Add support for stable MSC2858 API (#9617)

The stable format uses different brand identifiers, so we need to support two
identifiers for each IdP.

synapse/handlers/cas_handler.py

@@ -83,6 +83,7 @@ class CasHandler:
         # the SsoIdentityProvider protocol type.
         self.idp_icon = None
         self.idp_brand = None
+        self.unstable_idp_brand = None
 
         self._sso_handler = hs.get_sso_handler()
 

synapse/handlers/oidc_handler.py

@@ -330,6 +330,9 @@ class OidcProvider:
         # optional brand identifier for this auth provider
         self.idp_brand = provider.idp_brand
 
+        # Optional brand identifier for the unstable API (see MSC2858).
+        self.unstable_idp_brand = provider.unstable_idp_brand
+
         self._sso_handler = hs.get_sso_handler()
 
         self._sso_handler.register_identity_provider(self)

synapse/handlers/saml_handler.py

@@ -81,6 +81,7 @@ class SamlHandler(BaseHandler):
         # the SsoIdentityProvider protocol type.
         self.idp_icon = None
         self.idp_brand = None
+        self.unstable_idp_brand = None
 
         # a map from saml session id to Saml2SessionData object
         self._outstanding_requests_dict = {}  # type: Dict[str, Saml2SessionData]

synapse/handlers/sso.py

@@ -98,6 +98,11 @@ class SsoIdentityProvider(Protocol):
         """Optional branding identifier"""
         return None
 
+    @property
+    def unstable_idp_brand(self) -> Optional[str]:
+        """Optional brand identifier for the unstable API (see MSC2858)."""
+        return None
+
     @abc.abstractmethod
     async def handle_redirect_request(
         self,