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add pcap printing to examples/xnet

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soypat
2025-12-31 13:21:46 -03:00
parent ed89f169d9
commit 7369ec0b7e
4 changed files with 181 additions and 140 deletions
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examples/xnet/main.go
+31 -8
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@@ -42,6 +42,7 @@ func run() (err error) {
flagRequestedIP = ""
flagDoNTP = false
flagHTTPGet = false
flagNoPcap = false
)
flag.BoolVar(&flagHTTPGet, "httpget", flagHTTPGet, "Do an HTTP GET request ")
flag.StringVar(&flagInterface, "i", flagInterface, "Interface to use. Either tap* or the name of an existing interface to bridge to.")
@@ -49,6 +50,7 @@ func run() (err error) {
flag.StringVar(&flagHostToResolve, "host", flagHostToResolve, "Hostname to resolve via DNS.")
flag.StringVar(&flagRequestedIP, "addr", flagRequestedIP, "IP address to request via DHCP.")
flag.BoolVar(&flagDoNTP, "ntp", flagDoNTP, "Do NTP round and print result time")
flag.BoolVar(&flagNoPcap, "nopcap", flagNoPcap, "Disable pcap logging.")
flag.Parse()
fmt.Println("softrand", softRand)
_, err = dns.NewName(flagHostToResolve)
@@ -108,18 +110,37 @@ func run() (err error) {
buf := make([]byte, mtu)
var cap pcap.PacketBreakdown
var frames []pcap.Frame
pf := pcap.Formatter{
FilterClasses: []pcap.FieldClass{pcap.FieldClassFlags, pcap.FieldClassDst, pcap.FieldClassSrc, pcap.FieldClassAddress},
}
var pfbuf []byte
logFrames := func(context string, pkt []byte) error {
if flagNoPcap {
return nil
}
frames, err = cap.CaptureEthernet(frames[:0], pkt, 0)
if err != nil {
return err
}
pfbuf = append(pfbuf[:0], context...)
pfbuf = append(pfbuf, ' ', '[')
pfbuf, err = pf.FormatFrames(pfbuf, frames, pkt)
pfbuf = append(pfbuf, ']', '\n')
if err != nil {
return err
}
_, err = os.Stdout.Write(pfbuf)
return err
}
for {
clear(buf)
nwrite, err := stack.Encapsulate(buf[:], -1, 0)
if err != nil {
fmt.Println("ERR:ENCAPSULATE", err)
log.Println("ERR:ENCAPSULATE", err)
} else if nwrite > 0 {
frames, err = cap.CaptureEthernet(frames[:0], buf[:nwrite], 0)
err = logFrames("OUT", buf[:nwrite])
if err != nil {
log.Println("ERR capture", err)
}
if len(frames) > 0 {
fmt.Println("OUT", frames)
log.Println("ERR:OUTLOG", err)
}
n, err := iface.Write(buf[:nwrite])
if err != nil {
@@ -137,8 +158,10 @@ func run() (err error) {
err = stack.Demux(buf[:nread], 0)
if err != nil {
if !errors.Is(err, lneto.ErrPacketDrop) {
frames, err = cap.CaptureEthernet(frames[:0], buf[:nread], 0)
log.Println("groutine demux:", err, frames)
err = logFrames("IN", buf[:nread])
if err != nil {
log.Println("ERR:INLOG", err)
}
}
}
}