Implement MSC3231: Token authenticated registration (#10142)

Signed-off-by: Callum Brown <callum@calcuode.com>

This is part of my GSoC project implementing [MSC3231](https://github.com/matrix-org/matrix-doc/pull/3231).

1 files changed, 5 insertions, 0 deletions

diff --git a/synapse/handlers/ui_auth/__init__.py b/synapse/handlers/ui_auth/__init__.py

index 4c3b669fae..13b0c61d2e 100644
--- a/synapse/handlers/ui_auth/__init__.py
+++ b/synapse/handlers/ui_auth/__init__.py
@@ -34,3 +34,8 @@ class UIAuthSessionDataConstants:
     # used by validate_user_via_ui_auth to store the mxid of the user we are validating
     # for.
     REQUEST_USER_ID = "request_user_id"
+
+    # used during registration to store the registration token used (if required) so that:
+    # - we can prevent a token being used twice by one session
+    # - we can 'use up' the token after registration has successfully completed
+    REGISTRATION_TOKEN = "org.matrix.msc3231.login.registration_token"