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