fix: should double check 0.0.0.0 and localhost

- closes #17
- closes #19

Author: fengmk2

lib/detect-port.js

@@ -15,17 +15,17 @@ module.exports = (port, callback) => {
   }
   debug('detect free port between [%s, %s)', port, maxPort);
   if (typeof callback === 'function') {
-    return tryListen(port, maxPort, callback);
+    return tryListen(port, maxPort, null, callback);
   }
   // promise
   return new Promise(resolve => {
-    tryListen(port, maxPort, (_, realPort) => {
+    tryListen(port, maxPort, null, (_, realPort) => {
       resolve(realPort);
     });
   });
 };
 
-function tryListen(port, maxPort, callback) {
+function tryListen(port, maxPort, hostname, callback) {
   const server = new net.Server();
 
   server.on('error', err => {
@@ -41,13 +41,19 @@ function tryListen(port, maxPort, callback) {
       maxPort = 0;
     }
     server.close();
-    return tryListen(port, maxPort, callback);
+    return tryListen(port, maxPort, hostname, callback);
   });
 
-  server.listen({ port }, () => {
+  // check 0.0.0.0 first
+  server.listen(port, hostname, () => {
     port = server.address().port;
     server.close();
-    debug('get free port: %s', port);
-    callback(null, port);
+    debug('get %s free port: %s', hostname, port);
+    if (hostname === 'localhost') {
+      return callback(null, port);
+    }
+
+    // check localhost second
+    tryListen(port, maxPort, 'localhost', callback);
   });
 }

test/detect-port.test.js

@@ -10,7 +10,7 @@ describe('detect port test', () => {
   before(done => {
     done = pedding(11, done);
     const server = new net.Server();
-    server.listen(3000, done);
+    server.listen(3000, 'localhost', done);
     servers.push(server);
     for (let port = 7000; port < 7010; port++) {
       const server = new net.Server();