nebula/overlay/tun_disabled.go

133 lines
2.6 KiB
Go

package overlay
import (
"fmt"
"io"
"net"
"strings"
"github.com/rcrowley/go-metrics"
"github.com/sirupsen/logrus"
"github.com/slackhq/nebula/iputil"
)
type disabledTun struct {
read chan []byte
cidr *net.IPNet
// Track these metrics since we don't have the tun device to do it for us
tx metrics.Counter
rx metrics.Counter
l *logrus.Logger
}
func newDisabledTun(cidr *net.IPNet, queueLen int, metricsEnabled bool, l *logrus.Logger) *disabledTun {
tun := &disabledTun{
cidr: cidr,
read: make(chan []byte, queueLen),
l: l,
}
if metricsEnabled {
tun.tx = metrics.GetOrRegisterCounter("messages.tx.message", nil)
tun.rx = metrics.GetOrRegisterCounter("messages.rx.message", nil)
} else {
tun.tx = &metrics.NilCounter{}
tun.rx = &metrics.NilCounter{}
}
return tun
}
func (*disabledTun) Activate() error {
return nil
}
func (*disabledTun) RouteFor(iputil.VpnIp) iputil.VpnIp {
return 0
}
func (t *disabledTun) Cidr() *net.IPNet {
return t.cidr
}
func (*disabledTun) Name() string {
return "disabled"
}
func (t *disabledTun) Read(b []byte) (int, error) {
r, ok := <-t.read
if !ok {
return 0, io.EOF
}
if len(r) > len(b) {
return 0, fmt.Errorf("packet larger than mtu: %d > %d bytes", len(r), len(b))
}
t.tx.Inc(1)
if t.l.Level >= logrus.DebugLevel {
t.l.WithField("raw", prettyPacket(r)).Debugf("Write payload")
}
return copy(b, r), nil
}
func (t *disabledTun) handleICMPEchoRequest(b []byte) bool {
out := make([]byte, len(b))
out = iputil.CreateICMPEchoResponse(b, out)
if out == nil {
return false
}
// attempt to write it, but don't block
select {
case t.read <- out:
default:
t.l.Debugf("tun_disabled: dropped ICMP Echo Reply response")
}
return true
}
func (t *disabledTun) Write(b []byte) (int, error) {
t.rx.Inc(1)
// Check for ICMP Echo Request before spending time doing the full parsing
if t.handleICMPEchoRequest(b) {
if t.l.Level >= logrus.DebugLevel {
t.l.WithField("raw", prettyPacket(b)).Debugf("Disabled tun responded to ICMP Echo Request")
}
} else if t.l.Level >= logrus.DebugLevel {
t.l.WithField("raw", prettyPacket(b)).Debugf("Disabled tun received unexpected payload")
}
return len(b), nil
}
func (t *disabledTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
return t, nil
}
func (t *disabledTun) Close() error {
if t.read != nil {
close(t.read)
t.read = nil
}
return nil
}
type prettyPacket []byte
func (p prettyPacket) String() string {
var s strings.Builder
for i, b := range p {
if i > 0 && i%8 == 0 {
s.WriteString(" ")
}
s.WriteString(fmt.Sprintf("%02x ", b))
}
return s.String()
}