make ifconfig parameters optional

ifconfig.js

@@ -236,14 +236,16 @@ function down(interface, callback) {
  * };
  *
  * ifconfig.up(options, function(err) {
- *   // the interface is up 
+ *   // the interface is up
  * });
  *
+ * ipv4_address, ipv4_broadcast and ipv4_subnet_mask are optional
  */
 function up(options, callback) {
   return this.exec('ifconfig ' + options.interface +
-    ' ' + options.ipv4_address +
-    ' netmask ' + options.ipv4_subnet_mask +
-    ' broadcast ' + options.ipv4_broadcast +
+    ' ' +
+    (options.ipv4_address ? options.ipv4_address : '0.0.0.0') +
+    (options.ipv4_subnet_mask ? ' netmask ' + options.ipv4_subnet_mask : '') +
+    (options.ipv4_broadcast ? ' broadcast ' + options.ipv4_broadcast : '') +
     ' up', callback);
 }

test/ifconfig.js

@@ -180,6 +180,39 @@ describe('ifconfig', function() {
       });
     })
 
+    it('should bring up the interface without broadcast nor subnet', function(done) {
+      ifconfig.exec = function(command, callback) {
+        should(command).eql('ifconfig wlan0 192.168.10.1 up');
+        callback(null, '', '');
+      };
+
+      var options = {
+        interface: 'wlan0',
+        ipv4_address: '192.168.10.1',
+      };
+
+      ifconfig.up(options, function(err) {
+        should(err).not.be.ok;
+        done();
+      });
+    })
+
+    it('should bring up the interface without ip/broadcast nor subnet', function(done) {
+      ifconfig.exec = function(command, callback) {
+        should(command).eql('ifconfig wlan0 0.0.0.0 up');
+        callback(null, '', '');
+      };
+
+      var options = {
+        interface: 'wlan0'
+      };
+
+      ifconfig.up(options, function(err) {
+        should(err).not.be.ok;
+        done();
+      });
+    })
+
     it('should handle errors', function(done) {
       ifconfig.exec = function(command, callback) {
         callback('error');