Re-introduce the outbound federation proxy (#15913)

Allow configuring the set of workers to proxy outbound federation traffic through (`outbound_federation_restricted_to`).

This is useful when you have a worker setup with `federation_sender` instances responsible for sending outbound federation requests and want to make sure *all* outbound federation traffic goes through those instances. Before this change, the generic workers would still contact federation themselves for things like profile lookups, backfill, etc. This PR allows you to set more strict access controls/firewall for all workers and only allow the `federation_sender`'s to contact the outside world.

1 files changed, 31 insertions, 24 deletions

diff --git a/synapse/http/server.py b/synapse/http/server.py
index e411ac7e62..f592600880 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -18,6 +18,7 @@ import html
 import logging
 import types
 import urllib
+import urllib.parse
 from http import HTTPStatus
 from http.client import FOUND
 from inspect import isawaitable
@@ -65,7 +66,6 @@ from synapse.api.errors import (
     UnrecognizedRequestError,
 )
 from synapse.config.homeserver import HomeServerConfig
-from synapse.http.site import SynapseRequest
 from synapse.logging.context import defer_to_thread, preserve_fn, run_in_background
 from synapse.logging.opentracing import active_span, start_active_span, trace_servlet
 from synapse.util import json_encoder
@@ -76,6 +76,7 @@ from synapse.util.iterutils import chunk_seq
 if TYPE_CHECKING:
     import opentracing
 
+    from synapse.http.site import SynapseRequest
     from synapse.server import HomeServer
 
 logger = logging.getLogger(__name__)
@@ -102,7 +103,7 @@ HTTP_STATUS_REQUEST_CANCELLED = 499
 
 
 def return_json_error(
-    f: failure.Failure, request: SynapseRequest, config: Optional[HomeServerConfig]
+    f: failure.Failure, request: "SynapseRequest", config: Optional[HomeServerConfig]
 ) -> None:
     """Sends a JSON error response to clients."""
 
@@ -220,8 +221,8 @@ def return_html_error(
 
 
 def wrap_async_request_handler(
-    h: Callable[["_AsyncResource", SynapseRequest], Awaitable[None]]
-) -> Callable[["_AsyncResource", SynapseRequest], "defer.Deferred[None]"]:
+    h: Callable[["_AsyncResource", "SynapseRequest"], Awaitable[None]]
+) -> Callable[["_AsyncResource", "SynapseRequest"], "defer.Deferred[None]"]:
     """Wraps an async request handler so that it calls request.processing.
 
     This helps ensure that work done by the request handler after the request is completed
@@ -235,7 +236,7 @@ def wrap_async_request_handler(
     """
 
     async def wrapped_async_request_handler(
-        self: "_AsyncResource", request: SynapseRequest
+        self: "_AsyncResource", request: "SynapseRequest"
     ) -> None:
         with request.processing():
             await h(self, request)
@@ -300,7 +301,7 @@ class _AsyncResource(resource.Resource, metaclass=abc.ABCMeta):
 
         self._extract_context = extract_context
 
-    def render(self, request: SynapseRequest) -> int:
+    def render(self, request: "SynapseRequest") -> int:
         """This gets called by twisted every time someone sends us a request."""
         request.render_deferred = defer.ensureDeferred(
             self._async_render_wrapper(request)
@@ -308,7 +309,7 @@ class _AsyncResource(resource.Resource, metaclass=abc.ABCMeta):
         return NOT_DONE_YET
 
     @wrap_async_request_handler
-    async def _async_render_wrapper(self, request: SynapseRequest) -> None:
+    async def _async_render_wrapper(self, request: "SynapseRequest") -> None:
         """This is a wrapper that delegates to `_async_render` and handles
         exceptions, return values, metrics, etc.
         """
@@ -326,9 +327,15 @@ class _AsyncResource(resource.Resource, metaclass=abc.ABCMeta):
             # of our stack, and thus gives us a sensible stack
             # trace.
             f = failure.Failure()
+            logger.exception(
+                "Error handling request",
+                exc_info=(f.type, f.value, f.getTracebackObject()),
+            )
             self._send_error_response(f, request)
 
-    async def _async_render(self, request: SynapseRequest) -> Optional[Tuple[int, Any]]:
+    async def _async_render(
+        self, request: "SynapseRequest"
+    ) -> Optional[Tuple[int, Any]]:
         """Delegates to `_async_render_<METHOD>` methods, or returns a 400 if
         no appropriate method exists. Can be overridden in sub classes for
         different routing.
@@ -358,7 +365,7 @@ class _AsyncResource(resource.Resource, metaclass=abc.ABCMeta):
     @abc.abstractmethod
     def _send_response(
         self,
-        request: SynapseRequest,
+        request: "SynapseRequest",
         code: int,
         response_object: Any,
     ) -> None:
@@ -368,7 +375,7 @@ class _AsyncResource(resource.Resource, metaclass=abc.ABCMeta):
     def _send_error_response(
         self,
         f: failure.Failure,
-        request: SynapseRequest,
+        request: "SynapseRequest",
     ) -> None:
         raise NotImplementedError()
 
