inet/ether_hton.c

   1 /* Copyright (C) 1996-2019 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <netinet/ether.h>
  21 #include <netinet/if_ether.h>
  22 #include <string.h>
  23
  24 #include "../nss/nsswitch.h"
  25
  26 /* Type of the lookup function we need here.  */
  27 typedef int (*lookup_function) (const char *, struct etherent *, char *, int,
  28                                 int *);
  29
  30 int
  31 ether_hostton (const char *hostname, struct ether_addr *addr)
  32 {
  33   static service_user *startp;
  34   static lookup_function start_fct;
  35   service_user *nip;
  36   union
  37   {
  38     lookup_function f;
  39     void *ptr;
  40   } fct;
  41   int no_more;
  42   enum nss_status status = NSS_STATUS_UNAVAIL;
  43   struct etherent etherent;
  44
  45   if (startp == NULL)
  46     {
  47       no_more = __nss_ethers_lookup2 (&nip, "gethostton_r", NULL, &fct.ptr);
  48       if (no_more)
  49         startp = (service_user *) -1;
  50       else
  51         {
  52           startp = nip;
  53           start_fct = fct.f;
  54         }
  55     }
  56   else
  57     {
  58       fct.f = start_fct;
  59       no_more = (nip = startp) == (service_user *) -1;
  60     }
  61
  62   while (no_more == 0)
  63     {
  64       char buffer[1024];
  65
  66       status = (*fct.f) (hostname, &etherent, buffer, sizeof buffer, &errno);
  67
  68       no_more = __nss_next2 (&nip, "gethostton_r", NULL, &fct.ptr, status, 0);
  69     }
  70
  71   if (status == NSS_STATUS_SUCCESS)
  72     memcpy (addr, etherent.e_addr.ether_addr_octet,
  73             sizeof (struct ether_addr));
  74
  75   return status == NSS_STATUS_SUCCESS ? 0 : -1;
  76 }