Don't apply the IP range blacklist to proxy connections (#9084)

It is expected that the proxy would be on a private IP address so the
configured proxy should be connected to regardless of the IP range
blacklist.

1 files changed, 13 insertions, 3 deletions

diff --git a/synapse/http/proxyagent.py b/synapse/http/proxyagent.py

index e32d3f43e0..b730d2c634 100644
--- a/synapse/http/proxyagent.py
+++ b/synapse/http/proxyagent.py
@@ -39,6 +39,10 @@ class ProxyAgent(_AgentBase):
         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
@@ -59,6 +63,7 @@ class ProxyAgent(_AgentBase):
     def __init__(
         self,
         reactor,
+        proxy_reactor=None,
         contextFactory=BrowserLikePolicyForHTTPS(),
         connectTimeout=None,
         bindAddress=None,
@@ -68,6 +73,11 @@ class ProxyAgent(_AgentBase):
     ):
         _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
@@ -75,11 +85,11 @@ class ProxyAgent(_AgentBase):
             self._endpoint_kwargs["bindAddress"] = bindAddress
 
         self.http_proxy_endpoint = _http_proxy_endpoint(
-            http_proxy, reactor, **self._endpoint_kwargs
+            http_proxy, self.proxy_reactor, **self._endpoint_kwargs
         )
 
         self.https_proxy_endpoint = _http_proxy_endpoint(
-            https_proxy, reactor, **self._endpoint_kwargs
+            https_proxy, self.proxy_reactor, **self._endpoint_kwargs
         )
 
         self._policy_for_https = contextFactory
@@ -137,7 +147,7 @@ class ProxyAgent(_AgentBase):
             request_path = uri
         elif parsed_uri.scheme == b"https" and self.https_proxy_endpoint:
             endpoint = HTTPConnectProxyEndpoint(
-                self._reactor,
+                self.proxy_reactor,
                 self.https_proxy_endpoint,
                 parsed_uri.host,
                 parsed_uri.port,