public void TestMask()
{
var crc = new Crc32C();
crc.Update(Encoding.ASCII.GetBytes("foo"), 0, 3);
Assert.Equal(crc.GetMaskedValue(), Mask(crc.GetIntValue()));
Assert.False(crc.GetIntValue() == crc.GetMaskedValue(), "crc should not match masked crc");
Assert.False(crc.GetIntValue() == Mask(crc.GetMaskedValue()), "crc should not match double masked crc");
Assert.Equal(crc.GetIntValue(), Unmask(crc.GetMaskedValue()));
Assert.Equal(crc.GetIntValue(), Unmask(Unmask(Mask(crc.GetMaskedValue()))));
}
private static uint ComputeCrc(byte[] data)
{
var crc = new Crc32C();
crc.Update(data, 0, data.Length);
return(crc.GetIntValue());
}
public byte[] ToByteArray()
{
using (MemoryStream ms = new MemoryStream())
using (BinaryWriter writer = new BinaryWriter(ms))
{
writer.Write((byte)(((byte)packetType) | (usingChecksum ? 0x80 : 0)));
writer.Write(retryCount);
writer.Write(from);
writer.Write(to);
writer.Write(channel);
writer.Write(fragment);
writer.Write(seq);
writer.Write(timestamp);
writer.Write(payload);
writer.Flush();
if (usingChecksum)
{
byte[] data = ms.ToArray();
Crc32C crc = new Crc32C();
crc.Update(data, 0, data.Length);
uint checksum = crc.GetIntValue();
writer.Write(checksum);
writer.Flush();
}
return(ms.ToArray());
}
}
public void TestComposes()
{
var crc = new Crc32C();
crc.Update(Encoding.ASCII.GetBytes("hello "), 0, 6);
crc.Update(Encoding.ASCII.GetBytes("world"), 0, 5);
Assert.Equal(crc.GetIntValue(), ComputeCrc(Encoding.ASCII.GetBytes("hello world")));
}
public static NetworkPacket FromByteArray(byte[] data)
{
NetworkPacket packet = new NetworkPacket();
using (MemoryStream ms = new MemoryStream(data, false))
using (BinaryReader reader = new BinaryReader(ms))
{
byte packetFlags = reader.ReadByte();
packet.usingChecksum = (packetFlags & 0x80) != 0;
packet.packetType = (PacketType)(byte)(packetFlags & ~0x80);
packet.retryCount = reader.ReadByte();
packet.from = reader.ReadByte();
packet.to = reader.ReadByte();
packet.channel = reader.ReadByte();
packet.fragment = reader.ReadUInt16();
packet.seq = reader.ReadUInt16();
packet.timestamp = reader.ReadUInt32();
if (packet.usingChecksum)
{
packet.payload = reader.ReadBytes(data.Length - 13 - 4);
uint checksum = reader.ReadUInt32();
Crc32C crc = new Crc32C();
crc.Update(data, 0, data.Length - 4);
uint validChecksum = crc.GetIntValue();
if (checksum != validChecksum)
{
throw new IOException("Invalid checksum! Got 0x" + checksum.ToString("X8") + ", should be 0x" + validChecksum.ToString("X8"));
}
}
else
{
packet.payload = reader.ReadBytes(data.Length - 13);
}
return(packet);
}
}