1 /*
2 * Copyright (c) 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 <errno.h>
30 #include <fcntl.h>
31 #include <stdio.h>
32 #include <stdint.h>
33 #include <unistd.h>
34 #include <sys/socket.h>
35 #include <netinet/in.h>
36 #include <arpa/inet.h>
37
38 static void
print_pktinfo(const struct cmsghdr * c)39 print_pktinfo(const struct cmsghdr *c)
40 {
41 printf("IP_PKTINFO, {ipi_ifindex=if_nametoindex(\"lo\")"
42 ", ipi_spec_dst=inet_addr(\"127.0.0.1\")"
43 ", ipi_addr=inet_addr(\"127.0.0.1\")}");
44 }
45
46 static void
print_ttl(const struct cmsghdr * c)47 print_ttl(const struct cmsghdr *c)
48 {
49 const unsigned int *ttl = (const unsigned int *) CMSG_DATA(c);
50
51 printf("IP_TTL, {ttl=%u}", *ttl);
52 }
53
54 static void
print_tos(const struct cmsghdr * c)55 print_tos(const struct cmsghdr *c)
56 {
57 const uint8_t *tos = (const uint8_t *) CMSG_DATA(c);
58
59 printf("IP_TOS, {tos=%x}", *tos);
60 }
61
62 static void
print_opts(const char * name,const struct cmsghdr * c)63 print_opts(const char *name, const struct cmsghdr *c)
64 {
65 const unsigned char *opts = (const unsigned char *) CMSG_DATA(c);
66 const size_t len = c->cmsg_len - CMSG_ALIGN(sizeof(*c));
67
68 printf("%s", name);
69 if (len) {
70 printf(", {opts=0x");
71 size_t i;
72 for (i = 0; i < len; ++i)
73 printf("%02x", opts[i]);
74 printf("}");
75 }
76 }
77
78 static void
print_origdstaddr(const struct cmsghdr * c)79 print_origdstaddr(const struct cmsghdr *c)
80 {
81 const struct sockaddr_in *sin =
82 (const struct sockaddr_in *) CMSG_DATA(c);
83
84 printf("IP_ORIGDSTADDR, {sa_family=AF_INET, sin_port=htons(%u)"
85 ", sin_addr=inet_addr(\"127.0.0.1\")}", ntohs(sin->sin_port));
86 }
87
88 int
main(void)89 main(void)
90 {
91 int i;
92 while ((i = open("/dev/null", O_RDWR)) < 3)
93 assert(i >= 0);
94 assert(!close(0));
95 assert(!close(3));
96
97 if (socket(PF_INET, SOCK_DGRAM, 0)) {
98 perror("socket");
99 return 77;
100 }
101 struct sockaddr_in addr = {
102 .sin_family = AF_INET,
103 .sin_addr.s_addr = htonl(INADDR_LOOPBACK)
104 };
105 socklen_t len = sizeof(addr);
106 if (bind(0, (struct sockaddr *) &addr, len)) {
107 perror("bind");
108 return 77;
109 }
110 assert(!getsockname(0, (struct sockaddr *) &addr, &len));
111
112 assert(socket(PF_INET, SOCK_DGRAM, 0) == 3);
113 assert(!connect(3, (struct sockaddr *) &addr, len));
114
115 const int opt_1 = htonl(0x01000000);
116 #define SETSOCKOPT(fd, name) assert(!setsockopt(fd, IPPROTO_IP, (name), &opt_1, sizeof(opt_1)))
117 SETSOCKOPT(3, IP_OPTIONS);
118 SETSOCKOPT(0, IP_PKTINFO);
119 SETSOCKOPT(0, IP_RECVTTL);
120 SETSOCKOPT(0, IP_RECVTOS);
121 SETSOCKOPT(0, IP_RECVOPTS);
122 SETSOCKOPT(0, IP_RETOPTS);
123 #ifdef IP_RECVORIGDSTADDR
124 SETSOCKOPT(0, IP_RECVORIGDSTADDR);
125 #endif
126
127 static const char data[] = "data";
128 const size_t size = sizeof(data) - 1;
129 assert(send(3, data, size, 0) == (int) size);
130 assert(!close(3));
131
132 char buf[size];
133 struct iovec iov = {
134 .iov_base = buf,
135 .iov_len = sizeof(buf)
136 };
137 struct cmsghdr control[16];
138 struct msghdr mh = {
139 .msg_name = &addr,
140 .msg_namelen = len,
141 .msg_iov = &iov,
142 .msg_iovlen = 1,
143 .msg_control = control,
144 .msg_controllen = sizeof(control)
145 };
146
147 assert(recvmsg(0, &mh, 0) == (int) size);
148 assert(!close(0));
149
150 printf("recvmsg(0, {msg_name(%u)={sa_family=AF_INET, sin_port=htons(%u)"
151 ", sin_addr=inet_addr(\"127.0.0.1\")}, msg_iov(1)=[{\"%s\", %zu}]"
152 ", msg_controllen=%zu, [",
153 (unsigned) mh.msg_namelen, ntohs(addr.sin_port),
154 data, size, mh.msg_controllen);
155
156 struct cmsghdr *c;
157 for (c = CMSG_FIRSTHDR(&mh); c; c = CMSG_NXTHDR(&mh, c)) {
158 if (IPPROTO_IP != c->cmsg_level)
159 continue;
160 if (c != control)
161 printf(", ");
162 printf("{cmsg_len=%zu, cmsg_level=SOL_IP, cmsg_type=",
163 c->cmsg_len);
164 switch (c->cmsg_type) {
165 case IP_PKTINFO:
166 print_pktinfo(c);
167 break;
168 case IP_TTL:
169 print_ttl(c);
170 break;
171 case IP_TOS:
172 print_tos(c);
173 break;
174 case IP_RECVOPTS:
175 print_opts("IP_RECVOPTS", c);
176 break;
177 case IP_RETOPTS:
178 print_opts("IP_RETOPTS", c);
179 break;
180 #ifdef IP_ORIGDSTADDR
181 case IP_ORIGDSTADDR:
182 print_origdstaddr(c);
183 break;
184 #endif
185 default:
186 printf("%d", c->cmsg_type);
187 break;
188 }
189 printf("}");
190 }
191 printf("], msg_flags=0}, 0) = %zu\n", size);
192 puts("+++ exited with 0 +++");
193
194 return 0;
195 }
196