fix: spell out the delegated port and serve well-known as json

Author: eleboucher

src/index.ts

@@ -29,9 +29,11 @@ export default {
 		const url = new URL(request.url);
 		// The address it is reached on, unless a deployment pins another one:
 		// a placeholder default ships on every deploy and delegates the media
-		// away from this worker.
+		// away from this worker. The port is always spelled out: a port-less
+		// delegation sends the requesting server to an SRV lookup and then to
+		// 8448, which no worker answers on.
 		const serverName = env.SERVERNAME || url.hostname;
-		const delegate = env.HOSTNAME ? `${env.HOSTNAME}:${env.PORT || 443}` : url.host;
+		const delegate = `${env.HOSTNAME || url.hostname}:${env.PORT || url.port || 443}`;
 
 		if (url.pathname === '/_matrix/federation/v1/version') {
 			return new Response(JSON.stringify(returnMatrixServerVers()), {
@@ -60,7 +62,9 @@ export default {
 				mxcId: matrixId
 			} satisfies SoliditasAddressConvertResponse))
 		} else if (url.pathname === '/.well-known/matrix/server') {
-			return new Response(JSON.stringify({ 'm.server': delegate } satisfies MatrixWellKnownServer));
+			return new Response(JSON.stringify({ 'm.server': delegate } satisfies MatrixWellKnownServer), {
+				headers: { 'Content-Type': 'application/json' },
+			});
 		} else {
 			return new Response(JSON.stringify(matrixEndpointNotImplemented('only implements media endpoints')), {
 				headers: { 'Content-Type': 'application/json' },

test/index.spec.ts

@@ -12,7 +12,18 @@ describe('well-known delegation', () => {
 			{}
 		);
 
-		expect(await response.json()).toEqual({ 'm.server': 'gifs.example' });
+		expect(await response.json()).toEqual({ 'm.server': 'gifs.example:443' });
+		expect(response.headers.get('Content-Type')).toBe('application/json');
+	});
+
+	it('keeps the port it was reached on', async () => {
+		const response = await worker.fetch(
+			{ url: 'https://gifs.example:8443/.well-known/matrix/server' },
+			env,
+			{}
+		);
+
+		expect(await response.json()).toEqual({ 'm.server': 'gifs.example:8443' });
 	});
 
 	it('delegates to a pinned hostname and port when one is configured', async () => {