Support for MSC4108 via delegation (#17086)

This adds support for MSC4108 via delegation, similar to what has been done for MSC3886

---------

Co-authored-by: Hugh Nimmo-Smith <hughns@element.io>

1 files changed, 12 insertions, 1 deletions

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

index c76500e14f..45b2cbffcd 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -909,7 +909,18 @@ def set_cors_headers(request: "SynapseRequest") -> None:
     request.setHeader(
         b"Access-Control-Allow-Methods", b"GET, HEAD, POST, PUT, DELETE, OPTIONS"
     )
-    if request.experimental_cors_msc3886:
+    if request.path is not None and request.path.startswith(
+        b"/_matrix/client/unstable/org.matrix.msc4108/rendezvous"
+    ):
+        request.setHeader(
+            b"Access-Control-Allow-Headers",
+            b"Content-Type, If-Match, If-None-Match",
+        )
+        request.setHeader(
+            b"Access-Control-Expose-Headers",
+            b"Synapse-Trace-Id, Server, ETag",
+        )
+    elif request.experimental_cors_msc3886:
         request.setHeader(
             b"Access-Control-Allow-Headers",
             b"X-Requested-With, Content-Type, Authorization, Date, If-Match, If-None-Match",