Proxying implementation finished

NDPRequest.go

@@ -9,8 +9,10 @@ const (
 
 type NDRequest struct {
 	requestType      NDPType
-	//TODO use global unicast for router advertisements
 	srcIP            []byte
 	answeringForIP   []byte
+	dstIP            []byte
 	mac              []byte
+	receivedIfaceMac []byte
+	sourceIface      string
 }

main.go

@@ -3,6 +3,8 @@ package main
 import (
 	"fmt"
 	"os"
+	"os/signal"
+	"syscall"
 )
 
 func main() {
@@ -27,8 +29,14 @@ func simpleRespond(iface string) {
 	defer close(requests)
 	go respond(iface, requests, NDP_ADV)
 	go listen(iface, requests, NDP_SOL)
-	select {}
+
-	//TODO os.signal
+	sigCh := make(chan os.Signal)
+	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
+	select {
+	case <-sigCh:
+		fmt.Println("Exit")
+		os.Exit(0)
+	}
 }
 
 func proxy(iface1, iface2 string) {
@@ -52,7 +60,11 @@ func proxy(iface1, iface2 string) {
 	go listen(iface2, req_iface2_adv_iface1, NDP_ADV)
 	go respond(iface1, req_iface2_adv_iface1, NDP_ADV)
 
-	select {}
+	sigCh := make(chan os.Signal)
-	// TODO os.signal
+	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
-
+	select {
+	case <-sigCh:
+		fmt.Println("Exit")
+		os.Exit(0)
+	}
 }

packet.go

@@ -2,6 +2,9 @@ package main
 
 import (
 	"encoding/binary"
+	"errors"
+	"net"
+	"strings"
 )
 
 var emptyIpv6 = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
@@ -18,8 +21,11 @@ type IPv6Header struct {
 	payload    []byte
 }
 
-func newIpv6Header(srcIp []byte, dstIp []byte) *IPv6Header {
+func newIpv6Header(srcIp []byte, dstIp []byte) (*IPv6Header, error) {
-	return &IPv6Header{dstIP: dstIp, srcIP: srcIp, protocol: 0x3a}
+	if len(dstIp) != 16 || len(srcIp) != 16 {
+		return nil, errors.New("malformed IP")
+	}
+	return &IPv6Header{dstIP: dstIp, srcIP: srcIp, protocol: 0x3a}, nil
 }
 
 func (h *IPv6Header) addPayload(payload Payload) {
@@ -61,23 +67,29 @@ type NdpPayload struct {
 	mac            []byte
 }
 
-func newNdpPacket(answeringForIP []byte, mac []byte, packetType NDPType) *NdpPayload {
+func newNdpPacket(answeringForIP []byte, mac []byte, packetType NDPType) (*NdpPayload, error) {
+	if len(answeringForIP) != 16 || len(mac) != 6 {
+		return nil, errors.New("malformed IP")
+	}
 	return &NdpPayload{
 		packetType:     packetType,
 		answeringForIP: answeringForIP,
 		mac:            mac,
-	}
+	}, nil
 }
 
 func (p *NdpPayload) constructPacket() ([]byte, int) {
 	var protocol byte
 	var flags byte
+	var linkType byte
 	if p.packetType == NDP_SOL {
 		protocol = 0x87
 		flags = 0x0
+		linkType = 0x01
 	} else {
 		protocol = 0x88
 		flags = 0x60
+		linkType = 0x02
 	}
 	header := []byte{
 		protocol, // Type: NDPType
@@ -89,13 +101,10 @@ func (p *NdpPayload) constructPacket() ([]byte, int) {
 		0x0,      // Reserved
 		0x0,      // Reserved
 	}
-	if len(p.answeringForIP) != 16 {
-		panic("malformed IP")
-	} //TODO check IP lengths on assign everywhere
 	final := append(header, p.answeringForIP...)
 
 	secondHeader := []byte{
-		0x02, // Type: Target link-layer address (2)
+		linkType, // Type
 		0x01,     // Length: 1 (8 bytes)
 	}
 	final = append(final, secondHeader...)
@@ -123,3 +132,8 @@ func checksumAddition(b []byte) uint32 {
 	}
 	return sum
 }
+
+func IsIPv6(ip string) bool {
+	rip := net.ParseIP(ip)
+	return rip != nil && strings.Contains(ip, ":")
+}

rawsocket.go

@@ -50,7 +50,6 @@ func listen(iface string, responder chan *NDRequest, requestType NDPType) {
 		Protocol: htons16(syscall.ETH_P_IPV6),
 		Ifindex:  niface.Index,
 	}
-	fmt.Println(niface.HardwareAddr)
 
 	fd, err := syscall.Socket(syscall.AF_PACKET, syscall.SOCK_RAW, htons(syscall.ETH_P_IPV6))
 	if err != nil {
@@ -65,7 +64,7 @@ func listen(iface string, responder chan *NDRequest, requestType NDPType) {
 
 	err = syscall.Bind(fd, tiface)
 	if err != nil {
-		fmt.Println(err.Error())
+		panic(err.Error())
 	}
 
