From 9b6224577e7a387bf94f2332301f21e9514286ff Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Tue, 6 Dec 2022 07:23:03 -0500 Subject: Failover on proper error responses. (#14620) When querying a remote server handle a 404/405 with an errcode of M_UNRECOGNIZED as an unimplemented endpoint. --- changelog.d/14620.bugfix | 1 + synapse/federation/federation_client.py | 29 ++++++++++++++++++++--------- 2 files changed, 21 insertions(+), 9 deletions(-) create mode 100644 changelog.d/14620.bugfix diff --git a/changelog.d/14620.bugfix b/changelog.d/14620.bugfix new file mode 100644 index 0000000000..cb95a87d92 --- /dev/null +++ b/changelog.d/14620.bugfix @@ -0,0 +1 @@ +Return spec-compliant JSON errors when unknown endpoints are requested. diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py index 8bccc9c60d..137cfb3346 100644 --- a/synapse/federation/federation_client.py +++ b/synapse/federation/federation_client.py @@ -771,17 +771,28 @@ class FederationClient(FederationBase): """ if synapse_error is None: synapse_error = e.to_synapse_error() - # There is no good way to detect an "unknown" endpoint. + # MSC3743 specifies that servers should return a 404 or 405 with an errcode + # of M_UNRECOGNIZED when they receive a request to an unknown endpoint or + # to an unknown method, respectively. # - # Dendrite returns a 404 (with a body of "404 page not found"); - # Conduit returns a 404 (with no body); and Synapse returns a 400 - # with M_UNRECOGNIZED. - # - # This needs to be rather specific as some endpoints truly do return 404 - # errors. + # Older versions of servers don't properly handle this. This needs to be + # rather specific as some endpoints truly do return 404 errors. return ( - e.code == 404 and (not e.response or e.response == b"404 page not found") - ) or (e.code == 400 and synapse_error.errcode == Codes.UNRECOGNIZED) + # 404 is an unknown endpoint, 405 is a known endpoint, but unknown method. + (e.code == 404 or e.code == 405) + and ( + # Older Dendrites returned a text or empty body. + # Older Conduit returned an empty body. + not e.response + or e.response == b"404 page not found" + # The proper response JSON with M_UNRECOGNIZED errcode. + or synapse_error.errcode == Codes.UNRECOGNIZED + ) + ) or ( + # Older Synapses returned a 400 error. + e.code == 400 + and synapse_error.errcode == Codes.UNRECOGNIZED + ) async def _try_destination_list( self, -- cgit 1.4.1