/* Copyright (C) 1996, 1997 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 Library General Public License as published by the Free Software Foundation; either version 2 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 Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with the GNU C Library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include <netinet/ether.h> #include <netinet/if_ether.h> #include <string.h> #include <nss/nsswitch.h> /* Because the `ethers' lookup does not fit so well in the scheme so we define a dummy struct here which helps us to use the available functions. */ struct etherent { const char *e_name; struct ether_addr e_addr; }; /* Type of the lookup function we need here. */ typedef int (*lookup_function) (const struct ether_addr *, struct etherent *, char *, int); /* The lookup function for the first entry of this service. */ extern int __nss_ethers_lookup (service_user **nip, const char *name, void **fctp); int ether_ntohost (char *hostname, const struct ether_addr *addr) { static service_user *startp = NULL; static lookup_function start_fct; service_user *nip; lookup_function fct; int no_more; enum nss_status status = NSS_STATUS_UNAVAIL; struct etherent etherent; if (startp == NULL) { no_more = __nss_ethers_lookup (&nip, "getntohost_r", (void **) &fct); if (no_more) startp = (service_user *) -1; else { startp = nip; start_fct = fct; } } else { fct = start_fct; no_more = (nip = startp) == (service_user *) -1; } while (no_more == 0) { char buffer[1024]; status = (*fct) (addr, ðerent, buffer, sizeof buffer); no_more = __nss_next (&nip, "getntohost_r", (void **) &fct, 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; }