further improvements to ID extension support

lib/Connection.js

@@ -310,20 +310,21 @@ Connection.prototype.id = function(identification, cb) {
   if (!this.serverSupports('ID'))
     throw new Error('Server does not support ID');
   var cmd = 'ID';
-  if (identification === null)
+  if ((identification === null) || (Object.keys(identification).length === 0))
     cmd += ' NIL';
   else {
     if (Object.keys(identification).length > 30)
       throw new Error('Max allowed number of keys is 30');
-    cmd += ' (';
+    var kv = [];
     for (var k in identification) {
-      if (k.length > 30)
+      if (Buffer.byteLength(k) > 30)
         throw new Error('Max allowed key length is 30');
-      if (identification[k].length > 1024)
+      if (Buffer.byteLength(identification[k]) > 1024)
         throw new Error('Max allowed value length is 1024');
-      cmd += '"' + escape(k) + '" "' + escape(identification[k]) + '"';
+      kv.push('"' + escape(k) + '"');
+      kv.push('"' + escape(identification[k]) + '"');
     }
-    cmd += ')';
+    cmd += ' (' + kv.join(' ') + ')';
   }
   this._enqueue(cmd, cb);
 };