1 | /* Determine protocol families for which interfaces exist. Linux version. |
---|
2 | Copyright (C) 2003 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, write to the Free |
---|
17 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
---|
18 | 02111-1307 USA. */ |
---|
19 | |
---|
20 | #include <errno.h> |
---|
21 | #include <stdint.h> |
---|
22 | #include <ifaddrs.h> |
---|
23 | #include <netdb.h> |
---|
24 | #include <string.h> |
---|
25 | #include <time.h> |
---|
26 | #include <unistd.h> |
---|
27 | #include <sys/socket.h> |
---|
28 | |
---|
29 | #include <asm/types.h> |
---|
30 | #include <linux/netlink.h> |
---|
31 | #include <linux/rtnetlink.h> |
---|
32 | |
---|
33 | #include <stdbool.h> |
---|
34 | #include <sys/uio.h> |
---|
35 | |
---|
36 | #include "config.h" |
---|
37 | #include "local.h" |
---|
38 | |
---|
39 | #define __ASSUME_NETLINK_SUPPORT 1 |
---|
40 | |
---|
41 | static int |
---|
42 | make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6) |
---|
43 | { |
---|
44 | struct |
---|
45 | { |
---|
46 | struct nlmsghdr nlh; |
---|
47 | struct rtgenmsg g; |
---|
48 | } req; |
---|
49 | struct sockaddr_nl nladdr; |
---|
50 | |
---|
51 | req.nlh.nlmsg_len = sizeof (req); |
---|
52 | req.nlh.nlmsg_type = RTM_GETADDR; |
---|
53 | req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST; |
---|
54 | req.nlh.nlmsg_pid = 0; |
---|
55 | req.nlh.nlmsg_seq = time (NULL); |
---|
56 | req.g.rtgen_family = AF_UNSPEC; |
---|
57 | |
---|
58 | memset (&nladdr, '\0', sizeof (nladdr)); |
---|
59 | nladdr.nl_family = AF_NETLINK; |
---|
60 | |
---|
61 | if (TEMP_FAILURE_RETRY (sendto (fd, (void *) &req, sizeof (req), 0, |
---|
62 | (struct sockaddr *) &nladdr, |
---|
63 | sizeof (nladdr))) < 0) |
---|
64 | return -1; |
---|
65 | |
---|
66 | *seen_ipv4 = false; |
---|
67 | *seen_ipv6 = false; |
---|
68 | |
---|
69 | bool done = false; |
---|
70 | char buf[4096]; |
---|
71 | struct iovec iov = { buf, sizeof (buf) }; |
---|
72 | |
---|
73 | do |
---|
74 | { |
---|
75 | struct msghdr msg = |
---|
76 | { |
---|
77 | (void *) &nladdr, sizeof (nladdr), |
---|
78 | &iov, 1, |
---|
79 | NULL, 0, |
---|
80 | 0 |
---|
81 | }; |
---|
82 | |
---|
83 | ssize_t read_len = TEMP_FAILURE_RETRY (recvmsg (fd, &msg, 0)); |
---|
84 | if (read_len < 0) |
---|
85 | return -1; |
---|
86 | |
---|
87 | if (msg.msg_flags & MSG_TRUNC) |
---|
88 | return -1; |
---|
89 | |
---|
90 | struct nlmsghdr *nlmh; |
---|
91 | for (nlmh = (struct nlmsghdr *) buf; |
---|
92 | NLMSG_OK (nlmh, (size_t) read_len); |
---|
93 | nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, read_len)) |
---|
94 | { |
---|
95 | if (nladdr.nl_pid != 0 || (pid_t) nlmh->nlmsg_pid != pid |
---|
96 | || nlmh->nlmsg_seq != req.nlh.nlmsg_seq) |
---|
97 | continue; |
---|
98 | |
---|
99 | if (nlmh->nlmsg_type == RTM_NEWADDR) |
---|
100 | { |
---|
101 | struct ifaddrmsg *ifam = (struct ifaddrmsg *) NLMSG_DATA (nlmh); |
---|
102 | |
---|
103 | switch (ifam->ifa_family) |
---|
104 | { |
---|
105 | case AF_INET: |
---|
