#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "btime_int.h"

static unsigned int get_btime(void);

int
main(int argc, char **argv)
{
	int sd;
	char inmsg[BTIME_MSGLEN];
	char btimeonly[BTIME_MSGLEN];
	char cookiemsg[BTIME_MSGLEN];
	char *outmsg;
	struct sockaddr_in cli_addr;
	socklen_t cli_addr_len;
	ssize_t nbytes;
	unsigned int local_btime;

	openlog("btimed", LOG_PID, LOG_USER);

	/* Running out of (x)inetd the socket was duped onto stdin. */
	sd = fileno(stdin);

	/* We want to exit after 30 seconds of inactivity */
	alarm(30);

	/* Generate the standard btime message */
	memset(btimeonly, 0, BTIME_MSGLEN);
	local_btime = get_btime();
	sprintf(btimeonly, "%u\n", local_btime);

	syslog(LOG_INFO, "started with btime = %u", local_btime);
	for (;;) {
		memset(&cli_addr, 0, sizeof cli_addr);
		memset(inmsg, 0, BTIME_MSGLEN);
		cli_addr_len = sizeof cli_addr;
		nbytes = recvfrom(sd, &inmsg, BTIME_MSGLEN, MSG_WAITALL, 
		         (struct sockaddr *)&cli_addr, &cli_addr_len);

		if (nbytes < 0) {		
			/* Bail, we may have had an alarm(), or other error.
			 * client side resends request, no need to retry here.
			 */
			syslog(LOG_INFO, "exitting");
			exit(0);
		}
		if (inmsg[0] == 'B' && inmsg[1] == 'T' ) {
			/* New style heartbeat with cookie */
			/* Copy cookie to message and append timestamp */
			memset(cookiemsg, 0, BTIME_MSGLEN);
			memcpy(cookiemsg, inmsg, COOKIE_LEN);
			strcpy(cookiemsg + COOKIE_LEN, btimeonly);
			outmsg = cookiemsg;
		} else {
			outmsg = btimeonly;
		}

		sendto(sd, outmsg, BTIME_MSGLEN, MSG_DONTWAIT, 
		       (struct sockaddr *)&cli_addr, cli_addr_len);
		/* We want to exit after 30 seconds of inactivity */
		alarm(30);
	}

	return 0;
}


/*
 *---------------------------------------------------------------------------
 *
 * get_btime --
 *
 *	Return machine's boot time.
 *
 * Returns:
 *	0 on failure
 * 	non-zero on success.
 *
 *---------------------------------------------------------------------------
 */

static unsigned int 
get_btime(void)
{
	FILE *statf;
	char line[1024];
	unsigned int btime = 0;

	if ((statf = fopen("/proc/stat", "r")) == NULL) {
		syslog(LOG_ERR, "/proc/stat open failure: %s\n", 
		        strerror(errno));
		exit(1);
	}

	while (fgets(line, 1024, statf) != NULL) {
		if (strstr(line, "btime") != NULL) {
			sscanf(line, "%*s%u", &btime); 
		}
			
	}

	fclose(statf);

	return btime;
}