public void TestTryDecodePieceMessge()
{
PieceMessage message;
int offset = 0;
byte[] data = "0000000B070000000500000006ABCD".ToByteArray();
bool isIncomplete;
if (PieceMessage.TryDecode(data, ref offset, data.Length, out message, out isIncomplete))
{
Assert.AreEqual(15, message.Length);
Assert.AreEqual(5, message.PieceIndex);
Assert.AreEqual(6, message.BlockOffset);
Assert.AreEqual(171, message.Data[0]);
Assert.AreEqual(205, message.Data[1]);
Assert.AreEqual(false, isIncomplete);
Assert.AreEqual(data.Length, offset);
CollectionAssert.AreEqual(data, message.Encode());
}
else
{
Assert.Fail();
}
}
/// <summary>
/// Asynchronous write callback.
/// </summary>
/// <param name="ar">The async result.</param>
private void Receive(IAsyncResult ar)
{
AsyncReadData data = ar.AsyncState as AsyncReadData;
int bytesRead = 0;
int offset = data.OffsetStart;
PeerMessage message;
PieceMessage pieceMessage;
bool isIncomplete;
lock (this.locker)
{
if (!this.IsDisposed)
{
try
{
// read data
bytesRead = this.stream.EndRead(ar);
if (bytesRead > 0)
{
data.OffsetEnd += bytesRead;
// walk through the array and try to decode messages
while (offset <= data.OffsetEnd)
{
if (PieceMessage.TryDecode(data.Buffer, ref offset, data.OffsetEnd, out pieceMessage, out isIncomplete, this.PieceData))
{
// successfully decoded message
this.OnMessageReceived(this, new PeerMessgeReceivedEventArgs((PeerMessage)pieceMessage));
// remember where we left off
data.OffsetStart = offset;
}
else if (PeerMessage.TryDecode(data.Buffer, ref offset, data.OffsetEnd, out message, out isIncomplete))
{
// successfully decoded message
this.OnMessageReceived(this, new PeerMessgeReceivedEventArgs(message));
// remember where we left off
data.OffsetStart = offset;
}
else if (isIncomplete)
{
// message of variable length is present but incomplete -> stop advancing
break;
}
else
{
// move to next byte
offset++;
}
}
if (data.OffsetStart == data.OffsetEnd)
{
// reset offset
data.OffsetStart = 0;
data.OffsetEnd = 0;
}
else if (data.OffsetStart > 0 &&
data.OffsetStart < data.OffsetEnd)
{
// move data to beginning of the buffere
for (int i = data.OffsetStart; i < data.OffsetEnd; i++)
{
data.Buffer[i - data.OffsetStart] = data.Buffer[i];
}
// reset offset
data.OffsetEnd = data.OffsetEnd - data.OffsetStart;
data.OffsetStart = 0;
}
else if (data.OffsetStart > data.OffsetEnd)
{
throw new PeerWireProtocolException("Invalid data.");
}
this.tm.Read(bytesRead);
// resume reading
if (!this.IsDisposed)
{
this.stream.BeginRead(data.Buffer, data.OffsetEnd, data.Buffer.Length - data.OffsetEnd, this.Receive, data);
}
}
else
{
// we received no data
Debug.WriteLine($"received no data from {this.Endpoint}");
}
}
catch (IOException ex)
{
Debug.WriteLine($"could not read data from {this.Endpoint}: {ex.Message}");
this.OnCommunicationError(this, new CommunicationErrorEventArgs(ex.Message));
}
}
}
}