Track further neighbor state, don't send more NDPs than needed

src/yggdrasil/icmpv6.go

@@ -13,6 +13,7 @@ import (
 	"encoding/binary"
 	"errors"
 	"net"
+	"time"
 
 	"golang.org/x/net/icmp"
 	"golang.org/x/net/ipv6"
@@ -26,7 +27,14 @@ type icmpv6 struct {
 	tun      *tunDevice
 	mylladdr net.IP
 	mymac    macAddress
-	peermacs map[address]macAddress
+	peermacs map[address]neighbor
+}
+
+type neighbor struct {
+	mac               macAddress
+	learned           bool
+	lastadvertisement time.Time
+	lastsolicitation  time.Time
 }
 
 // Marshal returns the binary encoding of h.
@@ -51,7 +59,7 @@ func ipv6Header_Marshal(h *ipv6.Header) ([]byte, error) {
 // addresses.
 func (i *icmpv6) init(t *tunDevice) {
 	i.tun = t
-	i.peermacs = make(map[address]macAddress)
+	i.peermacs = make(map[address]neighbor)
 
 	// Our MAC address and link-local address
 	i.mymac = macAddress{
@@ -168,7 +176,11 @@ func (i *icmpv6) parse_packet_tun(datain []byte, datamac *[]byte) ([]byte, error
 			var mac macAddress
 			copy(addr[:], ipv6Header.Src[:])
 			copy(mac[:], (*datamac)[:])
-			i.peermacs[addr] = mac
+			neighbor := i.peermacs[addr]
+			neighbor.mac = mac
+			neighbor.learned = true
+			neighbor.lastadvertisement = time.Now()
+			i.peermacs[addr] = neighbor
 		}
 		return nil, errors.New("No response needed")
 	}
@@ -242,27 +254,11 @@ func (i *icmpv6) create_icmpv6_tun(dst net.IP, src net.IP, mtype ipv6.ICMPType,
 	return responsePacket, nil
 }
 
-func (i *icmpv6) create_ndp_tap(in []byte) ([]byte, error) {
-	// Parse the IPv6 packet headers
-	ipv6Header, err := ipv6.ParseHeader(in[:ipv6.HeaderLen])
-	if err != nil {
-		return nil, err
-	}
-
-	// Check if the packet is IPv6
-	if ipv6Header.Version != ipv6.Version {
-		return nil, err
-	}
-
-	// Check if the packet is ICMPv6
-	if ipv6Header.NextHeader != 58 {
-		return nil, err
-	}
-
+func (i *icmpv6) create_ndp_tap(dst address) ([]byte, error) {
 	// Create the ND payload
 	var payload [28]byte
 	copy(payload[:4], []byte{0x00, 0x00, 0x00, 0x00})
-	copy(payload[4:20], ipv6Header.Dst[:])
+	copy(payload[4:20], dst[:])
 	copy(payload[20:22], []byte{0x01, 0x01})
 	copy(payload[22:28], i.mymac[:6])
 
@@ -272,7 +268,7 @@ func (i *icmpv6) create_ndp_tap(in []byte) ([]byte, error) {
 		0xFF, 0x02, 0x00, 0x00,
 		0x00, 0x00, 0x00, 0x00,
 		0x00, 0x00, 0x00, 0x01, 0xFF})
-	copy(dstaddr[13:], ipv6Header.Dst[13:16])
+	copy(dstaddr[13:], dst[13:16])
 
 	// Create the multicast MAC
 	var dstmac macAddress
@@ -287,6 +283,9 @@ func (i *icmpv6) create_ndp_tap(in []byte) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
+	neighbor := i.peermacs[dstaddr]
+	neighbor.lastsolicitation = time.Now()
+	i.peermacs[dstaddr] = neighbor
 
 	return requestPacket, nil
 }

src/yggdrasil/tun.go

@@ -4,6 +4,7 @@ package yggdrasil
 
 import (
 	"errors"
+	"time"
 	"yggdrasil/defaults"
 
 	"github.com/songgao/packets/ethernet"
@@ -49,6 +50,21 @@ func (tun *tunDevice) start(ifname string, iftapmode bool, addr string, mtu int)
 	}
 	go func() { panic(tun.read()) }()
 	go func() { panic(tun.write()) }()
+	go func() {
+		for {
+			if _, ok := tun.icmpv6.peermacs[tun.core.router.addr]; ok {
+				break
+			}
+			request, err := tun.icmpv6.create_ndp_tap(tun.core.router.addr)
+			if err != nil {
+				panic(err)
+			}
+			if _, err := tun.iface.Write(request); err != nil {
+				panic(err)
+			}
+			time.Sleep(time.Second)
+		}
+	}()
 	return nil
 }
 
@@ -76,7 +92,35 @@ func (tun *tunDevice) write() error {
 			} else {
 				return errors.New("Invalid address family")
 			}
-			if peermac, ok := tun.icmpv6.peermacs[destAddr]; ok {
+			sendndp := func(destAddr address) {
+				neigh, known := tun.icmpv6.peermacs[destAddr]
+				known = known && (time.Since(neigh.lastsolicitation).Seconds() < 30)
+				if !known {
+					request, err := tun.icmpv6.create_ndp_tap(destAddr)
+					if err != nil {
+						panic(err)
+					}
+					if _, err := tun.iface.Write(request); err != nil {
+						panic(err)
+					}
+					tun.icmpv6.peermacs[destAddr] = neighbor{
+						lastsolicitation: time.Now(),
+					}
+				}
+			}
+			var peermac macAddress
+			var peerknown bool
+			if neighbor, ok := tun.icmpv6.peermacs[destAddr]; ok && neighbor.learned {
+				peermac = neighbor.mac
+				peerknown = true
+			} else if neighbor, ok := tun.icmpv6.peermacs[tun.core.router.addr]; ok && neighbor.learned {
+				peermac = neighbor.mac
+				peerknown = true
+				sendndp(destAddr)
+			} else {
+				sendndp(tun.core.router.addr)
+			}
+			if peerknown {
 				var frame ethernet.Frame
 				frame.Prepare(
 					peermac[:6],          // Destination MAC address
@@ -88,16 +132,7 @@ func (tun *tunDevice) write() error {
 				if _, err := tun.iface.Write(frame); err != nil {
 					panic(err)
 				}
-			} else {
-				request, err := tun.icmpv6.create_ndp_tap(data)
-				if err != nil {
-					panic(err)
 			}
-				if _, err := tun.iface.Write(request); err != nil {
-					panic(err)
-				}
-			}
-
 		} else {
 			if _, err := tun.iface.Write(data); err != nil {
 				panic(err)