/*-------------------------------------------------------------------------
udp-recv.c
Receives numbered (not really) datagrams on a port
-------------------------------------------------------------------------*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>

void print_usage(void)
{
	printf("receives numbered datagrams from a remote host.\n\n");
	printf("Usage:\n");
	printf("    udp-recv [-p <port_number>][-s <datagrams_size>]\n\n");
	printf("    <port_number> defaults to 9870.\n");
	printf("    <datagrams_size> defaults to 32.\n");
}

main(int argc, char *argv[])
{
	int sock, length;
	struct hostent *hp;
	struct sockaddr_in name;
	struct sockaddr_in name2;
	char buf[1024];
	clock_t timeout;
	int i;

	int port_number = 9870;
	int datagrams_size = 32;

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

	/* create the socket */
	sock = socket(AF_INET, SOCK_DGRAM, 0);
	if (sock < 0) {
		perror("socket()");
		exit(1);
	}

	/* bind the sockets to a port */
	name.sin_family = AF_INET;
	name.sin_addr.s_addr = INADDR_ANY;
	name.sin_port = htons(port_number);
	if (bind(sock, (const struct sockaddr *)&name, sizeof(name))) {
		perror("bind()");
		exit(1);
	}
	printf("listening for data on port #%d\n", port_number);
	for (i=1; ; i++) {
		if (read(sock, buf, datagrams_size) < 0) {
			perror("read()");
			close(sock);
			exit(1);
		}
		printf("Received datagram %d, length %d\n", i, datagrams_size);
	}
	close(sock);
}