Support for routing outbound HTTP requests via a proxy (#6239)

The `http_proxy` and `HTTPS_PROXY` env vars can be set to a `host[:port]` value which should point to a proxy.

The address of the proxy should be excluded from IP blacklists such as the `url_preview_ip_range_blacklist`.

The proxy will then be used for
 * push
 * url previews
 * phone-home stats
 * recaptcha validation
 * CAS auth validation

It will *not* be used for:
 * Application Services
 * Identity servers
 * Outbound federation
 * In worker configurations, connections from workers to masters

Fixes #4198.

1 files changed, 1 insertions, 1 deletions

diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py

index a0cf37a9f9..9a2ff177a6 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -420,7 +420,7 @@ class AuthHandler(BaseHandler):
         # TODO: get this from the homeserver rather than creating a new one for
         # each request
         try:
-            client = self.hs.get_simple_http_client()
+            client = self.hs.get_proxied_http_client()
             resp_body = yield client.post_urlencoded_get_json(
                 self.hs.config.recaptcha_siteverify_api,
                 args={