1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <net/if.h>
30
31 #include <errno.h>
32 #include <ifaddrs.h>
33 #include <linux/if_packet.h>
34 #include <linux/netlink.h>
35 #include <linux/rtnetlink.h>
36 #include <linux/sockios.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <sys/ioctl.h>
40 #include <sys/socket.h>
41 #include <unistd.h>
42
43 #include "private/ErrnoRestorer.h"
44
45 #include "bionic_netlink.h"
46
if_indextoname(unsigned ifindex,char * ifname)47 char* if_indextoname(unsigned ifindex, char* ifname) {
48 int s = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0);
49 if (s == -1) return nullptr;
50
51 struct ifreq ifr;
52 memset(&ifr, 0, sizeof(ifr));
53 ifr.ifr_ifindex = ifindex;
54
55 int rc = ioctl(s, SIOCGIFNAME, &ifr);
56 ErrnoRestorer errno_restorer;
57 close(s);
58 return (rc == -1) ? nullptr : strncpy(ifname, ifr.ifr_name, IFNAMSIZ);
59 }
60
if_nametoindex(const char * ifname)61 unsigned if_nametoindex(const char* ifname) {
62 int s = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0);
63 if (s == -1) return 0;
64
65 struct ifreq ifr;
66 memset(&ifr, 0, sizeof(ifr));
67 strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
68 ifr.ifr_name[IFNAMSIZ - 1] = 0;
69
70 int rc = ioctl(s, SIOCGIFINDEX, &ifr);
71 ErrnoRestorer errno_restorer;
72 close(s);
73 return (rc == -1) ? 0 : ifr.ifr_ifindex;
74 }
75
76 struct if_list {
77 if_list* next;
78 struct if_nameindex data;
79
if_listif_list80 explicit if_list(if_list** list) {
81 // push_front onto `list`.
82 next = *list;
83 *list = this;
84 }
85
Freeif_list86 static void Free(if_list* list, bool names_too) {
87 while (list) {
88 if_list* it = list;
89 list = it->next;
90 if (names_too) free(it->data.if_name);
91 free(it);
92 }
93 }
94 };
95
__if_nameindex_callback(void * context,nlmsghdr * hdr)96 static void __if_nameindex_callback(void* context, nlmsghdr* hdr) {
97 if_list** list = reinterpret_cast<if_list**>(context);
98 if (hdr->nlmsg_type == RTM_NEWLINK) {
99 ifinfomsg* ifi = reinterpret_cast<ifinfomsg*>(NLMSG_DATA(hdr));
100
101 // Create a new entry and set the interface index.
102 if_list* new_link = new if_list(list);
103 new_link->data.if_index = ifi->ifi_index;
104
105 // Go through the various bits of information and find the name.
106 rtattr* rta = IFLA_RTA(ifi);
107 size_t rta_len = IFLA_PAYLOAD(hdr);
108 while (RTA_OK(rta, rta_len)) {
109 if (rta->rta_type == IFLA_IFNAME) {
110 new_link->data.if_name = strndup(reinterpret_cast<char*>(RTA_DATA(rta)), RTA_PAYLOAD(rta));
111 }
112 rta = RTA_NEXT(rta, rta_len);
113 }
114 }
115 }
116
if_nameindex()117 struct if_nameindex* if_nameindex() {
118 if_list* list = nullptr;
119
120 // Open the netlink socket and ask for all the links;
121 NetlinkConnection nc;
122 bool okay = nc.SendRequest(RTM_GETLINK) && nc.ReadResponses(__if_nameindex_callback, &list);
123 if (!okay) {
124 if_list::Free(list, true);
125 return nullptr;
126 }
127
128 // Count the interfaces.
129 size_t interface_count = 0;
130 for (if_list* it = list; it != nullptr; it = it->next) {
131 ++interface_count;
132 }
133
134 // Build the array POSIX requires us to return.
135 struct if_nameindex* result = new struct if_nameindex[interface_count + 1];
136 if (result) {
137 struct if_nameindex* out = result;
138 for (if_list* it = list; it != nullptr; it = it->next) {
139 out->if_index = it->data.if_index;
140 out->if_name = it->data.if_name;
141 ++out;
142 }
143 out->if_index = 0;
144 out->if_name = nullptr;
145 }
146
147 // Free temporary storage.
148 if_list::Free(list, false);
149
150 return result;
151 }
152
if_freenameindex(struct if_nameindex * array)153 void if_freenameindex(struct if_nameindex* array) {
154 if (array == nullptr) return;
155
156 struct if_nameindex* ptr = array;
157 while (ptr->if_index != 0 || ptr->if_name != nullptr) {
158 free(ptr->if_name);
159 ++ptr;
160 }
161
162 delete[] array;
163 }
164