mirror of
https://github.com/fumiama/WireGold.git
synced 2026-06-04 23:40:26 +08:00
143 lines
3.5 KiB
Go
143 lines
3.5 KiB
Go
package head
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import (
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"encoding/binary"
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"errors"
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"net"
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"unsafe"
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blake2b "github.com/minio/blake2b-simd"
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"github.com/sirupsen/logrus"
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)
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// Packet 是发送和接收的最小单位
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type Packet struct {
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// Ver 协议版本
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Ver uint16
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// DataSZ len(Data)
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// 不得超过 65507-head 字节
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DataSZ uint16
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// Proto 详见 head
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Proto uint8
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// TTL is time to live
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TTL uint8
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// SrcPort 源端口
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SrcPort uint16
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// DstPort 目的端口
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DstPort uint16
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// Flags 高3位为标志(xDM)，低13位为分片偏移
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Flags uint16
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// Src 源 ip (ipv4)
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Src net.IP
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// Dst 目的 ip (ipv4)
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Dst net.IP
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// Hash 使用 BLAKE2 生成加密前 Packet 的摘要
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// 生成时 Hash 全 0
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// https://github.com/minio/blake2b-simd
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Hash [32]byte
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// Data 承载的数据
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Data []byte
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// 记录还有多少字节未到达
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rembytes uint16
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}
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// NewPacket 生成一个新包
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func NewPacket(proto uint8, srcPort uint16, dst net.IP, dstPort uint16, data []byte) *Packet {
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logrus.Debugln("[packet] new: [proto:", proto, ", srcport:", srcPort, ", dstport:", dstPort, ", dst:", dst, ", data:", data)
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return &Packet{
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Ver: 1,
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Proto: proto,
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TTL: 16,
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SrcPort: srcPort,
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DstPort: dstPort,
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Dst: dst,
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Data: data,
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}
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}
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// Unmarshal 将 data 的数据解码到自身
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func (p *Packet) Unmarshal(data []byte) (complete bool, err error) {
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if len(data) < 12 {
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err = errors.New("data len < 12")
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return
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}
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if p.DataSZ == 0 && len(p.Data) == 0 {
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p.Ver = binary.LittleEndian.Uint16(data[:2])
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if p.Ver != 1 {
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err = errors.New("unknown protocol version")
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return
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}
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p.DataSZ = binary.LittleEndian.Uint16(data[2:4])
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p.Data = make([]byte, p.DataSZ)
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pt := binary.LittleEndian.Uint16(data[4:6])
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p.Proto = uint8(pt)
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p.TTL = uint8(pt >> 8)
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p.SrcPort = binary.LittleEndian.Uint16(data[6:8])
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p.DstPort = binary.LittleEndian.Uint16(data[8:10])
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p.rembytes = p.DataSZ
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}
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p.Flags = binary.LittleEndian.Uint16(data[10:12])
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p.Src = make(net.IP, 4)
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copy(p.Src, data[12:16])
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p.Dst = make(net.IP, 4)
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copy(p.Dst, data[16:20])
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copy(p.Hash[:], data[20:52])
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p.rembytes -= uint16(copy(p.Data[p.Flags<<3:], data[52:]))
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complete = p.rembytes == 0
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return
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}
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// Marshal 将自身数据编码为 []byte
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// offset 必须为 8 的倍数，表示偏移的 8 位
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func (p *Packet) Marshal(src net.IP, offset uint16, dontfrag, hasmore bool) []byte {
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p.TTL--
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if p.TTL == 0 {
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return nil
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}
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p.DataSZ = uint16(len(p.Data))
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if src != nil {
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p.Src = src
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offset >>= 3
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if dontfrag {
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offset |= 0x4000
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}
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if hasmore {
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offset |= 0x2000
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}
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p.Flags = offset
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}
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packet := make([]byte, 52+len(p.Data))
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binary.LittleEndian.PutUint16(packet[:2], p.Ver)
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binary.LittleEndian.PutUint16(packet[2:4], p.DataSZ)
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binary.LittleEndian.PutUint16(packet[4:6], (uint16(p.TTL)<<8)|uint16(p.Proto))
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binary.LittleEndian.PutUint16(packet[6:8], p.SrcPort)
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binary.LittleEndian.PutUint16(packet[8:10], p.DstPort)
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binary.LittleEndian.PutUint16(packet[10:12], p.Flags)
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copy(packet[12:16], p.Src.To4())
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copy(packet[16:20], p.Dst.To4())
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copy(packet[20:52], p.Hash[:])
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copy(packet[52:], p.Data)
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// logrus.Debugln("[packet] marshaled packet:", hex.EncodeToString(packet))
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return packet
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}
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// FillHash 生成 p.Data 的 Hash
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func (p *Packet) FillHash() {
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sum := blake2b.New256().Sum(p.Data)
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p.Hash = *(*[32]byte)(*(*unsafe.Pointer)(unsafe.Pointer(&sum)))
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}
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// IsVaildHash 验证 packet 合法性
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func (p *Packet) IsVaildHash() bool {
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sum := blake2b.New256().Sum(p.Data)
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return *(*[32]byte)(*(*unsafe.Pointer)(unsafe.Pointer(&sum))) == p.Hash
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}
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