1/* Get source filter. Linux version.
2 Copyright (C) 2004-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include <alloca.h>
21#include <assert.h>
22#include <errno.h>
23#include <stdlib.h>
24#include <string.h>
25#include <stdint.h>
26#include <netatalk/at.h>
27#include <netax25/ax25.h>
28#include <netinet/in.h>
29#include <netipx/ipx.h>
30#include <netpacket/packet.h>
31#include <netrose/rose.h>
32#include <sys/param.h>
33#include <sys/socket.h>
34#include "getsourcefilter.h"
35
36
37static const struct
38{
39 int sol;
40 int af;
41 socklen_t size;
42} sol_map[] =
43 {
44 /* Sort the array according to importance of the protocols. Add
45 more protocols when they become available. */
46 { SOL_IP, AF_INET, sizeof (struct sockaddr_in) },
47 { SOL_IPV6, AF_INET6, sizeof (struct sockaddr_in6) },
48 { SOL_AX25, AF_AX25, sizeof (struct sockaddr_ax25) },
49 { SOL_IPX, AF_IPX, sizeof (struct sockaddr_ipx) },
50 { SOL_ATALK, AF_APPLETALK, sizeof (struct sockaddr_at) },
51 { SOL_ROSE, AF_ROSE, sizeof (struct sockaddr_rose) },
52 { SOL_PACKET, AF_PACKET, sizeof (struct sockaddr_ll) }
53 };
54#define NSOL_MAP (sizeof (sol_map) / sizeof (sol_map[0]))
55
56
57/* Try to determine the socket level value. Ideally both side and
58 family are set. But sometimes only the size is correct and the
59 family value might be bogus. Loop over the array entries and look
60 for a perfect match or the first match based on size. */
61int
62__get_sol (int af, socklen_t len)
63{
64 int first_size_sol = -1;
65
66 for (size_t cnt = 0; cnt < NSOL_MAP; ++cnt)
67 {
68 /* Just a test so that we make sure the special value used to
69 signal the "we have so far no socket level value" is OK. */
70 assert (sol_map[cnt].sol != -1);
71
72 if (len == sol_map[cnt].size)
73 {
74 /* The size matches, which is a requirement. If the family
75 matches, too, we have a winner. Otherwise we remember the
76 socket level value for this protocol if it is the first
77 match. */
78 if (af == sol_map[cnt].af)
79 /* Bingo! */
80 return sol_map[cnt].sol;
81
82 if (first_size_sol == -1)
83 first_size_sol = sol_map[cnt].sol;
84 }
85 }
86
87 return first_size_sol;
88}
89
90
91int
92getsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
93 socklen_t grouplen, uint32_t *fmode, uint32_t *numsrc,
94 struct sockaddr_storage *slist)
95{
96 /* We have to create an struct ip_msfilter object which we can pass
97 to the kernel. */
98 socklen_t needed = GROUP_FILTER_SIZE (*numsrc);
99 int use_alloca = __libc_use_alloca (needed);
100
101 struct group_filter *gf;
102 if (use_alloca)
103 gf = (struct group_filter *) alloca (needed);
104 else
105 {
106 gf = (struct group_filter *) malloc (needed);
107 if (gf == NULL)
108 return -1;
109 }
110
111 gf->gf_interface = interface;
112 memcpy (&gf->gf_group, group, grouplen);
113 gf->gf_numsrc = *numsrc;
114
115 /* We need to provide the appropriate socket level value. */
116 int result;
117 int sol = __get_sol (group->sa_family, grouplen);
118 if (sol == -1)
119 {
120 __set_errno (EINVAL);
121 result = -1;
122 }
123 else
124 {
125 result = __getsockopt (s, sol, MCAST_MSFILTER, gf, &needed);
126
127 /* If successful, copy the results to the places the caller wants
128 them in. */
129 if (result == 0)
130 {
131 *fmode = gf->gf_fmode;
132 memcpy (slist, gf->gf_slist,
133 MIN (*numsrc, gf->gf_numsrc)
134 * sizeof (struct sockaddr_storage));
135 *numsrc = gf->gf_numsrc;
136 }
137 }
138
139 if (! use_alloca)
140 {
141 int save_errno = errno;
142 free (gf);
143 __set_errno (save_errno);
144 }
145
146 return result;
147}
148