feat: add MTU random range

config/cfg.go

@@ -31,8 +31,10 @@ type Peer struct {
 	QuerySeconds     int64    `yaml:"QuerySeconds"`
 	AllowTrans       bool     `yaml:"AllowTrans"`
 	MTU              int64    `yaml:"MTU"`
+	MTURandomRange   int64    `yaml:"MTURandomRange"`
 }
 
+// Parse 解析配置文件
 func Parse(path string) (c Config) {
 	file, err := os.ReadFile(path)
 	if err != nil {

gold/link/link.go

@@ -34,11 +34,13 @@ type Link struct {
 	// 本机信息
 	me *Me
 	// 连接的状态，详见下方 const
-	status int
+	status int8
 	// 是否允许转发
 	allowtrans bool
 	// udp 数据包的最大大小
 	mtu uint16
+	// 随机放缩 mtu 范围 (只减不增)
+	mturandomrange uint16
 }
 
 const (

gold/link/peer.go

@@ -19,6 +19,7 @@ type PeerConfig struct {
 	PresharedKey            *[32]byte
 	KeepAliveDur, QueryTick int64
 	MTU                     uint16
+	MTURandomRange          uint16
 	AllowTrans, NoPipe      bool
 }
 
@@ -34,11 +35,12 @@ func (m *Me) AddPeer(cfg *PeerConfig) (l *Link) {
 		panic("invalid mtu for peer " + cfg.PeerIP)
 	}
 	l = &Link{
-		pubk:       cfg.PubicKey,
-		peerip:     net.ParseIP(cfg.PeerIP),
-		allowtrans: cfg.AllowTrans,
-		me:         m,
-		mtu:        uint16(cfg.MTU),
+		pubk:           cfg.PubicKey,
+		peerip:         net.ParseIP(cfg.PeerIP),
+		allowtrans:     cfg.AllowTrans,
+		me:             m,
+		mtu:            uint16(cfg.MTU),
+		mturandomrange: uint16(cfg.MTURandomRange),
 	}
 
 	if !cfg.NoPipe {

gold/link/send.go

@@ -15,7 +15,11 @@ func (l *Link) WriteAndPut(p *head.Packet, istransfer bool) (n int, err error) {
 	teatype := uint8(rand.Intn(16))
 	sndcnt := atomic.AddUintptr(&l.sendcount, 1)
 	logrus.Debugln("[send] count:", sndcnt, ", additional data:", uint16(sndcnt))
-	if len(p.Data) <= int(l.mtu) {
+	mtu := l.mtu
+	if l.mturandomrange > 0 {
+		mtu -= uint16(rand.Intn(int(l.mturandomrange)))
+	}
+	if len(p.Data) <= int(mtu) {
 		if !istransfer {
 			p.FillHash()
 			if l.aead != nil {
@@ -24,7 +28,7 @@ func (l *Link) WriteAndPut(p *head.Packet, istransfer bool) (n int, err error) {
 			p.Data = l.Encode(teatype, p.Data)
 		}
 		defer p.Put()
-		return l.write(p, teatype, uint16(sndcnt), uint32(len(p.Data)), 0, istransfer, false)
+		return l.write(p, teatype, uint16(sndcnt), mtu, uint32(len(p.Data)), 0, istransfer, false)
 	}
 	if !istransfer {
 		p.FillHash()
@@ -39,31 +43,31 @@ func (l *Link) WriteAndPut(p *head.Packet, istransfer bool) (n int, err error) {
 	i := 0
 	packet := head.SelectPacket()
 	*packet = *p
-	for ; int(totl)-i > int(l.mtu); i += int(l.mtu) {
-		logrus.Debugln("[send] split frag", i, ":", i+int(l.mtu), ", remain:", int(totl)-i-int(l.mtu))
-		packet.Data = data[:int(l.mtu)]
-		cnt, err := l.write(packet, teatype, uint16(sndcnt), totl, uint16(i>>3), istransfer, true)
+	for ; int(totl)-i > int(mtu); i += int(mtu) {
+		logrus.Debugln("[send] split frag", i, ":", i+int(mtu), ", remain:", int(totl)-i-int(mtu))
+		packet.Data = data[:int(mtu)]
+		cnt, err := l.write(packet, teatype, uint16(sndcnt), mtu, totl, uint16(i>>3), istransfer, true)
 		n += cnt
 		if err != nil {
 			return n, err
 		}
-		data = data[int(l.mtu):]
+		data = data[int(mtu):]
 		packet.TTL = ttl
 	}
 	packet.Put()
 	p.Data = data
-	cnt, err := l.write(p, teatype, uint16(sndcnt), totl, uint16(i>>3), istransfer, false)
+	cnt, err := l.write(p, teatype, uint16(sndcnt), mtu, totl, uint16(i>>3), istransfer, false)
 	p.Put()
 	n += cnt
 	return n, err
 }
 
