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yggdrasil-go/src/tuntap/tun.go
Fyodor Ustinov 52345a2de4
Check tun.config is not equal to nil before usage (#830)
We have to check tun.config is not nil before first use, not after.
2021-09-21 21:19:25 +01:00

177 lines
5.1 KiB
Go

package tuntap
// This manages the tun driver to send/recv packets to/from applications
// TODO: Crypto-key routing support
// TODO: Set MTU of session properly
// TODO: Reject packets that exceed session MTU with ICMPv6 for PMTU Discovery
// TODO: Connection timeouts (call Conn.Close() when we want to time out)
// TODO: Don't block in reader on writes that are pending searches
import (
"errors"
"fmt"
"net"
//"sync"
"github.com/Arceliar/phony"
"github.com/gologme/log"
"golang.zx2c4.com/wireguard/tun"
"github.com/yggdrasil-network/yggdrasil-go/src/address"
"github.com/yggdrasil-network/yggdrasil-go/src/config"
"github.com/yggdrasil-network/yggdrasil-go/src/defaults"
"github.com/yggdrasil-network/yggdrasil-go/src/ipv6rwc"
)
type MTU uint16
// TunAdapter represents a running TUN interface and extends the
// yggdrasil.Adapter type. In order to use the TUN adapter with Yggdrasil, you
// should pass this object to the yggdrasil.SetRouterAdapter() function before
// calling yggdrasil.Start().
type TunAdapter struct {
rwc *ipv6rwc.ReadWriteCloser
config *config.NodeConfig
log *log.Logger
addr address.Address
subnet address.Subnet
mtu uint64
iface tun.Device
phony.Inbox // Currently only used for _handlePacket from the reader, TODO: all the stuff that currently needs a mutex below
//mutex sync.RWMutex // Protects the below
isOpen bool
isEnabled bool // Used by the writer to drop sessionTraffic if not enabled
}
// Gets the maximum supported MTU for the platform based on the defaults in
// defaults.GetDefaults().
func getSupportedMTU(mtu uint64) uint64 {
if mtu < 1280 {
return 1280
}
if mtu > MaximumMTU() {
return MaximumMTU()
}
return mtu
}
// Name returns the name of the adapter, e.g. "tun0". On Windows, this may
// return a canonical adapter name instead.
func (tun *TunAdapter) Name() string {
if name, err := tun.iface.Name(); err == nil {
return name
}
return ""
}
// MTU gets the adapter's MTU. This can range between 1280 and 65535, although
// the maximum value is determined by your platform. The returned value will
// never exceed that of MaximumMTU().
func (tun *TunAdapter) MTU() uint64 {
return getSupportedMTU(tun.mtu)
}
// DefaultName gets the default TUN interface name for your platform.
func DefaultName() string {
return defaults.GetDefaults().DefaultIfName
}
// DefaultMTU gets the default TUN interface MTU for your platform. This can
// be as high as MaximumMTU(), depending on platform, but is never lower than 1280.
func DefaultMTU() uint64 {
return defaults.GetDefaults().DefaultIfMTU
}
// MaximumMTU returns the maximum supported TUN interface MTU for your
// platform. This can be as high as 65535, depending on platform, but is never
// lower than 1280.
func MaximumMTU() uint64 {
return defaults.GetDefaults().MaximumIfMTU
}
// Init initialises the TUN module. You must have acquired a Listener from
// the Yggdrasil core before this point and it must not be in use elsewhere.
func (tun *TunAdapter) Init(rwc *ipv6rwc.ReadWriteCloser, config *config.NodeConfig, log *log.Logger, options interface{}) error {
tun.rwc = rwc
tun.config = config
tun.log = log
return nil
}
// Start the setup process for the TUN adapter. If successful, starts the
// reader actor to handle packets on that interface.
func (tun *TunAdapter) Start() error {
var err error
phony.Block(tun, func() {
err = tun._start()
})
return err
}
func (tun *TunAdapter) _start() error {
if tun.isOpen {
return errors.New("TUN module is already started")
}
if tun.config == nil {
return errors.New("no configuration available to TUN")
}
tun.config.RLock()
defer tun.config.RUnlock()
tun.addr = tun.rwc.Address()
tun.subnet = tun.rwc.Subnet()
addr := fmt.Sprintf("%s/%d", net.IP(tun.addr[:]).String(), 8*len(address.GetPrefix())-1)
if tun.config.IfName == "none" || tun.config.IfName == "dummy" {
tun.log.Debugln("Not starting TUN as ifname is none or dummy")
tun.isEnabled = false
go tun.write()
return nil
}
mtu := tun.config.IfMTU
if tun.rwc.MaxMTU() < mtu {
mtu = tun.rwc.MaxMTU()
}
if err := tun.setup(tun.config.IfName, addr, mtu); err != nil {
return err
}
if tun.MTU() != mtu {
tun.log.Warnf("Warning: Interface MTU %d automatically adjusted to %d (supported range is 1280-%d)", tun.config.IfMTU, tun.MTU(), MaximumMTU())
}
tun.rwc.SetMTU(tun.MTU())
tun.isOpen = true
tun.isEnabled = true
go tun.read()
go tun.write()
return nil
}
// IsStarted returns true if the module has been started.
func (tun *TunAdapter) IsStarted() bool {
var isOpen bool
phony.Block(tun, func() {
isOpen = tun.isOpen
})
return isOpen
}
// Start the setup process for the TUN adapter. If successful, starts the
// read/write goroutines to handle packets on that interface.
func (tun *TunAdapter) Stop() error {
var err error
phony.Block(tun, func() {
err = tun._stop()
})
return err
}
func (tun *TunAdapter) _stop() error {
tun.isOpen = false
// by TUN, e.g. readers/writers, sessions
if tun.iface != nil {
// Just in case we failed to start up the iface for some reason, this can apparently happen on Windows
tun.iface.Close()
}
return nil
}