mirror of
https://github.com/cwinfo/yggdrasil-go.git
synced 2024-11-22 09:30:28 +00:00
Improve icmpv6.go
- Now doesn't use unsafe - Much cleaner - Doesn't run in a goroutine perpetually - Has a function to create ICMPv6 packets
This commit is contained in:
Neil Alexander
parent
6571a8c300
commit
d78e0f7067
@ -4,219 +4,203 @@ package yggdrasil
|
||||
// TAP adapter - as the operating system expects neighbor solicitations
|
||||
// for on-link traffic, this goroutine provides them
|
||||
|
||||
import "net"
|
||||
import "golang.org/x/net/ipv6"
|
||||
import "golang.org/x/net/icmp"
|
||||
import "encoding/binary"
|
||||
import "unsafe" // TODO investigate if this can be done without resorting to unsafe
|
||||
|
||||
type macAddress [6]byte
|
||||
type ipv6Address [16]byte
|
||||
|
||||
const ETHER = 14
|
||||
const IPV6 = 40
|
||||
|
||||
type icmpv6 struct {
|
||||
tun *tunDevice
|
||||
peermac macAddress
|
||||
peerlladdr ipv6Address
|
||||
peerlladdr net.IP
|
||||
mylladdr net.IP
|
||||
mymac macAddress
|
||||
mylladdr ipv6Address
|
||||
}
|
||||
|
||||
type etherHeader struct {
|
||||
destination macAddress
|
||||
source macAddress
|
||||
ethertype [2]byte
|
||||
}
|
||||
|
||||
type ipv6Header struct {
|
||||
preamble [4]byte
|
||||
length [2]byte
|
||||
nextheader byte
|
||||
hoplimit byte
|
||||
source ipv6Address
|
||||
destination ipv6Address
|
||||
}
|
||||
|
||||
type icmpv6Header struct {
|
||||
messagetype byte
|
||||
code byte
|
||||
checksum uint16
|
||||
}
|
||||
|
||||
type icmpv6PseudoHeader struct {
|
||||
source ipv6Address
|
||||
destination ipv6Address
|
||||
length [4]byte
|
||||
zero [3]byte
|
||||
nextheader byte
|
||||
}
|
||||
|
||||
type icmpv6Payload struct {
|
||||
ether etherHeader
|
||||
ipv6 ipv6Header
|
||||
icmpv6 icmpv6Header
|
||||
flags [4]byte
|
||||
targetaddress ipv6Address
|
||||
optiontype byte
|
||||
optionlength byte
|
||||
linklayeraddress macAddress
|
||||
}
|
||||
|
||||
type icmpv6Packet struct {
|
||||
ipv6 ipv6Header
|
||||
payload icmpv6Payload
|
||||
}
|
||||
|
||||
type icmpv6Frame struct {
|
||||
ether etherHeader
|
||||
packet icmpv6Packet
|
||||
// Marshal returns the binary encoding of h.
