zeromq node.js example with router and multiple req sockets, CURVE authentication and identity

index.js

//most of the code on the internet is for version 5 so here is a workign sample
//hope it helps somebody

//  Demonstrate request-reply identities
var zmq = require('zeromq')
var helper = require('./zhelpers')

const serverkey = zmq.curveKeyPair()
const clientkey = zmq.curveKeyPair()
const addr = "tcp://127.0.0.1:12345"//CURVE don't work for inproc schema

var sink = new zmq.Router({
  curveServer: true,
  curveSecretKey: serverkey.secretKey,
  curvePublicKey: serverkey.publicKey
});

//  First allow 0MQ to set the identity
var anonymous = new zmq.Request({
  curveSecretKey: clientkey.secretKey,
  curvePublicKey: clientkey.publicKey,
  curveServerKey: serverkey.publicKey
});
anonymous.connect(addr);

//  Then set the identity ourselves
var identified = new zmq.Request({
  routingId: 'peepee',//identity does not work when connecting to a router, instead use routingId
  curveSecretKey: clientkey.secretKey,
  curvePublicKey: clientkey.publicKey,
  curveServerKey: serverkey.publicKey
});
identified.connect(addr);

async function watch(){
  await sink.bind(addr);
  for await (const msg of sink){
    helper.dumpFrames(msg)
  }
}
async function send() {
  await anonymous.send("ROUTER uses generated 5 byte identity");
  await identified.send("ROUTER uses REQ's socket identity");
}
watch()
send()

setTimeout(function() {
  anonymous.close();
  identified.close();
  sink.close();
}, 250);

zhelpers.js

// Return the buffer's length as a three-character,
// zero-padded string (e.g. printf's `%03d`)
function bufferLength(buffer) {
  var lenStr = "" + buffer.length;
  while (lenStr.length < 3) {
    lenStr = "0" + lenStr;
  }

  return lenStr;
}

// Return the buffer's contents as printable text if every
// character is printable, or as hexadecimal otherwise
function formatBuffer(buffer) {
  for (var i = 0; i < buffer.length; i++) {
    if (buffer[i] < 32 || buffer[i] > 127) {
      return buffer.toString("hex")
    }
  }

  return buffer.toString("utf8");
}

module.exports = {
  dumpFrames: function() {
    var frames;
    if (arguments.length == 1) {
      var arg = arguments[0];
      if (Array.isArray(arg)) {
        // Single argument is an array of frames (buffers)
        frames = arg;
      } else {
        // Single argument is a single frame (buffer)
        frames = [arg];
      }
    } else {
      // Multiple arguments; each is a frame (buffer)
      frames = Array.prototype.slice.call(arguments);
    }

    console.log("----------------------------------------");
    frames.forEach(function(frame) {
      console.log("[%s] %s", bufferLength(frame), formatBuffer(frame));
    });
  }
};