make wire an internal package

internal/wire/stop_waiting_frame.go

@@ -0,0 +1,81 @@
+package wire
+
+import (
+	"bytes"
+	"errors"
+
+	"github.com/lucas-clemente/quic-go/internal/utils"
+	"github.com/lucas-clemente/quic-go/protocol"
+	"github.com/lucas-clemente/quic-go/qerr"
+)
+
+// A StopWaitingFrame in QUIC
+type StopWaitingFrame struct {
+	LeastUnacked    protocol.PacketNumber
+	PacketNumberLen protocol.PacketNumberLen
+	// PacketNumber is the packet number of the packet that this StopWaitingFrame will be sent with
+	PacketNumber protocol.PacketNumber
+}
+
+var (
+	errLeastUnackedHigherThanPacketNumber = errors.New("StopWaitingFrame: LeastUnacked can't be greater than the packet number")
+	errPacketNumberNotSet                 = errors.New("StopWaitingFrame: PacketNumber not set")
+	errPacketNumberLenNotSet              = errors.New("StopWaitingFrame: PacketNumberLen not set")
+)
+
+func (f *StopWaitingFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
+	// make sure the PacketNumber was set
+	if f.PacketNumber == protocol.PacketNumber(0) {
+		return errPacketNumberNotSet
+	}
+	if f.LeastUnacked > f.PacketNumber {
+		return errLeastUnackedHigherThanPacketNumber
+	}
+
+	b.WriteByte(0x06)
+	leastUnackedDelta := uint64(f.PacketNumber - f.LeastUnacked)
+	switch f.PacketNumberLen {
+	case protocol.PacketNumberLen1:
+		b.WriteByte(uint8(leastUnackedDelta))
+	case protocol.PacketNumberLen2:
+		utils.GetByteOrder(version).WriteUint16(b, uint16(leastUnackedDelta))
+	case protocol.PacketNumberLen4:
+		utils.GetByteOrder(version).WriteUint32(b, uint32(leastUnackedDelta))
+	case protocol.PacketNumberLen6:
+		utils.GetByteOrder(version).WriteUint48(b, leastUnackedDelta&(1<<48-1))
+	default:
+		return errPacketNumberLenNotSet
+	}
+	return nil
+}
+
+// MinLength of a written frame
+func (f *StopWaitingFrame) MinLength(version protocol.VersionNumber) (protocol.ByteCount, error) {
+	minLength := protocol.ByteCount(1) // typeByte
+
+	if f.PacketNumberLen == protocol.PacketNumberLenInvalid {
+		return 0, errPacketNumberLenNotSet
+	}
+	minLength += protocol.ByteCount(f.PacketNumberLen)
+	return minLength, nil
+}
+
+// ParseStopWaitingFrame parses a StopWaiting frame
+func ParseStopWaitingFrame(r *bytes.Reader, packetNumber protocol.PacketNumber, packetNumberLen protocol.PacketNumberLen, version protocol.VersionNumber) (*StopWaitingFrame, error) {
+	frame := &StopWaitingFrame{}
+
+	// read the TypeByte
+	if _, err := r.ReadByte(); err != nil {
+		return nil, err
+	}
+
+	leastUnackedDelta, err := utils.GetByteOrder(version).ReadUintN(r, uint8(packetNumberLen))
+	if err != nil {
+		return nil, err
+	}
+	if leastUnackedDelta >= uint64(packetNumber) {
+		return nil, qerr.Error(qerr.InvalidStopWaitingData, "invalid LeastUnackedDelta")
+	}
+	frame.LeastUnacked = protocol.PacketNumber(uint64(packetNumber) - leastUnackedDelta)
+	return frame, nil
+}