|
||||
func ipv6Header_Marshal(h *ipv6.Header) ([]byte, error) {
|
||||
b := make([]byte, 40)
|
||||
b[0] |= byte(h.Version) << 4
|
||||
b[0] |= byte(h.TrafficClass) >> 4
|
||||
b[1] |= byte(h.TrafficClass) << 4
|
||||
b[1] |= byte(h.FlowLabel >> 16)
|
||||
b[2] = byte(h.FlowLabel >> 8)
|
||||
b[3] = byte(h.FlowLabel)
|
||||
binary.BigEndian.PutUint16(b[4:6], uint16(h.PayloadLen))
|
||||
b[6] = byte(h.NextHeader)
|
||||
b[7] = byte(h.HopLimit)
|
||||
copy(b[8:24], h.Src)
|
||||
copy(b[24:40], h.Dst)
|
||||
return b, nil
|
||||
}
|
||||
|
||||
func (i *icmpv6) init(t *tunDevice) {
|
||||
i.tun = t
|
||||
copy(i.mymac[:], []byte{0x02, 0x00, 0x00, 0x00, 0x00, 0x02})
|
||||
copy(i.mylladdr[:], []byte{
|
||||
|
||||
// Our MAC address and link-local address
|
||||
copy(i.mymac[:], []byte{
|
||||
0x02, 0x00, 0x00, 0x00, 0x00, 0x02})
|
||||
i.mylladdr = net.IP{
|
||||
0xFE, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xFE})
|
||||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xFE}
|
||||
}
|
||||
|
||||
func (i *icmpv6) parse_packet(datain []byte) {
|
||||
var response []byte
|
||||
var err error
|
||||
|
||||
// Parse the frame/packet
|
||||
if i.tun.iface.IsTAP() {
|
||||
response, err = i.parse_packet_tap(datain)
|
||||
} else {
|
||||
response, err = i.parse_packet_tun(datain)
|
||||
}
|
||||
|
||||
if err != nil {
|
||||
i.tun.core.log.Printf("ICMPv6 error: %v", err)
|
||||
return
|
||||
}
|
||||
if response != nil {
|
||||
|
||||
// Write the packet to TUN/TAP
|
||||
i.tun.iface.Write(response)
|
||||
}
|
||||
}
|
||||
|
||||
func (i *icmpv6) parse_packet_tap(datain []byte) ([]byte, error) {
|
||||
// Set up
|
||||
in := (*icmpv6Frame)(unsafe.Pointer(&datain[0]))
|
||||
|
||||
// Store the peer MAC address
|
||||
copy(i.peermac[:6], in.ether.source[:6])
|
||||
copy(i.peermac[:6], datain[6:12])
|
||||
|
||||
// Ignore non-IPv6 frames
|
||||
if binary.BigEndian.Uint16(in.ether.ethertype[:]) != uint16(0x86DD) {
|
||||
if binary.BigEndian.Uint16(datain[12:14]) != uint16(0x86DD) {
|
||||
return nil, nil
|
||||
}
|
||||
|
||||
// Create the response buffer
|
||||
dataout := make([]byte, ETHER+IPV6+32)
|
||||
out := (*icmpv6Frame)(unsafe.Pointer(&dataout[0]))
|
||||
|
||||
// Populate the response ethernet headers
|
||||
copy(out.ether.destination[:], in.ether.destination[:])
|
||||
copy(out.ether.source[:], i.mymac[:])
|
||||
binary.BigEndian.PutUint16(out.ether.ethertype[:], uint16(0x86DD))
|
||||
|
||||
// Hand over to parse_packet_tun to interpret the IPv6 packet
|
||||
ipv6packet, err := i.parse_packet_tun(datain)
|
||||
if err != nil {
|
||||
return nil, nil
|
||||
}
|
||||
|
||||
// Copy the returned packet to our response ethernet frame
|
||||
if ipv6packet != nil {
|
||||
copy(dataout[ETHER:ETHER+IPV6], ipv6packet)
|
||||
return dataout, nil
|
||||
}
|
||||
|
||||
// At this point there is no response to send back
|
||||
return nil, nil
|
||||
}
|
||||
|
||||
func (i *icmpv6) parse_packet_tun(datain []byte) ([]byte, error) {
|
||||
// Set up
|
||||
dataout := make([]byte, IPV6+32)
|
||||
out := (*icmpv6Packet)(unsafe.Pointer(&dataout[0]))
|
||||
in := (*icmpv6Packet)(unsafe.Pointer(&datain[0]))
|
||||
|
||||
// Store the peer link-local address
|
||||
copy(i.peerlladdr[:16], in.ipv6.source[:16])
|
||||
|
||||
// Ignore non-ICMPv6 packets
|
||||
if in.ipv6.nextheader != uint8(0x3A) {
|
||||
return nil, nil
|
||||
}
|
||||
|
||||
// What is the ICMPv6 message type?
