mirror of
https://github.com/yggdrasil-network/yggdrasil-go
synced 2024-09-21 10:00:26 +03:00
243 lines
6.3 KiB
Go
243 lines
6.3 KiB
Go
package yggdrasil
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// This manages the tun driver to send/recv packets to/from applications
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import (
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"bytes"
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"errors"
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"sync"
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"time"
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"github.com/songgao/packets/ethernet"
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"github.com/yggdrasil-network/water"
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"github.com/yggdrasil-network/yggdrasil-go/src/address"
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"github.com/yggdrasil-network/yggdrasil-go/src/defaults"
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"github.com/yggdrasil-network/yggdrasil-go/src/util"
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)
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const tun_IPv6_HEADER_LENGTH = 40
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const tun_ETHER_HEADER_LENGTH = 14
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// Represents a running TUN/TAP interface.
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type tunAdapter struct {
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Adapter
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icmpv6 icmpv6
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mtu int
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iface *water.Interface
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mutex sync.RWMutex // Protects the below
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isOpen bool
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}
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// Gets the maximum supported MTU for the platform based on the defaults in
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// defaults.GetDefaults().
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func getSupportedMTU(mtu int) int {
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if mtu > defaults.GetDefaults().MaximumIfMTU {
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return defaults.GetDefaults().MaximumIfMTU
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}
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return mtu
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}
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// Initialises the TUN/TAP adapter.
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func (tun *tunAdapter) init(core *Core, send chan<- []byte, recv <-chan []byte) {
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tun.Adapter.init(core, send, recv)
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tun.icmpv6.init(tun)
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}
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// Starts the setup process for the TUN/TAP adapter, and if successful, starts
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// the read/write goroutines to handle packets on that interface.
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func (tun *tunAdapter) start(ifname string, iftapmode bool, addr string, mtu int) error {
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if ifname != "none" {
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if err := tun.setup(ifname, iftapmode, addr, mtu); err != nil {
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return err
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}
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}
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if ifname == "none" || ifname == "dummy" {
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return nil
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}
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tun.mutex.Lock()
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tun.isOpen = true
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tun.mutex.Unlock()
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go func() { tun.core.log.Println("WARNING: tun.read() exited with error:", tun.read()) }()
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go func() { tun.core.log.Println("WARNING: tun.write() exited with error:", tun.write()) }()
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if iftapmode {
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go func() {
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for {
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if _, ok := tun.icmpv6.peermacs[tun.core.router.addr]; ok {
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break
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}
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request, err := tun.icmpv6.create_ndp_tap(tun.core.router.addr)
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if err != nil {
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panic(err)
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}
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if _, err := tun.iface.Write(request); err != nil {
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panic(err)
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}
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time.Sleep(time.Second)
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}
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}()
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}
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return nil
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}
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// Writes a packet to the TUN/TAP adapter. If the adapter is running in TAP
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// mode then additional ethernet encapsulation is added for the benefit of the
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// host operating system.
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func (tun *tunAdapter) write() error {
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for {
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data := <-tun.recv
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if tun.iface == nil {
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continue
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}
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if tun.iface.IsTAP() {
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var destAddr address.Address
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if data[0]&0xf0 == 0x60 {
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if len(data) < 40 {
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panic("Tried to send a packet shorter than an IPv6 header...")
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}
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copy(destAddr[:16], data[24:])
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} else if data[0]&0xf0 == 0x40 {
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if len(data) < 20 {
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panic("Tried to send a packet shorter than an IPv4 header...")
