private static string UrlDecodeImpl(byte[] bytes, int offset, int count, Encoding encoding)
{
if (encoding is null)
{
encoding = Encoding.UTF8;
}
UrlDecoder helper = new UrlDecoder(count, encoding);
// go through the bytes collapsing %XX and %uXXXX and appending
// each byte as byte, with exception of %uXXXX constructs that
// are appended as chars
for (int i = 0; i < count; i++)
{
int pos = offset + i;
byte b = bytes[pos];
// The code assumes that + and % cannot be in multibyte sequence
if (b == '+')
{
b = (byte)' ';
}
else if (b == '%' && i < count - 2)
{
if (bytes[pos + 1] == 'u' && i < count - 5)
{
int h1 = HttpEncoderUtility.HexToInt((char)bytes[pos + 2]);
int h2 = HttpEncoderUtility.HexToInt((char)bytes[pos + 3]);
int h3 = HttpEncoderUtility.HexToInt((char)bytes[pos + 4]);
int h4 = HttpEncoderUtility.HexToInt((char)bytes[pos + 5]);
if (h1 >= 0 && h2 >= 0 && h3 >= 0 && h4 >= 0)
{ // valid 4 hex chars
char ch = (char)((h1 << 12) | (h2 << 8) | (h3 << 4) | h4);
i += 5;
// don't add as byte
helper.AddChar(ch);
continue;
}
}
else
{
int h1 = HttpEncoderUtility.HexToInt((char)bytes[pos + 1]);
int h2 = HttpEncoderUtility.HexToInt((char)bytes[pos + 2]);
if (h1 >= 0 && h2 >= 0)
{ // valid 2 hex chars
b = (byte)((h1 << 4) | h2);
i += 2;
}
}
}
helper.AddByte(b);
}
return(Utf16StringValidator.ValidateString(helper.GetString()));
}
private static string UrlDecodeImpl(string value, Encoding encoding)
{
if (value is null)
{
return(null);
}
int count = value.Length;
UrlDecoder helper = new UrlDecoder(count, encoding);
// go through the string's chars collapsing %XX and %uXXXX and
// appending each char as char, with exception of %XX constructs
// that are appended as bytes
for (int pos = 0; pos < count; pos++)
{
char ch = value[pos];
if (ch == '+')
{
ch = ' ';
}
else if (ch == '%' && pos < count - 2)
{
if (value[pos + 1] == 'u' && pos < count - 5)
{
int h1 = HttpEncoderUtility.HexToInt(value[pos + 2]);
int h2 = HttpEncoderUtility.HexToInt(value[pos + 3]);
int h3 = HttpEncoderUtility.HexToInt(value[pos + 4]);
int h4 = HttpEncoderUtility.HexToInt(value[pos + 5]);
if (h1 >= 0 && h2 >= 0 && h3 >= 0 && h4 >= 0)
{ // valid 4 hex chars
ch = (char)((h1 << 12) | (h2 << 8) | (h3 << 4) | h4);
pos += 5;
// only add as char
helper.AddChar(ch);
continue;
}
}
else
{
int h1 = HttpEncoderUtility.HexToInt(value[pos + 1]);
int h2 = HttpEncoderUtility.HexToInt(value[pos + 2]);
if (h1 >= 0 && h2 >= 0)
{ // valid 2 hex chars
byte b = (byte)((h1 << 4) | h2);
pos += 2;
// don't add as char
helper.AddByte(b);
continue;
}
}
}
if (0u >= (uint)(ch & 0xFF80))
{
helper.AddByte((byte)ch); // 7 bit have to go as bytes because of Unicode
}
else
{
helper.AddChar(ch);
}
}
return(Utf16StringValidator.ValidateString(helper.GetString()));
}