/*
** udp_server.c
**
** Based on network_interface.c from the netvision program.
**
** Initiated: 9/6/05
*/

#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>

#define MAX_PACKET_SIZE 80000
#define SOCK_PORT 5691

typedef struct {
	unsigned short sequence;
	unsigned short flags;
	unsigned long params;
} MessageHeaderType;

static int sock_fd, sock_port;
static unsigned char buffer[MAX_PACKET_SIZE];

int get_packet(void *packet, int length)
/*
** Receive a packet on the datagram socket, and place the packet in <packet>.
*/
{
	int n, cli_len;
	int echo_len = sizeof(MessageHeaderType);
	struct sockaddr_in cli_addr;

	cli_len = sizeof(cli_addr);
	n = recvfrom(
		sock_fd,
		(char *) packet, length,
		0, 
		(struct sockaddr *)&cli_addr, &cli_len
	);
	if(n < 0) {
		perror("recvfrom");
		return -1;
	}
	if(sendto(
		sock_fd,
		(char *) packet, echo_len,
		0,
		(struct sockaddr *)&cli_addr, cli_len
	) != echo_len) {
		perror("sendto");
		return -1;
	}

	return n;
}

int socket_init(void)
/*
*/
{
	struct sockaddr_in serv_addr;
	int one = 1;
	int i;

	/*
	** Fill in some fields -
	*/
	sock_port = SOCK_PORT;
	sock_fd = -1;

	/*
	** Open the UDP socket -
	*/
	sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
	if(sock_fd < 0) {
		perror("socket");
		return -1;
	}

	if(setsockopt(
		sock_fd,
		SOL_SOCKET,
		SO_REUSEADDR,
		(char *)&one,
		sizeof(one)
	) < 0) {
		perror("setsockopt");
		return -1;
	}

	/*
	** Bind our local address so that the client can send to us -
	*/
	memset((char *) &serv_addr, 0, sizeof(serv_addr));
	serv_addr.sin_family = AF_INET;
	serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	serv_addr.sin_port = htons(sock_port);

	if(bind(
		sock_fd,
		(struct sockaddr *) &serv_addr,
		sizeof(serv_addr)
	) < 0) {
		perror("bind");
		return -1;
	}

	return 0;
}

int main()
{
	int i, n, total_bytes = 0;
	time_t start, run;
	double elapsed;

	if(socket_init() < 0) {
		printf("Error initializing UDP socket\n");
		return 1;
	}

	printf("Elapsed Time\tTotal Bytes\tThroughput\n");
	start = time(NULL);
	for(i = 1; ; i++) {
		n = get_packet(buffer, sizeof(buffer));
		if(n < 0) {
			printf("get_packet returned error code %d\n", n);
		}
		else {
			total_bytes += n;
		}
		if((i % 1000) == 0) {
			run = time(NULL);
			elapsed = difftime(run, start);
			printf(
				"%g\t%d\t%g\n",
				elapsed,
				total_bytes,
				(double) total_bytes / elapsed
			);
		}
	}
	return 0;
}