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
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
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 	if (connect(s, (const struct sockaddr *)&in, sizeof(in)) < 0)
85 		err(2, "connect failed");
86 
87 	n = write(s, buf, sizeof(buf));
88 	if (n < 0)
89 		err(2, "write failed");
90 	else if (n != (int)sizeof(buf))
91 		errx(2, "written truncated data %d", n);
92 
93 	n = read(s, buf, sizeof(buf));
94 	if (n < 0)
95 		err(2, "read failed");
96 	printf("read %d, done\n", n);
97 
98 	exit(0);
99 }
100