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duidreader/main.go
2025-05-09 20:34:54 +02:00

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package main
import (
"bytes"
"encoding/hex"
"errors"
"fmt"
"io/fs"
"os"
"path/filepath"
"runtime"
"strings"
"golang.org/x/sys/windows/registry"
)
// ---------- Linux ----------
func duidsLinux() (map[string][]byte, error) {
candidates := []string{
"/var/lib/NetworkManager",
"/var/lib/dhcp",
"/var/lib/systemd/network",
"/run/systemd/netif/leases",
}
out := map[string][]byte{}
for _, dir := range candidates {
_ = filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
if err != nil || d.IsDir() {
return nil
}
// lease/duid files are small, read entire file
buf, err := os.ReadFile(path)
if err != nil {
return nil
}
duid := extractDUID(buf)
if len(duid) > 0 {
out[path] = duid
}
return nil
})
}
if len(out) == 0 {
return nil, errors.New("keine DUID-Datei gefunden")
}
return out, nil
}
// very tolerant parser: tries common patterns
func extractDUID(b []byte) []byte {
// Pattern „default-duid "\x00\x03\x00\x01\xaa…"“
if bytes.Contains(b, []byte("default-duid")) || bytes.Contains(b, []byte("dhclient.duid")) {
start := bytes.IndexByte(b, '"')
end := bytes.LastIndexByte(b, '"')
if start >= 0 && end > start {
hexEsc := b[start+1 : end]
hexEsc = bytes.ReplaceAll(hexEsc, []byte(`\x`), nil)
duid, _ := hex.DecodeString(string(hexEsc))
return duid
}
}
// systemd-networkd file: plain hex without 0x
if allHex(b) {
duid, _ := hex.DecodeString(strings.TrimSpace(string(b)))
return duid
}
return nil
}
func allHex(b []byte) bool {
for _, c := range bytes.TrimSpace(b) {
if !strings.ContainsRune("0123456789abcdefABCDEF", rune(c)) {
return false
}
}
return true
}
// ---------- Windows ----------
func duidsWindows() (map[string][]byte, error) {
k, err := registry.OpenKey(registry.LOCAL_MACHINE,
`SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters`,
registry.READ)
if err != nil {
return nil, err
}
defer k.Close()
val, _, err := k.GetBinaryValue("Dhcpv6DUID")
if err != nil {
return nil, err
}
return map[string][]byte{"registry": val}, nil
}
// ---------- macOS (scutil) ----------
// (Beispielskizze nicht implementiert)
// func duidsDarwin() ...
// ---------- main ----------
func main() {
var duids map[string][]byte
var err error
switch runtime.GOOS {
case "windows":
duids, err = duidsWindows()
default: // linux, darwin, ...
duids, err = duidsLinux()
}
if err != nil {
fmt.Fprintln(os.Stderr, "Fehler:", err)
os.Exit(1)
}
hostName, _ := os.Hostname()
for _, d := range duids {
fmt.Printf("%s", hex.EncodeToString(d))
fmt.Printf("%s", hostName)
}
}