1 #include <sys/types.h>
2 #include <sys/socket.h>
3
4 #include <arpa/inet.h>
5 #include <net/if.h>
6 #include <netinet/in.h>
7
8 #include <err.h>
9 #include <stdint.h>
10 #include <stdio.h>
11 #include <stdlib.h>
12 #include <string.h>
13 #include <unistd.h>
14
15 static void
usage(const char * cmd)16 usage(const char *cmd)
17 {
18 fprintf(stderr, "%s -m addr -p port (-i addr | -I iface) [-a]\n", cmd);
19 exit(1);
20 }
21
22 static int
create_sock(const struct sockaddr_in * in0,const struct in_addr * iface,int iface_idx,int bind_any)23 create_sock(const struct sockaddr_in *in0, const struct in_addr *iface,
24 int iface_idx, int bind_any)
25 {
26 struct sockaddr_in in;
27 int s, on;
28
29 s = socket(AF_INET, SOCK_DGRAM, 0);
30 if (s < 0)
31 err(2, "socket failed");
32
33 on = 1;
34 if (setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &on, sizeof(on)) < 0)
35 err(2, "setsockopt SO_REUSEPORT failed");
36
37 in = *in0;
38 if (bind_any)
39 in.sin_addr.s_addr = htonl(INADDR_ANY);
40
41 if (bind(s, (const struct sockaddr *)&in, sizeof(in)) < 0)
42 err(2, "bind failed");
43
44 if (iface_idx < 0) {
45 struct ip_mreq mreq;
46
47 fprintf(stderr, "ip_mreq add_member\n");
48 memset(&mreq, 0, sizeof(mreq));
49 mreq.imr_multiaddr = in0->sin_addr;
50 mreq.imr_interface = *iface;
51 if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
52 &mreq, sizeof(mreq)) < 0)
53 err(2, "setsockopt IP_ADD_MEMBERSHIP ip_mreq failed");
54 } else {
55 struct ip_mreqn mreqn;
56
57 fprintf(stderr, "ip_mreqn add_member, ifindex %d\n", iface_idx);
58 memset(&mreqn, 0, sizeof(mreqn));
59 mreqn.imr_multiaddr = in0->sin_addr;
60 mreqn.imr_address = *iface;
61 mreqn.imr_ifindex = iface_idx;
62 if (setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
63 &mreqn, sizeof(mreqn)) < 0)
64 err(2, "setsockopt IP_ADD_MEMBERSHIP ip_mreqn failed");
65 }
66
67 return s;
68 }
69
70 int
main(int argc,char * argv[])71 main(int argc, char *argv[])
72 {
73 struct sockaddr_in in;
74 struct in_addr iface;
75 int s1, s2, opt, n, bind_any, iface_idx;
76 uint8_t buf[18];
77
78 memset(&in, 0, sizeof(in));
79 in.sin_family = AF_INET;
80
81 memset(&iface, 0, sizeof(iface));
82 bind_any = 0;
83 iface_idx = -1;
84
85 while ((opt = getopt(argc, argv, "I:ai:m:p:")) != -1) {
86 switch (opt) {
87 case 'I':
88 iface_idx = if_nametoindex(optarg);
89 break;
90
91 case 'a':
92 bind_any = 1;
93 break;
94
95 case 'i':
96 if (inet_pton(AF_INET, optarg, &iface) <= 0)
97 usage(argv[0]);
98 break;
99
100 case 'm':
101 if (inet_pton(AF_INET, optarg, &in.sin_addr) <= 0)
102 usage(argv[0]);
103 break;
104
105 case 'p':
106 in.sin_port = strtol(optarg, NULL, 10);
107 in.sin_port = htons(in.sin_port);
108 break;
109
110 default:
111 usage(argv[0]);
112 }
113 }
114
115 if (in.sin_addr.s_addr == INADDR_ANY || in.sin_port == 0 ||
116 (iface.s_addr == INADDR_ANY && iface_idx < 0))
117 usage(argv[0]);
118
119 s1 = create_sock(&in, &iface, iface_idx, bind_any);
120 s2 = create_sock(&in, &iface, iface_idx, bind_any);
121
122 n = read(s1, buf, sizeof(buf));
123 if (n < 0)
124 err(2, "read 1 failed");
125 fprintf(stderr, "read 1 got %d\n", n);
126
127 n = read(s2, buf, sizeof(buf));
128 if (n < 0)
129 err(2, "read 2 failed");
130 fprintf(stderr, "read 2 got %d\n", n);
131
132 exit(0);
133 }
134