1 #include <sys/types.h>
2 #include <sys/socket.h>
3
4 #include <arpa/inet.h>
5 #include <netinet/in.h>
6
7 #include <err.h>
8 #include <stdint.h>
9 #include <stdio.h>
10 #include <stdlib.h>
11 #include <string.h>
12 #include <unistd.h>
13
14 static void
usage(const char * cmd)15 usage(const char *cmd)
16 {
17 fprintf(stderr, "%s -m addr -p port -i addr "
18 "-r remote_ip4 -P remote_port\n", cmd);
19 exit(1);
20 }
21
22 static int
create_sock(const struct sockaddr_in * in,const struct in_addr * iface)23 create_sock(const struct sockaddr_in *in, const struct in_addr *iface)
24 {
25 struct ip_mreq mreq;
26 int s, on;
27
28 s = socket(AF_INET, SOCK_DGRAM, 0);
29 if (s < 0)
30 err(2, "socket failed");
31
32 on = 1;
33 if (setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &on, sizeof(on)) < 0)
34 err(2, "setsockopt SO_REUSEPORT failed");
35
36 if (bind(s, (const struct sockaddr *)in, sizeof(*in)) < 0)
37 err(2, "bind failed");
38
39 memset(&mreq, 0, sizeof(mreq));
40 mreq.imr_multiaddr = in->sin_addr;
41 mreq.imr_interface = *iface;
42 if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
43 &mreq, sizeof(mreq)) < 0)
44 err(2, "setsockopt IP_ADD_MEMBERSHIP failed");
45
46 return s;
47 }
48
49 int
main(int argc,char * argv[])50 main(int argc, char *argv[])
51 {
52 struct sockaddr_in in, remote_in;
53 struct in_addr iface;
54 int s1, s2, opt, n;
55 uint8_t buf[18];
56
57 memset(&in, 0, sizeof(in));
58 in.sin_family = AF_INET;
59
60 memset(&remote_in, 0, sizeof(remote_in));
61 remote_in.sin_family = AF_INET;
62
63 memset(&iface, 0, sizeof(iface));
64
65 while ((opt = getopt(argc, argv, "P:i:m:p:r:")) != -1) {
66 switch (opt) {
67 case 'P':
68 remote_in.sin_port = strtol(optarg, NULL, 10);
69 remote_in.sin_port = htons(remote_in.sin_port);
70 break;
71
72 case 'i':
73 if (inet_pton(AF_INET, optarg, &iface) <= 0)
74 usage(argv[0]);
75 break;
76
77 case 'm':
78 if (inet_pton(AF_INET, optarg, &in.sin_addr) <= 0)
79 usage(argv[0]);
80 break;
81
82 case 'p':
83 in.sin_port = strtol(optarg, NULL, 10);
84 in.sin_port = htons(in.sin_port);
85 break;
86
87 case 'r':
88 if (inet_pton(AF_INET, optarg,
89 &remote_in.sin_addr) <= 0)
90 usage(argv[0]);
91 break;
92
93 default:
94 usage(argv[0]);
95 }
96 }
97
98 if (in.sin_addr.s_addr == INADDR_ANY || in.sin_port == 0 ||
99 iface.s_addr == INADDR_ANY ||
100 remote_in.sin_addr.s_addr == INADDR_ANY ||
101 remote_in.sin_port == 0)
102 usage(argv[0]);
103
104 s1 = create_sock(&in, &iface);
105 s2 = create_sock(&in, &iface);
106
107 if (connect(s2, (const struct sockaddr *)&remote_in,
108 sizeof(remote_in)) < 0)
109 err(2, "connect failed");
110
111 n = read(s1, buf, sizeof(buf));
112 if (n < 0)
113 err(2, "read 1 failed");
114 fprintf(stderr, "read 1 got %d\n", n);
115
116 n = read(s2, buf, sizeof(buf));
117 if (n < 0)
118 err(2, "read 2 failed");
119 fprintf(stderr, "read 2 got %d\n", n);
120
121 exit(0);
122 }
123