Use zerolog + intercept SIGINT (#2)
* Use zerolog + intercept SIGINT * Use RFC3339 for time format and add -json flag to disable pretty printing * Added new flags to README and fixed issue when command exit was not successful
This commit is contained in:
VaiTon
GitHub
@@ -2,12 +2,13 @@ package main
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import (
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"context"
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"errors"
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"flag"
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"fmt"
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"log"
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"net"
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"os"
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"os/exec"
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"os/signal"
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"time"
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"github.com/google/shlex"
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@@ -15,6 +16,9 @@ import (
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"github.com/google/gopacket"
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"github.com/google/gopacket/pcap"
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"github.com/google/gopacket/pcapgo"
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"github.com/rs/zerolog"
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"github.com/rs/zerolog/log"
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)
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type PcapClient struct {
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@@ -50,17 +54,34 @@ func lookupHostnameWithTimeout(addr net.Addr, timeout time.Duration) (string, st
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return names[0], port, nil
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}
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func main() {
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var (
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pcapCommand = flag.String("cmd", "", "command to execute for pcap data (eg: tcpdump -i eth0 -n --immediate-mode -s 65535 -U -w -)")
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listenAddress = flag.String("listen", "", "listen address for pcap-over-ip (eg: localhost:4242)")
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noReverseLookup = flag.Bool("n", false, "disable reverse lookup of connecting PCAP-over-IP client IP address")
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debug = flag.Bool("debug", false, "enable debug logging")
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json = flag.Bool("json", false, "enable json logging")
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)
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pcapCommand := flag.String("cmd", "", "command to execute for pcap data (eg: tcpdump -i eth0 -n --immediate-mode -s 65535 -U -w -)")
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listenAddress := flag.String("listen", "", "listen address for pcap-over-ip (eg: localhost:4242)")
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noReverseLookup := flag.Bool("n", false, "disable reverse lookup of connecting PCAP-over-IP client IP address")
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func main() {
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flag.Parse()
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if !*json {
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log.Logger = log.Output(zerolog.ConsoleWriter{
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Out: os.Stderr,
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TimeFormat: time.RFC3339,
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})
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}
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if *debug {
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zerolog.SetGlobalLevel(zerolog.DebugLevel)
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} else {
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zerolog.SetGlobalLevel(zerolog.InfoLevel)
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}
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if *pcapCommand == "" {
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*pcapCommand = os.Getenv("PCAP_COMMAND")
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if *pcapCommand == "" {
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log.Fatalf("Error: PCAP_COMMAND or -cmd not set, see --help for usage")
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log.Fatal().Msg("PCAP_COMMAND or -cmd not set, see --help for usage")
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}
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}
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@@ -71,68 +92,83 @@ func main() {
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}
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}
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log.Printf("config PCAP_COMMAND = %q", *pcapCommand)
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log.Printf("config LISTEN_ADDRESS = %q", *listenAddress)
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log.Debug().Str("pcapCommand", *pcapCommand).Send()
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log.Debug().Str("listenAddress", *listenAddress).Send()
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ctx, cancelFunc := signal.NotifyContext(context.Background(), os.Interrupt)
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// Create connections to PcapClient map
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var connMap = map[net.Conn]PcapClient{}
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connMap := map[net.Conn]PcapClient{}
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// Create a pipe for the command to write to, will be read by pcap.OpenOfflineFile
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rStdout, wStdout, err := os.Pipe()
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if err != nil {
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log.Fatal(err)
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log.Fatal().Err(err).Msg("failed to create pipe")
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}
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// Important or these will eventually be garbage collected and the pipe will close
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defer rStdout.Close()
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defer wStdout.Close()
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// Acquire pcap data
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args, err := shlex.Split(*pcapCommand)
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if err != nil {
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log.Fatal(err)
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log.Fatal().Err(err).Msg("failed to parse PCAP_COMMAND")
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}
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cmd := exec.Command(args[0], args[1:]...)
