add peerwise mtu

gold/link/link.go

@@ -32,6 +32,8 @@ type Link struct {
 	status int
 	// 是否允许转发
 	allowtrans bool
+	// udp 数据包的最大大小
+	mtu uint16
 }
 
 const (

gold/link/me.go

@@ -88,6 +88,7 @@ func NewMe(cfg *MyConfig) (m Me) {
 		EndPoint:   "127.0.0.1:56789",
 		AllowedIPs: []string{cfg.MyIPwithMask},
 		NoPipe:     cfg.NIC != nil,
+		MTU:        cfg.MTU,
 	})
 	m.srcport = cfg.SrcPort
 	m.dstport = cfg.DstPort

gold/link/peer.go

@@ -16,6 +16,7 @@ type PeerConfig struct {
 	AllowedIPs, Querys      []string
 	PubicKey                *[32]byte
 	KeepAliveDur, QueryTick int64
+	MTU                     uint16
 	AllowTrans, NoPipe      bool
 }
 
@@ -27,11 +28,15 @@ func (m *Me) AddPeer(cfg *PeerConfig) (l *Link) {
 	if ok {
 		return
 	}
+	if cfg.MTU == 0 || cfg.MTU == 65535 {
+		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),
 	}
 
 	if !cfg.NoPipe {

gold/link/send.go

@@ -12,7 +12,7 @@ import (
 // WriteAndPut 向 peer 发包并将包放回缓存池
 func (l *Link) WriteAndPut(p *head.Packet, istransfer bool) (n int, err error) {
 	teatype := uint8(rand.Intn(16))
-	if len(p.Data) <= int(l.me.mtu) {
+	if len(p.Data) <= int(l.mtu) {
 		if !istransfer {
 			p.FillHash()
 			p.Data = l.Encode(teatype, p.Data)
@@ -30,15 +30,15 @@ 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.me.mtu); i += int(l.me.mtu) {
-		logrus.Debugln("[link] split frag", i, ":", i+int(l.me.mtu), ", remain:", int(totl)-i-int(l.me.mtu))
-		packet.Data = data[:int(l.me.mtu)]
+	for ; int(totl)-i > int(l.mtu); i += int(l.mtu) {
+		logrus.Debugln("[link] 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, totl, uint16(uint(i)>>3), istransfer, true)
 		n += cnt
 		if err != nil {
 			return n, err
 		}
-		data = data[int(l.me.mtu):]
+		data = data[int(l.mtu):]
 		packet.TTL = ttl
 	}
 	packet.Put()
@@ -54,7 +54,7 @@ func (l *Link) write(p *head.Packet, teatype uint8, datasz uint32, offset uint16
 	var d []byte
 	var cl func()
 	if istransfer {
-		if p.Flags&0x4000 == 0x4000 && len(p.Data) > int(l.me.mtu) {
+		if p.Flags&0x4000 == 0x4000 && len(p.Data) > int(l.mtu) {
 			return len(p.Data), errors.New("drop dont fragmnet big trans packet")
 		}
 		d, cl = p.Marshal(nil, teatype, 0, 0, false, false)