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Merge pull request #6 from neilalexander/master

Support for Windows, TAP interfaces and NDP
This commit is contained in:
Arceliar 2018-01-24 17:43:15 -06:00 committed by GitHub
commit e52b099d05
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4 changed files with 232 additions and 6 deletions

165
src/yggdrasil/ndp.go Normal file
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@ -0,0 +1,165 @@
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"
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)
}
}

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@ -2,7 +2,7 @@ package yggdrasil
// This manages the tun driver to send/recv packets to/from applications
// import water "github.com/songgao/water"
import ethernet "github.com/songgao/packets/ethernet"
const IPv6_HEADER_LENGTH = 40
@ -17,6 +17,7 @@ type tunInterface interface {
type tunDevice struct {
core *Core
ndp ndp
send chan<- []byte
recv <-chan []byte
mtu int
@ -25,13 +26,28 @@ type tunDevice struct {
func (tun *tunDevice) init(core *Core) {
tun.core = core
tun.ndp.init(tun)
}
func (tun *tunDevice) write() error {
for {
data := <-tun.recv
if _, err := tun.iface.Write(data); err != nil {
return err
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
copy(frame[14:], data[:])
if _, err := tun.iface.Write(frame); err != nil {
return err
}
} else {
if _, err := tun.iface.Write(data); err != nil {
return err
}
}
util_putBytes(data)
}
@ -44,13 +60,20 @@ func (tun *tunDevice) read() error {
if err != nil {
return err
}
if buf[0]&0xf0 != 0x60 ||
n != 256*int(buf[4])+int(buf[5])+IPv6_HEADER_LENGTH {
o := 0
if tun.iface.IsTAP() {
o = 14
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 {
// Either not an IPv6 packet or not the complete packet for some reason
//panic("Should not happen in testing")
continue
}
packet := append(util_getBytes(), buf[:n]...)
packet := append(util_getBytes(), buf[o:n]...)
tun.send <- packet
}
}

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@ -1,5 +1,6 @@
// +build !linux
// +build !darwin
// +build !windows
package yggdrasil

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@ -0,0 +1,37 @@
package yggdrasil
import water "github.com/songgao/water"
import "os/exec"
import "strings"
import "fmt"
// This is to catch Windows platforms
func (tun *tunDevice) setup(ifname string, addr string, mtu int) error {
config := water.Config{DeviceType: water.TAP}
config.PlatformSpecificParams.ComponentID = "tap0901"
config.PlatformSpecificParams.Network = "169.254.0.1/32"
iface, err := water.New(config)
if err != nil {
panic(err)
}
tun.iface = iface
tun.mtu = mtu
return tun.setupAddress(addr)
}
func (tun *tunDevice) setupAddress(addr string) error {
// Set address
// addr = strings.TrimRight(addr, "/8")
cmd := exec.Command("netsh", "interface", "ipv6", "set", "address",
fmt.Sprintf("interface=%s", tun.iface.Name()),
fmt.Sprintf("addr=%s", addr))
tun.core.log.Printf("netsh command: %v", strings.Join(cmd.Args, " "))
output, err := cmd.CombinedOutput()
if err != nil {
tun.core.log.Printf("Windows netsh failed: %v.", err)
tun.core.log.Println(string(output))
return err
}
return nil
}