bool PassStatelessPoWfilter(ICcpRemoteEndpoint clientEndpoint, ClientHelloPacket0 packet)// packets processor thread // sends responses
{
switch (packet.StatelessProofOfWorkType)
{
case StatelessProofOfWorkType._2019_06:
// verify size of PoW data
if (packet.StatelessProofOfWorkData.Length < 12 || packet.StatelessProofOfWorkData.Length > 64)
{
throw new CcpBadPacketException();
}
// verify datetime ("period")
// return err code if time is wrong, with correct server's UTC time
uint receivedTimeSec32;
unsafe
{
fixed(byte *statelessProofOfWorkDataPtr = packet.StatelessProofOfWorkData)
{
fixed(byte *addressBytesPtr = clientEndpoint.AddressBytes)
{
receivedTimeSec32 = *((uint *)statelessProofOfWorkDataPtr);
if (addressBytesPtr[0] != statelessProofOfWorkDataPtr[4] ||
addressBytesPtr[1] != statelessProofOfWorkDataPtr[5] ||
addressBytesPtr[2] != statelessProofOfWorkDataPtr[6] ||
addressBytesPtr[3] != statelessProofOfWorkDataPtr[7]
)
{
if (_config.RespondErrors)
{
RespondToHello0(clientEndpoint, ServerHello0Status.ErrorBadStatelessProofOfWork_BadSourceIp, packet.Cnonce0);
}
return(false);
}
}
}
}
var localTimeSec32 = TimeSec32UTC;
var diffSec = Math.Abs((int)unchecked (localTimeSec32 - receivedTimeSec32));
if (diffSec > _config.StatelessPoW_MaxClockDifferenceS)
{
// respond with error "try again with valid clock" - legitimate user has to get valid clock from some time server and synchronize itself with the server
if (_config.RespondErrors)
{
RespondToHello0(clientEndpoint, ServerHello0Status.ErrorBadStatelessProofOfWork_BadClock, packet.Cnonce0);
}
return(false);
}
var hash = _cryptoLibrary.GetHashSHA256(packet.OriginalPacketPayload);
// calculate hash, considering entire packet data (including stateless PoW result)
// verify hash result
if (!StatelessPowHashIsOK(hash))
{
HandleBadStatelessPowPacket(clientEndpoint);
// no response
return(false);
}
// check if hash is unique
var dataIsUnique = _recentUniquePowData.TryInputData(hash, localTimeSec32);
if (dataIsUnique)
{
return(true);
}
else
{
// respond with error "try again with unique PoW data"
if (_config.RespondErrors)
{
RespondToHello0(clientEndpoint, ServerHello0Status.ErrorTryAgainRightNowWithThisServer, packet.Cnonce0);
}
return(false);
}
default:
throw new CcpBadPacketException();
}
}
/// <summary>
/// sends responses
/// executed by receiver thread
/// </summary>
bool PassPow1filter(IPEndPoint requesterEndpoint, RegisterPow1RequestPacket packet)
{
// verify size of Pow1 data
if (packet.ProofOfWork1.Length != 64)
{
if (Configuration.VisionChannel?.GetAttentionTo(Configuration.VisionChannelSourceId, VisionChannelModuleName_reg_epSide) <= AttentionLevel.needsAttention)
{
Configuration.VisionChannel?.Emit(Configuration.VisionChannelSourceId, VisionChannelModuleName_reg_epSide, AttentionLevel.needsAttention, $"pow1 filter rejected request from {requesterEndpoint}: invalid pow1 length");
}
return(false);
}
var localTimeSec32 = Timestamp32S;
var timeDifferenceSec = Math.Abs((int)unchecked (localTimeSec32 - packet.Timestamp32S));
if (timeDifferenceSec > Configuration.RegisterPow1_MaxTimeDifferenceS)
{
if (Configuration.VisionChannel?.GetAttentionTo(Configuration.VisionChannelSourceId, VisionChannelModuleName_reg_epSide) <= AttentionLevel.needsAttention)
{
Configuration.VisionChannel?.Emit(Configuration.VisionChannelSourceId, VisionChannelModuleName_reg_epSide, AttentionLevel.needsAttention, $"pow1 filter rejected request from {requesterEndpoint}: invalid timestamp");
}
// respond with error "try again with valid clock" - legitimate user has to get valid clock from some time server and synchronize itself with the server
if (Configuration.RespondToRegisterPow1Errors)
{
RespondToRegisterPow1withError(requesterEndpoint, RegisterPow1ResponseStatusCode.rejected_badtimestamp, packet.Pow1RequestId);
}
return(false);
}
if (!Pow1IsOK(packet, requesterEndpoint.Address.GetAddressBytes()))
{
if (Configuration.VisionChannel?.GetAttentionTo(Configuration.VisionChannelSourceId, VisionChannelModuleName_reg_epSide) <= AttentionLevel.needsAttention)
{
Configuration.VisionChannel?.Emit(Configuration.VisionChannelSourceId, VisionChannelModuleName_reg_epSide, AttentionLevel.needsAttention, $"pow1 filter rejected request from {requesterEndpoint}: invalid pow1");
}
OnReceivedBadRegisterReqPow1(requesterEndpoint);
// no response
return(false);
}
if (_recentUniquePow1Data != null)
{
// check if pow1 data is unique
var dataIsUnique = _recentUniquePow1Data.TryInputData(packet.ProofOfWork1, localTimeSec32);
if (dataIsUnique)
{
return(true);
}
else
{
if (Configuration.VisionChannel?.GetAttentionTo(Configuration.VisionChannelSourceId, VisionChannelModuleName_reg_epSide) <= AttentionLevel.needsAttention)
{
Configuration.VisionChannel?.Emit(Configuration.VisionChannelSourceId, VisionChannelModuleName_reg_epSide, AttentionLevel.needsAttention, $"pow1 filter rejected request from {requesterEndpoint}: pow1 data is not unique");
}
// respond with error "try again with unique PoW data"
if (Configuration.RespondToRegisterPow1Errors)
{
RespondToRegisterPow1withError(requesterEndpoint, RegisterPow1ResponseStatusCode.rejected_tryagainRightNowWithThisServer, packet.Pow1RequestId);
}
return(false);
}
}
return(true);
}