106 | *seen_ipv4 = true; |
---|
107 | break; |
---|
108 | case AF_INET6: |
---|
109 | *seen_ipv6 = true; |
---|
110 | break; |
---|
111 | default: |
---|
112 | /* Ignore. */ |
---|
113 | break; |
---|
114 | } |
---|
115 | } |
---|
116 | else if (nlmh->nlmsg_type == NLMSG_DONE) |
---|
117 | /* We found the end, leave the loop. */ |
---|
118 | done = true; |
---|
119 | else ; |
---|
120 | } |
---|
121 | } |
---|
122 | while (! done); |
---|
123 | |
---|
124 | close (fd); |
---|
125 | |
---|
126 | return 0; |
---|
127 | } |
---|
128 | |
---|
129 | |
---|
130 | /* We don't know if we have NETLINK support compiled in in our |
---|
131 | Kernel. */ |
---|
132 | #if __ASSUME_NETLINK_SUPPORT == 0 |
---|
133 | /* Define in ifaddrs.h. */ |
---|
134 | extern int __no_netlink_support attribute_hidden; |
---|
135 | #else |
---|
136 | # define __no_netlink_support 0 |
---|
137 | #endif |
---|
138 | |
---|
139 | |
---|
140 | void |
---|
141 | attribute_hidden |
---|
142 | __check_pf (bool *seen_ipv4, bool *seen_ipv6) |
---|
143 | { |
---|
144 | if (! __no_netlink_support) |
---|
145 | { |
---|
146 | int fd = socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE); |
---|
147 | |
---|
148 | struct sockaddr_nl nladdr; |
---|
149 | memset (&nladdr, '\0', sizeof (nladdr)); |
---|
150 | nladdr.nl_family = AF_NETLINK; |
---|
151 | |
---|
152 | socklen_t addr_len = sizeof (nladdr); |
---|
153 | |
---|
154 | if (fd >= 0 |
---|
155 | && bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) == 0 |
---|
156 | && getsockname (fd, (struct sockaddr *) &nladdr, &addr_len) == 0 |
---|
157 | && make_request (fd, nladdr.nl_pid, seen_ipv4, seen_ipv6) == 0) |
---|
158 | /* It worked. */ |
---|
159 | return; |
---|
160 | |
---|
161 | if (fd >= 0) |
---|
162 | close (fd); |
---|
163 | |
---|
164 | #if __ASSUME_NETLINK_SUPPORT == 0 |
---|
165 | /* Remember that there is no netlink support. */ |
---|
166 | __no_netlink_support = 1; |
---|
167 | #else |
---|
168 | /* We cannot determine what interfaces are available. Be |
---|
169 | pessimistic. */ |
---|
170 | *seen_ipv4 = true; |
---|
171 | *seen_ipv6 = true; |
---|
172 | #endif |
---|
173 | } |
---|
174 | |
---|
175 | #if __ASSUME_NETLINK_SUPPORT == 0 |
---|
176 | /* No netlink. Get the interface list via getifaddrs. */ |
---|
177 | struct ifaddrs *ifa = NULL; |
---|
178 | if (getifaddrs (&ifa) != 0) |
---|
179 | { |
---|
180 | /* We cannot determine what interfaces are available. Be |
---|
181 | pessimistic. */ |
---|
182 | *seen_ipv4 = true; |
---|
183 | *seen_ipv6 = true; |
---|
184 | return; |
---|
185 | } |
---|
186 | |
---|
187 | *seen_ipv4 = false; |
---|
188 | *seen_ipv6 = false; |
---|
189 | |
---|
190 | struct ifaddrs *runp; |
---|
191 | for (runp = ifa; runp != NULL; runp = runp->ifa_next) |
---|
192 | if (runp->ifa_addr->sa_family == PF_INET) |
---|
193 | *seen_ipv4 = true; |
---|
194 | else if (runp->ifa_addr->sa_family == PF_INET6) |
---|
195 | *seen_ipv6 = true; |
---|
196 | |
---|
197 | (void) freeifaddrs (ifa); |
---|
198 | #endif |
---|
199 | } |
---|