1/* Copyright (C) 1997-2023 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 <alloca.h>
19#include <errno.h>
20#include <string.h>
21#include <stdio.h>
22#include <stdlib.h>
23#include <unistd.h>
24#include <net/if.h>
25#include <sys/socket.h>
26#include <sys/ioctl.h>
27#include <libc-lock.h>
28#include <not-cancel.h>
29
30#include "netlinkaccess.h"
31
32
33unsigned int
34__if_nametoindex (const char *ifname)
35{
36#ifndef SIOCGIFINDEX
37 __set_errno (ENOSYS);
38 return 0;
39#else
40 struct ifreq ifr;
41 if (strlen (ifname) >= IFNAMSIZ)
42 {
43 __set_errno (ENODEV);
44 return 0;
45 }
46
47 strncpy (ifr.ifr_name, ifname, sizeof (ifr.ifr_name));
48
49 int fd = __opensock ();
50
51 if (fd < 0)
52 return 0;
53
54 if (__ioctl (fd, SIOCGIFINDEX, &ifr) < 0)
55 {
56 int saved_errno = errno;
57 __close_nocancel_nostatus (fd);
58 if (saved_errno == EINVAL)
59 __set_errno (ENOSYS);
60 return 0;
61 }
62 __close_nocancel_nostatus (fd);
63 return ifr.ifr_ifindex;
64#endif
65}
66libc_hidden_def (__if_nametoindex)
67weak_alias (__if_nametoindex, if_nametoindex)
68libc_hidden_weak (if_nametoindex)
69
70
71void
72__if_freenameindex (struct if_nameindex *ifn)
73{
74 struct if_nameindex *ptr = ifn;
75 while (ptr->if_name || ptr->if_index)
76 {
77 free (ptr->if_name);
78 ++ptr;
79 }
80 free (ifn);
81}
82libc_hidden_def (__if_freenameindex)
83weak_alias (__if_freenameindex, if_freenameindex)
84libc_hidden_weak (if_freenameindex)
85
86
87static struct if_nameindex *
88if_nameindex_netlink (void)
89{
90 struct netlink_handle nh = { 0, 0, 0, NULL, NULL };
91 struct if_nameindex *idx = NULL;
92
93 if (__netlink_open (&nh) < 0)
94 return NULL;
95
96
97 /* Tell the kernel that we wish to get a list of all
98 active interfaces. Collect all data for every interface. */
99 if (__netlink_request (&nh, RTM_GETLINK) < 0)
100 goto exit_free;
101
102 /* Count the interfaces. */
103 unsigned int nifs = 0;
104 for (struct netlink_res *nlp = nh.nlm_list; nlp; nlp = nlp->next)
105 {
106 struct nlmsghdr *nlh;
107 size_t size = nlp->size;
108
109 if (nlp->nlh == NULL)
110 continue;
111
112 /* Walk through all entries we got from the kernel and look, which
113 message type they contain. */
114 for (nlh = nlp->nlh; NLMSG_OK (nlh, size); nlh = NLMSG_NEXT (nlh, size))
115 {
116 /* Check if the message is what we want. */
117 if ((pid_t) nlh->nlmsg_pid != nh.pid || nlh->nlmsg_seq != nlp->seq)
118 continue;
119
120 if (nlh->nlmsg_type == NLMSG_DONE)
121 break; /* ok */
122
123 if (nlh->nlmsg_type == RTM_NEWLINK)
124 ++nifs;
125 }
126 }
127
128 idx = malloc ((nifs + 1) * sizeof (struct if_nameindex));
129 if (idx == NULL)
130 {
131 nomem:
132 __set_errno (ENOBUFS);
133 goto exit_free;
134 }
135
136 /* Add the interfaces. */
137 nifs = 0;
138 for (struct netlink_res *nlp = nh.nlm_list; nlp; nlp = nlp->next)
139 {
140 struct nlmsghdr *nlh;
141 size_t size = nlp->size;
142
143 if (nlp->nlh == NULL)
144 continue;
145
146 /* Walk through all entries we got from the kernel and look, which
147 message type they contain. */
148 for (nlh = nlp->nlh; NLMSG_OK (nlh, size); nlh = NLMSG_NEXT (nlh, size))
149 {
150 /* Check if the message is what we want. */
151 if ((pid_t) nlh->nlmsg_pid != nh.pid || nlh->nlmsg_seq != nlp->seq)
152 continue;
153
154 if (nlh->nlmsg_type == NLMSG_DONE)
155 break; /* ok */
156
157 if (nlh->nlmsg_type == RTM_NEWLINK)
158 {
159 struct ifinfomsg *ifim = (struct ifinfomsg *) NLMSG_DATA (nlh);
160 struct rtattr *rta = IFLA_RTA (ifim);
161 size_t rtasize = IFLA_PAYLOAD (nlh);
162
163 idx[nifs].if_index = ifim->ifi_index;
164
165 while (RTA_OK (rta, rtasize))
166 {
167 char *rta_data = RTA_DATA (rta);
168 size_t rta_payload = RTA_PAYLOAD (rta);
169
170 if (rta->rta_type == IFLA_IFNAME)
171 {
172 idx[nifs].if_name = __strndup (rta_data, rta_payload);
173 if (idx[nifs].if_name == NULL)
174 {
175 idx[nifs].if_index = 0;
176 __if_freenameindex (idx);
177 idx = NULL;
178 goto nomem;
179 }
180 break;
181 }
182
183 rta = RTA_NEXT (rta, rtasize);
184 }
185
186 ++nifs;
187 }
188 }
189 }
190
191 idx[nifs].if_index = 0;
192 idx[nifs].if_name = NULL;
193
194 exit_free:
195 __netlink_free_handle (&nh);
196 __netlink_close (&nh);
197
198 return idx;
199}
200
201
202struct if_nameindex *
203__if_nameindex (void)
204{
205#ifndef SIOCGIFINDEX
206 __set_errno (ENOSYS);
207 return NULL;
208#else
209 struct if_nameindex *result = if_nameindex_netlink ();
210 return result;
211#endif
212}
213weak_alias (__if_nameindex, if_nameindex)
214libc_hidden_weak (if_nameindex)
215
216
217char *
218__if_indextoname (unsigned int ifindex, char ifname[IF_NAMESIZE])
219{
220 /* We may be able to do the conversion directly, rather than searching a
221 list. This ioctl is not present in kernels before version 2.1.50. */
222 struct ifreq ifr;
223 int fd;
224 int status;
225
226 fd = __opensock ();
227
228 if (fd < 0)
229 return NULL;
230
231 ifr.ifr_ifindex = ifindex;
232 status = __ioctl (fd, SIOCGIFNAME, &ifr);
233
234 __close_nocancel_nostatus (fd);
235
236 if (status < 0)
237 {
238 if (errno == ENODEV)
239 /* POSIX requires ENXIO. */
240 __set_errno (ENXIO);
241
242 return NULL;
243 }
244 else
245 return strncpy (ifname, ifr.ifr_name, IFNAMSIZ);
246}
247weak_alias (__if_indextoname, if_indextoname)
248libc_hidden_weak (if_indextoname)
249