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