/* Copyright (C) 1996-2019 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see <http://www.gnu.org/licenses/>. */ #include <errno.h> #include <netinet/ether.h> #include <netinet/if_ether.h> #include <string.h> #include <nss/nsswitch.h> /* Type of the lookup function we need here. */ typedef int (*lookup_function) (const struct ether_addr *, struct etherent *, char *, size_t, int *); int ether_ntohost (char *hostname, const struct ether_addr *addr) { static service_user *startp; static lookup_function start_fct; service_user *nip; union { lookup_function f; void *ptr; } fct; int no_more; enum nss_status status = NSS_STATUS_UNAVAIL; struct etherent etherent; if (startp == NULL) { no_more = __nss_ethers_lookup2 (&nip, "getntohost_r", NULL, &fct.ptr); if (no_more) startp = (service_user *) -1; else { startp = nip; start_fct = fct.f; } } else { fct.f = start_fct; no_more = (nip = startp) == (service_user *) -1; } while (no_more == 0) { char buffer[1024]; status = (*fct.f) (addr, ðerent, buffer, sizeof buffer, &errno); no_more = __nss_next2 (&nip, "getntohost_r", NULL, &fct.ptr, status, 0); } if (status == NSS_STATUS_SUCCESS) /* XXX This is a potential cause of trouble because the size of the HOSTNAME buffer is not known but the interface does not provide this information. */ strcpy (hostname, etherent.e_name); return status == NSS_STATUS_SUCCESS ? 0 : -1; }