (parsed_uri.scheme, parsed_uri.host, parsed_uri.port)
request_path = parsed_uri.originForm
should_skip_proxy = False
if self.no_proxy is not None:
should_skip_proxy = proxy_bypass_environment(
parsed_uri.host.decode(),
proxies={"no": self.no_proxy},
)
if (
parsed_uri.scheme == b"http"
and self.http_proxy_endpoint
and not should_skip_proxy
):
# Cache *all* connections under the same key, since we are only
# connecting to a single destination, the proxy:
pool_key = ("http-proxy", self.http_proxy_endpoint)
endpoint = self.http_proxy_endpoint
request_path = uri
elif (
parsed_uri.scheme == b"https"
and self.https_proxy_endpoint
and not should_skip_proxy
):
endpoint = HTTPConnectProxyEndpoint(
self.proxy_reactor,
self.https_proxy_endpoint,
parsed_uri.host,
parsed_uri.port,
)
else:
# not using a proxy
endpoint = HostnameEndpoint(
self._reactor, parsed_uri.host, parsed_uri.port, **self._endpoint_kwargs
)
logger.debug("Requesting %s via %s", uri, endpoint)
if parsed_uri.scheme == b"https":
tls_connection_creator = self._policy_for_https.creatorForNetloc(
parsed_uri.host, parsed_uri.port
)
endpoint = wrapClientTLS(tls_connection_creator, endpoint)
elif parsed_uri.scheme == b"http":
pass
else:
return defer.fail(
Failure(
SchemeNotSupported("Unsupported scheme: %r" % (parsed_uri.scheme,))
)
)
return self._requestWithEndpoint(
pool_key, endpoint, method, parsed_uri, headers, bodyProducer, request_path
)
def _http_proxy_endpoint(proxy, reactor, **kwargs):
"""Parses an http proxy setting and returns an endpoint for the proxy
Args:
proxy (bytes|None): the proxy setting
reactor: reactor to be used to connect to the proxy
kwargs: other args to be passed to HostnameEndpoint
Returns:
interfaces.IStreamClientEndpoint|None: endpoint to use to connect to the proxy,
or None
"""
if proxy is None:
return None
# currently we only support hostname:port. Some apps also support
# protocol://<host>[:port], which allows a way of requiring a TLS connection to the
# proxy.
host, port = parse_host_port(proxy, default_port=1080)
return HostnameEndpoint(reactor, host, port, **kwargs)
def parse_host_port(hostport, default_port=None):
# could have sworn we had one of these somewhere else...
if b":" in hostport:
host, port = hostport.rsplit(b":", 1)
try:
port = int(port)
return host, port
except ValueError:
# the thing after the : wasn't a valid port; presumably this is an
# IPv6 address.
pass
return hostport, default_port
|