 // write 向 peer 发一个包
-func (l *Link) write(p *head.Packet, teatype uint8, additional uint16, datasz uint32, offset uint16, istransfer, hasmore bool) (n int, err error) {
+func (l *Link) write(p *head.Packet, teatype uint8, additional, mtu uint16, datasz uint32, offset uint16, istransfer, hasmore bool) (n int, err error) {
 	var d []byte
 	var cl func()
 	if istransfer {
-		if p.Flags&0x4000 == 0x4000 && len(p.Data) > int(l.mtu) {
+		if p.Flags&0x4000 == 0x4000 && len(p.Data) > int(mtu) {
 			return len(p.Data), errors.New("drop dont fragmnet big trans packet")
 		}
 		d, cl = p.Marshal(nil, teatype, additional, 0, 0, false, false)

upper/services/wg/wg.go

@@ -107,7 +107,7 @@ func (wg *WG) init(srcport, dstport uint16) {
 		}
 		n := copy(peerkey[:], base14.Decode(k))
 		if n != 32 {
-			panic("peer public key length < 32")
+			panic("peer " + peer.IP + ": public key length < 32")
 		}
 		var pshk *[32]byte
 		if peer.PresharedKey != "" {
@@ -118,21 +118,28 @@ func (wg *WG) init(srcport, dstport uint16) {
 			pshk = &[32]byte{}
 			n := copy(pshk[:], base14.Decode(k))
 			if n != 32 {
-				panic("peer preshared key length < 32")
+				panic("peer " + peer.IP + ": preshared key length < 32")
 			}
 		}
+		if peer.MTU >= 65535 {
+			panic("peer " + peer.IP + ": MTU too large")
+		}
+		if peer.MTURandomRange >= peer.MTU/2 {
+			panic("peer " + peer.IP + ": MTURandomRange too large")
+		}
 		wg.me.AddPeer(&link.PeerConfig{
-			PeerIP:       peer.IP,
-			EndPoint:     peer.EndPoint,
-			AllowedIPs:   peer.AllowedIPs,
-			Querys:       peer.QueryList,
-			PubicKey:     &peerkey,
-			PresharedKey: pshk,
-			KeepAliveDur: peer.KeepAliveSeconds,
-			QueryTick:    peer.QuerySeconds,
-			MTU:          uint16(peer.MTU),
-			AllowTrans:   peer.AllowTrans,
-			NoPipe:       true,
+			PeerIP:         peer.IP,
+			EndPoint:       peer.EndPoint,
+			AllowedIPs:     peer.AllowedIPs,
+			Querys:         peer.QueryList,
+			PubicKey:       &peerkey,
+			PresharedKey:   pshk,
+			KeepAliveDur:   peer.KeepAliveSeconds,
+			QueryTick:      peer.QuerySeconds,
+			MTU:            uint16(peer.MTU),
+			MTURandomRange: uint16(peer.MTURandomRange),
+			AllowTrans:     peer.AllowTrans,
+			NoPipe:         true,
 		})
 	}
 }