Catch errors on websocket connections (#940)

* Catch errors on websocket connections

Signed-off-by: Matteo Collina <[email protected]>

* fixup

Signed-off-by: Matteo Collina <[email protected]>

Signed-off-by: Matteo Collina <[email protected]>

lib/subscription-connection.js

@@ -37,7 +37,11 @@ module.exports = class SubscriptionConnection {
 
     this.protocolMessageTypes = getProtocolByName(socket.protocol)
     this.socket.on('error', this.handleConnectionClose.bind(this))
-    this.handleConnection()
+
+    // We need a catch here because the socket might be closed before the connection is established
+    // and we don't want to crash the server. Note that the errors are already
+    // logged elsewhere @fastify/websocket so there is no need to log them again.
+    this.handleConnection().catch(noop)
   }
 
   async handleConnection () {
@@ -301,3 +305,5 @@ module.exports = class SubscriptionConnection {
     this.handleConnectionClose()
   }
 }
+
+function noop () {}

test/subscription.js

@@ -5,6 +5,7 @@ const mq = require('mqemitter')
 const { EventEmitter } = require('events')
 const fastifyWebsocket = require('@fastify/websocket')
 const GQL = require('..')
+const { once } = require('events')
 
 const FakeTimers = require('@sinonjs/fake-timers')
 
@@ -2049,3 +2050,34 @@ test('subscription passes context to its loaders', t => {
     })
   })
 })
+
+test('wrong messages do not crash the server', async (t) => {
+  const schema = `
+    type Query {
+      add(x: Int, y: Int): Int
+    }
+  `
+
+  const resolvers = {
+    Query: {
+      add: async (_, { x, y }) => x + y
+    }
+  }
+
+  const fastify = Fastify()
+  fastify.register(GQL, {
+    schema,
+    resolvers,
+    subscription: true
+  })
+
+  await fastify.listen({ port: 0 })
+
+  t.teardown(fastify.close.bind(fastify))
+
+  const ws = new WebSocket(`ws://127.0.0.1:${fastify.server.address().port}/graphql`, 'graphql-ws')
+
+  await once(ws, 'open')
+  ws._socket.write(Buffer.from([0xa2, 0x00]))
+  await once(ws, 'close')
+})