//returns: doRetry?
private bool CheckHeader(byte[] response, out FidoHidMsgType msgType)
{
msgType = FidoHidMsgType.Error;
if (response.Length < 5)
{
return(false);
}
//ignore messages for other channels
if (!response.Take(4).SequenceEqual(_channelId))
{
return(false);
}
msgType = (FidoHidMsgType)response[4];
if (msgType != FidoHidMsgType.Error)
{
return(true);
}
if (response.Length < 8)
{
throw new FidoException(FidoError.ProtocolViolation, "error message too short");
}
var errorCode = (FidoHidError)response[7];
switch (errorCode)
{
case FidoHidError.MessageTimeout: throw new FidoException(FidoError.Timeout);
case FidoHidError.ChannelBusy: throw new FidoException(FidoError.TokenBusy);
default: throw new FidoException(FidoError.ProtocolViolation, $"U2FHID Error: [{errorCode}]");
}
}
private async Task SendRequestAsync(FidoHidMsgType msgType, byte[] data = null)
{
if (data == null)
{
data = new byte[0];
}
var size = data.Length;
var payloadData = data.Take(HidReportSize - 7).ToArray();
var payloadBuilder = new ByteArrayBuilder();
payloadBuilder.Append(_channelId);
payloadBuilder.Append((byte)msgType);
payloadBuilder.Append((byte)(size >> 8 & 0xff));
payloadBuilder.Append((byte)(size & 0xff));
payloadBuilder.Append(payloadData);
payloadBuilder.AppendZerosTill(HidReportSize);
var report = _hidDevice.CreateReport();
report.Data = payloadBuilder.GetBytes();
if (!await _hidDevice.WriteReportAsync(report, HidTimeoutMs).ConfigureAwait(false))
{
throw new FidoException(FidoError.InterruptedIO, "Error writing to token");
}
var remainingData = data.Skip(HidReportSize - 7).ToArray();
var seq = 0;
while (remainingData.Length > 0)
{
payloadData = remainingData.Take(HidReportSize - 5).ToArray();
payloadBuilder.Clear();
payloadBuilder.Append(_channelId);
payloadBuilder.Append((byte)(0x7f & seq));
payloadBuilder.Append(payloadData);
payloadBuilder.AppendZerosTill(HidReportSize);
report = _hidDevice.CreateReport();
report.Data = payloadBuilder.GetBytes();
if (!await _hidDevice.WriteReportAsync(report, HidTimeoutMs).ConfigureAwait(false))
{
throw new FidoException(FidoError.InterruptedIO, "Error writing to token");
}
remainingData = remainingData.Skip(HidReportSize - 5).ToArray();
seq++;
}
}
private async Task <byte[]> ReadResponseAsync(FidoHidMsgType msgType)
{
HidReport report;
FidoHidMsgType recvdMsgType;
do
{
report = await _hidDevice.ReadReportAsync(HidTimeoutMs).ConfigureAwait(false);
if (report.ReadStatus != HidDeviceData.ReadStatus.Success)
{
throw new FidoException(FidoError.InterruptedIO, $"Error reading from token: {report.ReadStatus}");
}
} while (!CheckHeader(report.Data, out recvdMsgType));
if (msgType != recvdMsgType)
{
throw new FidoException(FidoError.ProtocolViolation, $"received {recvdMsgType} instead of {msgType}");
}
var dataLength = (report.Data[5] << 8) + report.Data[6];
var payloadData = report.Data.Skip(7).Take(Math.Min(dataLength, HidReportSize)).ToArray();
var payload = new ByteArrayBuilder();
payload.Append(payloadData);
dataLength -= (int)payload.Length;
var seq = 0;
while (dataLength > 0)
{
do
{
report = await _hidDevice.ReadReportAsync(HidTimeoutMs).ConfigureAwait(false);
if (report.ReadStatus != HidDeviceData.ReadStatus.Success)
{
throw new FidoException(FidoError.InterruptedIO, $"Error reading from token: {report.ReadStatus}");
}
} while (!CheckHeader(report.Data, out recvdMsgType));
if ((recvdMsgType & FidoHidMsgType.CommandFlag) > 0)
{
throw new FidoException(FidoError.ProtocolViolation, "fragmented message continuation had command flag set");
}
if ((byte)recvdMsgType != (seq & (byte)FidoHidMsgType.SequenceIdMask))
{
throw new FidoException(FidoError.ProtocolViolation, $"received out-of-sequence message: Recvd:0x{(byte)recvdMsgType:X}, seq-nr:{seq}");
}
seq++;
payloadData = report.Data.Skip(5).Take(Math.Min(dataLength, HidReportSize)).ToArray();
dataLength -= payloadData.Length;
payload.Append(payloadData);
}
return(payload.GetBytes());
}
protected async Task <byte[]> CallAsync(FidoHidMsgType command, byte[] data = null)
{
await SendRequestAsync(command, data).ConfigureAwait(false);
return(await ReadResponseAsync(command).ConfigureAwait(false));
}
