1 /*
2 * Copyright (c) 2014-2015 Dmitry V. Levin <ldv@altlinux.org>
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 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include <assert.h>
29 #include <string.h>
30 #include <unistd.h>
31 #include <netinet/in.h>
32 #include <linux/netlink.h>
33 #include <linux/sock_diag.h>
34 #include <linux/inet_diag.h>
35
36 static int
send_query(const int fd,const int family,const int proto)37 send_query(const int fd, const int family, const int proto)
38 {
39 struct sockaddr_nl nladdr = {
40 .nl_family = AF_NETLINK
41 };
42 struct {
43 struct nlmsghdr nlh;
44 struct inet_diag_req_v2 idr;
45 } req = {
46 .nlh = {
47 .nlmsg_len = sizeof(req),
48 .nlmsg_type = SOCK_DIAG_BY_FAMILY,
49 .nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST
50 },
51 .idr = {
52 .sdiag_family = family,
53 .sdiag_protocol = proto,
54 .idiag_states = -1
55 }
56 };
57 struct iovec iov = {
58 .iov_base = &req,
59 .iov_len = sizeof(req)
60 };
61 struct msghdr msg = {
62 .msg_name = (void*)&nladdr,
63 .msg_namelen = sizeof(nladdr),
64 .msg_iov = &iov,
65 .msg_iovlen = 1
66 };
67
68 return sendmsg(fd, &msg, 0) > 0;
69 }
70
71 static int
check_responses(const int fd)72 check_responses(const int fd)
73 {
74 static char buf[8192];
75 struct sockaddr_nl nladdr = {
76 .nl_family = AF_NETLINK
77 };
78 struct iovec iov = {
79 .iov_base = buf,
80 .iov_len = sizeof(buf)
81 };
82 struct msghdr msg = {
83 .msg_name = (void*)&nladdr,
84 .msg_namelen = sizeof(nladdr),
85 .msg_iov = &iov,
86 .msg_iovlen = 1
87 };
88
89 ssize_t ret = recvmsg(fd, &msg, 0);
90 if (ret <= 0)
91 return 0;
92
93 struct nlmsghdr *h = (struct nlmsghdr*)buf;
94 return (NLMSG_OK(h, ret) &&
95 h->nlmsg_type != NLMSG_ERROR &&
96 h->nlmsg_type != NLMSG_DONE) ? 1 : 0;
97 }
98
main(void)99 int main(void)
100 {
101 struct sockaddr_in addr;
102 socklen_t len = sizeof(addr);
103
104 memset(&addr, 0, sizeof(addr));
105 addr.sin_family = AF_INET;
106 addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
107
108 close(0);
109 close(1);
110
111 if (socket(PF_INET, SOCK_STREAM, 0) ||
112 bind(0, (struct sockaddr *) &addr, len) ||
113 listen(0, 5) ||
114 socket(AF_NETLINK, SOCK_RAW, NETLINK_INET_DIAG) != 1)
115 return 77;
116
117 return (send_query(1, AF_INET, IPPROTO_TCP) &&
118 check_responses(1)) ? 0 : 77;
119 }
120