inet/ether_hton.c

   1 /* Copyright (C) 1996, 1999, 2002, 2007 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    <http://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 /* The lookup function for the first entry of this service.  */
  31 extern int __nss_ethers_lookup (service_user **nip, const char *name,
  32                                 void **fctp) internal_function;
  33
  34
  35 int
  36 ether_hostton (const char *hostname, struct ether_addr *addr)
  37 {
  38   static service_user *startp;
  39   static lookup_function start_fct;
  40   service_user *nip;
  41   union
  42   {
  43     lookup_function f;
  44     void *ptr;
  45   } fct;
  46   int no_more;
  47   enum nss_status status = NSS_STATUS_UNAVAIL;
  48   struct etherent etherent;
  49
  50   if (startp == NULL)
  51     {
  52       no_more = __nss_ethers_lookup (&nip, "gethostton_r", &fct.ptr);
  53       if (no_more)
  54         startp = (service_user *) -1;
  55       else
  56         {
  57           startp = nip;
  58           start_fct = fct.f;
  59         }
  60     }
  61   else
  62     {
  63       fct.f = start_fct;
  64       no_more = (nip = startp) == (service_user *) -1;
  65     }
  66
  67   while (no_more == 0)
  68     {
  69       char buffer[1024];
  70
  71       status = (*fct.f) (hostname, &etherent, buffer, sizeof buffer, &errno);
  72
  73       no_more = __nss_next2 (&nip, "gethostton_r", NULL, &fct.ptr, status, 0);
  74     }
  75
  76   if (status == NSS_STATUS_SUCCESS)
  77     memcpy (addr, etherent.e_addr.ether_addr_octet,
  78             sizeof (struct ether_addr));
  79
  80   return status == NSS_STATUS_SUCCESS ? 0 : -1;
  81 }