/* Sample UDP server */

#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>

#define MAX_DGRAM_SIZE 1500
#define RTR_RESPONDER_PORT 65500

struct rtr_mesg {
	unsigned short	saa_engine;
	unsigned short	reserved1;
	unsigned long	sender_tstamp;
	unsigned long 	responder_tstamp;
	unsigned short	index;
	unsigned short 	reserved2;
	char		payload[MAX_DGRAM_SIZE - 16];
};

int main(int argc, char**argv)
{
	int sockfd, n;
	struct sockaddr_in servaddr, cliaddr;
	socklen_t len;
	struct rtr_mesg mesg;
	struct timeval tv;
	unsigned long tod;

	sockfd = socket(AF_INET, SOCK_DGRAM, 0);

	memset(&servaddr, 0, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(RTR_RESPONDER_PORT);
	bind(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr));

	for (;;) {
		len = sizeof(cliaddr);
		n = recvfrom(sockfd, (void *) &mesg, sizeof(mesg), 0, (struct sockaddr *) &cliaddr, &len);
		gettimeofday(&tv, 0);
		tod = ( tv.tv_sec % 86400 ) * 1000 + ( tv.tv_usec / 1000 );
		mesg.responder_tstamp = htonl(tod);
		sendto(sockfd, (void *)&mesg, n, 0, (struct sockaddr *) &cliaddr, sizeof(cliaddr));
	}
}