13#define DATA1 0
15main(argc, argv)
16int argc;
17char *argv[];
18{
19int i, sock;
20short dataLength;
21short networkDataLength;
22long npackets= 0;
23char buf[1024];
24struct sockaddr_in name;
25struct hostent *hp, *gethostbyname();
27if (argc < 3) {
28printf(“Usage: udpsend hostname port#\n”);
29exit(3);
30}
31
32/* Create socket on which to send:
33Protocol family= Internet (AF_INET)
34Type = UDP (SOCK_DGRAM)
35Protocol = 0: This field is not used
36*/
37sock= socket(AF_INET, SOCK_DGRAM, 0);
38if (sock < 0) {
39perror(“opening datagram socket”);
40exit(1);
41}
42
43/* Create a name, with no wildcards, of the destination socket.
44Gethostbyname() returns an IP address, given a host name.
45*/
46hp= gethostbyname(argv[1]);
47if (hp==0) {
48fprintf(stderr, “%s: Unknown host\n”, argv[1]);
49exit(2);
50}
51
52/* Fill in socket data structure with destination IP address,
53socket protocol family, and port number. */
54memcpy( (char *)&name.sin_addr, (char
98
