dgram: hide _healthCheck() and _stopReceiving()

These methods are private APIs of dgram sockets, but do not
need to be exposed via the Socket prototype.

PR-URL: #21923
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Wyatt Preul <wpreul@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/dgram.js

@@ -199,7 +199,7 @@ function bufferSize(self, size, buffer) {
 Socket.prototype.bind = function(port_, address_ /* , callback */) {
   let port = port_;
 
-  this._healthCheck();
+  healthCheck(this);
 
   if (this._bindState !== BIND_STATE_UNBOUND)
     throw new ERR_SOCKET_ALREADY_BOUND();
@@ -444,7 +444,7 @@ Socket.prototype.send = function(buffer,
     throw new ERR_INVALID_ARG_TYPE('address', ['string', 'falsy'], address);
   }
 
-  this._healthCheck();
+  healthCheck(this);
 
   if (this._bindState === BIND_STATE_UNBOUND)
     this.bind({ port: 0, exclusive: true }, null);
@@ -525,8 +525,8 @@ Socket.prototype.close = function(callback) {
     return this;
   }
 
-  this._healthCheck();
-  this._stopReceiving();
+  healthCheck(this);
+  stopReceiving(this);
   this._handle.close();
   this._handle = null;
   defaultTriggerAsyncIdScope(this[async_id_symbol],
@@ -544,7 +544,7 @@ function socketCloseNT(self) {
 
 
 Socket.prototype.address = function() {
-  this._healthCheck();
+  healthCheck(this);
 
   var out = {};
   var err = this._handle.getsockname(out);
@@ -603,7 +603,7 @@ Socket.prototype.setMulticastLoopback = function(arg) {
 
 
 Socket.prototype.setMulticastInterface = function(interfaceAddress) {
-  this._healthCheck();
+  healthCheck(this);
 
   if (typeof interfaceAddress !== 'string') {
     throw new ERR_INVALID_ARG_TYPE(
@@ -618,7 +618,7 @@ Socket.prototype.setMulticastInterface = function(interfaceAddress) {
 
 Socket.prototype.addMembership = function(multicastAddress,
                                           interfaceAddress) {
-  this._healthCheck();
+  healthCheck(this);
 
   if (!multicastAddress) {
     throw new ERR_MISSING_ARGS('multicastAddress');
@@ -633,7 +633,7 @@ Socket.prototype.addMembership = function(multicastAddress,
 
 Socket.prototype.dropMembership = function(multicastAddress,
                                            interfaceAddress) {
-  this._healthCheck();
+  healthCheck(this);
 
   if (!multicastAddress) {
     throw new ERR_MISSING_ARGS('multicastAddress');
@@ -646,22 +646,22 @@ Socket.prototype.dropMembership = function(multicastAddress,
 };
 
 
-Socket.prototype._healthCheck = function() {
-  if (!this._handle) {
+function healthCheck(socket) {
+  if (!socket._handle) {
     // Error message from dgram_legacy.js.
     throw new ERR_SOCKET_DGRAM_NOT_RUNNING();
   }
-};
+}
 
 
-Socket.prototype._stopReceiving = function() {
-  if (!this._receiving)
+function stopReceiving(socket) {
+  if (!socket._receiving)
     return;
 
-  this._handle.recvStop();
-  this._receiving = false;
-  this.fd = null; // compatibility hack
-};
+  socket._handle.recvStop();
+  socket._receiving = false;
+  socket.fd = null; // compatibility hack
+}
 
 
 function onMessage(nread, handle, buf, rinfo) {