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mirror of https://github.com/cwinfo/yggdrasil-go.git synced 2024-12-22 19:55:39 +00:00

Remove ndp.go and add icmpv6.go

This commit is contained in:
Neil Alexander 2018-02-12 18:19:31 +00:00
parent 38567fffef
commit be0d6feeba
3 changed files with 221 additions and 180 deletions

203
src/yggdrasil/icmpv6.go Normal file
View File

@ -0,0 +1,203 @@
package yggdrasil
// The NDP functions are needed when you are running with a
// TAP adapter - as the operating system expects neighbor solicitations
// for on-link traffic, this goroutine provides them
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
mymac macAddress
mylladdr ipv6Address
recv chan []byte
}
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
}
func (i *icmpv6) init(t *tunDevice) {
i.tun = t
i.recv = make(chan []byte)
copy(i.mymac[:], []byte{0x02, 0x00, 0x00, 0x00, 0x00, 0x02})
copy(i.mylladdr[:], []byte{
0xFE, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xFE})
go i.listen()
}
func (i *icmpv6) listen() {
for {
datain := <-i.recv
if i.tun.iface.IsTAP() {
// TAP mode
dataout := make([]byte, ETHER+IPV6+32)
i.read_tap(datain, dataout)
i.tun.iface.Write(dataout)
} else {
// TUN mode
dataout := make([]byte, IPV6+32)
i.read_tun(datain, dataout)
i.tun.iface.Write(dataout)
}
}
}
func (i *icmpv6) read_tap(datain []byte, dataout []byte) {
// Set up
in := (*icmpv6Frame)(unsafe.Pointer(&datain[0]))
out := (*icmpv6Frame)(unsafe.Pointer(&dataout[0]))
// Store the peer MAC address
copy(i.peermac[:6], in.ether.source[:6])
// Ignore non-IPv6 frames
if binary.BigEndian.Uint16(in.ether.ethertype[:]) != uint16(0x86DD) {
return
}
// Populate the out ethernet headers
copy(out.ether.destination[:], in.ether.destination[:])
copy(out.ether.source[:], i.mymac[:])
binary.BigEndian.PutUint16(out.ether.ethertype[:], uint16(0x86DD))
// And for now just copy the rest of the packet we were sent
copy(dataout[ETHER:ETHER+IPV6], datain[ETHER:ETHER+IPV6])
// Then pass the IP packet onto the next function
i.read_tun(datain[ETHER:], dataout[ETHER:])
}
func (i *icmpv6) read_tun(datain []byte, dataout []byte) {
// Set up
in := (*icmpv6Packet)(unsafe.Pointer(&datain[0]))
out := (*icmpv6Packet)(unsafe.Pointer(&dataout[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
}
// 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
i.calculate_checksum(dataout)
}
func (i *icmpv6) calculate_checksum(dataout []byte) {
// 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:])
if err != nil {
return
}
// And copy the payload
payload, err := icmpv6.Marshal(ps)
if err != nil {
return
}
copy(dataout[IPV6:], payload)
}
func (i *icmpv6) handle_ndp(in *icmpv6Payload, out *icmpv6Payload) {
// Ignore NDP requests for anything outside of fd00::/8
if in.targetaddress[0] != 0xFD {
return
}
// Update the ICMPv6 headers
out.icmpv6.messagetype = uint8(136)
out.icmpv6.code = uint8(0)
// 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))
}

