addressing change made in server 2.4rc0.

Author: craiggwilson

MongoDB.Driver/CommandResults/CommandResult.cs

@@ -50,6 +50,14 @@ public CommandResult(IMongoCommand command, BsonDocument response)
         }
 
         // public properties
+        /// <summary>
+        /// Gets the code.
+        /// </summary>
+        public int? Code
+        {
+            get { return _response.GetValue("code", null).AsNullableInt32; }
+        }
+
         /// <summary>
         /// Gets the command.
         /// </summary>

MongoDB.Driver/Communication/Security/SaslAuthenticationProtocol.cs

@@ -70,12 +70,24 @@ public void Authenticate(MongoConnection connection, MongoCredential credential)
 
                 while (true)
                 {
-                    var result = connection.RunCommand(credential.Source, QueryFlags.SlaveOk, command, true);
-                    var code = result.Response["code"].AsInt32;
-                    if (code != 0)
+                    CommandResult result;
+                    try
                     {
-                        HandleError(result, code);
+                        result = connection.RunCommand(credential.Source, QueryFlags.SlaveOk, command, true);
                     }
+                    catch (MongoCommandException ex)
+                    {
+                        var message = "Unknown error occured during authentication.";
+                        var code = ex.CommandResult.Code;
+                        var errmsg = ex.CommandResult.ErrorMessage;
+                        if(code.HasValue && errmsg != null)
+                        {
+                            message = string.Format("Error: {0} - {1}", code, errmsg);
+                        }
+
+                        throw new MongoSecurityException(message, ex);
+                    }
+
                     if (result.Response["done"].AsBoolean)
                     {
                         break;
@@ -104,11 +116,5 @@ public bool CanUse(MongoCredential credential)
         {
             return _mechanism.CanUse(credential);
         }
-
-        // private methods
-        private void HandleError(CommandResult result, int code)
-        {
-            throw new MongoSecurityException(string.Format("Error: {0} - {1}", code, result.Response["errmsg"].AsString));
-        }
     }
 }