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773e79b3 | 1 | /* Determine whether interfaces use native transport. Linux version. |
d614a753 | 2 | Copyright (C) 2007-2020 Free Software Foundation, Inc. |
773e79b3 UD |
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 | |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
773e79b3 UD |
18 | |
19 | #include <assert.h> | |
20 | #include <errno.h> | |
21 | #include <ifaddrs.h> | |
22 | #include <stddef.h> | |
23 | #include <stdint.h> | |
24 | #include <stdlib.h> | |
c71ca1f8 | 25 | #include <string.h> |
773e79b3 UD |
26 | #include <time.h> |
27 | #include <unistd.h> | |
28 | #include <net/if.h> | |
29 | #include <net/if_arp.h> | |
30 | #include <sys/ioctl.h> | |
31 | ||
715db78b | 32 | #include <asm/types.h> |
773e79b3 UD |
33 | #include <linux/netlink.h> |
34 | #include <linux/rtnetlink.h> | |
35 | ||
36 | #include <not-cancel.h> | |
37 | ||
2eecc8af | 38 | #include "netlinkaccess.h" |
773e79b3 UD |
39 | |
40 | void | |
41 | __check_native (uint32_t a1_index, int *a1_native, | |
42 | uint32_t a2_index, int *a2_native) | |
43 | { | |
2f83a729 | 44 | int fd = __socket (PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE); |
773e79b3 UD |
45 | |
46 | struct sockaddr_nl nladdr; | |
47 | memset (&nladdr, '\0', sizeof (nladdr)); | |
48 | nladdr.nl_family = AF_NETLINK; | |
49 | ||
50 | socklen_t addr_len = sizeof (nladdr); | |
51 | ||
52 | if (fd < 0 | |
53 | || __bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) != 0 | |
54 | || __getsockname (fd, (struct sockaddr *) &nladdr, &addr_len) != 0) | |
55 | return; | |
56 | ||
57 | pid_t pid = nladdr.nl_pid; | |
58 | struct req | |
59 | { | |
60 | struct nlmsghdr nlh; | |
61 | struct rtgenmsg g; | |
62 | /* struct rtgenmsg consists of a single byte. This means there | |
63 | are three bytes of padding included in the REQ definition. | |
64 | We make them explicit here. */ | |
65 | char pad[3]; | |
66 | } req; | |
67 | ||
68 | req.nlh.nlmsg_len = sizeof (req); | |
69 | req.nlh.nlmsg_type = RTM_GETLINK; | |
70 | req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST; | |
71 | req.nlh.nlmsg_pid = 0; | |
f9a75540 | 72 | req.nlh.nlmsg_seq = time_now (); |
773e79b3 UD |
73 | req.g.rtgen_family = AF_UNSPEC; |
74 | ||
75 | assert (sizeof (req) - offsetof (struct req, pad) == 3); | |
76 | memset (req.pad, '\0', sizeof (req.pad)); | |
77 | ||
78 | memset (&nladdr, '\0', sizeof (nladdr)); | |
79 | nladdr.nl_family = AF_NETLINK; | |
80 | ||
81 | #ifdef PAGE_SIZE | |
82 | /* Help the compiler optimize out the malloc call if PAGE_SIZE | |
83 | is constant and smaller or equal to PTHREAD_STACK_MIN/4. */ | |
84 | const size_t buf_size = PAGE_SIZE; | |
85 | #else | |
86 | const size_t buf_size = __getpagesize (); | |
87 | #endif | |
88 | bool use_malloc = false; | |
89 | char *buf; | |
90 | ||
91 | if (__libc_use_alloca (buf_size)) | |
92 | buf = alloca (buf_size); | |
93 | else | |
94 | { | |
95 | buf = malloc (buf_size); | |
96 | if (buf != NULL) | |
97 | use_malloc = true; | |
98 | else | |
99 | goto out_fail; | |
100 | } | |
101 | ||
102 | struct iovec iov = { buf, buf_size }; | |
103 | ||
104 | if (TEMP_FAILURE_RETRY (__sendto (fd, (void *) &req, sizeof (req), 0, | |
105 | (struct sockaddr *) &nladdr, | |
106 | sizeof (nladdr))) < 0) | |
107 | goto out_fail; | |
108 | ||
109 | bool done = false; | |
773e79b3 UD |
110 | do |
111 | { | |
112 | struct msghdr msg = | |
113 | { | |
af7f7c7e AZ |
114 | .msg_name = (void *) &nladdr, |
115 | .msg_namelen = sizeof (nladdr), | |
116 | .msg_iov = &iov, | |
117 | .msg_iovlen = 1, | |
118 | .msg_control = NULL, | |
119 | .msg_controllen = 0, | |
120 | .msg_flags = 0 | |
773e79b3 UD |
121 | }; |
122 | ||
123 | ssize_t read_len = TEMP_FAILURE_RETRY (__recvmsg (fd, &msg, 0)); | |
2eecc8af | 124 | __netlink_assert_response (fd, read_len); |
773e79b3 UD |
125 | if (read_len < 0) |
126 | goto out_fail; | |
127 | ||
128 | if (msg.msg_flags & MSG_TRUNC) | |
129 | goto out_fail; | |
130 | ||
131 | struct nlmsghdr *nlmh; | |
132 | for (nlmh = (struct nlmsghdr *) buf; | |
133 | NLMSG_OK (nlmh, (size_t) read_len); | |
134 | nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, read_len)) | |
135 | { | |
136 | if (nladdr.nl_pid != 0 || (pid_t) nlmh->nlmsg_pid != pid | |
137 | || nlmh->nlmsg_seq != req.nlh.nlmsg_seq) | |
138 | continue; | |
139 | ||
140 | if (nlmh->nlmsg_type == RTM_NEWLINK) | |
141 | { | |
773e79b3 | 142 | struct ifinfomsg *ifim = (struct ifinfomsg *) NLMSG_DATA (nlmh); |
1e2692c9 UD |
143 | int native = (ifim->ifi_type != ARPHRD_TUNNEL6 |
144 | && ifim->ifi_type != ARPHRD_TUNNEL | |
145 | && ifim->ifi_type != ARPHRD_SIT); | |
146 | ||
147 | if (a1_index == ifim->ifi_index) | |
148 | { | |
149 | *a1_native = native; | |
150 | a1_index = 0xffffffffu; | |
151 | } | |
152 | if (a2_index == ifim->ifi_index) | |
153 | { | |
154 | *a2_native = native; | |
155 | a2_index = 0xffffffffu; | |
156 | } | |
157 | ||
158 | if (a1_index == 0xffffffffu | |
159 | && a2_index == 0xffffffffu) | |
160 | goto out; | |
773e79b3 UD |
161 | } |
162 | else if (nlmh->nlmsg_type == NLMSG_DONE) | |
163 | /* We found the end, leave the loop. */ | |
164 | done = true; | |
165 | } | |
166 | } | |
167 | while (! done); | |
168 | ||
169 | out: | |
c181840c | 170 | __close_nocancel_nostatus (fd); |
773e79b3 UD |
171 | |
172 | return; | |
173 | ||
174 | out_fail: | |
175 | if (use_malloc) | |
176 | free (buf); | |
177 | } |