How can I filter socket hang up errors?

[JSteunou]

I'm using node-http-proxy for a while now, and I think I'm using it quite right catching errors like this

proxy.on('error', function(err, req, res) {
    // log
    // ...
    // handle
    if (!res.headersSent) {
        res.writeHead(500, { 'content-type': 'application/json' });
    }
    res.end(JSON.stringify({ error: 'proxy_error', reason: err.message }));
});

But I can have two cases that make a "socket hang up" error happen.

1. Crash behind
2. Client cancelling the request

Watching at my log I can make no differences between those two cases and it's quite frustrating. Before knowing about request abort (thank #527) I really though I have an error going on.

So, what's the best practice to filter the request.abort case out?

[theoephraim]

+1

[FoghostCn]

+1

[vvo]

You should be able to use the proxy error event or the error callback and check for res.socket.destroyed === true and error.code === ECONNRESET which means the request was canceled

[JSteunou]

Merci @vvo ;) Will try that asap

[JSteunou]

It works very fine, thank you again @vvo

@jcrugzz should I let this issue open? Maybe http-proxy should filter those error inside the library, or maybe it's better to let it unopinionated...

[vvo]

or maybe it's better to let it unopinionated...

Yes it depends on the use case, sometime you will want the error to pop out if the client canceled the request.

[JSteunou]

What I thought. Closing it then.

[JSteunou]

Quick question again: I want to use request abort to prevent the underlying server to handle that client cancelled request. But, very surprisingly, req.abort is undefined O_O

Any thoughts?

[vvo]

nope sorry,

[JSteunou]

I think the req I got is the received request, not the request currently sent by http-proxy

[JSteunou]

Ok for the record, in case anyone was interested at doing the same thing

How to catch request client cancelled and abort ongoing proxied request

proxy.on('proxyReq', function(proxyReq, req) {
    // keep a ref
    req._proxyReq = proxyReq;
});

proxy.on('error', function(err, req, res) {
  if (req.socket.destroyed && err.code === 'ECONNRESET') {
    req._proxyReq.abort();
  }
});

[jcrugzz]

This is a bug and should be fixed within http-proxy itself. Currently we are emitting an error on the client request when we should only be cancelling the proxy request when this happens.