105 lines
2.0 KiB
Go
105 lines
2.0 KiB
Go
package main
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import (
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"container/ring"
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"context"
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"flag"
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"log"
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"sync"
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"github.com/google/gopacket"
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"github.com/google/gopacket/layers"
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"github.com/google/gopacket/pcapgo"
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"golang.org/x/sync/errgroup"
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_ "net/http/pprof"
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)
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var (
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hostKeyPath = flag.String("host_key",
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"/perm/breakglass.host_key",
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"path to a PEM-encoded RSA, DSA or ECDSA private key (create using e.g. ssh-keygen -f /perm/breakglass.host_key -N '' -t rsa)")
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)
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func capturePackets(ctx context.Context) (chan gopacket.Packet, error) {
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packets := make(chan gopacket.Packet)
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for _, ifname := range []string{"uplink0", "lan0"} {
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handle, err := pcapgo.OpenEthernet(ifname)
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if err != nil {
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return nil, err
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}
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if err := handle.SetBPF(instructions); err != nil {
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return nil, err
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}
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pkgsrc := gopacket.NewPacketSource(handle, layers.LayerTypeEthernet)
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go func() {
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defer handle.Close()
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for packet := range pkgsrc.Packets() {
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select {
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case packets <- packet:
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case <-ctx.Done():
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return
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}
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}
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}()
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}
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return packets, nil
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}
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type packetRingBuffer struct {
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sync.Mutex
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r *ring.Ring
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}
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func newPacketRingBuffer(size int) *packetRingBuffer {
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return &packetRingBuffer{
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r: ring.New(size),
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}
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}
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func (prb *packetRingBuffer) writePacket(p gopacket.Packet) {
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prb.Lock()
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defer prb.Unlock()
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prb.r.Value = p
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prb.r = prb.r.Next()
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}
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func (prb *packetRingBuffer) packetsLocked() []gopacket.Packet {
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packets := make([]gopacket.Packet, 0, prb.r.Len())
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prb.r.Do(func(x interface{}) {
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if x != nil {
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packets = append(packets, x.(gopacket.Packet))
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}
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})
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return packets
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}
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func logic() error {
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prb := newPacketRingBuffer(50000)
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var eg errgroup.Group
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eg.Go(func() error { return listenAndServe(prb) })
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eg.Go(func() error {
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packets, err := capturePackets(context.Background())
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if err != nil {
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return err
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}
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for packet := range packets {
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prb.writePacket(packet)
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}
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return nil
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})
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return eg.Wait()
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}
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func main() {
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flag.Parse()
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if err := logic(); err != nil {
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log.Fatal(err)
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}
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}
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