Restify hangs when ending route chain without closing response

[cprussin]

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• Title adequately and concisely reflects the feature or the bug

Bug Report

Restify Version

Tested on 8.3.0.

Node.js Version

Tested on v8.15.1.

Expected behaviour

Restify should not hang (in express this same case automatically 404s)

Actual behaviour

Restify hangs

Repro case

const restify = require('restify');
const server = restify.createServer();
server.get('/', (req, res, next) => next()); // also could be server.get('/', () => {});
server.listen(8080, () => console.log('Server up on port 8080'));

Cause

Restify does not detect cases where the middleware chain is completed and no response has been flushed.

Are you willing and able to fix this?

Yes

[retrohacker]

Comparing this to express' behavior:

Express uses https://github.com/pillarjs/finalhandler at the end of the middleware chain. It does a check to see if headers have started being flushed yet as a heuristic.

This snippet 404s:

require('express')().get('/', function(req, res, next) { next(); }).listen(8080);

This snippet hangs:

require('express')().get('/', function(req, res, next) { res.flushHeaders(); next(); }).listen(8080);

It also requires calling the continuation, otherwise it hangs:

require('express')().get('/', function(req, res, next) {}).listen(8080);

[ghermeto]

merged :)