ECONNRESET due to upstream timeout causes crash

[ImranR-TI]

I'm seeing the http-proxy-3 crash with ECONNRESET in a specific scenario (minimal reproducible example below).

Basically I have the following setup: [client] --> [HAProxy] --> [Node proxy] --> [backend]

1. A backend socket server
2. A Node proxy server powered by http-proxy-3
   • This has some conditional logic which ensures that only specific requests are forwarded to the backend - the rest are simply ignored (no response). So clients are left waiting forever.
3. A second proxy (HAProxy) in front of the Node proxy, that has some default request timeout value
   • This ensures that requests left waiting forever for some response (that will never come) do eventually have to break the connection.
   • I'm using HAProxy but I think anything similar would work here.

The bug I'm seeing has to do with this external timeout - it causes the Node proxy to crash with ECONNRESET. The error itself is not a problem, we would expect to see an error in this kind of situation. The problem is that the error crashes the entire process despite the presence of a proxy.on('error') listener.

I know this is a weird use case (my code should ideally respond to "ignored" requests with a 404 or something instead of completely ignoring them) but it does still expose what I think is a bug.

Minimal code to reproduce the bug:

// proxy.js

const http = require('http')
const httpProxy = require('http-proxy-3')

const proxy = httpProxy.createProxyServer({})

proxy.on('error', (err, req, res) => {
  console.error('Proxy error:', err)
  res.end('Something went wrong.')
})

const server = http.createServer((req, res) => {
  const target = 'http://localhost:3004'
  proxy.web(req, res, { target })
})

server.on('upgrade', (req, socket, head) => {
  if (false) { // Real use case has some specific condition, where some requests would go through and others wouldn't
    // We just do 'if (false)' to demonstrate the bug
    proxy.ws(req, socket, head, { target: 'ws://localhost:3004' })
  }
})

const port = 8000
server.listen(port, () => {
  console.log(`Proxy server listening on port ${port}`)
})

# haproxy.cfg

global
        maxconn 100000
        user haproxy
        group haproxy
        daemon
        log /dev/log local0 debug

        # Default ciphers to use on SSL-enabled listening sockets.
        # For more information, see ciphers(1SSL).
        ssl-default-bind-ciphers kEECDH+aRSA+AES:kRSA+AES:+AES256:RC4-SHA:!kEDH:!LOW:!EXP:!MD5:!aNULL:!eNULL
        ssl-default-bind-options no-sslv3

defaults
        mode    http
        timeout connect 180000 # 3 minutes
        timeout client  180000
        timeout server  180000
        fullconn 10000
        maxconn   5000

frontend ft_http
        bind :80
        mode http
        default_backend bk_http

backend bk_http
    mode http
    balance roundrobin
    option forwardfor
    default-server inter 1s
    server proxy1 127.0.0.1:8000 weight 255 check

Note backend.js has been omitted since it doesn't really matter in this case whether or not a backend exists - we never proxy the request anyways.

I test this with the wscat command: wscat -c http://localhost:80/socket

It eventually crashes with this error: error: Unexpected server response: 502

Proxy logs:

Proxy server listening on port 8000
node:events:496
      throw er; // Unhandled 'error' event
      ^

Error: read ECONNRESET
    at TCP.onStreamRead (node:internal/stream_base_commons:216:20)
Emitted 'error' event on Socket instance at:
    at emitErrorNT (node:internal/streams/destroy:170:8)
    at emitErrorCloseNT (node:internal/streams/destroy:129:3)
    at process.processTicksAndRejections (node:internal/process/task_queues:90:21) {
  errno: -104,
  code: 'ECONNRESET',
  syscall: 'read'
}

Node.js v22.14.0

Thanks for this rewrite BTW, the old one had a bad memory leak (among other issues).