From 9b2223e38303aa64482ec1e2bee957748383704e Mon Sep 17 00:00:00 2001
From: Half-Shot <will@half-shot.uk>
Date: Mon, 21 Jul 2025 11:30:51 +0100
Subject: [PATCH] Trim roomId when parsing from URL

---
 src/UrlParams.test.ts | 10 ++++++++++
 src/UrlParams.ts      | 12 ++++++++----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/UrlParams.test.ts b/src/UrlParams.test.ts
index b65638e0..14635a91 100644
--- a/src/UrlParams.test.ts
+++ b/src/UrlParams.test.ts
@@ -82,6 +82,16 @@ describe("UrlParams", () => {
         getRoomIdentifierFromUrl("", `?roomId=${ROOM_ID}`, "").roomId,
       ).toBe(ROOM_ID);
     });
+    it("(roomId with unprintable chatacters)", () => {
+      const invisibleChar = "⁦";
+      expect(
+        getRoomIdentifierFromUrl(
+          "",
+          `?roomId=${invisibleChar}${ROOM_ID}${invisibleChar}`,
+          "",
+        ).roomId,
+      ).toBe(ROOM_ID);
+    });
   });
 
   it("ignores room alias", () => {
diff --git a/src/UrlParams.ts b/src/UrlParams.ts
index 9f89fd47..3b55ed2a 100644
--- a/src/UrlParams.ts
+++ b/src/UrlParams.ts
@@ -387,10 +387,14 @@ export function getRoomIdentifierFromUrl(
 
   // Make sure roomId is valid
   let roomId: string | null = parser.getParam("roomId");
-  if (!roomId?.startsWith("!")) {
-    roomId = null;
-  } else if (!roomId.includes("")) {
-    roomId = null;
+  if (roomId !== null) {
+    // Replace any non-printable characters that another client may have inserted.
+    roomId = roomId.replaceAll(/^[^ -~]+|[^ -~]+$/g, "");
+    if (!roomId.startsWith("!")) {
+      roomId = null;
+    } else if (!roomId.includes("")) {
+      roomId = null;
+    }
   }
 
   return {