TUN-4597: Add a QUIC server skeleton

- Added a QUIC server to accept streams
- Unit test for this server also tests ALPN
- Temporary echo capability for HTTP ConnectionType

vendor/github.com/lucas-clemente/quic-go/internal/wire/stream_frame.go

@@ -0,0 +1,189 @@
+package wire
+
+import (
+	"bytes"
+	"errors"
+	"io"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/quicvarint"
+)
+
+// A StreamFrame of QUIC
+type StreamFrame struct {
+	StreamID       protocol.StreamID
+	Offset         protocol.ByteCount
+	Data           []byte
+	Fin            bool
+	DataLenPresent bool
+
+	fromPool bool
+}
+
+func parseStreamFrame(r *bytes.Reader, _ protocol.VersionNumber) (*StreamFrame, error) {
+	typeByte, err := r.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+
+	hasOffset := typeByte&0x4 > 0
+	fin := typeByte&0x1 > 0
+	hasDataLen := typeByte&0x2 > 0
+
+	streamID, err := quicvarint.Read(r)
+	if err != nil {
+		return nil, err
+	}
+	var offset uint64
+	if hasOffset {
+		offset, err = quicvarint.Read(r)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	var dataLen uint64
+	if hasDataLen {
+		var err error
+		dataLen, err = quicvarint.Read(r)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		// The rest of the packet is data
+		dataLen = uint64(r.Len())
+	}
+
+	var frame *StreamFrame
+	if dataLen < protocol.MinStreamFrameBufferSize {
+		frame = &StreamFrame{Data: make([]byte, dataLen)}
+	} else {
+		frame = GetStreamFrame()
+		// The STREAM frame can't be larger than the StreamFrame we obtained from the buffer,
+		// since those StreamFrames have a buffer length of the maximum packet size.
+		if dataLen > uint64(cap(frame.Data)) {
+			return nil, io.EOF
+		}
+		frame.Data = frame.Data[:dataLen]
+	}
+
+	frame.StreamID = protocol.StreamID(streamID)
+	frame.Offset = protocol.ByteCount(offset)
+	frame.Fin = fin
+	frame.DataLenPresent = hasDataLen
+
+	if dataLen != 0 {
+		if _, err := io.ReadFull(r, frame.Data); err != nil {
+			return nil, err
+		}
+	}
+	if frame.Offset+frame.DataLen() > protocol.MaxByteCount {
+		return nil, errors.New("stream data overflows maximum offset")
+	}
+	return frame, nil
+}
+
+// Write writes a STREAM frame
+func (f *StreamFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
+	if len(f.Data) == 0 && !f.Fin {
+		return errors.New("StreamFrame: attempting to write empty frame without FIN")
+	}
+
+	typeByte := byte(0x8)
+	if f.Fin {
+		typeByte ^= 0x1
+	}
+	hasOffset := f.Offset != 0
+	if f.DataLenPresent {
+		typeByte ^= 0x2
+	}
+	if hasOffset {
+		typeByte ^= 0x4
+	}
+	b.WriteByte(typeByte)
+	quicvarint.Write(b, uint64(f.StreamID))
+	if hasOffset {
+		quicvarint.Write(b, uint64(f.Offset))
+	}
+	if f.DataLenPresent {
+		quicvarint.Write(b, uint64(f.DataLen()))
+	}
+	b.Write(f.Data)
+	return nil
+}
+
+// Length returns the total length of the STREAM frame
+func (f *StreamFrame) Length(version protocol.VersionNumber) protocol.ByteCount {
+	length := 1 + quicvarint.Len(uint64(f.StreamID))
+	if f.Offset != 0 {
+		length += quicvarint.Len(uint64(f.Offset))
+	}
+	if f.DataLenPresent {
+		length += quicvarint.Len(uint64(f.DataLen()))
+	}
+	return length + f.DataLen()
+}
+
+// DataLen gives the length of data in bytes
+func (f *StreamFrame) DataLen() protocol.ByteCount {
+	return protocol.ByteCount(len(f.Data))
+}
+
+// MaxDataLen returns the maximum data length
+// If 0 is returned, writing will fail (a STREAM frame must contain at least 1 byte of data).
+func (f *StreamFrame) MaxDataLen(maxSize protocol.ByteCount, version protocol.VersionNumber) protocol.ByteCount {
+	headerLen := 1 + quicvarint.Len(uint64(f.StreamID))
+	if f.Offset != 0 {
+		headerLen += quicvarint.Len(uint64(f.Offset))
+	}
+	if f.DataLenPresent {
+		// pretend that the data size will be 1 bytes
+		// if it turns out that varint encoding the length will consume 2 bytes, we need to adjust the data length afterwards
+		headerLen++
+	}
+	if headerLen > maxSize {
+		return 0
+	}
+	maxDataLen := maxSize - headerLen
+	if f.DataLenPresent && quicvarint.Len(uint64(maxDataLen)) != 1 {
+		maxDataLen--
+	}
+	return maxDataLen
+}
+
+// MaybeSplitOffFrame splits a frame such that it is not bigger than n bytes.
+// It returns if the frame was actually split.
+// The frame might not be split if:
+// * the size is large enough to fit the whole frame
+// * the size is too small to fit even a 1-byte frame. In that case, the frame returned is nil.
+func (f *StreamFrame) MaybeSplitOffFrame(maxSize protocol.ByteCount, version protocol.VersionNumber) (*StreamFrame, bool /* was splitting required */) {
+	if maxSize >= f.Length(version) {
+		return nil, false
+	}
+
+	n := f.MaxDataLen(maxSize, version)
+	if n == 0 {
+		return nil, true
+	}
+
+	new := GetStreamFrame()
+	new.StreamID = f.StreamID
+	new.Offset = f.Offset
+	new.Fin = false
+	new.DataLenPresent = f.DataLenPresent
+
+	// swap the data slices
+	new.Data, f.Data = f.Data, new.Data
+	new.fromPool, f.fromPool = f.fromPool, new.fromPool
+
+	f.Data = f.Data[:protocol.ByteCount(len(new.Data))-n]
+	copy(f.Data, new.Data[n:])
+	new.Data = new.Data[:n]
+	f.Offset += n
+
+	return new, true
+}
+
+func (f *StreamFrame) PutBack() {
+	putStreamFrame(f)
+}