util_darwin_test.go 1.4 KB

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  1. package main
  2. import (
  3. "fmt"
  4. "net"
  5. "net/netip"
  6. "syscall"
  7. "golang.org/x/net/route"
  8. )
  9. func defaultRouteIP() (netip.Addr, error) {
  10. idx, err := defaultRouteInterfaceIndex()
  11. if err != nil {
  12. return netip.Addr{}, err
  13. }
  14. iface, err := net.InterfaceByIndex(idx)
  15. if err != nil {
  16. return netip.Addr{}, err
  17. }
  18. addrs, err := iface.Addrs()
  19. if err != nil {
  20. return netip.Addr{}, err
  21. }
  22. for _, addr := range addrs {
  23. ip := addr.(*net.IPNet).IP
  24. if ip.To4() != nil {
  25. a, _ := netip.AddrFromSlice(ip)
  26. return a, nil
  27. }
  28. }
  29. return netip.Addr{}, err
  30. }
  31. func defaultRouteInterfaceIndex() (int, error) {
  32. rib, err := route.FetchRIB(syscall.AF_UNSPEC, syscall.NET_RT_DUMP2, 0)
  33. if err != nil {
  34. return 0, fmt.Errorf("route.FetchRIB: %w", err)
  35. }
  36. msgs, err := route.ParseRIB(syscall.NET_RT_IFLIST2, rib)
  37. if err != nil {
  38. return 0, fmt.Errorf("route.ParseRIB: %w", err)
  39. }
  40. for _, message := range msgs {
  41. routeMessage := message.(*route.RouteMessage)
  42. if routeMessage.Flags&(syscall.RTF_UP|syscall.RTF_GATEWAY|syscall.RTF_STATIC) == 0 {
  43. continue
  44. }
  45. addresses := routeMessage.Addrs
  46. destination, ok := addresses[0].(*route.Inet4Addr)
  47. if !ok {
  48. continue
  49. }
  50. if destination.IP != [4]byte{0, 0, 0, 0} {
  51. continue
  52. }
  53. switch addresses[1].(type) {
  54. case *route.Inet4Addr:
  55. return routeMessage.Index, nil
  56. default:
  57. continue
  58. }
  59. }
  60. return 0, fmt.Errorf("ambiguous gateway interfaces found")
  61. }