Support trying multiple localparts for OpenID Connect. (#8801)

Abstracts the SAML and OpenID Connect code which attempts to regenerate
the localpart of a matrix ID if it is already in use.

1 files changed, 10 insertions, 1 deletions

diff --git a/docs/sso_mapping_providers.md b/docs/sso_mapping_providers.md
index 707dd73978..dee53b5d40 100644
--- a/docs/sso_mapping_providers.md
+++ b/docs/sso_mapping_providers.md
@@ -63,13 +63,22 @@ A custom mapping provider must specify the following methods:
                      information from.
     - This method must return a string, which is the unique identifier for the
       user. Commonly the ``sub`` claim of the response.
-* `map_user_attributes(self, userinfo, token)`
+* `map_user_attributes(self, userinfo, token, failures)`
     - This method must be async.
     - Arguments:
       - `userinfo` - A `authlib.oidc.core.claims.UserInfo` object to extract user
                      information from.
       - `token` - A dictionary which includes information necessary to make
                   further requests to the OpenID provider.
+      - `failures` - An `int` that represents the amount of times the returned
+                     mxid localpart mapping has failed.  This should be used
+                     to create a deduplicated mxid localpart which should be
+                     returned instead. For example, if this method returns
+                     `john.doe` as the value of `localpart` in the returned
+                     dict, and that is already taken on the homeserver, this
+                     method will be called again with the same parameters but
+                     with failures=1. The method should then return a different
+                     `localpart` value, such as `john.doe1`.
     - Returns a dictionary with two keys:
       - localpart: A required string, used to generate the Matrix ID.
       - displayname: An optional string, the display name for the user.