public const int SettingSize = 6; // 2 bytes for the id, 4 bytes for the value.
public static bool ReadFrame(ReadOnlySequence <byte> readableBuffer, Proto2Frame frame, uint maxFrameSize, out ReadOnlySequence <byte> framePayload)
{
framePayload = ReadOnlySequence <byte> .Empty;
if (readableBuffer.Length < HeaderLength)
{
return(false);
}
var headerSlice = readableBuffer.Slice(0, HeaderLength);
var header = headerSlice.ToSpan();
var payloadLength = (int)Bitshifter.ReadUInt24BigEndian(header);
if (payloadLength > maxFrameSize)
{
throw new Proto2ConnectionErrorException(CoreStrings.FormatProto2ErrorFrameOverLimit(payloadLength, maxFrameSize), Proto2ErrorCode.FRAME_SIZE_ERROR);
}
// Make sure the whole frame is buffered
var frameLength = HeaderLength + payloadLength;
if (readableBuffer.Length < frameLength)
{
return(false);
}
frame.PayloadLength = payloadLength;
frame.Type = (Proto2FrameType)header[TypeOffset];
frame.Flags = header[FlagsOffset];
frame.StreamId = (int)Bitshifter.ReadUInt31BigEndian(header.Slice(StreamIdOffset));
var extendedHeaderLength = ReadExtendedFields(frame, readableBuffer);
// The remaining payload minus the extra fields
framePayload = readableBuffer.Slice(HeaderLength + extendedHeaderLength, payloadLength - extendedHeaderLength);
return(true);
}
private static int ReadExtendedFields(Proto2Frame frame, ReadOnlySequence <byte> readableBuffer)
{
// Copy in any extra fields for the given frame type
var extendedHeaderLength = GetPayloadFieldsLength(frame);
if (extendedHeaderLength > frame.PayloadLength)
{
throw new Proto2ConnectionErrorException(
CoreStrings.FormatProto2ErrorUnexpectedFrameLength(frame.Type, expectedLength: extendedHeaderLength), Proto2ErrorCode.FRAME_SIZE_ERROR);
}
var extendedHeaders = readableBuffer.Slice(HeaderLength, extendedHeaderLength).ToSpan();
// Parse frame type specific fields
switch (frame.Type)
{
/*
+---------------+
|Pad Length? (8)|
+---------------+-----------------------------------------------+
| Data (*) ...
+---------------------------------------------------------------+
| Padding (*) ...
+---------------------------------------------------------------+
*/
case Proto2FrameType.DATA: // Variable 0 or 1
frame.DataPadLength = frame.DataHasPadding ? extendedHeaders[0] : (byte)0;
break;
/* https://tools.ietf.org/html/rfc7540#section-6.2
+---------------+
|Pad Length? (8)|
+-+-------------+-----------------------------------------------+
|E| Stream Dependency? (31) |
+-+-------------+-----------------------------------------------+
| Weight? (8) |
+-+-------------+-----------------------------------------------+
| Header Block Fragment (*) ...
+---------------------------------------------------------------+
| Padding (*) ...
+---------------------------------------------------------------+
*/
case Proto2FrameType.HEADERS:
if (frame.HeadersHasPadding)
{
frame.HeadersPadLength = extendedHeaders[0];
extendedHeaders = extendedHeaders.Slice(1);
}
else
{
frame.HeadersPadLength = 0;
}
if (frame.HeadersHasPriority)
{
frame.HeadersStreamDependency = (int)Bitshifter.ReadUInt31BigEndian(extendedHeaders);
frame.HeadersPriorityWeight = extendedHeaders.Slice(4)[0];
}
else
{
frame.HeadersStreamDependency = 0;
frame.HeadersPriorityWeight = 0;
}
break;
/* https://tools.ietf.org/html/rfc7540#section-6.8
+-+-------------------------------------------------------------+
|R| Last-Stream-ID (31) |
+-+-------------------------------------------------------------+
| Error Code (32) |
+---------------------------------------------------------------+
| Additional Debug Data (*) |
+---------------------------------------------------------------+
*/
case Proto2FrameType.GOAWAY:
frame.GoAwayLastStreamId = (int)Bitshifter.ReadUInt31BigEndian(extendedHeaders);
frame.GoAwayErrorCode = (Proto2ErrorCode)BinaryPrimitives.ReadUInt32BigEndian(extendedHeaders.Slice(4));
break;
/* https://tools.ietf.org/html/rfc7540#section-6.3
+-+-------------------------------------------------------------+
|E| Stream Dependency (31) |
+-+-------------+-----------------------------------------------+
| Weight (8) |
+-+-------------+
*/
case Proto2FrameType.PRIORITY:
frame.PriorityStreamDependency = (int)Bitshifter.ReadUInt31BigEndian(extendedHeaders);
frame.PriorityWeight = extendedHeaders.Slice(4)[0];
break;
/* https://tools.ietf.org/html/rfc7540#section-6.4
+---------------------------------------------------------------+
| Error Code (32) |
+---------------------------------------------------------------+
*/
case Proto2FrameType.RST_STREAM:
frame.RstStreamErrorCode = (Proto2ErrorCode)BinaryPrimitives.ReadUInt32BigEndian(extendedHeaders);
break;
/* https://tools.ietf.org/html/rfc7540#section-6.9
+-+-------------------------------------------------------------+
|R| Window Size Increment (31) |
+-+-------------------------------------------------------------+
*/
case Proto2FrameType.WINDOW_UPDATE:
frame.WindowUpdateSizeIncrement = (int)Bitshifter.ReadUInt31BigEndian(extendedHeaders);
break;
case Proto2FrameType.PING: // Opaque payload 8 bytes long
case Proto2FrameType.SETTINGS: // Settings are general payload
case Proto2FrameType.CONTINUATION: // None
case Proto2FrameType.PUSH_PROMISE: // Not implemented frames are ignored at this phase
default:
return(0);
}
return(extendedHeaderLength);
}
