1/* Get IPv4 source filter. Linux version.
2 Copyright (C) 2004-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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 <alloca.h>
20#include <errno.h>
21#include <stdlib.h>
22#include <string.h>
23#include <stdint.h>
24#include <netinet/in.h>
25#include <sys/param.h>
26#include <sys/socket.h>
27
28
29int
30getipv4sourcefilter (int s, struct in_addr interface, struct in_addr group,
31 uint32_t *fmode, uint32_t *numsrc, struct in_addr *slist)
32{
33 /* We have to create an struct ip_msfilter object which we can pass
34 to the kernel. */
35 socklen_t needed = IP_MSFILTER_SIZE (*numsrc);
36 int use_alloca = __libc_use_alloca (needed);
37
38 struct ip_msfilter *imsf;
39 if (use_alloca)
40 imsf = (struct ip_msfilter *) alloca (needed);
41 else
42 {
43 imsf = (struct ip_msfilter *) malloc (needed);
44 if (imsf == NULL)
45 return -1;
46 }
47
48 imsf->imsf_multiaddr = group;
49 imsf->imsf_interface = interface;
50 imsf->imsf_numsrc = *numsrc;
51
52 int result = __getsockopt (s, SOL_IP, IP_MSFILTER, imsf, &needed);
53
54 /* If successful, copy the results to the places the caller wants
55 them in. */
56 if (result == 0)
57 {
58 *fmode = imsf->imsf_fmode;
59 memcpy (slist, imsf->imsf_slist,
60 MIN (*numsrc, imsf->imsf_numsrc) * sizeof (struct in_addr));
61 *numsrc = imsf->imsf_numsrc;
62 }
63
64 if (! use_alloca)
65 {
66 int save_errno = errno;
67 free (imsf);
68 __set_errno (save_errno);
69 }
70
71 return result;
72}
73