/// <summary>
/// is executed by receiver thread
/// </summary>
void ProcessRegisterPow1RequestPacket(IPEndPoint requesterEndpoint, byte[] udpData)
{
var packet = new RegisterPow1RequestPacket(udpData);
if (!PassPow1filter(requesterEndpoint, packet))
{
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}");
}
return;
}
// create Pow2 request state
var pow2RequestState = _pow2RequestsTable.GenerateOrGetExistingPow2(requesterEndpoint);
var response = new RegisterPow1ResponsePacket
{
ProofOfWork2Request = pow2RequestState.ProofOfWork2Request,
StatusCode = RegisterPow1ResponseStatusCode.succeeded_Pow2Challenge,
Pow1RequestId = packet.Pow1RequestId
};
SendPacket(response.Encode(), requesterEndpoint);
}
/// <summary>
/// performs PoW#1 (stateless proof of work)
/// </summary>
RegisterPow1RequestPacket GenerateRegisterPow1RequestPacket(byte[] clientPublicIp, uint timeSec32UTC)
{
var packet = new RegisterPow1RequestPacket();
packet.Timestamp32S = timeSec32UTC;
packet.ProofOfWork1 = new byte[64];
var rnd = new Random(_insecureRandom.Next());
for (; ;)
{
rnd.NextBytes(packet.ProofOfWork1);
if (Pow1IsOK(packet, clientPublicIp))
{
break;
}
}
packet.Pow1RequestId = (uint)rnd.Next();
return(packet);
}
bool Pow1IsOK(RegisterPow1RequestPacket packet, byte[] clientPublicIP)
{
var ms = new MemoryStream(sizeof(uint) + packet.ProofOfWork1.Length + clientPublicIP.Length);
using (var writer = new BinaryWriter(ms))
{
writer.Write(packet.Timestamp32S);
writer.Write(packet.ProofOfWork1);
writer.Write(clientPublicIP);
ms.Position = 0;
var hash = _cryptoLibrary.GetHashSHA512(ms);
if (hash[4] != 7 || (hash[5] != 7 && hash[5] != 8))
{
return(false);
}
else
{
return(true);
}
}
}
/// <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);
}