 	var f Filter
@@ -83,7 +82,7 @@ func listen(iface string, responder chan *NDRequest, requestType NDPType) {
 			bpf.LoadAbsolute{Off: 54, Size: 1},
 			// Jump to the drop packet instruction if Type is not Neighbor Solicitation.
 			bpf.JumpIf{Cond: bpf.JumpNotEqual, Val: 0x87, SkipTrue: 1},
-			// Verdict is "send up to 4k of the packet to userspace."
+			// Verdict is "send up to 4k of the packet to userspace."buf
 			bpf.RetConstant{Val: 4096},
 			// Verdict is "ignore packet."
 			bpf.RetConstant{Val: 0},
@@ -122,6 +121,8 @@ func listen(iface string, responder chan *NDRequest, requestType NDPType) {
 		}
 		fmt.Println("Source IP:")
 		fmt.Printf("% X\n", buf[:numRead][22:38])
+		fmt.Println("Destination IP:")
+		fmt.Printf("% X\n", buf[:numRead][38:54])
 		fmt.Println("Requested IP:")
 		fmt.Printf("% X\n", buf[:numRead][62:78])
 		fmt.Println("Source MAC")
@@ -130,8 +131,11 @@ func listen(iface string, responder chan *NDRequest, requestType NDPType) {
 		responder <- &NDRequest{
 			requestType:      requestType,
 			srcIP:            buf[:numRead][22:38],
+			dstIP:            buf[:numRead][38:54],
 			answeringForIP:   buf[:numRead][62:78],
 			mac:              buf[:numRead][80:86],
+			receivedIfaceMac: niface.HardwareAddr,
+			sourceIface:      iface,
 		}
 	}
 }

responder.go

@@ -1,48 +1,84 @@
 package main
 
 import (
+	"bytes"
+	"fmt"
 	"net"
 	"syscall"
 )
 
-var fd int
+var globalFd int
 
 func respond(iface string, requests chan *NDRequest, respondType NDPType) {
-	fd, _ = syscall.Socket(syscall.AF_INET6, syscall.SOCK_RAW, syscall.IPPROTO_RAW)
+	fd, err := syscall.Socket(syscall.AF_INET6, syscall.SOCK_RAW, syscall.IPPROTO_RAW)
-	syscall.BindToDevice(fd, iface)
+	if err != nil {
+		panic(err)
+	}
+	defer syscall.Close(globalFd)
+	globalFd = fd
+	err = syscall.BindToDevice(fd, iface)
+	if err != nil {
+		panic(err)
+	}
 
 	niface, err := net.InterfaceByName(iface)
 	if err != nil {
 		panic(err.Error())
 	}
 
-	for {
+	var result = emptyIpv6
-		n := <-requests
+	ifaceaddrs, err := niface.Addrs()
-		pkt(n.srcIP, n.answeringForIP, niface.HardwareAddr, respondType)
+
+	for _, n := range ifaceaddrs {
+		tip, _, err := net.ParseCIDR(n.String())
+		if err != nil {
+			break
+		}
+		if IsIPv6(tip.String()) {
+			if tip.IsGlobalUnicast() {
+				result = tip
+				_, tnet, _ := net.ParseCIDR("fc00::/7")
+				if !tnet.Contains(tip) {
+					break
+				}
+			}
 		}
 	}
 
-func pkt(srcip []byte, tgtip []byte, mac []byte, respondType NDPType) {
+	for {
-	v6 := newIpv6Header(emptyIpv6, srcip)
+		n := <-requests
-	NDPa := newNdpPacket(tgtip, mac, respondType)
+		if n.sourceIface == iface {
+			pkt(result, n.srcIP, n.answeringForIP, niface.HardwareAddr, respondType)
+		} else {
+			if !bytes.Equal(n.mac, n.receivedIfaceMac) {
+				pkt(n.srcIP, n.dstIP, n.answeringForIP, niface.HardwareAddr, respondType)
+			}
+		}
+	}
+}
+
+func pkt(ownIP []byte, dstIP []byte, tgtip []byte, mac []byte, respondType NDPType) {
+	v6, err := newIpv6Header(ownIP, dstIP)
+	if err != nil {
+		return
+	}
+	NDPa, err := newNdpPacket(tgtip, mac, respondType)
+	if err != nil {
+		return
+	}
 	v6.addPayload(NDPa)
 	response := v6.constructPacket()
 
 	var t [16]byte
-	if respondType == NDP_SOL {
+	copy(t[:], dstIP)
-		copy(t[:], []byte{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x02})
-	} else {
-		copy(t[:], srcip)
-	}
 
 	d := syscall.SockaddrInet6{
 		Port: 0,
 		Addr: t,
 	}
-	err := syscall.Sendto(fd, response, 0, &d)
+	fmt.Println("Sending packet of type", respondType, "to")
-	if err != nil {
+	fmt.Printf("% X\n", t)
-		panic(err)
-	}
 
-	syscall.Close(fd)
+	err = syscall.Sendto(globalFd, response, 0, &d)
+	fmt.Println(err.Error())
 }