public static (int bytesConsumed, HttpHeaderData) DecodeHeader(ReadOnlySpan <byte> buffer)
{
switch (BitOperations.LeadingZeroCount(buffer[0]) - 24) // byte 'b' is extended to uint, so will have 24 extra 0s.
{
case 0: // Indexed Header Field
{
if ((buffer[0] & 0b0100_0000) == 0)
{
throw new Exception("QPack dynamic table is not yet supported.");
}
(int bytesConsumed, int staticIndex) = DecodeInteger(buffer, 0b0011_1111);
var staticHeader = s_staticTable[staticIndex];
var header = new HttpHeaderData(staticHeader.Name, staticHeader.Value, raw: buffer.Slice(0, bytesConsumed).ToArray());
return(bytesConsumed, header);
}
case 1: // Literal Header Field With Name Reference
{
if ((buffer[0] & 0b0001_0000) == 0)
{
throw new Exception("QPack dynamic table is not yet supported.");
}
(int nameLength, int staticIndex) = DecodeInteger(buffer, 0b0000_1111);
(int valueLength, string value) = DecodeString(buffer.Slice(nameLength), 0b0111_1111);
int headerLength = nameLength + valueLength;
var header = new HttpHeaderData(s_staticTable[staticIndex].Name, value, raw: buffer.Slice(0, headerLength).ToArray());
return(headerLength, header);
}
case 2: // Literal Header Field Without Name Reference
{
(int nameLength, string name) = DecodeString(buffer, 0b0000_0111);
(int valueLength, string value) = DecodeString(buffer.Slice(nameLength), 0b0111_1111);
int headerLength = nameLength + valueLength;
var header = new HttpHeaderData(name, value, raw: buffer.Slice(0, headerLength).ToArray());
return(headerLength, header);
}
case 3: // Indexed Header Field With Post-Base Index
default: // Literal Header Field With Post-Base Name Reference (at least 4 zeroes, maybe more)
throw new Exception("QPack dynamic table is not yet supported.");
}
}
public static (int bytesConsumed, HttpHeaderData) DecodeHeader(ReadOnlySpan <byte> buffer)
{
int firstByte = buffer[0];
// Indexed Header Field, dynamic.
if ((firstByte & 0b1100_0000) == 0b1000_0000)
{
throw new Exception("QPack dynamic table is not yet supported.");
}
// Indexed Header Field, static.
if ((firstByte & 0b1100_0000) == 0b1100_0000)
{
(int bytesConsumed, int staticIndex) = DecodeInteger(buffer, 0b1100_0000);
var staticHeader = s_staticTable[staticIndex];
var header = new HttpHeaderData(staticHeader.Name, staticHeader.Value, raw: buffer.Slice(0, bytesConsumed).ToArray());
return(bytesConsumed, header);
}
// Indexed Header Field With Post-Base Index
if ((firstByte & 0b1111_0000) == 0b0001_0000)
{
throw new Exception("QPack dynamic table is not yet supported.");
}
// Literal Header Field With Name Reference
if ((firstByte & 0b1100_0000) == 0b0100_0000)
{
if ((firstByte & 0b0001_0000) != 0)
{
throw new Exception("QPack dynamic table is not yet supported.");
}
(int nameLength, int staticIndex) = DecodeInteger(buffer, 0b1111_0000);
(int valueLength, string value) = DecodeString(buffer.Slice(nameLength), 0b1000_0000);
int headerLength = nameLength + valueLength;
var header = new HttpHeaderData(s_staticTable[staticIndex].Name, value, raw: buffer.Slice(0, headerLength).ToArray());
return(headerLength, header);
}
// Literal Header Field With Post-Base Name Reference.
if ((firstByte & 0b1111_0000) == 0b0000_0000)
{
throw new Exception("QPack dynamic table is not yet supported.");
}
// Literal Header Field Without Name Reference.
if ((firstByte & 0b1110_0000) == 0b0010_0000)
{
(int nameLength, string name) = DecodeString(buffer, 0b1111_1000);
(int valueLength, string value) = DecodeString(buffer.Slice(nameLength), 0b1000_0000);
int headerLength = nameLength + valueLength;
var header = new HttpHeaderData(name, value, raw: buffer.Slice(0, headerLength).ToArray());
return(headerLength, header);
}
throw new Exception("Invalid QPack.");
}