1/* Copyright (C) 1996-2016 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
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
31/* The lookup function for the first entry of this service. */
32extern int __nss_ethers_lookup (service_user **nip, const char *name,
33 void **fctp) internal_function;
34
35
36int
37ether_ntohost (char *hostname, const struct ether_addr *addr)
38{
39 static service_user *startp;
40 static lookup_function start_fct;
41 service_user *nip;
42 union
43 {
44 lookup_function f;
45 void *ptr;
46 } fct;
47 int no_more;
48 enum nss_status status = NSS_STATUS_UNAVAIL;
49 struct etherent etherent;
50
51 if (startp == NULL)
52 {
53 no_more = __nss_ethers_lookup (&nip, "getntohost_r", &fct.ptr);
54 if (no_more)
55 startp = (service_user *) -1;
56 else
57 {
58 startp = nip;
59 start_fct = fct.f;
60 }
61 }
62 else
63 {
64 fct.f = start_fct;
65 no_more = (nip = startp) == (service_user *) -1;
66 }
67
68 while (no_more == 0)
69 {
70 char buffer[1024];
71
72 status = (*fct.f) (addr, &etherent, buffer, sizeof buffer, &errno);
73
74 no_more = __nss_next2 (&nip, "getntohost_r", NULL, &fct.ptr, status, 0);
75 }
76
77 if (status == NSS_STATUS_SUCCESS)
78 /* XXX This is a potential cause of trouble because the size of
79 the HOSTNAME buffer is not known but the interface does not
80 provide this information. */
81 strcpy (hostname, etherent.e_name);
82
83 return status == NSS_STATUS_SUCCESS ? 0 : -1;
84}
85