fixes sync bug.

OpenRa.Game/Network/Connection.cs

@@ -44,6 +44,8 @@ namespace OpenRa.Network
 
 		public virtual void Send( byte[] packet )
 		{
+			if( packet.Length == 0 )
+				throw new NotImplementedException();
 			lock( this )
 				receivedPackets.Add( new ReceivedPacket { FromClient = LocalClientId, Data = packet } );
 		}
@@ -82,9 +84,12 @@ namespace OpenRa.Network
 					for( ; ; )
 					{
 						var len = reader.ReadInt32();
+						var client = reader.ReadInt32();
 						var buf = reader.ReadBytes( len );
+						if( len == 0 )
+							throw new NotImplementedException();
 						lock( this )
-							receivedPackets.Add( new ReceivedPacket { FromClient = -1, Data = buf } );
+							receivedPackets.Add( new ReceivedPacket { FromClient = client, Data = buf } );
 					}
 				}
 				catch

OpenRa.Game/Network/OrderManager.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Text;
 
 namespace OpenRa.Network
 {
@@ -129,8 +130,8 @@ namespace OpenRa.Network
 			}
 
 			var ss = sync.SerializeSync( FrameNumber );
-			CheckSync( ss );
 			Connection.Send( ss );
+			CheckSync( ss );
 
 			++frameNumber;
 		}