@@ -384,7 +391,7 @@ class DirectServeJsonResource(_AsyncResource):
 
     def _send_response(
         self,
-        request: SynapseRequest,
+        request: "SynapseRequest",
         code: int,
         response_object: Any,
     ) -> None:
@@ -401,7 +408,7 @@ class DirectServeJsonResource(_AsyncResource):
     def _send_error_response(
         self,
         f: failure.Failure,
-        request: SynapseRequest,
+        request: "SynapseRequest",
     ) -> None:
         """Implements _AsyncResource._send_error_response"""
         return_json_error(f, request, None)
@@ -473,7 +480,7 @@ class JsonResource(DirectServeJsonResource):
             )
 
     def _get_handler_for_request(
-        self, request: SynapseRequest
+        self, request: "SynapseRequest"
     ) -> Tuple[ServletCallback, str, Dict[str, str]]:
         """Finds a callback method to handle the given request.
 
@@ -503,7 +510,7 @@ class JsonResource(DirectServeJsonResource):
         # Huh. No one wanted to handle that? Fiiiiiine.
         raise UnrecognizedRequestError(code=404)
 
-    async def _async_render(self, request: SynapseRequest) -> Tuple[int, Any]:
+    async def _async_render(self, request: "SynapseRequest") -> Tuple[int, Any]:
         callback, servlet_classname, group_dict = self._get_handler_for_request(request)
 
         request.is_render_cancellable = is_function_cancellable(callback)
@@ -535,7 +542,7 @@ class JsonResource(DirectServeJsonResource):
     def _send_error_response(
         self,
         f: failure.Failure,
-        request: SynapseRequest,
+        request: "SynapseRequest",
     ) -> None:
         """Implements _AsyncResource._send_error_response"""
         return_json_error(f, request, self.hs.config)
@@ -551,7 +558,7 @@ class DirectServeHtmlResource(_AsyncResource):
 
     def _send_response(
         self,
-        request: SynapseRequest,
+        request: "SynapseRequest",
         code: int,
         response_object: Any,
     ) -> None:
@@ -565,7 +572,7 @@ class DirectServeHtmlResource(_AsyncResource):
     def _send_error_response(
         self,
         f: failure.Failure,
-        request: SynapseRequest,
+        request: "SynapseRequest",
     ) -> None:
         """Implements _AsyncResource._send_error_response"""
         return_html_error(f, request, self.ERROR_TEMPLATE)
@@ -592,7 +599,7 @@ class UnrecognizedRequestResource(resource.Resource):
     errcode of M_UNRECOGNIZED.
     """
 
-    def render(self, request: SynapseRequest) -> int:
+    def render(self, request: "SynapseRequest") -> int:
         f = failure.Failure(UnrecognizedRequestError(code=404))
         return_json_error(f, request, None)
         # A response has already been sent but Twisted requires either NOT_DONE_YET
@@ -622,7 +629,7 @@ class RootRedirect(resource.Resource):
 class OptionsResource(resource.Resource):
     """Responds to OPTION requests for itself and all children."""
 
-    def render_OPTIONS(self, request: SynapseRequest) -> bytes:
+    def render_OPTIONS(self, request: "SynapseRequest") -> bytes:
         request.setResponseCode(204)
         request.setHeader(b"Content-Length", b"0")
 
@@ -737,7 +744,7 @@ def _encode_json_bytes(json_object: object) -> bytes:
 
 
 def respond_with_json(
-    request: SynapseRequest,
+    request: "SynapseRequest",
     code: int,
     json_object: Any,
     send_cors: bool = False,
@@ -787,7 +794,7 @@ def respond_with_json(
 
 
 def respond_with_json_bytes(
-    request: SynapseRequest,
+    request: "SynapseRequest",
     code: int,
     json_bytes: bytes,
     send_cors: bool = False,
@@ -825,7 +832,7 @@ def respond_with_json_bytes(
 
 
 async def _async_write_json_to_request_in_thread(
-    request: SynapseRequest,
+    request: "SynapseRequest",
     json_encoder: Callable[[Any], bytes],
     json_object: Any,
 ) -> None:
@@ -883,7 +890,7 @@ def _write_bytes_to_request(request: Request, bytes_to_write: bytes) -> None:
     _ByteProducer(request, bytes_generator)
 
 
-def set_cors_headers(request: SynapseRequest) -> None:
+def set_cors_headers(request: "SynapseRequest") -> None:
     """Set the CORS headers so that javascript running in a web browsers can
     use this API
 
@@ -981,7 +988,7 @@ def set_clickjacking_protection_headers(request: Request) -> None:
 
 
 def respond_with_redirect(
-    request: SynapseRequest, url: bytes, statusCode: int = FOUND, cors: bool = False
+    request: "SynapseRequest", url: bytes, statusCode: int = FOUND, cors: bool = False
 ) -> None:
     """
     Write a 302 (or other specified status code) response to the request, if it is still alive.