[api] Added new `close()` method which cleans up sockets from HttpProxy instances

lib/node-http-proxy/http-proxy.js

@@ -662,6 +662,21 @@ HttpProxy.prototype.proxyWebSocketRequest = function (req, socket, head, buffer)
   }
 };
 
+//
+// ### function close()
+// Closes all sockets associated with the Agents
+// belonging to this instance.
+//
+HttpProxy.prototype.close = function () {
+  [this.forward, this.target].forEach(function (proxy) {
+    if (proxy.agent) {
+      proxy.agent.sockets.forEach(function (socket) {
+        socket.end();
+      });
+    }
+  });
+};
+
 //
 // ### @private function _forwardRequest (req)
 // #### @req {ServerRequest} Incoming HTTP Request to proxy.