CC3K can't connect to localhost/127.0.0.1 [or even own network IP address?!]

[natevw]

runtime/test/suite/net.js fails with this error:

…

server-basic

ok 107 ok
ok 108 ok
ok 109 ok
ok 110 ok
Error: ENOENT Cannot connect to 127.0.0.1 Got: err-1
stack traceback:
[T]:src/colony/modules/net.js:205: in function <[T]:src/colony/modules/net.js:209>

[natevw]

I don't really blame the CC3K for this one, as connections to that IP address are usually done through a separate loopback interface…but how should we handle this in both tests and any code that might rely on this? (Note the situation isn't unheard of, IIRC Heroku doesn't route localhost either.)

[natevw]

Related-ish, though perhaps deserves it's own issue: "localhost" does not resolve on Tessel either.

[natevw]

Hmmm, also related-ish, the CC3K doesn't seem to be able to connect to itself at all, perhaps. Noticed this while trying to test tessel/t1-runtime#336 with this script, modified to hardcode the IP address reported by tessel wifi -l:

var net = require('net');

var server = net.createServer(function (c) {
   console.log("connection");
   c.on('end', function () {
    console.log("connection end");
  });
  c.end("«§»");
});
server.listen(0, function () {
  console.log("listening");
  testConnection(server.address().port);
});

function testConnection(port) {
  console.log("testConnection", port);
//return;
  var client = net.connect(port, "192.168.4.122").on('data', function (d) {
    console.log(d.toString());
    setTimeout(function () {
      console.log("*** CLOSE ***");
      server.close();
      //client.end();
    }, 2e3);
  });
}

This basically hangs after the "testConnection" log, the on-Tessel client doesn't connect (IIRC eventually times out with an error UPDATE: nope) although I can telnet to the server from my laptop as expected.

[natevw]

At a broader level, there's already at least one other network interface that would like to play on Tessel: https://forums.tessel.io/t/tcp-commands-with-gprs-chip-not-working-as-expected-another-node-stream-issue/287/2

Maybe this is a situation (much like 'fs' module vs sdcard filesystems) where the firmware "kernel" itself needs to play better at routing calls?

[johnnyman727]

@natevw, loopbacks aren't implemented in hardware. How does Heroku handle this?

[natevw]

That's what I mean, on Tessel we don't support multiple "drivers" and so adding one for a software loopback interface (or a cell module) doesn't fit the current architecture.

It's been a while and I didn't probe deeply with Heroku, just IIRC I couldn't make a connection to my own server from itself. This "making a client connection to own server" is the reason I noticed it, since that's what some of the 'net' module tests do — in practice it's probably not a showstopper for many "real" use case.