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@ -1,165 +0,0 @@
package yggdrasil
// The NDP functions are needed when you are running with a
// TAP adapter - as the operating system expects neighbor solicitations
// for on-link traffic, this goroutine provides them
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 ndp struct {
tun *tunDevice
peermac macAddress
peerlladdr ipv6Address
mymac macAddress
mylladdr ipv6Address
recv chan []byte
}
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 icmpv6Packet struct {
ether etherHeader
ipv6 ipv6Header
icmpv6 icmpv6Header
flags [4]byte
targetaddress ipv6Address
optiontype byte
optionlength byte
linklayeraddress macAddress
}
func (n *ndp) init(t *tunDevice) {
n.tun = t
n.recv = make(chan []byte)
copy(n.mymac[:], []byte{0x02, 0x00, 0x00, 0x00, 0x00, 0x02})
copy(n.mylladdr[:], []byte{
0xFE, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xFE})
go n.listen()
}
func (n *ndp) listen() {
for {
// Receive from the channel and check if we're using TAP instead
// of TUN mode - NDP is only relevant for TAP
datain := <-n.recv
if !n.tun.iface.IsTAP() {
continue
}
// Create our return frame buffer and also the unsafe pointers to
// map them to the structs
dataout := make([]byte, ETHER+IPV6+32)
in := (*icmpv6Packet)(unsafe.Pointer(&datain[0]))
out := (*icmpv6Packet)(unsafe.Pointer(&dataout[0]))
// Store peer MAC address and link-local IP address -
// these will be used later by tun.go
copy(n.peermac[:6], in.ether.source[:6])
copy(n.peerlladdr[:16], in.ipv6.source[:16])
// Ignore non-IPv6 packets
if binary.BigEndian.Uint16(in.ether.ethertype[:]) != uint16(0x86DD) {
continue
}
// Ignore non-ICMPv6 packets
if in.ipv6.nextheader != uint8(0x3A) {
continue
}
// Ignore non-NDP Solicitation packets
if in.icmpv6.messagetype != uint8(135) {
continue
}
// Ignore NDP requests for anything outside of fd00::/8
if in.targetaddress[0] != 0xFD {
continue
}
// Populate the out ethernet headers
copy(out.ether.destination[:], in.ether.destination[:])
copy(out.ether.source[:], n.mymac[:])
binary.BigEndian.PutUint16(out.ether.ethertype[:], uint16(0x86DD))
// And for now just copy the rest of the packet we were sent
copy(dataout[ETHER:ETHER+IPV6], datain[ETHER:ETHER+IPV6])
// Update the source and destination addresses in the IPv6 header
copy(out.ipv6.destination[:], in.ipv6.source[:])
copy(out.ipv6.source[:], n.mylladdr[:])
binary.BigEndian.PutUint16(out.ipv6.length[:], uint16(32))
// Copy the payload
copy(dataout[ETHER+IPV6:], datain[ETHER+IPV6:])
// Update the ICMPv6 headers
out.icmpv6.messagetype = uint8(136)
out.icmpv6.code = uint8(0)
// Update the ICMPv6 payload
copy(out.targetaddress[:], in.targetaddress[:])
out.optiontype = uint8(2)
out.optionlength = uint8(1)
copy(out.linklayeraddress[:], n.mymac[:])
binary.BigEndian.PutUint32(out.flags[:], uint32(0x20000000))
// 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[ETHER+IPV6:])
if err != nil {
continue
}
payload, err := icmpv6.Marshal(ps)
if err != nil {
continue
}
copy(dataout[ETHER+IPV6:], payload)
// Send the frame back to the TAP adapter
n.tun.iface.Write(dataout)
}
}

View File

@ -17,17 +17,17 @@ type tunInterface interface {
}
type tunDevice struct {
core *Core
ndp ndp
send chan<- []byte
recv <-chan []byte
mtu int
iface tunInterface
core *Core
icmpv6 icmpv6
send chan<- []byte
recv <-chan []byte
mtu int
iface tunInterface
}
func (tun *tunDevice) init(core *Core) {
tun.core = core
tun.ndp.init(tun)
tun.icmpv6.init(tun)
}
func (tun *tunDevice) write() error {
@ -36,11 +36,11 @@ func (tun *tunDevice) write() error {
if tun.iface.IsTAP() {
var frame ethernet.Frame
frame.Prepare(
tun.ndp.peermac[:6], // Destination MAC address
tun.ndp.mymac[:6], // Source MAC address
ethernet.NotTagged, // VLAN tagging
ethernet.IPv6, // Ethertype
len(data)) // Payload length
tun.icmpv6.peermac[:6], // Destination MAC address
tun.icmpv6.mymac[:6], // Source MAC address
ethernet.NotTagged, // VLAN tagging
ethernet.IPv6, // Ethertype
len(data)) // Payload length
copy(frame[ETHER_HEADER_LENGTH:], data[:])
if _, err := tun.iface.Write(frame); err != nil {
panic(err)
@ -68,9 +68,6 @@ func (tun *tunDevice) read() error {
o := 0
if tun.iface.IsTAP() {
o = ETHER_HEADER_LENGTH
b := make([]byte, n)
copy(b, buf)
tun.ndp.recv <- b
}
if buf[o]&0xf0 != 0x60 ||
n != 256*int(buf[o+4])+int(buf[o+5])+IPv6_HEADER_LENGTH+o {
@ -78,6 +75,12 @@ func (tun *tunDevice) read() error {
//panic("Should not happen in testing")
continue
}
if buf[o+6] == 58 {
// Found an ICMPv6 packet
b := make([]byte, n)
copy(b, buf)
tun.icmpv6.recv <- b
}
packet := append(util_getBytes(), buf[o:n]...)
tun.send <- packet
}