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.

[JSteunou]

Which one? Getting all errors even from client cancelled request or be forced to tricky save proxyReq to be able to abort?

[jcrugzz]

@JSteunou To put it simply, your workaround here should be handled within http-proxy for the req.on('error')

[JSteunou]

Would be nice :)

[jcrugzz]

@JSteunou Pull requests always welcome if you want to take a stab at it! :)

[jcrugzz]

also @vvo if you want the error handled, you could handle the error directly on req.on('error'). Im of the opinion that we need to cleanup our proxyReq regardless and if you want it as an error in your code the error can be handled there. Does this seem reasonable?

[vvo]

Yep makes sense

[JSteunou]

@jcrugzz I'm afraid I have the necessary solution and motivation but not the time to do it.

[jcrugzz]

@JSteunou it would be a simple change right around here. You may be overestimating the time :). It would be a good opportunity for first contribution

[tkers]

Fairly old thread, but still an issue afaik. Resolving it by comparing the error code to ECONNRESET and ignoring the error as suggested before.

Would be happy to submit a PR to handle this exception internally, but aren't there any use cases where you'd actually want to handle this manually? At the very least you'd need to emit a new event instead (abort perhaps?). Any thoughts?

[cycold]

mark

[flevour]

Should we consider this closed?