/// <inheritdoc cref="IMessageReader.ReadFrom"/>
public IMessage ReadFrom(ref SpanBufferReader bufferReader, byte packetProperty)
{
if (packetProperty != 0x00)
{
var readPacketProperty = bufferReader.ReadUInt8();
if (readPacketProperty != packetProperty)
{
throw new InvalidDataContractException(
"Invalid packet property " +
$"(PacketProperty={readPacketProperty}, Expected={packetProperty})."
);
}
}
var messageGroup = bufferReader.ReadUInt32();
if (!_messageRegistries.TryGetValue(messageGroup, out var messageRegistry))
{
throw new InvalidDataContractException($"Invalid message group (MessageGroup={messageGroup}).");
}
var protocolVersion = bufferReader.ReadVarUInt();
if (protocolVersion != ProtocolVersion)
{
throw new InvalidDataContractException($"Invalid message protocol version (ProtocolVersion={protocolVersion}).");
}
var length = bufferReader.ReadVarUInt();
if (bufferReader.RemainingSize < length)
{
throw new InvalidDataContractException($"Message truncated (RemainingSize={bufferReader.RemainingSize}, Expected={length}).");
}
var messageId = bufferReader.ReadVarUInt();
if (!messageRegistry.TryCreateMessage(messageId, out var message))
{
throw new InvalidDataContractException($"Invalid message identifier (MessageId={messageId}).");
}
if (message is IReliableRequest)
{
((IReliableRequest)message).RequestId = bufferReader.ReadUInt32();
}
if (message is IReliableResponse)
{
((IReliableResponse)message).ResponseId = bufferReader.ReadUInt32();
}
message.ReadFrom(ref bufferReader);
return(message);
}
/// <inheritdoc cref="IEncryptedMessageReader.ReadFrom"/>
public IEncryptedMessage ReadFrom(ref SpanBufferReader bufferReader, byte[] key, HMAC hmac, byte?packetProperty)
{
var sequenceId = bufferReader.ReadUInt32();
var iv = bufferReader.ReadBytes(16).ToArray();
var decryptedBuffer = bufferReader.RemainingData.ToArray();
using (var cryptoTransform = _aesCryptoServiceProvider.CreateDecryptor(key, iv))
{
var bytesWritten = 0;
for (var i = decryptedBuffer.Length; i >= cryptoTransform.InputBlockSize; i -= bytesWritten)
{
var inputCount = cryptoTransform.CanTransformMultipleBlocks
? (i / cryptoTransform.InputBlockSize * cryptoTransform.InputBlockSize)
: cryptoTransform.InputBlockSize;
bytesWritten = cryptoTransform.TransformBlock(
decryptedBuffer, bytesWritten, inputCount,
decryptedBuffer, bytesWritten
);
}
}
var paddingByteCount = decryptedBuffer[decryptedBuffer.Length - 1] + 1;
var hmacStart = decryptedBuffer.Length - paddingByteCount - 10;
var decryptedBufferSpan = decryptedBuffer.AsSpan();
var hash = decryptedBufferSpan.Slice(hmacStart, 10);
var hashBufferWriter = new SpanBufferWriter(stackalloc byte[decryptedBuffer.Length + 4]);
hashBufferWriter.WriteBytes(decryptedBufferSpan.Slice(0, hmacStart));
hashBufferWriter.WriteUInt32(sequenceId);
Span <byte> computedHash = stackalloc byte[32];
if (!hmac.TryComputeHash(hashBufferWriter.Data, computedHash, out _))
{
throw new Exception("Failed to compute message hash.");
}
if (!hash.SequenceEqual(computedHash.Slice(0, 10)))
{
throw new Exception("Message hash does not match the computed hash.");
}
bufferReader = new SpanBufferReader(decryptedBuffer);
if (_messageReader.ReadFrom(ref bufferReader, packetProperty) is not IEncryptedMessage message)
{
throw new Exception(
"Successfully decrypted message but failed to cast to type " +
$"'{nameof(IEncryptedMessage)}'."
);
}
message.SequenceId = sequenceId;
return(message);
}
public override void ReadFrom(ref SpanBufferReader bufferReader)
{
MultipartMessageId = bufferReader.ReadUInt32();
Offset = bufferReader.ReadVarUInt();
Length = bufferReader.ReadVarUInt();
TotalLength = bufferReader.ReadVarUInt();
if (Length > _maximumLength)
{
throw new InvalidDataContractException($"Length must not surpass {_maximumLength} bytes");
}
if (TotalLength > _maximumTotalLength)
{
throw new InvalidDataContractException($"Length must not surpass {_maximumTotalLength} bytes");
}
Data = bufferReader.ReadBytes((int)Length).ToArray();
}
public void ReadFrom(ref SpanBufferReader bufferReader)
{
CertificateResponseId = bufferReader.ReadUInt32();
Random = bufferReader.ReadBytes(32).ToArray();
Cookie = bufferReader.ReadBytes(32).ToArray();
}