spare enough space for UDP packet

shadowsocks-csharp/Controller/Service/UDPRelay.cs

@@ -53,7 +53,7 @@ namespace Shadowsocks.Controller
             private Socket _remote;
 
             private Server _server;
-            private byte[] _buffer = new byte[1500];
+            private byte[] _buffer = new byte[65536];
 
             private IPEndPoint _localEndPoint;
             private IPEndPoint _remoteEndPoint;
@@ -81,7 +81,7 @@ namespace Shadowsocks.Controller
                 IEncryptor encryptor = EncryptorFactory.GetEncryptor(_server.method, _server.password);
                 byte[] dataIn = new byte[length - 3];
                 Array.Copy(data, 3, dataIn, 0, length - 3);
-                byte[] dataOut = new byte[length - 3 + 16];
+                byte[] dataOut = new byte[65536];  // enough space for AEAD ciphers
                 int outlen;
                 encryptor.EncryptUDP(dataIn, length - 3, dataOut, out outlen);
                 Logging.Debug(_localEndPoint, _remoteEndPoint, outlen, "UDP Relay");

shadowsocks-csharp/Encryption/AEAD/AEADEncryptor.cs

@@ -18,7 +18,7 @@ namespace Shadowsocks.Encryption.AEAD
         private static readonly byte[] InfoBytes = Encoding.ASCII.GetBytes(Info);
 
         // for UDP only
-        protected static byte[] _udpTmpBuf = new byte[MAX_INPUT_SIZE];
+        protected static byte[] _udpTmpBuf = new byte[65536];
 
         // every connection should create its own buffer
         private CircularBuffer<byte> _encCircularBuffer = new CircularBuffer<byte>(MAX_INPUT_SIZE * 2, false);

shadowsocks-csharp/Encryption/Stream/StreamEncryptor.cs

@@ -11,7 +11,7 @@ namespace Shadowsocks.Encryption.Stream
         : EncryptorBase
     {
         // for UDP only
-        protected static byte[] _udpTmpBuf = new byte[MAX_INPUT_SIZE];
+        protected static byte[] _udpTmpBuf = new byte[65536];
 
         // every connection should create its own buffer
         private CircularBuffer<byte> _encCircularBuffer = new CircularBuffer<byte>(TCPHandler.BufferSize * 2, false);