add license key auth and an accessor for the internal RPC client

src/client/NP/NPClient.cs

@@ -34,6 +34,11 @@ namespace NPSharp.NP
             _log = LogManager.GetLogger("NPClient");
         }
 
+        /// <summary>
+        ///     The internal RPC client.
+        /// </summary>
+        public RPCClientStream RPCClient { get { return _rpc; } }
+
         /// <summary>
         ///     The assigned NP user ID. Will be set on successful authentication.
         /// </summary>
@@ -137,6 +142,33 @@ namespace NPSharp.NP
             _rpc.Send(new AuthenticateWithTokenMessage {Token = token});
 
             return await tcs.Task;
+        }
+
+        /// <summary>
+        ///     Authenticates this connection via a platform-specific license key. This may very well include ""
+        ///     if the server chooses to allow anonymous logon.
+        /// </summary>
+        /// <param name="key">The license key to use for authentication</param>
+        /// <returns>True if the login succeeded, otherwise false.</returns>
+        public async Task<bool> AuthenticateWithLicenseKey(string key)
+        {
+            var tcs = new TaskCompletionSource<bool>();
+
+            _rpc.AttachHandlerForNextMessage(packet =>
+            {
+                var result = packet as AuthenticateResultMessage;
+                if (result == null)
+                    return;
+
+                if (result.Result != 0)
+                    tcs.SetResult(false);
+                LoginId = result.NPID;
+                SessionToken = result.SessionToken;
+                tcs.SetResult(true);
+            });
+            _rpc.Send(new AuthenticateWithKeyMessage { LicenseKey = key });
+
+            return await tcs.Task;
         }
 
         // TODO: Try to use an exception for failed action instead