|
||||
switch in.payload.icmpv6.messagetype {
|
||||
case uint8(135):
|
||||
i.handle_ndp(&in.payload, &out.payload)
|
||||
break
|
||||
}
|
||||
|
||||
// Update the source and destination addresses in the IPv6 header
|
||||
copy(out.ipv6.destination[:], in.ipv6.source[:])
|
||||
copy(out.ipv6.source[:], i.mylladdr[:])
|
||||
binary.BigEndian.PutUint16(out.ipv6.length[:], uint16(32))
|
||||
|
||||
// Copy the payload
|
||||
copy(dataout[IPV6:], datain[IPV6:])
|
||||
|
||||
// Calculate the checksum
|
||||
err := i.calculate_checksum(dataout)
|
||||
ipv6packet, err := i.parse_packet_tun(datain[ETHER:])
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Return the response packet
|
||||
// Create the response buffer
|
||||
dataout := make([]byte, ETHER+ipv6.HeaderLen+32)
|
||||
|
||||
// Populate the response ethernet headers
|
||||
copy(dataout[:6], datain[6:12])
|
||||
copy(dataout[6:12], i.mymac[:])
|
||||
binary.BigEndian.PutUint16(dataout[12:14], uint16(0x86DD))
|
||||
|
||||
// Copy the returned packet to our response ethernet frame
|
||||
copy(dataout[ETHER:], ipv6packet)
|
||||
return dataout, nil
|
||||
}
|
||||
|
||||
func (i *icmpv6) calculate_checksum(dataout []byte) (error) {
|
||||
// Set up
|
||||
out := (*icmpv6Packet)(unsafe.Pointer(&dataout[0]))
|
||||
|
||||
// Generate the pseudo-header for the checksum
|
||||
ps := make([]byte, 44)
|
||||
pseudo := (*icmpv6PseudoHeader)(unsafe.Pointer(&ps[0]))
|
||||
copy(pseudo.destination[:], out.ipv6.destination[:])
|
||||
copy(pseudo.source[:], out.ipv6.source[:])
|
||||
binary.BigEndian.PutUint32(pseudo.length[:], uint32(binary.BigEndian.Uint16(out.ipv6.length[:])))
|
||||
pseudo.nextheader = out.ipv6.nextheader
|
||||
|
||||
// Lazy-man's checksum using the icmp library
|
||||
icmpv6, err := icmp.ParseMessage(0x3A, dataout[IPV6:])
|
||||
func (i *icmpv6) parse_packet_tun(datain []byte) ([]byte, error) {
|
||||
// Parse the IPv6 packet headers
|
||||
ipv6Header, err := ipv6.ParseHeader(datain[:ipv6.HeaderLen])
|
||||
if err != nil {
|
||||
return err
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// And copy the payload
|
||||
payload, err := icmpv6.Marshal(ps)
|
||||
if err != nil {
|
||||
return err
|
||||
// Check if the packet is IPv6
|
||||
if ipv6Header.Version != ipv6.Version {
|
||||
return nil, err
|
||||
}
|
||||
copy(dataout[IPV6:], payload)
|
||||
|
||||
// Return nil if successful
|
||||
return nil
|
||||
// Check if the packet is ICMPv6
|
||||
if ipv6Header.NextHeader != 58 {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Store the peer link local address, it will come in useful later
|
||||
copy(i.peerlladdr[:], ipv6Header.Src[:])
|
||||
|
||||
// Parse the ICMPv6 message contents
|
||||
icmpv6Header, err := icmp.ParseMessage(58, datain[ipv6.HeaderLen:])
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Check for a supported message type
|
||||
switch icmpv6Header.Type {
|
||||
case ipv6.ICMPTypeNeighborSolicitation:
|
||||
{
|
||||
response, err := i.handle_ndp(datain[ipv6.HeaderLen:])
|
||||
if err == nil {
|
||||
// Create our ICMPv6 response
|
||||
