private static PreparedHeader GetHeaderForIndex(ulong headerIndex)
{
if (headerIndex is > 0 and <= HPack.StaticTableMaxIndex)
{
return(HPack.GetStaticHeader((uint)headerIndex));
}
throw new Exception($"Invalid header index {headerIndex}");
}
public static int Decode(ReadOnlySpan <byte> buffer, IHttpHeadersSink sink, object?state)
{
int originalLength = buffer.Length;
while (buffer.Length != 0)
{
HttpHeaderFlags flags;
ulong nameIndex;
int headerLength;
byte prefixMask;
byte firstByte = buffer[0];
switch (BitOperations.LeadingZeroCount(firstByte) - 24)
{
case 0:
if (HPack.TryDecodeIndexedHeader(firstByte, buffer, out nameIndex, out headerLength))
{
buffer = buffer.Slice(headerLength);
OnHeader(sink, state, nameIndex);
continue;
}
else
{
return(originalLength - buffer.Length);
}
case 1:
prefixMask = HPack.IncrementalIndexingMask;
flags = HttpHeaderFlags.None;
break;
case 2: // Dynamic table size update.
if (HPack.TryDecodeDynamicTableSizeUpdate(firstByte, buffer, out nameIndex, out headerLength))
{
buffer = buffer.Slice(headerLength);
OnDynamicTableSizeUpdate(nameIndex);
continue;
}
else
{
return(originalLength - buffer.Length);
}
case 3: // Literal header never indexed.
prefixMask = HPack.WithoutIndexingOrNeverIndexMask;
flags = HttpHeaderFlags.NeverCompressed;
break;
default: // Literal header without indexing.
prefixMask = HPack.WithoutIndexingOrNeverIndexMask;
flags = HttpHeaderFlags.None;
break;
}
if (!HPack.TryDecodeHeader(prefixMask, flags, firstByte, buffer, out nameIndex, out ReadOnlySpan <byte> name, out ReadOnlySpan <byte> value, out flags, out headerLength))
{
return(originalLength - buffer.Length);
}
buffer = buffer.Slice(headerLength);
if (nameIndex != 0)
{
OnHeader(sink, state, nameIndex, value, flags);
}
else
{
OnHeader(sink, state, name, value, flags);
}
}
return(originalLength - buffer.Length);
}