1 | /* Copyright (C) 1996-2020 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. */ |
28 | typedef int (*lookup_function) (const struct ether_addr *, struct etherent *, |
29 | char *, size_t, int *); |
30 | |
31 | int |
32 | ether_ntohost (char *hostname, const struct ether_addr *addr) |
33 | { |
34 | static service_user *startp; |
35 | static lookup_function start_fct; |
36 | service_user *nip; |
37 | union |
38 | { |
39 | lookup_function f; |
40 | void *ptr; |
41 | } fct; |
42 | int no_more; |
43 | enum nss_status status = NSS_STATUS_UNAVAIL; |
44 | struct etherent etherent; |
45 | |
46 | if (startp == NULL) |
47 | { |
48 | no_more = __nss_ethers_lookup2 (&nip, "getntohost_r" , NULL, &fct.ptr); |
49 | if (no_more) |
50 | startp = (service_user *) -1; |
51 | else |
52 | { |
53 | startp = nip; |
54 | start_fct = fct.f; |
55 | } |
56 | } |
57 | else |
58 | { |
59 | fct.f = start_fct; |
60 | no_more = (nip = startp) == (service_user *) -1; |
61 | } |
62 | |
63 | while (no_more == 0) |
64 | { |
65 | char buffer[1024]; |
66 | |
67 | status = (*fct.f) (addr, ðerent, buffer, sizeof buffer, &errno); |
68 | |
69 | no_more = __nss_next2 (&nip, "getntohost_r" , NULL, &fct.ptr, status, 0); |
70 | } |
71 | |
72 | if (status == NSS_STATUS_SUCCESS) |
73 | /* XXX This is a potential cause of trouble because the size of |
74 | the HOSTNAME buffer is not known but the interface does not |
75 | provide this information. */ |
76 | strcpy (hostname, etherent.e_name); |
77 | |
78 | return status == NSS_STATUS_SUCCESS ? 0 : -1; |
79 | } |
80 | |