fix(fastify-websocket): Handle server emitted errors

enisdenjo · Oct 27, 2021 · 3fa17a7 · 3fa17a7
1 parent cb16588
commit 3fa17a7
Show file tree

Hide file tree

Showing 2 changed files with 39 additions and 5 deletions.
diff --git a/src/__tests__/use.ts b/src/__tests__/use.ts
@@ -355,8 +355,7 @@ for (const { tServer, itForWS, skipUWS, startTServer } of tServers) {
     });
 
     // uWebSocket.js cannot have errors emitted on the server instance
-    // TODO-db-211027 fastify-websocket
-    itForWS(
+    skipUWS(
       'should report server emitted errors to clients by closing the connection',
       async () => {
         const { url, server } = await startTServer();
@@ -376,8 +375,7 @@ for (const { tServer, itForWS, skipUWS, startTServer } of tServers) {
     );
 
     // uWebSocket.js cannot have errors emitted on the server instance
-    // TODO-db-211027 fastify-websocket
-    itForWS('should limit the server emitted error message size', async () => {
+    skipUWS('should limit the server emitted error message size', async () => {
       const { url, server, waitForClient } = await startTServer();
 
       const client = await createTClient(url);

diff --git a/src/use/fastify-websocket.ts b/src/use/fastify-websocket.ts
@@ -43,9 +43,45 @@ export function makeHandler<
   const isProd = process.env.NODE_ENV === 'production';
   const server = makeServer(options);
 
-  return (connection, request) => {
+  // we dont have access to the fastify-websocket server instance yet,
+  // register an error handler on first connection ONCE only
+  let handlingServerEmittedErrors = false;
+
+  return function handler(connection, request) {
     const { socket } = connection;
 
+    // handle server emitted errors only if not already handling
+    if (!handlingServerEmittedErrors) {
+      handlingServerEmittedErrors = true;
+      this.websocketServer.once('error', (err) => {
+        console.error(
+          'Internal error emitted on the WebSocket server. ' +
+            'Please check your implementation.',
+          err,
+        );
+
+        // catch the first thrown error and re-throw it once all clients have been notified
+        let firstErr: Error | null = null;
+
+        // report server errors by erroring out all clients with the same error
+        for (const client of this.websocketServer.clients) {
+          try {
+            client.close(
+              CloseCode.InternalServerError,
+              // close reason should fit in one frame https://datatracker.ietf.org/doc/html/rfc6455#section-5.2
+              isProd || err.message.length > 123
+                ? 'Internal server error'
+                : err.message,
+            );
+          } catch (err) {
+            firstErr = firstErr ?? err;
+          }
+        }
+
+        if (firstErr) throw firstErr;
+      });
+    }
+
     // used as listener on two streams, prevent superfluous calls on close
     let emittedErrorHandled = false;
     function handleEmittedError(err: Error) {