#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>

void print_usage(void)
{
	printf("sends numbered UDP datagrams to a remote host.\n\n");
	printf("Usage: udp-send host\n\n");
	printf("                [-n <datagrams_number>]\n");
	printf("                [-s <datagrams_size>]\n");
	printf("                [-p <port_number>]\n");
	printf("<datagrams_number defaults to 16, <datagrams_size> to 32\n");
	printf("and <port_number> to 9870.\n");
}

main(int argc, char *argv[])
{
	int sock;
	struct hostent *hp;
	struct sockaddr_in name;
	char buf[1024];
	int i;
	int datagrams_number = 16;
	int datagrams_size = 32;
	int port_number = 9870;

	if (argc < 2) {
		print_usage();
		exit(1);
	}

	for (i=1; i<argc; i++) {
		if (argv[i][0] == '-') {
			switch (argv[i][1]) {
				case 'n':
				    sscanf(argv[++i], "%d", &datagrams_number);
					break;
				case 's':
					sscanf(argv[++i], "%d", &datagrams_size);
					break;
				case 'p':
					sscanf(argv[++i], "%d", &port_number);
					break;
				case '-':
					if (!strcmp(argv[i]+2, "help")) {
						print_usage();
						exit(1);
					}
				default:
					printf("unknown argument: %s\n", argv[i]);
					print_usage();
					exit(2);
			}
		}
	}

	sock = socket(AF_INET, SOCK_DGRAM, 0);
	if (sock < 0) {
		perror("socket()");
		exit(1);
	}
	hp = gethostbyname(argv[1]);
	if (hp == 0) {
		printf("unknown host: %s\n", argv[1]);
		exit(1);
	}
	bcopy(hp->h_addr, &name.sin_addr, hp->h_length);
	name.sin_family = AF_INET;
	name.sin_port = htons(port_number);
	printf("sending datagrams to %s, port #%d\n", argv[1], port_number);

	for (i = 0; i<datagrams_size; i++)
		buf[i] = '*';

	/* send datagrams */
	for (i=1; i<datagrams_number; i++) {
		if (sendto(sock, buf, datagrams_size, 0, (const struct sockaddr *)&name, sizeof(name)) < 0)
			perror("error sending datgram\n");
		printf("Sent datagram %d, length %d\n", i, datagrams_size);
		sleep(1);
	}
	close(sock);
}