Renamed isPortInUse to isPortListendedOn, added new isPortInUse and canConnect

Author: luca-vogels

package.json

@@ -1,6 +1,6 @@
 {
   "name": "lup-system",
-  "version": "1.5.1",
+  "version": "1.5.2",
   "description": "NodeJS library to retrieve system information and utilization.",
   "main": "./lib/index",
   "types": "./lib/index.d.ts",

src/__tests__/Net.test.ts

@@ -1,13 +1,15 @@
 import { isPortInUse, getNetworkInterfaces, stopNetworkUtilizationComputation } from '../net';
 import net from 'net';
 
+
 test('getNetworkInterfaces', async () => {
   const nics = await getNetworkInterfaces();
   //console.log(nics); // TODO REMOVE
   expect(nics).toBeDefined();
   expect(nics.length).toBeGreaterThan(0);
 }, 10000);
 
+
 test('isPortInUse(12345)', async () => {
   const port = 12345;
 
@@ -27,6 +29,25 @@ test('isPortInUse(12345)', async () => {
   server.close();
 });
 
+/*
+test('DEBUG', async () => {
+  const ports = {
+    5050: false,
+    5432: false,
+    6379: false,
+    27017: false,
+  };
+
+  await Promise.allSettled(Object.keys(ports).map(async p => {
+    const inUse1 = await isPortInUse(parseInt(p), '0.0.0.0');
+    const inUse2 = await isPortInUse(parseInt(p), '127.0.0.1');
+    ports[p] = inUse1 || inUse2;
+  }));
+
+  console.log(JSON.stringify(ports, null, '  '));
+});
+*/
+
 afterAll(() => {
   stopNetworkUtilizationComputation();
 });

src/net.ts

@@ -169,13 +169,36 @@ export function stopNetworkUtilizationComputation() {
 }
 
 
+/**
+ * Tries to connect to a given server over TCP.
+ *
+ * @param port Port number to connect to.
+ * @param host Hostname or IP address of the server (default '127.0.0.1').
+ * @returns True if the connection was successful, false otherwise.
+ */
+export async function canConnect(port: number, host: string = '127.0.0.1'): Promise<boolean> {
+  return new Promise<boolean>((resolve) => {
+    const socket = net.connect(port, host, () => {
+      socket.end();
+      resolve(true);
+    });
+    socket.on('error', () => {
+      resolve(false);
+    });
+  });
+}
+
 /**
  * Checks if a process is listening on a given port.
+ *
+ * @warning If a Docker proxy is involved multiple processes can bind to the same port.
+ * Use canConnect() as an alternative to check if a port is already being listened on.
+ *
  * @param port Port number to check.
  * @param bindAddress Address of the interface to bind to (default '0.0.0.0' which binds to all interfaces).
  * @returns Promise that resolves to true if the port is in use, false otherwise.
  */
-export async function isPortInUse(port: number, bindAddress: string = '0.0.0.0'): Promise<boolean> {
+export async function isPortListendedOn(port: number, bindAddress: string = '0.0.0.0'): Promise<boolean> {
   const server = net.createServer();
   return new Promise((resolve) => {
     server.unref();
@@ -195,6 +218,22 @@ export async function isPortInUse(port: number, bindAddress: string = '0.0.0.0')
 }
 
 
+/**
+ * Uses isPortListenedOn() and canConnect() to determine if a port is in use.
+ * @param port Port number to check.
+ * @param bindAddress Address of the interface to bind to (default '0.0.0.0').
+ */
+export async function isPortInUse(port: number, bindAddress: string = '0.0.0.0'): Promise<boolean> {
+  let canConn = false;
+  let isListened = false;
+  await Promise.allSettled([
+    canConnect(port, bindAddress).then(res => canConn = res),
+    isPortListendedOn(port, bindAddress).then(res => isListened = res)
+  ])
+  return canConn || isListened;
+}
+
+
 /**
  * Returns information about the network interfaces on the system.
  *