127.0.0.1:0 causes exception

[stevenvachon]

require("request")("http://127.0.0.1:0");

events.js:141
      throw er; // Unhandled 'error' event
            ^
Error: connect EADDRNOTAVAIL 127.0.0.1 - Local (0.0.0.0:54620)
    at Object.exports._errnoException (util.js:843:11)
    at exports._exceptionWithHostPort (util.js:866:20)
    at connect (net.js:824:14)
    at lookupAndConnect (net.js:917:5)
    at Socket.connect (net.js:886:5)
    at Agent.exports.connect.exports.createConnection (net.js:61:35)
    at Agent.createSocket (_http_agent.js:177:16)
    at Agent.addRequest (_http_agent.js:147:23)
    at new ClientRequest (_http_client.js:132:16)
    at Object.exports.request (http.js:30:10)

[julien-f]

What does it mean to connect to the port 0?

0 can be used to bind to a random available port but it does not make sense to use it to connect…

[stevenvachon]

Makes perfect sense in a test suite

[mmalecki]

@stevenvachon would you mind explaining your use-case for connecting to port 0 in a test suite?

This one appears to be a difference in behavior between Node.js and Io.js - node v0.10.32 returns a ECONNREFUSED error to the callback while io.js v1.4.3 throws a RangeError. I believe that Io.js' behavior is more accurate as trying to connect to 0 does sound like a programmer's error.

[stevenvachon]

Oops, I'd misunderstood the question. Serving on port 0 is perfect for test suites, however connecting (as was said) to port 0 is stupid.

I forget now why I'd ran that line of code, but it's at least evident at this point that the result is inconsistent than that of previous node.js versions. However, it's an io.js issue.

I'd ran that line of code to illustrate how this library is now inconsistent across node.js versions. Most errors are returned, while EADDRNOTAVAIL is thrown. Should this library do a try/catch to remain consistent and abstracted? Yes, it'd be a result of developer error, but catching it would avoid a server restart.

If anyone doesn't know, serving on port 0 is a standard way of connecting to any port that the OS has available, often a high number. Common ports such as 80 and 3000 are often not available and sniffing for such is faulty.

var server = require("http").createServer();
server.listen(0, host, function() {
    port = server.address().port;
});

[stevenvachon]

Clarifying here as well: the issue is that this error is thrown, while all other errors are asynchronously passed to the callback function.

[simov]

Fixed in v2.72 #2164