1/* Copyright (C) 1996-2021 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
27/* Type of the lookup function we need here. */
28typedef int (*lookup_function) (const struct ether_addr *, struct etherent *,
29 char *, size_t, int *);
30
31int
32ether_ntohost (char *hostname, const struct ether_addr *addr)
33{
34 nss_action_list nip;
35 union
36 {
37 lookup_function f;
38 void *ptr;
39 } fct;
40 int no_more;
41 enum nss_status status = NSS_STATUS_UNAVAIL;
42 struct etherent etherent;
43
44 no_more = __nss_ethers_lookup2 (&nip, "getntohost_r", NULL, &fct.ptr);
45
46 while (no_more == 0)
47 {
48 char buffer[1024];
49
50 status = (*fct.f) (addr, &etherent, buffer, sizeof buffer, &errno);
51
52 no_more = __nss_next2 (&nip, "getntohost_r", NULL, &fct.ptr, status, 0);
53 }
54
55 if (status == NSS_STATUS_SUCCESS)
56 /* XXX This is a potential cause of trouble because the size of
57 the HOSTNAME buffer is not known but the interface does not
58 provide this information. */
59 strcpy (hostname, etherent.e_name);
60
61 return status == NSS_STATUS_SUCCESS ? 0 : -1;
62}
63