1/* Copyright (C) 1996-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <errno.h>
19#include <netinet/ether.h>
20#include <netinet/if_ether.h>
21#include <string.h>
22
23#include <nss/nsswitch.h>
24
25
26/* Type of the lookup function we need here. */
27typedef int (*lookup_function) (const struct ether_addr *, struct etherent *,
28 char *, size_t, int *);
29
30int
31ether_ntohost (char *hostname, const struct ether_addr *addr)
32{
33 nss_action_list nip;
34 union
35 {
36 lookup_function f;
37 void *ptr;
38 } fct;
39 int no_more;
40 enum nss_status status = NSS_STATUS_UNAVAIL;
41 struct etherent etherent;
42
43 no_more = __nss_ethers_lookup2 (&nip, "getntohost_r", NULL, &fct.ptr);
44
45 while (no_more == 0)
46 {
47 char buffer[1024];
48
49 status = (*fct.f) (addr, &etherent, buffer, sizeof buffer, &errno);
50
51 no_more = __nss_next2 (&nip, "getntohost_r", NULL, &fct.ptr, status, 0);
52 }
53
54 if (status == NSS_STATUS_SUCCESS)
55 /* XXX This is a potential cause of trouble because the size of
56 the HOSTNAME buffer is not known but the interface does not
57 provide this information. */
58 strcpy (hostname, etherent.e_name);
59
60 return status == NSS_STATUS_SUCCESS ? 0 : -1;
61}
62