public void Encode(string name, string value, byte[] buffer, ref int offset, ref int bytesAvailableInBuffer)
{
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
var header = GetIndexedHeader(name, value);
if (header != null && header.Name.Length >= _maxDynamicTableSize)
{
header = null;
}
if (header != null && header.Value.Equals(value))
{
var flagOffset = offset;
IntegerCodec.Encode(7, header.IndexPosition, buffer, ref offset, ref bytesAvailableInBuffer);
buffer[flagOffset] += 128;
return;
}
//Literal Header Field with Incremental Indexing — New Name
if (header == null)
{
buffer[offset++] = 64;
bytesAvailableInBuffer -= 1;
_dynamicTable.Append(name, value);
EncodeLiteral(name, buffer, ref offset, ref bytesAvailableInBuffer);
}
else
{
var flagOffset = offset;
IntegerCodec.Encode(6, header.IndexPosition, buffer, ref offset, ref bytesAvailableInBuffer);
buffer[flagOffset] += 64;
}
EncodeLiteral(value, buffer, ref offset, ref bytesAvailableInBuffer);
}
public void Decode(byte[] buffer, ref int offset, ref int count)
{
while (count > 0)
{
_headerEventArgs.IsIndexingAllowed = true;
// 6.1 Indexed Header Field Representation
if ((buffer[offset] & 128) == 128)
{
var index = buffer[offset] & ~128;
if (index == 0)
{
throw new DecoderException(Http2ErrorCode.ProtocolError, "HPACK, Indexed header 0 is not allowed.");
}
++offset;
--count;
AssignIndexedHeaderToEventArgs(index);
}
// 6.2.1 Literal Header Field
else if ((buffer[offset] & 64) == 64)
{
var index = buffer[offset] & ~64;
++offset;
--count;
// Header name is in the static or dynamic table
if (index > 0)
{
AssignIndexedHeaderToEventArgs(index);
}
else
{
_headerEventArgs.Name = ReadStringLiteral(buffer, ref offset, ref count);
}
_headerEventArgs.Value = ReadStringLiteral(buffer, ref offset, ref count);
// A literal header field with incremental indexing representation results in appending a
// header field to the decoded header list and inserting it as a new entry into the dynamic table
_dynamicTable.Append(_headerEventArgs.Name, _headerEventArgs.Value);
}
// 6.2.2 Literal Header Field without Indexing
else if ((buffer[offset] & 240) == 0)
{
var index = buffer[offset] & ~240;
++offset;
--count;
// Header name is in the static or dynamic table
if (index > 0)
{
AssignIndexedHeaderToEventArgs(index);
}
else
{
_headerEventArgs.Name = ReadStringLiteral(buffer, ref offset, ref count);
}
_headerEventArgs.Value = ReadStringLiteral(buffer, ref offset, ref count);
}
// 6.2.3 Literal Header Field Never Indexed
else if ((buffer[offset] & 240) == 16)
{
var index = buffer[offset] & ~240;
++offset;
--count;
// Header name is in the static or dynamic table
if (index > 0)
{
AssignIndexedHeaderToEventArgs(index);
}
else
{
_headerEventArgs.Name = ReadStringLiteral(buffer, ref offset, ref count);
}
_headerEventArgs.Value = ReadStringLiteral(buffer, ref offset, ref count);
_headerEventArgs.IsIndexingAllowed = false;
}
// 6.3 Dynamic Table Size Update
else if ((buffer[offset] & 224) == 32)
{
var maxSize = buffer[offset] & ~224;
++offset;
--count;
if (DynamicTableSizeReceived != null)
{
DynamicTableSizeReceived(this, new DynamicTableSizeReceivedEventArgs(maxSize));
}
return;
}
if (HeaderDecoded != null)
{
HeaderDecoded(this, _headerEventArgs);
}
}
}
