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/crypto_stream.go

@@ -0,0 +1,115 @@
+package quic
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/qerr"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+	"github.com/lucas-clemente/quic-go/internal/wire"
+)
+
+type cryptoStream interface {
+	// for receiving data
+	HandleCryptoFrame(*wire.CryptoFrame) error
+	GetCryptoData() []byte
+	Finish() error
+	// for sending data
+	io.Writer
+	HasData() bool
+	PopCryptoFrame(protocol.ByteCount) *wire.CryptoFrame
+}
+
+type cryptoStreamImpl struct {
+	queue  *frameSorter
+	msgBuf []byte
+
+	highestOffset protocol.ByteCount
+	finished      bool
+
+	writeOffset protocol.ByteCount
+	writeBuf    []byte
+}
+
+func newCryptoStream() cryptoStream {
+	return &cryptoStreamImpl{queue: newFrameSorter()}
+}
+
+func (s *cryptoStreamImpl) HandleCryptoFrame(f *wire.CryptoFrame) error {
+	highestOffset := f.Offset + protocol.ByteCount(len(f.Data))
+	if maxOffset := highestOffset; maxOffset > protocol.MaxCryptoStreamOffset {
+		return &qerr.TransportError{
+			ErrorCode:    qerr.CryptoBufferExceeded,
+			ErrorMessage: fmt.Sprintf("received invalid offset %d on crypto stream, maximum allowed %d", maxOffset, protocol.MaxCryptoStreamOffset),
+		}
+	}
+	if s.finished {
+		if highestOffset > s.highestOffset {
+			// reject crypto data received after this stream was already finished
+			return &qerr.TransportError{
+				ErrorCode:    qerr.ProtocolViolation,
+				ErrorMessage: "received crypto data after change of encryption level",
+			}
+		}
+		// ignore data with a smaller offset than the highest received
+		// could e.g. be a retransmission
+		return nil
+	}
+	s.highestOffset = utils.MaxByteCount(s.highestOffset, highestOffset)
+	if err := s.queue.Push(f.Data, f.Offset, nil); err != nil {
+		return err
+	}
+	for {
+		_, data, _ := s.queue.Pop()
+		if data == nil {
+			return nil
+		}
+		s.msgBuf = append(s.msgBuf, data...)
+	}
+}
+
+// GetCryptoData retrieves data that was received in CRYPTO frames
+func (s *cryptoStreamImpl) GetCryptoData() []byte {
+	if len(s.msgBuf) < 4 {
+		return nil
+	}
+	msgLen := 4 + int(s.msgBuf[1])<<16 + int(s.msgBuf[2])<<8 + int(s.msgBuf[3])
+	if len(s.msgBuf) < msgLen {
+		return nil
+	}
+	msg := make([]byte, msgLen)
+	copy(msg, s.msgBuf[:msgLen])
+	s.msgBuf = s.msgBuf[msgLen:]
+	return msg
+}
+
+func (s *cryptoStreamImpl) Finish() error {
+	if s.queue.HasMoreData() {
+		return &qerr.TransportError{
+			ErrorCode:    qerr.ProtocolViolation,
+			ErrorMessage: "encryption level changed, but crypto stream has more data to read",
+		}
+	}
+	s.finished = true
+	return nil
+}
+
+// Writes writes data that should be sent out in CRYPTO frames
+func (s *cryptoStreamImpl) Write(p []byte) (int, error) {
+	s.writeBuf = append(s.writeBuf, p...)
+	return len(p), nil
+}
+
+func (s *cryptoStreamImpl) HasData() bool {
+	return len(s.writeBuf) > 0
+}
+
+func (s *cryptoStreamImpl) PopCryptoFrame(maxLen protocol.ByteCount) *wire.CryptoFrame {
+	f := &wire.CryptoFrame{Offset: s.writeOffset}
+	n := utils.MinByteCount(f.MaxDataLen(maxLen), protocol.ByteCount(len(s.writeBuf)))
+	f.Data = s.writeBuf[:n]
+	s.writeBuf = s.writeBuf[n:]
+	s.writeOffset += n
+	return f
+}