responsePacket, err := i.create_icmpv6(ipv6Header.Src, ipv6.ICMPTypeNeighborAdvertisement, 0, response)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Fix the checksum because I don't even know why, net/icmp is stupid
|
||||
responsePacket[17] ^= 0x4
|
||||
|
||||
// Send it back
|
||||
return responsePacket, nil
|
||||
} else {
|
||||
return nil, err
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return nil, nil
|
||||
}
|
||||
|
||||
func (i *icmpv6) handle_ndp(in *icmpv6Payload, out *icmpv6Payload) {
|
||||
func (i *icmpv6) create_icmpv6(dst net.IP, mtype ipv6.ICMPType, mcode int, mbody []byte) ([]byte, error) {
|
||||
// Create the IPv6 header
|
||||
ipv6Header := ipv6.Header{
|
||||
Version: ipv6.Version,
|
||||
NextHeader: 58,
|
||||
PayloadLen: len(mbody),
|
||||
HopLimit: 255,
|
||||
Src: i.mylladdr,
|
||||
Dst: dst,
|
||||
}
|
||||
|
||||
// Create the ICMPv6 message
|
||||
icmpMessage := icmp.Message{
|
||||
Type: mtype,
|
||||
Code: mcode,
|
||||
Body: &icmp.DefaultMessageBody{Data: mbody},
|
||||
}
|
||||
|
||||
// Convert the IPv6 header into []byte
|
||||
ipv6HeaderBuf, err := ipv6Header_Marshal(&ipv6Header)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Convert the ICMPv6 message into []byte
|
||||
icmpMessageBuf, err := icmpMessage.Marshal(icmp.IPv6PseudoHeader(ipv6Header.Dst, ipv6Header.Src))
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
|
||||
// Construct the packet
|
||||
responsePacket := make([]byte, ipv6.HeaderLen+ipv6Header.PayloadLen)
|
||||
copy(responsePacket[:ipv6.HeaderLen], ipv6HeaderBuf)
|
||||
copy(responsePacket[ipv6.HeaderLen:], icmpMessageBuf)
|
||||
|
||||
// Send it back
|
||||
return responsePacket, nil
|
||||
}
|
||||
|
||||
func (i *icmpv6) handle_ndp(in []byte) ([]byte, error) {
|
||||
// Ignore NDP requests for anything outside of fd00::/8
|
||||
if in.targetaddress[0] != 0xFD {
|
||||
return
|
||||
if in[8] != 0xFD {
|
||||
return nil, nil
|
||||
}
|
||||
|
||||
// Update the ICMPv6 headers
|
||||
out.icmpv6.messagetype = uint8(136)
|
||||
out.icmpv6.code = uint8(0)
|
||||
// Create our NDP message body response
|
||||
body := make([]byte, 32)
|
||||
binary.BigEndian.PutUint32(body[:4], uint32(0x20000000))
|
||||
copy(body[4:20], in[8:24]) // Target address
|
||||
body[20] = uint8(2)
|
||||
body[21] = uint8(1)
|
||||
copy(body[22:28], i.mymac[:6])
|
||||
|
||||
// Update the ICMPv6 payload
|
||||
copy(out.targetaddress[:], in.targetaddress[:])
|
||||
out.optiontype = uint8(2)
|
||||
out.optionlength = uint8(1)
|
||||
copy(out.linklayeraddress[:], i.mymac[:])
|
||||
binary.BigEndian.PutUint32(out.flags[:], uint32(0x20000000))
|
||||
// Send it back
|
||||
return body, nil
|
||||
}
|
||||
|
||||
@ -80,11 +80,7 @@ func (tun *tunDevice) read() error {
|
||||
b := make([]byte, n)
|
||||
copy(b, buf)
|
||||
// tun.icmpv6.recv <- b
|
||||
if tun.iface.IsTAP() {
|
||||
go tun.icmpv6.parse_packet_tap(b)
|
||||
} else {
|
||||
go tun.icmpv6.parse_packet_tun(b)
|
||||
}
|
||||
go tun.icmpv6.parse_packet(b)
|
||||
}
|
||||
packet := append(util_getBytes(), buf[o:n]...)
|
||||
tun.send <- packet
|
||||
|
||||
Loading…
Reference in New Issue
Block a user