From 6bf811a7f4fc8152706b709faff92b47fffc8cd1 Mon Sep 17 00:00:00 2001
From: Quentin Gliech <quenting@element.io>
Date: Tue, 2 Dec 2025 18:09:47 +0100
Subject: [PATCH] Add the Matrix user display name in the compat SSO login
 context

---
 .../handlers/src/compat/login_sso_complete.rs | 41 +++++++++++++++++--
 crates/templates/src/context.rs               | 29 +++++++++----
 2 files changed, 58 insertions(+), 12 deletions(-)

diff --git a/crates/handlers/src/compat/login_sso_complete.rs b/crates/handlers/src/compat/login_sso_complete.rs
index a4fbb24fb..0062a65da 100644
--- a/crates/handlers/src/compat/login_sso_complete.rs
+++ b/crates/handlers/src/compat/login_sso_complete.rs
@@ -4,7 +4,7 @@
 // SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
 // Please see LICENSE files in the repository root for full details.
 
-use std::collections::HashMap;
+use std::{collections::HashMap, sync::Arc};
 
 use anyhow::Context;
 use axum::{
@@ -18,7 +18,8 @@ use mas_axum_utils::{
     cookies::CookieJar,
     csrf::{CsrfExt, ProtectedForm},
 };
-use mas_data_model::{BoxClock, BoxRng, Clock};
+use mas_data_model::{BoxClock, BoxRng, Clock, MatrixUser};
+use mas_matrix::HomeserverConnection;
 use mas_router::{CompatLoginSsoAction, UrlBuilder};
 use mas_storage::{BoxRepository, RepositoryAccess, compat::CompatSsoLoginRepository};
 use mas_templates::{CompatSsoContext, ErrorContext, TemplateContext, Templates};
@@ -56,6 +57,7 @@ pub async fn get(
     mut repo: BoxRepository,
     State(templates): State<Templates>,
     State(url_builder): State<UrlBuilder>,
+    State(homeserver): State<Arc<dyn HomeserverConnection>>,
     cookie_jar: CookieJar,
     Path(id): Path<Ulid>,
     Query(params): Query<Params>,
@@ -96,6 +98,9 @@ pub async fn get(
         .context("Could not find compat SSO login")
         .map_err(InternalError::from_anyhow)?;
 
+    // We can close the repository early, we don't need it at this point
+    repo.save().await?;
+
     // Bail out if that login session is more than 30min old
     if clock.now() > login.created_at + Duration::microseconds(30 * 60 * 1000 * 1000) {
         let ctx = ErrorContext::new()
@@ -107,7 +112,37 @@ pub async fn get(
         return Ok((cookie_jar, Html(content)).into_response());
     }
 
-    let ctx = CompatSsoContext::new(login)
+    // Fetch informations about the user. This is purely cosmetic, so we let it
+    // fail and put a 1s timeout to it in case we fail to query it
+    // XXX: we're likely to need this in other places
+    let localpart = &session.user.username;
+    let display_name = match tokio::time::timeout(
+        std::time::Duration::from_secs(1),
+        homeserver.query_user(localpart),
+    )
+    .await
+    {
+        Ok(Ok(user)) => user.displayname,
+        Ok(Err(err)) => {
+            tracing::warn!(
+                error = &*err as &dyn std::error::Error,
+                localpart,
+                "Failed to query user"
+            );
+            None
+        }
+        Err(_) => {
+            tracing::warn!(localpart, "Timed out while querying user");
+            None
+        }
+    };
+
+    let matrix_user = MatrixUser {
+        mxid: homeserver.mxid(localpart),
+        display_name,
+    };
+
+    let ctx = CompatSsoContext::new(login, matrix_user)
         .with_session(session)
         .with_csrf(csrf_token.form_value())
         .with_language(locale);
diff --git a/crates/templates/src/context.rs b/crates/templates/src/context.rs
index 73a38972f..c881198f8 100644
--- a/crates/templates/src/context.rs
+++ b/crates/templates/src/context.rs
@@ -872,6 +872,7 @@ impl PolicyViolationContext {
 pub struct CompatSsoContext {
     login: CompatSsoLogin,
     action: PostAuthAction,
+    matrix_user: MatrixUser,
 }
 
 impl TemplateContext for CompatSsoContext {
@@ -884,23 +885,33 @@ impl TemplateContext for CompatSsoContext {
         Self: Sized,
     {
         let id = Ulid::from_datetime_with_source(now.into(), rng);
-        sample_list(vec![CompatSsoContext::new(CompatSsoLogin {
-            id,
-            redirect_uri: Url::parse("https://app.element.io/").unwrap(),
-            login_token: "abcdefghijklmnopqrstuvwxyz012345".into(),
-            created_at: now,
-            state: CompatSsoLoginState::Pending,
-        })])
+        sample_list(vec![CompatSsoContext::new(
+            CompatSsoLogin {
+                id,
+                redirect_uri: Url::parse("https://app.element.io/").unwrap(),
+                login_token: "abcdefghijklmnopqrstuvwxyz012345".into(),
+                created_at: now,
+                state: CompatSsoLoginState::Pending,
+            },
+            MatrixUser {
+                mxid: "@alice:example.com".to_owned(),
+                display_name: Some("Alice".to_owned()),
+            },
+        )])
     }
 }
 
 impl CompatSsoContext {
     /// Constructs a context for the legacy SSO login page
     #[must_use]
-    pub fn new(login: CompatSsoLogin) -> Self
+    pub fn new(login: CompatSsoLogin, matrix_user: MatrixUser) -> Self
 where {
         let action = PostAuthAction::continue_compat_sso_login(login.id);
-        Self { login, action }
+        Self {
+            login,
+            action,
+            matrix_user,
+        }
     }
 }