dgram: make .bind() always asynchronous

lib/dgram.js

@@ -43,11 +43,6 @@ function isIP(address) {
 
 
 function lookup(address, family, callback) {
-  // implicit 'bind before send' needs to run on the same tick
-  var matchedFamily = isIP(address);
-  if (matchedFamily)
-    return callback(null, address, matchedFamily);
-
   if (!dns)
     dns = require('dns');
 
@@ -111,31 +106,36 @@ exports.createSocket = function(type, listener) {
 };
 
 
-Socket.prototype.bind = function(port, address) {
+Socket.prototype.bind = function(port, address, callback) {
   var self = this;
 
   self._healthCheck();
 
+  if (typeof callback === 'function')
+    self.once('listening', callback);
+
   // resolve address first
   self._handle.lookup(address, function(err, ip) {
-    if (!err) {
-      if (self._handle.bind(ip, port || 0, /*flags=*/0)) {
-        err = errnoException(errno, 'bind');
-      }
-      else {
-        self._bound = true;
-        self._startReceiving();
-        self.emit('listening');
-      }
-    }
+    if (!self._handle)
+      return; // handle has been closed in the mean time
 
     if (err) {
-      // caller may not have had a chance yet to register its
-      // error event listener so defer the error to the next tick
-      process.nextTick(function() {
-        self.emit('error', err);
-      });
+      self.emit('error', err);
+      return;
     }
+
+    if (self._handle.bind(ip, port || 0, /*flags=*/ 0)) {
+      self.emit('error', errnoException(errno, 'bind'));
+      return;
+    }
+
+    self._handle.onmessage = onMessage;
+    self._handle.recvStart();
+    self._receiving = true;
+    self._bound = true;
+    self.fd = -42; // compatibility hack
+
+    self.emit('listening');
   });
 };
 
@@ -174,7 +174,14 @@ Socket.prototype.send = function(buffer,
   callback = callback || noop;
 
   self._healthCheck();
-  self._startReceiving();
+
+  if (!self._bound) {
+    self.bind(0, null);
+    self.once('listening', function() {
+      self.send(buffer, offset, length, port, address, callback);
+    });
+    return;
+  }
 
   self._handle.lookup(address, function(err, ip) {
     if (err) {
@@ -309,25 +316,6 @@ Socket.prototype._healthCheck = function() {
 };
 
 
-Socket.prototype._startReceiving = function() {
-  if (this._receiving)
-    return;
-
-  if (!this._bound) {
-    this.bind(); // bind to random port
-
-    // sanity check
-    if (!this._bound)
-      throw new Error('implicit bind failed');
-  }
-
-  this._handle.onmessage = onMessage;
-  this._handle.recvStart();
-  this._receiving = true;
-  this.fd = -42; // compatibility hack
-};
-
-
 Socket.prototype._stopReceiving = function() {
   if (!this._receiving)
     return;