net: add local family

PR-URL: #43975
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: theanarkh

doc/api/net.md

@@ -294,6 +294,7 @@ TCP server, the argument is as follows, otherwise the argument is `undefined`.
 *`data` {Object} The argument passed to event listener.
 *`localAddress` {string} Local address.
 *`localPort` {number} Local port.
+*`localFamily` {string} Local family.
 *`remoteAddress` {string} Remote address.
 *`remotePort` {number} Remote port.
 *`remoteFamily` {string} Remote IP family. `'IPv4'` or `'IPv6'`.
@@ -1045,6 +1046,16 @@ added: v0.9.6
 
 The numeric representation of the local port. For example, `80` or `21`.
 
+### `socket.localFamily`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {string}
+
+The string representation of the local IP family. `'IPv4'` or `'IPv6'`.
+
 ### `socket.pause()`
 
 * Returns: {net.Socket} The socket itself.

lib/net.js

@@ -840,6 +840,9 @@ protoGetter('localPort', function localPort() {
 returnthis._getsockname().port;
 });
 
+protoGetter('localFamily',functionlocalFamily(){
+returnthis._getsockname().family;
+});
 
 Socket.prototype[kAfterAsyncWrite]=function(){
 this[kLastWriteQueueSize]=0;
@@ -1674,6 +1677,7 @@ function onconnection(err, clientHandle) {
 clientHandle.getsockname(localInfo);
 data.localAddress=localInfo.address;
 data.localPort=localInfo.port;
+data.localFamily=localInfo.family;
 }
 if(clientHandle.getpeername){
 constremoteInfo=ObjectCreate(null);

test/parallel/test-net-local-address-port.js

@@ -27,6 +27,7 @@ const net = require('net');
 constserver=net.createServer(common.mustCall(function(socket){
 assert.strictEqual(socket.localAddress,common.localhostIPv4);
 assert.strictEqual(socket.localPort,this.address().port);
+assert.strictEqual(socket.localFamily,this.address().family);
 socket.on('end',function(){
 server.close();
 });