fix: handle socket errors during upgrade hooks

index.js

@@ -110,6 +110,10 @@ function fastifyWebsocket (fastify, opts, next) {
   fastify.decorate('injectWS', injectWS)
 
   function onUpgrade (rawRequest, socket, head) {
+    // Node removes its socket error listener before emitting 'upgrade'. Keep
+    // the socket guarded while Fastify runs hooks and routes the request.
+    socket.on('error', onUpgradeSocketError)
+
     // Save a reference to the socket and then dispatch the request through the normal fastify router so that it will invoke hooks and then eventually a route handler that might upgrade the socket.
     rawRequest[kWs] = socket
     rawRequest[kWsHead] = head
@@ -124,13 +128,20 @@ function fastifyWebsocket (fastify, opts, next) {
   websocketListenServer.on('upgrade', onUpgrade)
 
   const handleUpgrade = (rawRequest, callback) => {
+    // `ws` installs its own socket error listener synchronously in
+    // handleUpgrade, so it is safe to hand error ownership over here.
+    rawRequest[kWs].removeListener('error', onUpgradeSocketError)
     wss.handleUpgrade(rawRequest, rawRequest[kWs], rawRequest[kWsHead], (socket) => {
       wss.emit('connection', socket, rawRequest)
 
       callback(socket)
     })
   }
 
+  function onUpgradeSocketError () {
+    this.destroy()
+  }
+
   fastify.addHook('onRequest', (request, _reply, done) => { // this adds req.ws to the Request object
     if (request.raw[kWs]) {
       request.ws = true

test/base.test.js

@@ -1,6 +1,7 @@
 'use strict'
 
 const http = require('node:http')
+const net = require('node:net')
 const split = require('split2')
 const { test } = require('node:test')
 const Fastify = require('fastify')
@@ -223,6 +224,45 @@ test('Should run custom errorHandler when the raw socket emits an error', async
   await p
 })
 
+test('Should handle raw socket errors while upgrade hooks are running', async (t) => {
+  const fastify = Fastify()
+  t.after(() => fastify.close())
+
+  await fastify.register(fastifyWebsocket)
+
+  let enterHook
+  const hookEntered = new Promise((resolve) => {
+    enterHook = resolve
+  })
+
+  fastify.addHook('onRequest', async () => {
+    enterHook()
+    await new Promise((resolve) => setTimeout(resolve, 100))
+  })
+
+  fastify.get('/', { websocket: true }, () => {})
+
+  await fastify.listen({ port: 0 })
+
+  const client = net.connect(fastify.server.address().port, '127.0.0.1', () => {
+    client.write(
+      'GET / HTTP/1.1\r\n' +
+      'Host: localhost\r\n' +
+      'Connection: Upgrade\r\n' +
+      'Upgrade: websocket\r\n' +
+      'Sec-WebSocket-Version: 13\r\n' +
+      'Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==\r\n\r\n'
+    )
+  })
+  client.on('error', () => {})
+
+  await hookEntered
+  client.resetAndDestroy()
+  await new Promise((resolve) => setTimeout(resolve, 200))
+
+  t.assert.strictEqual(fastify.server.listening, true)
+})
+
 test('Should be able to pass custom options to ws', async (t) => {
   t.plan(2)