package kcp import ( "v2ray.com/core/common" "v2ray.com/core/common/alloc" _ "v2ray.com/core/common/log" "v2ray.com/core/common/serial" ) type Command byte const ( CommandACK Command = 0 CommandData Command = 1 CommandTerminate Command = 2 CommandPing Command = 3 ) type SegmentOption byte const ( SegmentOptionClose SegmentOption = 1 ) type Segment interface { common.Releasable ByteSize() int Bytes([]byte) []byte } const ( DataSegmentOverhead = 18 ) type DataSegment struct { Conv uint16 Option SegmentOption Timestamp uint32 Number uint32 SendingNext uint32 Data *alloc.Buffer timeout uint32 ackSkipped uint32 transmit uint32 } func NewDataSegment() *DataSegment { return new(DataSegment) } func (this *DataSegment) Bytes(b []byte) []byte { b = serial.Uint16ToBytes(this.Conv, b) b = append(b, byte(CommandData), byte(this.Option)) b = serial.Uint32ToBytes(this.Timestamp, b) b = serial.Uint32ToBytes(this.Number, b) b = serial.Uint32ToBytes(this.SendingNext, b) b = serial.Uint16ToBytes(uint16(this.Data.Len()), b) b = append(b, this.Data.Value...) return b } func (this *DataSegment) ByteSize() int { return 2 + 1 + 1 + 4 + 4 + 4 + 2 + this.Data.Len() } func (this *DataSegment) Release() { this.Data.Release() this.Data = nil } type AckSegment struct { Conv uint16 Option SegmentOption ReceivingWindow uint32 ReceivingNext uint32 Timestamp uint32 Count byte NumberList []uint32 } func NewAckSegment() *AckSegment { return new(AckSegment) } func (this *AckSegment) PutTimestamp(timestamp uint32) { if timestamp-this.Timestamp < 0x7FFFFFFF { this.Timestamp = timestamp } } func (this *AckSegment) PutNumber(number uint32) { this.Count++ this.NumberList = append(this.NumberList, number) } func (this *AckSegment) IsFull() bool { return this.Count == 128 } func (this *AckSegment) ByteSize() int { return 2 + 1 + 1 + 4 + 4 + 4 + 1 + int(this.Count)*4 } func (this *AckSegment) Bytes(b []byte) []byte { b = serial.Uint16ToBytes(this.Conv, b) b = append(b, byte(CommandACK), byte(this.Option)) b = serial.Uint32ToBytes(this.ReceivingWindow, b) b = serial.Uint32ToBytes(this.ReceivingNext, b) b = serial.Uint32ToBytes(this.Timestamp, b) b = append(b, this.Count) for i := byte(0); i < this.Count; i++ { b = serial.Uint32ToBytes(this.NumberList[i], b) } return b } func (this *AckSegment) Release() { this.NumberList = nil } type CmdOnlySegment struct { Conv uint16 Command Command Option SegmentOption SendingNext uint32 ReceivinNext uint32 PeerRTO uint32 } func NewCmdOnlySegment() *CmdOnlySegment { return new(CmdOnlySegment) } func (this *CmdOnlySegment) ByteSize() int { return 2 + 1 + 1 + 4 + 4 + 4 } func (this *CmdOnlySegment) Bytes(b []byte) []byte { b = serial.Uint16ToBytes(this.Conv, b) b = append(b, byte(this.Command), byte(this.Option)) b = serial.Uint32ToBytes(this.SendingNext, b) b = serial.Uint32ToBytes(this.ReceivinNext, b) b = serial.Uint32ToBytes(this.PeerRTO, b) return b } func (this *CmdOnlySegment) Release() { } func ReadSegment(buf []byte) (Segment, []byte) { if len(buf) <= 4 { return nil, nil } conv := serial.BytesToUint16(buf) buf = buf[2:] cmd := Command(buf[0]) opt := SegmentOption(buf[1]) buf = buf[2:] if cmd == CommandData { seg := NewDataSegment() seg.Conv = conv seg.Option = opt if len(buf) < 16 { return nil, nil } seg.Timestamp = serial.BytesToUint32(buf) buf = buf[4:] seg.Number = serial.BytesToUint32(buf) buf = buf[4:] seg.SendingNext = serial.BytesToUint32(buf) buf = buf[4:] dataLen := int(serial.BytesToUint16(buf)) buf = buf[2:] if len(buf) < dataLen { return nil, nil } seg.Data = AllocateBuffer().Clear().Append(buf[:dataLen]) buf = buf[dataLen:] return seg, buf } if cmd == CommandACK { seg := NewAckSegment() seg.Conv = conv seg.Option = opt if len(buf) < 13 { return nil, nil } seg.ReceivingWindow = serial.BytesToUint32(buf) buf = buf[4:] seg.ReceivingNext = serial.BytesToUint32(buf) buf = buf[4:] seg.Timestamp = serial.BytesToUint32(buf) buf = buf[4:] count := int(buf[0]) buf = buf[1:] if len(buf) < count*4 { return nil, nil } for i := 0; i < count; i++ { seg.PutNumber(serial.BytesToUint32(buf)) buf = buf[4:] } return seg, buf } seg := NewCmdOnlySegment() seg.Conv = conv seg.Command = cmd seg.Option = opt if len(buf) < 12 { return nil, nil } seg.SendingNext = serial.BytesToUint32(buf) buf = buf[4:] seg.ReceivinNext = serial.BytesToUint32(buf) buf = buf[4:] seg.PeerRTO = serial.BytesToUint32(buf) buf = buf[4:] return seg, buf }