Pass additional headers from the worker to the main process.

changelog.d/7797.bugfix

@@ -0,0 +1 @@
+Fixes a long standing bug in worker mode where worker information was saved in the devices table instead of the original IP address and user agent.

synapse/app/generic_worker.py

@@ -206,10 +206,16 @@ async def on_POST(self, request, device_id):
 
         if body:
             # They're actually trying to upload something, proxy to main synapse.
-            # Pass through the auth headers, if any, in case the access token
-            # is there.
-            auth_headers = request.requestHeaders.getRawHeaders(b"Authorization", [])
-            headers = {"Authorization": auth_headers}
+
+            # Proxy headers from the original request, such as the auth headers
+            # (in case the access token is there) and the original IP /
+            # User-Agent of the request.
+            headers = {}
+            for header in (b"Authorization", b"X-Forwarded-For", b"User-Agent"):
+                header_value = request.requestHeaders.getRawHeaders(header)
+                if header_value:
+                    headers[header] = header_value
+
             try:
                 result = await self.http_client.post_json_get_json(
                     self.main_uri + request.uri.decode("ascii"), body, headers=headers