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log.Printf("cmd = %v", cmd.Args)
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cmd := exec.CommandContext(ctx, args[0], args[1:]...)
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log.Debug().Strs("args", args).Send()
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cmd.Stdout = wStdout
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cmd.Stderr = os.Stderr
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cmd.Stderr = log.Logger
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err = cmd.Start()
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if err != nil {
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log.Fatal(err)
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log.Fatal().Err(err).Msg("failed to start command")
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}
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log.Printf("PID %v", cmd.Process.Pid)
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log.Debug().Int("pid", cmd.Process.Pid).Msg("started process")
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// close context on process exit
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go func() {
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err := cmd.Wait()
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if err != nil {
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log.Fatal("Process exited with error: ", err)
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log.Fatal().Err(err).Msg("command exited with error")
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}
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log.Printf("process exited")
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os.Exit(0)
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cancelFunc()
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}()
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// Read from process stdout pipe
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handle, err := pcap.OpenOfflineFile(rStdout)
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if err != nil {
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log.Fatal(err)
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log.Fatal().Err(err).Msg("failed to open pcap file")
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}
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packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
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packetSource.Lazy = true
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packetSource.NoCopy = true
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go processPackets(packetSource, connMap)
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log.Printf("PCAP-over-IP server listening on %v", *listenAddress)
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l, err := net.Listen("tcp", *listenAddress)
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go processPackets(ctx, packetSource, connMap)
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log.Info().Msgf("PCAP-over-IP server listening on %v. press CTRL-C to exit", *listenAddress)
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config := net.ListenConfig{}
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l, err := config.Listen(ctx, "tcp", *listenAddress)
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if err != nil {
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log.Fatal(err)
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log.Fatal().Err(err).Msg("failed to listen")
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}
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// close listener on context cancel
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go func() {
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<-ctx.Done()
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cancelFunc()
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err := l.Close()
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if err != nil {
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log.Err(err).Msg("failed to close listener")
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}
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}()
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for {
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conn, err := l.Accept()
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if err != nil {
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log.Fatal(err)
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if err != nil && ctx.Err() == nil {
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log.Fatal().Err(err).Msg("failed to accept connection")
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} else if errors.Is(ctx.Err(), context.Canceled) {
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break
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}
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if *noReverseLookup {
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@@ -149,22 +185,56 @@ func main() {
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writer := pcapgo.NewWriter(conn)
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// Write pcap header
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writer.WriteFileHeader(65535, handle.LinkType())
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err = writer.WriteFileHeader(65535, handle.LinkType())
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if err != nil {
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log.Err(err).Msg("failed to write pcap header")
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err := conn.Close()
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if err != nil {
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log.Err(err).Msg("failed to close connection")
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}
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continue
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}
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// add connection to map
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connMap[conn] = PcapClient{writer: writer}
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}
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log.Info().Msg("PCAP-over-IP server exiting")
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err = rStdout.Close()
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if err != nil {
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log.Err(err).Msg("failed to close read pipe")
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}
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err = wStdout.Close()
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if err != nil {
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log.Err(err).Msg("failed to close write pipe")
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}
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}
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func processPackets(packetSource *gopacket.PacketSource, connMap map[net.Conn]PcapClient) {
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func processPackets(
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ctx context.Context,
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packetSource *gopacket.PacketSource,
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connMap map[net.Conn]PcapClient,
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) {
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for packet := range packetSource.Packets() {
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select {
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case <-ctx.Done():
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return
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default:
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}
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for conn, stats := range connMap {
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ci := packet.Metadata().CaptureInfo
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err := stats.writer.WritePacket(ci, packet.Data())
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if err != nil {
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log.Println(err)
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log.Err(err).Msg("failed to write packet to connection")
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delete(connMap, conn)
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conn.Close()
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err := conn.Close()
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if err != nil {
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log.Err(err).Msg("failed to close connection")
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}
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continue
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}
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stats.totalPackets += 1
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