private void ParseTLVData(byte[] data)
{
using (MemoryStream stream = new MemoryStream(data))
using (BinaryReader reader = new BinaryReader(stream))
{
while (stream.Position < stream.Length)
{
byte tag = reader.ReadByte();
int length = 0;
byte[] val = null;
if (tag != 0x00 && tag != 0xFE)
{
length = reader.ReadByte();
if (length >= 0xFF)
{
byte[] lengthBytes = reader.ReadBytes(2);
if (BitConverter.IsLittleEndian)
{
Array.Reverse(lengthBytes);
}
length = BitConverter.ToUInt16(lengthBytes, 0);
}
val = length > 0 ? reader.ReadBytes(length) : null;
}
switch (tag)
{
case 0x00:
StatusMessage?.Invoke("Skipping NULL TLV");
break;
case 0x01:
StatusMessage?.Invoke("Skipping Lock Control TLV");
break;
case 0x02:
StatusMessage?.Invoke("Skipping Memory Control TLV");
break;
case 0xFE:
StatusMessage?.Invoke("Reached terminator TLV");
return;
case 0x03:
if (val != null)
{
StatusMessage?.Invoke("Found NDEF TLV (" + length + " bytes)");
NdefMessage msg = NdefMessage.FromByteArray(val);
ReceiveNdefMessage?.Invoke(msg);
}
else
{
StatusMessage?.Invoke("Found empty NDEF TLV");
}
break;
default:
StatusMessage?.Invoke("Skipping unknown TLV " + BitConverter.ToString(new byte[] { tag }));
break;
}
}
}
}
private void HandleHCEClient(ICardReader reader)
{
StatusMessage?.Invoke("Attemtping to talk to Android HCE device.");
var selectCmd = new Iso7816.SelectCommand(FLAGCARRIER_HCE_AID, 0);
var res = reader.Transceive(selectCmd);
if (res.SW == 0x6a82)
{
ErrorMessage?.Invoke("Device has no idea who we are.");
return;
}
else if (!res.Succeeded)
{
ErrorMessage?.Invoke("Failed communicating with device: " + res.ToString());
return;
}
StatusMessage?.Invoke("Connected to FlagCarrier HCE device!");
byte[] challengeToken = new byte[32];
random.NextBytes(challengeToken, 0, challengeToken.Length);
var updateCmd = new Iso7816.UpdateBinaryCommand(challengeToken);
res = reader.Transceive(updateCmd);
if (res.SW == 0x6A82)
{
ErrorMessage?.Invoke("HCE Device does not have any data for us.");
return;
}
if (!res.Succeeded)
{
ErrorMessage?.Invoke("Failed sending challenge token: " + res.ToString());
return;
}
StatusMessage?.Invoke("Sent challenge token.");
byte[] ndefData = new byte[0];
const int len = 250;
int offset = 0;
do
{
var readCmd = new Iso7816.ReadBinaryCommand(len, offset);
res = reader.Transceive(readCmd);
if (!res.Succeeded)
{
ErrorMessage?.Invoke("Failed reading data at " + offset + ": " + res.ToString());
return;
}
if (res.ResponseData == null || res.ResponseData.Length == 0)
{
break;
}
Array.Resize(ref ndefData, ndefData.Length + res.ResponseData.Length);
res.ResponseData.CopyTo(ndefData, offset);
offset += res.ResponseData.Length;
} while (res.ResponseData.Length == len);
StatusMessage?.Invoke("Read " + ndefData.Length + " bytes of ndef data from device.");
NdefMessage msg = NdefMessage.FromByteArray(ndefData);
NewTagUid?.Invoke(challengeToken);
ReceiveNdefMessage?.Invoke(msg);
var eraseCmd = new Iso7816.EraseBinaryCommand();
res = reader.Transceive(eraseCmd);
if (!res.Succeeded)
{
ErrorMessage?.Invoke("Failed confirming transaction to device.");
}
}