nebula/overlay/tun_ios.go

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//go:build ios && !e2e_testing
// +build ios,!e2e_testing
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package overlay
import (
"errors"
"fmt"
"io"
"net"
"os"
"sync"
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"sync/atomic"
"syscall"
"github.com/sirupsen/logrus"
"github.com/slackhq/nebula/cidr"
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"github.com/slackhq/nebula/config"
"github.com/slackhq/nebula/iputil"
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"github.com/slackhq/nebula/util"
)
type tun struct {
io.ReadWriteCloser
cidr *net.IPNet
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Routes atomic.Pointer[[]Route]
routeTree atomic.Pointer[cidr.Tree4[iputil.VpnIp]]
l *logrus.Logger
}
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func newTun(_ *config.C, _ *logrus.Logger, _ *net.IPNet, _ bool) (*tun, error) {
return nil, fmt.Errorf("newTun not supported in iOS")
}
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func newTunFromFd(c *config.C, l *logrus.Logger, deviceFd int, cidr *net.IPNet) (*tun, error) {
file := os.NewFile(uintptr(deviceFd), "/dev/tun")
t := &tun{
cidr: cidr,
ReadWriteCloser: &tunReadCloser{f: file},
l: l,
}
err := t.reload(c, true)
if err != nil {
return nil, err
}
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c.RegisterReloadCallback(func(c *config.C) {
err := t.reload(c, false)
if err != nil {
util.LogWithContextIfNeeded("failed to reload tun device", err, t.l)
}
})
return t, nil
}
func (t *tun) Activate() error {
return nil
}
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func (t *tun) reload(c *config.C, initial bool) error {
change, routes, err := getAllRoutesFromConfig(c, t.cidr, initial)
if err != nil {
return err
}
if !initial && !change {
return nil
}
routeTree, err := makeRouteTree(t.l, routes, false)
if err != nil {
return err
}
// Teach nebula how to handle the routes
t.Routes.Store(&routes)
t.routeTree.Store(routeTree)
return nil
}
func (t *tun) RouteFor(ip iputil.VpnIp) iputil.VpnIp {
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_, r := t.routeTree.Load().MostSpecificContains(ip)
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return r
}
// The following is hoisted up from water, we do this so we can inject our own fd on iOS
type tunReadCloser struct {
f io.ReadWriteCloser
rMu sync.Mutex
rBuf []byte
wMu sync.Mutex
wBuf []byte
}
func (tr *tunReadCloser) Read(to []byte) (int, error) {
tr.rMu.Lock()
defer tr.rMu.Unlock()
if cap(tr.rBuf) < len(to)+4 {
tr.rBuf = make([]byte, len(to)+4)
}
tr.rBuf = tr.rBuf[:len(to)+4]
n, err := tr.f.Read(tr.rBuf)
copy(to, tr.rBuf[4:])
return n - 4, err
}
func (tr *tunReadCloser) Write(from []byte) (int, error) {
if len(from) == 0 {
return 0, syscall.EIO
}
tr.wMu.Lock()
defer tr.wMu.Unlock()
if cap(tr.wBuf) < len(from)+4 {
tr.wBuf = make([]byte, len(from)+4)
}
tr.wBuf = tr.wBuf[:len(from)+4]
// Determine the IP Family for the NULL L2 Header
ipVer := from[0] >> 4
if ipVer == 4 {
tr.wBuf[3] = syscall.AF_INET
} else if ipVer == 6 {
tr.wBuf[3] = syscall.AF_INET6
} else {
return 0, errors.New("unable to determine IP version from packet")
}
copy(tr.wBuf[4:], from)
n, err := tr.f.Write(tr.wBuf)
return n - 4, err
}
func (tr *tunReadCloser) Close() error {
return tr.f.Close()
}
func (t *tun) Cidr() *net.IPNet {
return t.cidr
}
func (t *tun) Name() string {
return "iOS"
}
func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
return nil, fmt.Errorf("TODO: multiqueue not implemented for ios")
}