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}
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copy(destAddr[:4], data[16:])
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} else {
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return errors.New("Invalid address family")
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}
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sendndp := func(destAddr address.Address) {
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neigh, known := tun.icmpv6.peermacs[destAddr]
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known = known && (time.Since(neigh.lastsolicitation).Seconds() < 30)
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if !known {
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request, err := tun.icmpv6.create_ndp_tap(destAddr)
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if err != nil {
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panic(err)
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}
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if _, err := tun.iface.Write(request); err != nil {
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panic(err)
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}
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tun.icmpv6.peermacs[destAddr] = neighbor{
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lastsolicitation: time.Now(),
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}
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}
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}
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var peermac macAddress
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var peerknown bool
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if data[0]&0xf0 == 0x40 {
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destAddr = tun.core.router.addr
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} else if data[0]&0xf0 == 0x60 {
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if !bytes.Equal(tun.core.router.addr[:16], destAddr[:16]) && !bytes.Equal(tun.core.router.subnet[:8], destAddr[:8]) {
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destAddr = tun.core.router.addr
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}
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}
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if neighbor, ok := tun.icmpv6.peermacs[destAddr]; ok && neighbor.learned {
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peermac = neighbor.mac
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peerknown = true
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} else if neighbor, ok := tun.icmpv6.peermacs[tun.core.router.addr]; ok && neighbor.learned {
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peermac = neighbor.mac
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peerknown = true
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sendndp(destAddr)
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} else {
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sendndp(tun.core.router.addr)
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}
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if peerknown {
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var proto ethernet.Ethertype
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switch {
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case data[0]&0xf0 == 0x60:
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proto = ethernet.IPv6
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case data[0]&0xf0 == 0x40:
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proto = ethernet.IPv4
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}
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var frame ethernet.Frame
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frame.Prepare(
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peermac[:6], // Destination MAC address
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tun.icmpv6.mymac[:6], // Source MAC address
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ethernet.NotTagged, // VLAN tagging
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proto, // Ethertype
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len(data)) // Payload length
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copy(frame[tun_ETHER_HEADER_LENGTH:], data[:])
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if _, err := tun.iface.Write(frame); err != nil {
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tun.mutex.RLock()
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open := tun.isOpen
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tun.mutex.RUnlock()
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if !open {
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return nil
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} else {
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panic(err)
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}
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}
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}
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} else {
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if _, err := tun.iface.Write(data); err != nil {
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tun.mutex.RLock()
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open := tun.isOpen
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tun.mutex.RUnlock()
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if !open {
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return nil
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} else {
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panic(err)
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}
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}
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}
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util.PutBytes(data)
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}
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}
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// Reads any packets that are waiting on the TUN/TAP adapter. If the adapter
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// is running in TAP mode then the ethernet headers will automatically be
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// processed and stripped if necessary. If an ICMPv6 packet is found, then
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// the relevant helper functions in icmpv6.go are called.
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func (tun *tunAdapter) read() error {
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mtu := tun.mtu
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if tun.iface.IsTAP() {
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mtu += tun_ETHER_HEADER_LENGTH
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}
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buf := make([]byte, mtu)
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for {
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n, err := tun.iface.Read(buf)
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if err != nil {
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tun.mutex.RLock()
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open := tun.isOpen
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tun.mutex.RUnlock()
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if !open {
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return nil
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} else {
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// panic(err)
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return err
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}
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}
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o := 0
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if tun.iface.IsTAP() {
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o = tun_ETHER_HEADER_LENGTH
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}
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switch {
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case buf[o]&0xf0 == 0x60 && n == 256*int(buf[o+4])+int(buf[o+5])+tun_IPv6_HEADER_LENGTH+o:
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case buf[o]&0xf0 == 0x40 && n == 256*int(buf[o+2])+int(buf[o+3])+o:
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default:
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continue
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}
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if buf[o+6] == 58 {
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if tun.iface.IsTAP() {
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// Found an ICMPv6 packet
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b := make([]byte, n)
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copy(b, buf)
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go tun.icmpv6.parse_packet(b)
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}
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}
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packet := append(util.GetBytes(), buf[o:n]...)
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tun.send <- packet
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}
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}
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// Closes the TUN/TAP adapter. This is only usually called when the Yggdrasil
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// process stops. Typically this operation will happen quickly, but on macOS
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// it can block until a read operation is completed.
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func (tun *tunAdapter) close() error {
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tun.mutex.Lock()
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tun.isOpen = false
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tun.mutex.Unlock()
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if tun.iface == nil {
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return nil
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}
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return tun.iface.Close()
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}
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