///////////////////////////////////////
// simple unix server to be used in 
// synchronizing client clocks
// 
// main algorithm:
// James Maxlow
//
// generic socket processes (modified):
// RPC Programming Nutshell
///////////////////////////////////////

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

#define PORT 		9090

int main()
{

	//////////////////////
	/* socket variables */
	//////////////////////
	struct   sockaddr_in sin;
	struct   sockaddr_in pin;
	int 	   sd, sd_current, cc, fromlen, tolen;
	int 	   addrlen;

	////////////////////////////////////////////////////
	/* used to hold and send server's time as strings */
	////////////////////////////////////////////////////
	char 	 timereplysec[sizeof(long)*8+3];
	char 	 timereplyusec[sizeof(long)*8+3];
	char 	 timereply[(sizeof(long)*8+3)*2+3] = "";

	int j = 0;

      timeval stime;			/* server's time struct in seconds and microseconds */

	char	 messagereq[4];		/* holds client junk request */
 

	//////////////////////////////
	/* generic socket processes */
	//////////////////////////////

	/* get an internet domain socket */
	if ((sd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
		perror("socket");
		exit(1);
	}

	/* complete the socket structure */
	memset(&sin, 0, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_addr.s_addr = INADDR_ANY;
	sin.sin_port = htons(PORT);

	/* bind the socket to the port number */
	if (bind(sd, (struct sockaddr *) &sin, sizeof(sin)) == -1) {
		perror("bind");
		exit(1);
	}

	/* show that we are willing to listen */
	if (listen(sd, 5) == -1) {
		perror("listen");
		exit(1);
	}

	/* wait for a client to talk to us */
	if ((sd_current = accept(sd, (struct sockaddr *)  &pin, &addrlen)) == -1) {
		perror("accept");
		exit(1);
	}

	/* get a message from the client */
	if (recv(sd_current, messagereq, 4, 0) == -1) {
		perror("recv");
		exit(1);
	}


	/////////////////////////////////////////////////////////////////////
	/* get server time, change to strings, combine to one string, send */
	/////////////////////////////////////////////////////////////////////

      gettimeofday(&stime,0);
        
      sprintf(timereplysec, "%ld", stime.tv_sec);
      sprintf(timereplyusec, "%ld", stime.tv_usec);

	strcat(timereply, timereplysec);
	strcat(timereply, " - ");
	strcat(timereply, timereplyusec);

	/* acknowledge the message, reply with time */
	if (send(sd_current, timereply, (sizeof(long)*8+3)*2+3, 0) == -1) {
		perror("send");
		exit(1);
	}

      /* close up both sockets */
	shutdown(sd_current, 2);
	shutdown(sd, 2);
        
      /* give client a chance to properly shutdown */
      sleep(1);

} //end main