private static IReadOnlyList <byte> ConvertHexToBinary(IReadOnlyList <byte> bytes)
{
var result = new List <byte>(bytes.Count / 2);
var last = '\0';
var offset = 0;
for (var i = 0; i < bytes.Count; i++)
{
var c = (char)bytes[i];
if (!ReadHelper.IsHex(c))
{
// TODO: do I need to assert this must be whitespace?
continue;
}
if (offset == 1)
{
result.Add(HexToken.Convert(last, c));
offset = 0;
}
else
{
offset++;
}
last = c;
}
return(result);
}
/// <summary>
/// To distinguish between binary and hex the first 4 bytes (of the ciphertext) for hex must obey these restrictions:
/// The first byte must not be whitespace.
/// One of the first four ciphertext bytes must not be an ASCII hex character.
/// </summary>
private static bool IsBinary(IReadOnlyList <byte> bytes)
{
if (bytes.Count < 4)
{
return(true);
}
if (ReadHelper.IsWhitespace(bytes[0]))
{
return(true);
}
for (var i = 1; i < 4; i++)
{
var b = bytes[i];
if (!ReadHelper.IsHex(b))
{
return(true);
}
}
return(false);
}
public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken token)
{
token = null;
if (currentByte != '/')
{
return(false);
}
var bytes = new List <byte>();
bool escapeActive = false;
int postEscapeRead = 0;
var escapedChars = new char[2];
while (inputBytes.MoveNext())
{
var b = inputBytes.CurrentByte;
if (b == '#')
{
escapeActive = true;
}
else if (escapeActive)
{
if (ReadHelper.IsHex((char)b))
{
escapedChars[postEscapeRead] = (char)b;
postEscapeRead++;
if (postEscapeRead == 2)
{
var hex = new string(escapedChars);
var characterToWrite = (byte)Convert.ToInt32(hex, 16);
bytes.Add(characterToWrite);
escapeActive = false;
postEscapeRead = 0;
}
}
else
{
bytes.Add((byte)'#');
if (postEscapeRead == 1)
{
bytes.Add((byte)escapedChars[0]);
}
if (ReadHelper.IsEndOfName(b))
{
break;
}
if (b == '#')
{
// Make it clear what's going on, we read something like #m#AE
// ReSharper disable once RedundantAssignment
escapeActive = true;
postEscapeRead = 0;
continue;
}
bytes.Add(b);
escapeActive = false;
postEscapeRead = 0;
}
}
else if (ReadHelper.IsEndOfName(b))
{
break;
}
else
{
bytes.Add(b);
}
}
byte[] byteArray = bytes.ToArray();
var str = ReadHelper.IsValidUtf8(byteArray)
? Encoding.UTF8.GetString(byteArray)
: Encoding.GetEncoding("windows-1252").GetString(byteArray);
token = NameToken.Create(str);
return(true);
}
