net: defer DNS lookup error events to next tick

net.createConnection() creates a net.Socket object
and immediately calls net.Socket.connect() on it.

There are no event listeners registered yet so
defer the error event to the next tick.

Fixes #1202.

lib/net_legacy.js

@@ -728,7 +728,13 @@ Socket.prototype.connect = function() {
     // TCP
     require('dns').lookup(host, function(err, ip, addressType) {
       if (err) {
-        self.emit('error', err);
+        // net.createConnection() creates a net.Socket object and
+        // immediately calls net.Socket.connect() on it (that's us).
+        // There are no event listeners registered yet so defer the
+        // error event to the next tick.
+        process.nextTick(function() {
+          self.emit('error', err);
+        });
       } else {
         addressType = addressType || 4;
 

lib/net_uv.js

@@ -469,7 +469,13 @@ Socket.prototype.connect = function(port /* [host], [cb] */) {
     debug("connect: find host " + host);
     require('dns').lookup(host, function(err, ip, addressType) {
       if (err) {
-        self.emit('error', err);
+        // net.createConnection() creates a net.Socket object and
+        // immediately calls net.Socket.connect() on it (that's us).
+        // There are no event listeners registered yet so defer the
+        // error event to the next tick.
+        process.nextTick(function() {
+          self.emit('error', err);
+        });
       } else {
         timers.active(self);