diff --git a/shadowsocks-csharp/Util/Sockets/LineReader.cs b/shadowsocks-csharp/Util/Sockets/LineReader.cs
index f51a9b71..93626371 100644
--- a/shadowsocks-csharp/Util/Sockets/LineReader.cs
+++ b/shadowsocks-csharp/Util/Sockets/LineReader.cs
@@ -18,14 +18,10 @@ namespace Shadowsocks.Util.Sockets
 
         private readonly byte[] _lineBuffer;
 
-        private int _bufferDataIndex;
-        private int _bufferDataLength;
+        private int _bufferIndex;
 
-        public LineReader(WrappedSocket socket, byte[] firstPackge, int index, int length,
-            Func<string, object, bool> onLineRead, Action<Exception, object> onException,
-            Action<byte[], int, int, object> onFinish,
-            Encoding encoding, string delimiter, int maxLineBytes,
-            object state)
+        public LineReader(WrappedSocket socket, Func<string, object, bool> onLineRead, Action<Exception, object> onException,
+            Action<byte[], int, int, object> onFinish, Encoding encoding, string delimiter, int maxLineBytes, object state)
         {
             if (socket == null)
             {
@@ -44,19 +40,6 @@ namespace Shadowsocks.Util.Sockets
                 throw new ArgumentNullException(nameof(delimiter));
             }
 
-            if (maxLineBytes < length)
-            {
-                throw new ArgumentException("Line buffer length can't less than first package length!", nameof(maxLineBytes));
-            }
-
-            if (length > 0)
-            {
-                if (firstPackge == null)
-                {
-                    throw new ArgumentNullException(nameof(firstPackge));
-                }
-            }
-
             _socket = socket;
             _onLineRead = onLineRead;
             _onException = onException;
@@ -83,95 +66,64 @@ namespace Shadowsocks.Util.Sockets
 
             _lineBuffer = new byte[maxLineBytes];
 
-            if (length > 0)
-            {
-                // process first package
-                Array.Copy(firstPackge, index, _lineBuffer, 0, length);
-                _bufferDataLength = length;
-
-                try
-                {
-                    NewPackageRecv();
-                }
-                catch (Exception ex)
-                {
-                    OnException(ex);
-                    OnFinish();
-                }
-            }
-            else
-            {
-                // start reading
-                socket.BeginReceive(_lineBuffer, 0, maxLineBytes, 0, ReceiveCallback, 0);
-            }
-        }
-
-        public LineReader(WrappedSocket socket, Func<string, object, bool> onLineRead,
-            Action<Exception, object> onException,
-            Action<byte[], int, int, object> onFinish, Encoding encoding, string delimiter, int maxLineBytes,
-            object state)
-            : this(socket, null, 0, 0, onLineRead, onException, onFinish, encoding, delimiter, maxLineBytes, state)
-        {
+            // start reading
+            socket.BeginReceive(_lineBuffer, 0, maxLineBytes, 0, ReceiveCallback, 0);
         }
 
         private void ReceiveCallback(IAsyncResult ar)
         {
+            int length = (int)ar.AsyncState;
             try
             {
                 var bytesRead = _socket.EndReceive(ar);
 
                 if (bytesRead == 0)
                 {
-                    OnFinish();
+                    OnFinish(length);
                     return;
                 }
 
-                _bufferDataLength += bytesRead;
+                length += bytesRead;
 
-                NewPackageRecv();
-            }
-            catch (Exception ex)
-            {
-                OnException(ex);
-                OnFinish();
-            }
-        }
-
-        private void NewPackageRecv()
-        {
-            int i;
-            while ((i = IndexOf(_lineBuffer, _bufferDataIndex, _bufferDataLength, _delimiterBytes, _delimiterSearchOffsetTable,
-                       _delimiterSearchCharTable)) != -1)
-            {
-                var decodeLen = i - _bufferDataIndex;
-                string line = _encoding.GetString(_lineBuffer, _bufferDataIndex, decodeLen);
+                int i;
+                while ((i = IndexOf(_lineBuffer, _bufferIndex, length, _delimiterBytes, _delimiterSearchOffsetTable,
+                           _delimiterSearchCharTable)) != -1)
+                {
+                    var decodeLen = i - _bufferIndex;
+                    string line = _encoding.GetString(_lineBuffer, _bufferIndex, decodeLen);
 
-                _bufferDataIndex = i + _delimiterBytes.Length;
-                _bufferDataLength -= decodeLen;
-                _bufferDataLength -= _delimiterBytes.Length;
+                    _bufferIndex = i + _delimiterBytes.Length;
+                    length -= decodeLen;
+                    length -= _delimiterBytes.Length;
 
-                var stop = _onLineRead(line, _state);
-                if (stop)
+                    var stop = _onLineRead(line, _state);
+                    if (stop)
+                    {
+                        OnFinish(length);
+                        return;
+                    }
+                }
+                if (length == _lineBuffer.Length)
                 {
-                    OnFinish();
+                    OnException(new IndexOutOfRangeException("LineBuffer full! Try increace maxLineBytes!"));
+                    OnFinish(length);
+
                     return;
                 }
-            }
-            if (_bufferDataLength == _lineBuffer.Length)
-            {
-                OnException(new IndexOutOfRangeException("LineBuffer full! Try increace maxLineBytes!"));
-                OnFinish();
 
-                return;
-            }
+                if (_bufferIndex > 0)
+                {
+                    Buffer.BlockCopy(_lineBuffer, _bufferIndex, _lineBuffer, 0, length);
+                    _bufferIndex = 0;
+                }
 
-            if (_bufferDataIndex > 0)
+                _socket.BeginReceive(_lineBuffer, length, _lineBuffer.Length - length, 0, ReceiveCallback, length);
+            }
+            catch (Exception ex)
             {
-                Buffer.BlockCopy(_lineBuffer, _bufferDataIndex, _lineBuffer, 0, _bufferDataLength);
-                _bufferDataIndex = 0;
+                OnException(ex);
+                OnFinish(length);
             }
-
-            _socket.BeginReceive(_lineBuffer, _bufferDataLength, _lineBuffer.Length - _bufferDataLength, 0, ReceiveCallback, _bufferDataLength);
         }
 
         private void OnException(Exception ex)
@@ -179,14 +131,14 @@ namespace Shadowsocks.Util.Sockets
             _onException?.Invoke(ex, _state);
         }
 
-        private void OnFinish()
+        private void OnFinish(int length)
         {
-            _onFinish?.Invoke(_lineBuffer, _bufferDataIndex, _bufferDataLength, _state);
+            _onFinish?.Invoke(_lineBuffer, _bufferIndex, length, _state);
         }
 
         #region Boyer-Moore string search
 
-        private static int IndexOf(byte[] haystack, int index, int length, byte[] needle, int[] offsetTable, int[] charTable)
+        public static int IndexOf(byte[] haystack, int index, int length, byte[] needle, int[] offsetTable, int[] charTable)
         {
             var end = index + length;
             for (int i = needle.Length - 1 + index, j; i < end;)