/*--------
From:     Doug Kingston <dpk@BRL.ARPA>
To:       Bruce Duncan <DUNCAN@sumex-aim.arpa>
cc:       info-iris@sumex-aim.arpa
Subject:  Re:  time servers
Message-ID:  <8610091913.aa04372@SEM.BRL.ARPA>
--------*/

/* $Header$ */

/* 
 * ndate.c - Get date from another network host
 *		variation on a theme by rsm@brl
 * 
 * Author:	Christopher A. Kent
 * 		Dept. of Computer Sciences
 * 		Purdue University
 * Date:	Thu Jun 23 1983
 * Copyright (c) 1983 Christopher A. Kent
 */
/* $Log$ */

static char rcs_ident[] = "$Header$";

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/time.h>
#include <stdio.h>
#include <netdb.h>
#include <utmp.h>
#define	WTMP "/usr/adm/wtmp"

struct utmp wtmp[2] = { {"|", "", 0}, {"{", "", 0}};

char *std_hostv[] =
{
	"saturn",
	"sri-nic",
	"bbng",
	"usc-isib",
	"mit-devmultics",
	0,
};

char **hosts;
char *u_hostv[128];
char u_hosts[256];

char	aflag;				/* all hosts */
char	sflag;				/* set time from first host */
char	uflag;				/* report time in GMT */

struct	sockaddr_in sin = { AF_INET };

char	*asctime();
char	*ctime();
struct tm *localtime();
char	*timezone();

main(argc, argv)
char **argv;
{
	register char *hostname;
	register struct hostent *host;
	register int s;
	struct timeval ntv, tv;
	struct timezone tz;
	char *tzn;
	char *ap;
	int wf;
	int success = 0;

	procargs(argc, argv);
	
	if(aflag && sflag){
		fprintf(stderr, "%s: -a and -s mutually exclusive\n", argv[0]);
		exit(-1);
	}

	gettimeofday(&tv, &tz);

	sin.sin_port = htons(IPPORT_TIMESERVER);

	while(hostname = *hosts++){	/* pick a host and connect */
		host = gethostbyname(hostname);
		if(host){
			sin.sin_family = host->h_addrtype;
			bcopy(host->h_addr, (caddr_t)&sin.sin_addr, host->h_length);
			hostname = host->h_name;
		}else{
			sin.sin_family = AF_INET;
			sin.sin_addr.s_addr = inet_addr(argv[1]);
			if(sin.sin_addr.s_addr == -1){
				printf("%s: unknown host\n", hostname);
				continue;
			}
		}
		s = socket(AF_INET, SOCK_STREAM, 0);
		if(s < 0){
			perror("ndate: socket");
			continue;
		}

		if(connect(s, (caddr_t)&sin, sizeof(sin)) < 0){
			extern int errno, sys_nerr;
			extern char *sys_errlist[];
			register char *c;

			fprintf(stderr, "ndate: Can't connect to %s: ", hostname);
			c = "Unknown error";
			if(errno < sys_nerr)
				c = sys_errlist[errno];
			fprintf(stderr, "%s\n", c);
			continue;
		}
		
		printf("%s: ", hostname);
		if(read(s, &ntv.tv_sec, sizeof(ntv.tv_sec)) < 0){
			perror("ndate: read");
			continue;
		}
		close(s);
		success++;
		tv.tv_sec = ntohl(ntv.tv_sec);
		tv.tv_sec -= 2208988800;	/* from Jan 1 1900 */
		tv.tv_usec = 0;
		/* time is now Unix normal form (GMT) */
		tzn = NULL;
		if(uflag){
			ap = asctime(gmtime(&tv.tv_sec));
			tzn = "GMT";
		}else{
			struct tm *tp;
			tp = localtime(&tv.tv_sec);
			ap = asctime(tp);
			tzn = timezone(tz.tz_minuteswest, tp->tm_isdst);
		}
		printf("%.20s", ap);
		if(tzn != NULL)
			printf("%s", tzn);
		printf("%s", ap+19);
		if(aflag == 0)
			break;
	}
	if(sflag == 0)
		exit(success == 0);

	wtmp[0].ut_time = tv.tv_sec;
	if (settimeofday(&tv, (struct timezone *)0) < 0) {
		success = 0;
		perror("Failed to set date");
	} else if ((wf = open(WTMP, 1)) >= 0) {
		time(&wtmp[1].ut_time);
		lseek(wf, 0L, 2);
		write(wf, (char *)wtmp, sizeof(wtmp));
		close(wf);
	}
	exit(success == 0);
}

/*
 * procargs - unified argument processing procedure
 *
 * This procedure contains the logic for converting the UNIX argument
 * list into global variables
 */
procargs(argc, argv)
int argc;
char *argv[];
{
	int arg, skip, unswitched, more;
	char *swptr;

	
	hosts = std_hostv;
	uflag = 0;
	aflag = 0;
	sflag = 0;

	unswitched = 0;
	skip = 1;
	for ( arg=1 ; arg<argc ; arg += skip ) {
		skip = 1;
		if ( argv[arg][0] == '-' ) {
			more = 1;
			swptr = &argv[arg][1];
			while ( more && *swptr!='\0' ) {
				switch ( *swptr++ ) {
				case 'a':
					aflag = 1;
					break;

				case 's':
					sflag = 1;
					break;

				case 'u':
					uflag = 1;
					break;

				default:
					usagexit(argv[0]);
				}
			}
		} else { /* there's no dash in front */
			unswitched++;
			strcat(u_hosts, argv[arg]);
			strcat(u_hosts, " ");
		}
	}
	if(unswitched){
		makevec(u_hosts, u_hostv);
		hosts = u_hostv;
	}
}

usagexit(pgm)
char *pgm;
{
	fprintf(stderr,"usage: %s [-u] -[a|s] [hosts] \n",pgm);
	exit(1);
}

/*
 * makevec - turn a comma or white space separated list into a vector
 */

makevec(list, ptrs)
char *list;
char *ptrs[];
{
	register char	*s;		/* speed things up */
	register int	i;		/* loop control */
	
	s = list;
	i = 0;
	
	while(1){
		ptrs[i] = NULL;
		while (*s == ' ' || *s == '\t' || *s == ',')
			*s++ = '\0';
		if (*s == '\n')
			*s = '\0';
		if (*s == '\0')
			break;
		ptrs[i++] = s++;
		while (*s != '\0' && *s != ' '
			&& *s != '\t' && *s != '\n' && *s != ',')
				s++;
	}
	return;
}