By default the homeserver will use the identity server used during the
binding of the 3PID to unbind the 3PID. However, we need to allow
clients to explicitly ask the homeserver to unbind via a particular
identity server, for the case where the 3PID was bound out of band from
the homeserver.
Implements MSC915.
This changes the behaviour from using the server specified trusted
identity server to using the IS that used during the binding of the
3PID, if known.
This is the behaviour specified by MSC1915.
Older identity servers may not support the unbind 3pid request, so we
shouldn't fail the requests if we received one of 400/404/501. The
request still fails if we receive e.g. 500 responses, allowing clients
to retry requests on transient identity server errors that otherwise do
support the API.
Fixes#3661
This code brings the SimpleHttpClient into line with the
MatrixFederationHttpClient by having it raise HttpResponseExceptions when a
request fails (rather than trying to parse for matrix errors and maybe raising
MatrixCodeMessageException).
Then, whenever we were checking for MatrixCodeMessageException and turning them
into SynapseErrors, we now need to check for HttpResponseExceptions and call
to_synapse_error.
Don't send requestToken request to untrusted ID servers
Also correct the THREEPID_IN_USE error to add the M_ prefix. This is a backwards incomaptible change, but the only thing using this is the angular client which is now unmaintained, so it's probably better to just do this now.
Erik Johnston