public static bool TryDecode(IList <byte> pBytes, out cByteList rBytes, out string rError)
{
if (pBytes.Count == 0)
{
rBytes = new cByteList();
rError = null;
return(true);
}
if (pBytes.Count % 4 != 0)
{
rBytes = null;
rError = "base64 bytes must be in multiples of 4";
return(false);
}
int lCount;
if (pBytes[pBytes.Count - 2] == cASCII.EQUALS)
{
if (pBytes[pBytes.Count - 1] != cASCII.EQUALS)
{
rBytes = null;
rError = "invalid termination";
return(false);
}
lCount = pBytes.Count - 2;
}
else if (pBytes[pBytes.Count - 1] == cASCII.EQUALS)
{
lCount = pBytes.Count - 1;
}
else
{
lCount = pBytes.Count;
}
rBytes = new cByteList((lCount + 2) / 4 * 3);
var lBuffer = new cFromBase64Buffer(rBytes);
for (int i = 0; i < lCount; i++)
{
if (!lBuffer.TryAdd(pBytes[i], out rError))
{
rBytes = null; return(false);
}
}
if (!lBuffer.TryFlush(out rError))
{
rBytes = null; return(false);
}
return(true);
}
public static bool TryDecode(IList <byte> pBytes, out string rString, out string rError)
{
if (pBytes.Count == 0)
{
rString = string.Empty;
rError = null;
return(true);
}
var lBuilder = new StringBuilder();
var lBuffer = new cFromBase64Buffer(lBuilder);
int lByteNumber = 1;
byte lByte = pBytes[0];
while (true)
{
if (lByte == cASCII.AMPERSAND)
{
if (lByteNumber == pBytes.Count)
{
rString = null;
rError = "ends with an ampersand";
return(false);
}
lByte = pBytes[lByteNumber++];
if (lByte == cASCII.HYPEN)
{
lBuilder.Append('&');
}
else
{
// base64 loop
while (true)
{
if (lByteNumber + 2 > pBytes.Count)
{
rString = null;
rError = "invalid base64 character sequence";
return(false);
}
if (!ZTryDecodeBase64Byte(lByte, out int l61) ||
!ZTryDecodeBase64Byte(pBytes[lByteNumber++], out int l62)
)
{
rString = null;
rError = "invalid base64 character";
return(false);
}
lBuffer.Add((l61 << 2) | (l62 >> 4));
lByte = pBytes[lByteNumber++];
if (lByte == cASCII.HYPEN)
{
if (lBuffer.ContainsAByte)
{
rString = null;
rError = "odd number of encoded bytes";
return(false);
}
break;
}
if (lByteNumber + 1 > pBytes.Count)
{
rString = null;
rError = "invalid base64 character sequence";
return(false);
}
if (!ZTryDecodeBase64Byte(lByte, out int l63))
{
rString = null;
rError = "invalid base64 character";
return(false);
}
lBuffer.Add(((l62 & 15) << 4) | (l63 >> 2));
lByte = pBytes[lByteNumber++];
if (lByte == cASCII.HYPEN)
{
if (lBuffer.ContainsAByte)
{
rString = null;
rError = "odd number of encoded bytes";
return(false);
}
break;
}
if (lByteNumber + 1 > pBytes.Count)
{
rString = null;
rError = "invalid base64 character sequence";
return(false);
}
if (!ZTryDecodeBase64Byte(lByte, out int l64))
{
rString = null;
rError = "invalid base64 character";
return(false);
}
lBuffer.Add(((l63 & 3) << 6) | l64);
lByte = pBytes[lByteNumber++];
if (lByte == cASCII.HYPEN)
{
if (lBuffer.ContainsAByte)
{
rString = null;
rError = "odd number of encoded bytes";
return(false);
}
break;
}
}
}
}
else
{
if (lByte < cASCII.SPACE || lByte > cASCII.TILDA)
{
rString = null;
rError = "invalid unencoded byte";
return(false);
}
lBuilder.Append((char)lByte);
}
if (lByteNumber == pBytes.Count)
{
rString = lBuilder.ToString();
rError = null;
return(true);
}
lByte = pBytes[lByteNumber++];
}
}
