From ff65153f7b312427d88fea8b6c6b05461c3696c0 Mon Sep 17 00:00:00 2001
From: Quentin Gliech <quenting@element.io>
Date: Mon, 28 Apr 2025 17:29:54 +0200
Subject: [PATCH] Don't check for availability of usernames that aren't ASCII

---
 crates/matrix-synapse/src/lib.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/crates/matrix-synapse/src/lib.rs b/crates/matrix-synapse/src/lib.rs
index 1b6627afe..b551c912d 100644
--- a/crates/matrix-synapse/src/lib.rs
+++ b/crates/matrix-synapse/src/lib.rs
@@ -209,6 +209,12 @@ impl HomeserverConnection for SynapseConnection {
         err(Debug),
     )]
     async fn is_localpart_available(&self, localpart: &str) -> Result<bool, anyhow::Error> {
+        // Synapse will give us a M_UNKNOWN error if the localpart is not ASCII,
+        // so we bail out early
+        if !localpart.is_ascii() {
+            return Ok(false);
+        }
+
         let localpart = urlencoding::encode(localpart);
 
         let response = self