Handle connecting directly to the event stream URL

src/api/znc-proxy.ts

@@ -213,7 +213,7 @@ export type PresenceUrlResponse =
     Friend | {friend: Friend};
 
 export async function getPresenceFromUrl(presence_url: string, useragent?: string) {
-    const [signal, cancel] = timeoutSignal();
+    const [signal, cancel, controller] = timeoutSignal();
     const response = await fetch(presence_url, {
         headers: {
             'User-Agent': getUserAgent(useragent),
@@ -227,6 +227,11 @@ export async function getPresenceFromUrl(presence_url: string, useragent?: strin
         throw new ErrorResponse('[zncproxy] Unknown error', response, await response.text());
     }
 
+    if (!response.headers.get('Content-Type')?.match(/^application\/json(;|$)$/)) {
+        controller.abort();
+        throw new ErrorResponse('[zncproxy] Unacceptable content type', response);
+    }
+
     const data = await response.json() as PresenceUrlResponse;
 
     const user: CurrentUser | Friend | undefined =

src/cli/presence-server.ts

@@ -515,6 +515,7 @@ class Server extends HttpServer {
 
         while (!req.socket.closed) {
             try {
+                debug('Updating data for event stream %d', stream.id);
                 const result = await this.handlePresenceRequest(req, null, presence_user_nsaid, true);
 
                 stream.sendEvent('update', 'debug: timestamp ' + new Date().toISOString());
@@ -553,6 +554,8 @@ class Server extends HttpServer {
                     });
                 }
 
+                debug('Error in event stream %d', stream.id, err);
+
                 res.end();
                 break;
             }

src/cli/util/http-server.ts

@@ -91,12 +91,25 @@ export class ResponseError extends Error {
 export class EventStreamResponse {
     json_replacer: ((key: string, value: unknown) => any) | null = null;
 
+    private static id = 0;
+    readonly id = EventStreamResponse.id++;
+
     constructor(
         readonly req: Request,
         readonly res: Response,
     ) {
         res.setHeader('Cache-Control', 'no-store');
         res.setHeader('Content-Type', 'text/event-stream');
+
+        console.log('[%s] Event stream %d connected to %s from %s, port %d%s, %s',
+            new Date(), this.id, req.url,
+            req.socket.remoteAddress, req.socket.remotePort,
+            req.headers['x-forwarded-for'] ? ' (' + req.headers['x-forwarded-for'] + ')' : '',
+            req.headers['user-agent']);
+
+        res.on('close', () => {
+            console.log('[%s] Event stream %d closed', new Date(), this.id);
+        });
     }
 
     sendEvent(event: string | null, ...data: unknown[]) {

src/common/presence.ts

@@ -577,6 +577,12 @@ export class ZncProxyDiscordPresence extends Loop {
             }
         } catch (err) {
             if (err instanceof ErrorResponse) {
+                if (err.response.headers.get('Content-Type')?.match(/^text\/event-stream(;|$)/)) {
+                    this.is_sse = true;
+                    debug('Presence URL responded with an event stream');
+                    return LoopResult.OK_SKIP_INTERVAL;
+                }
+
                 const retry_after = err.response.headers.get('Retry-After');
                 if (!retry_after || !/^\d+$/.test(retry_after)) throw err;
 
@@ -635,6 +641,7 @@ export class ZncProxyDiscordPresence extends Loop {
 
         let user: CurrentUser | Friend | undefined = undefined;
         let presence: Presence | null = null;
+        this.last_data = {};
 
         events.onmessage = event => {
             if (event.type === 'message') {

src/util/misc.ts

@@ -34,5 +34,5 @@ export function timeoutSignal(ms = 60 * 1000) {
         controller.abort(new Error('Timeout'));
     }, ms);
 
-    return [controller.signal, () => clearTimeout(timeout)] as const;
+    return [controller.signal, () => clearTimeout(timeout), controller] as const;
 }