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 <stdio.h>
9 #include <stdint.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 -4 ip4 -p port [-b ip4] -P bind_port [-r]\n", cmd);
18 exit(1);
19 }
20
21 int
main(int argc,char * argv[])22 main(int argc, char *argv[])
23 {
24 struct sockaddr_in in, local_in;
25 int s, opt, n, reuseport;
26 uint8_t buf[18];
27
28 memset(&in, 0, sizeof(in));
29 in.sin_family = AF_INET;
30
31 memset(&local_in, 0, sizeof(local_in));
32 local_in.sin_family = AF_INET;
33
34 reuseport = 0;
35
36 while ((opt = getopt(argc, argv, "4:P:b:p:r")) != -1) {
37 switch (opt) {
38 case '4':
39 if (inet_pton(AF_INET, optarg, &in.sin_addr) <= 0)
40 usage(argv[0]);
41 break;
42
43 case 'P':
44 local_in.sin_port = strtol(optarg, NULL, 10);
45 local_in.sin_port = htons(local_in.sin_port);
46 break;
47
48 case 'b':
49 if (inet_pton(AF_INET, optarg, &local_in.sin_addr) <= 0)
50 usage(argv[0]);
51 break;
52
53 case 'p':
54 in.sin_port = strtol(optarg, NULL, 10);
55 in.sin_port = htons(in.sin_port);
56 break;
57
58 case 'r':
59 reuseport = 1;
60 break;
61
62 default:
63 usage(argv[0]);
64 }
65 }
66
67 if (in.sin_addr.s_addr == INADDR_ANY || in.sin_port == 0 ||
68 local_in.sin_port == 0)
69 usage(argv[0]);
70
71 s = socket(AF_INET, SOCK_DGRAM, 0);
72 if (s < 0)
73 err(2, "socket failed");
74
75 if (reuseport) {
76 if (setsockopt(s, SOL_SOCKET, SO_REUSEPORT,
77 &reuseport, sizeof(reuseport)) < 0)
78 err(2, "setsockopt SO_REUSEPORT failed");
79 }
80
81 if (bind(s, (const struct sockaddr *)&local_in, sizeof(local_in)) < 0)
82 err(2, "bind failed");
83
84 n = sendto(s, buf, sizeof(buf), 0,
85 (const struct sockaddr *)&in, sizeof(in));
86 if (n < 0)
87 err(2, "sendto failed");
88 else if (n != (int)sizeof(buf))
89 errx(2, "sent truncated data %d", n);
90
91 n = read(s, buf, sizeof(buf));
92 if (n < 0)
93 err(2, "read failed");
94 printf("read %d, done\n", n);
95
96 exit(0);
97 }
98