ether_ntoh.c 1.8 KB

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  1. /* Copyright (C) 1996-2026 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. The GNU C Library is free software; you can redistribute it and/or
  4. modify it under the terms of the GNU Lesser General Public
  5. License as published by the Free Software Foundation; either
  6. version 2.1 of the License, or (at your option) any later version.
  7. The GNU C Library is distributed in the hope that it will be useful,
  8. but WITHOUT ANY WARRANTY; without even the implied warranty of
  9. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10. Lesser General Public License for more details.
  11. You should have received a copy of the GNU Lesser General Public
  12. License along with the GNU C Library; if not, see
  13. <https://www.gnu.org/licenses/>. */
  14. #include <errno.h>
  15. #include <netinet/ether.h>
  16. #include <netinet/if_ether.h>
  17. #include <string.h>
  18. #include <nsswitch.h>
  19. /* Type of the lookup function we need here. */
  20. typedef int (*lookup_function) (const struct ether_addr *, struct etherent *,
  21. char *, size_t, int *);
  22. int
  23. ether_ntohost (char *hostname, const struct ether_addr *addr)
  24. {
  25. nss_action_list nip;
  26. void *fct;
  27. int no_more;
  28. enum nss_status status = NSS_STATUS_UNAVAIL;
  29. struct etherent etherent;
  30. no_more = __nss_ethers_lookup2 (&nip, "getntohost_r", NULL, &fct);
  31. while (no_more == 0)
  32. {
  33. char buffer[1024];
  34. status = ((lookup_function) fct) (addr, &etherent, buffer,
  35. sizeof buffer, &errno);
  36. no_more = __nss_next2 (&nip, "getntohost_r", NULL, &fct, status, 0);
  37. }
  38. if (status == NSS_STATUS_SUCCESS)
  39. /* XXX This is a potential cause of trouble because the size of
  40. the HOSTNAME buffer is not known but the interface does not
  41. provide this information. */
  42. strcpy (hostname, etherent.e_name);
  43. return status == NSS_STATUS_SUCCESS ? 0 : -1;
  44. }