/* Copyright (C) 1996-2018 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, &etherent, 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;

}