UI Auth via SSO: redirect the user to an appropriate SSO. (#9081)

If we have integrations with multiple identity providers, when the user does a UI Auth, we need to redirect them to the right one.

There are a few steps to this. First of all we actually need to store the userid of the user we are trying to validate in the UIA session, since the /auth/sso/fallback/web request is unauthenticated.

Then, once we get the /auth/sso/fallback/web request, we can fish the user id out of the session, and use it to look up the external id mappings, and hence pick an SSO provider for them.

1 files changed, 15 insertions, 0 deletions

diff --git a/synapse/handlers/ui_auth/__init__.py b/synapse/handlers/ui_auth/__init__.py
index 824f37f8f8..a68d5e790e 100644
--- a/synapse/handlers/ui_auth/__init__.py
+++ b/synapse/handlers/ui_auth/__init__.py
@@ -20,3 +20,18 @@ TODO: move more stuff out of AuthHandler in here.
 """
 
 from synapse.handlers.ui_auth.checkers import INTERACTIVE_AUTH_CHECKERS  # noqa: F401
+
+
+class UIAuthSessionDataConstants:
+    """Constants for use with AuthHandler.set_session_data"""
+
+    # used during registration and password reset to store a hashed copy of the
+    # password, so that the client does not need to submit it each time.
+    PASSWORD_HASH = "password_hash"
+
+    # used during registration to store the mxid of the registered user
+    REGISTERED_USER_ID = "registered_user_id"
+
+    # used by validate_user_via_ui_auth to store the mxid of the user we are validating
+    # for.
+    REQUEST_USER_ID = "request_user_id"