NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/alt/sources/2845

Text File | 1992-12-22 | 24.4 KB | 930 lines

Newsgroups: alt.sources
Path: sparky!uunet!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!agate!spool.mu.edu!yale.edu!ira.uka.de!chx400!josef!maffeis
From: [e-mail] (Silvano Maffeis)
Subject: synclockd: Clock synchronization daemons
Message-ID: <[e-mail]>
Organization: University of Zurich, Department of Computer Science
Date: Tue, 22 Dec 92 12:58:36 GMT
Lines: 920


Submitted-by: [e-mail] (silvano maffeis)
Archive-name: synclockd.shar


Here are two simple and pretty accurate daemons for performing
clock synchronization in a LAN. Several workstations can be
synchronized with a central time server host for example.
The daemons work under SunOS 4, Ultrix, SYSV (Amiga), IRIX 4.0.X,
AIX 3.x and possibly on other UNIXes as well.

The daemons work independently of any daytime or time inetd
service. Clocks are advanced or retarded using adjtime(2),
which guarantees always monotonically increasing timevalues.
The implemented synchronization mechanism is an adaptation
of the Cristian's algorithm.

----------------- cut here -----------------------------------------------
#! /bin/sh
# This is a shell archive.  Remove anything before this line, then unpack
# it by saving it into a file and typing "sh file".  To overwrite existing
# files, type "sh file -c".  You can also feed this as standard input via
# unshar, or by typing "sh <file", e.g..  If this archive is complete, you
# will see the following message at the end:
#        "End of shell archive."
# Contents:  Makefile README getrtime.c synclockd.c synclockd.conf
#   synservd.c
# Wrapped by maffeis@sebastian on Wed Dec 16 15:26:19 1992
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'Makefile' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'Makefile'\"
else
echo shar: Extracting \"'Makefile'\" \(1744 characters\)
sed "s/^X//" >'Makefile' <<'END_OF_FILE'
X# This is the Makefile for building the clock synchronisation daemons.
X# Currently, we support SUNOS, Ultrix, Amiga Unix (SYSVR4) and AIX.
X# This software should also work on other Unix flavors
X# without or with only small adaptions.
X#
X# Author: Silvano Maffeis, [e-mail] 1992
X
X
X#CC=gcc
XCC=cc
X
X# Some defaults
XINSTALL = install
X
X# no extra flags necessary for SunOS 4
X
X# uncomment this for SYSV (Amiga)
X#LDLIBS=-lbsd43
X#STD_DEFINES = -DSYSV
X
X# uncomment this for IRIX 4.0.X (SiliconGraphics)
X#LDLIBS=-lsun
X#STD_DEFINES = -DSYSV
X#CCOPTIONS = -cckr
X#INSTALL = /usr/bin/X11/bsdinst.sh
X
X# uncomment this for Ultrix
X#STD_DEFINES = -DSYSV
X
X#uncomment this for AIX
X#LDLIBS=-lbsd
X#STD_DEFINES = -DSYSV
X
X# where binaries go:
XBINDIR=/usr/local/etc
X
X# path of the config file:
XCONF_FILE=/usr/local/etc/synclockd.conf
X
X# path of the log file:
XLOG_FILE=/usr/local/etc/synclockd.log
X
X# add -DPORT=number to 'DEFINES=' below to hardcode a udp port number
X# and avoid using /etc/services
X
XDEFINES=-DCONF=\"$(CONF_FILE)\" -DLOG_FILE=\"$(LOG_FILE)\" #-DPORT=9000
XCDEBUGFLAGS = -O
XCCLDFLAGS=
X
X# ------------You probably need not edit below this line ----------------------
X
XCFLAGS = $(CDEBUGFLAGS) $(CCOPTIONS) $(DEFINES) $(STD_DEFINES)
X
Xall:        synclockd synservd
X
Xsynclockd:    synclockd.o getrtime.o
X        $(CC) $(CCLDFLAGS) -o synclockd synclockd.o getrtime.o $(LDLIBS)
X        rm -f synmon
X        ln -s synclockd synmon
X
Xsynservd:    synservd.o
X        $(CC) $(CCLDFLAGS) -o synservd synservd.o $(LDLIBS)
X
X
Xinstall:    synclockd
X        $(INSTALL) -m 1755 -s synclockd $(BINDIR)
X        $(INSTALL) -m 1755 -s synservd $(BINDIR)
X        rm -f $(BINDIR)/synmon
X        ln -s $(BINDIR)/synclockd $(BINDIR)/synmon
X
X
Xclean:
X        rm -f core *.o *% *~
X
Xrealclean:    clean
X        rm -f synclockd synservd cs synmon
END_OF_FILE
if test 1744 -ne `wc -c <'Makefile'`; then
    echo shar: \"'Makefile'\" unpacked with wrong size!
fi
# end of 'Makefile'
fi
if test -f 'README' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'README'\"
else
echo shar: Extracting \"'README'\" \(4392 characters\)
sed "s/^X//" >'README' <<'END_OF_FILE'
XAuthor
X======
XSilvano Maffeis, [e-mail], Oct 1992
X
XThis directory contains two daemons: synclockd, a simple but pretty accurate
Xclock synchronization daemon and synservd, the server-daemon for
Xsynclockd. I think they work sufficiently exact to synchronize many
Xclient clocks in a LAN.
X
Xsynclockd
X=========
Xsynopsis: synclockd [serverhost timeinterval]
Xinvoked without arguments, synclockd reads its parameters from
X/usr/local/etc/synservd.conf
X(or whatever path you specified in the Makefile)
X
XThe underlying time-synchronization method is based upon the
Xassumption that the roundtrip delay of a UDP data packet in a LAN is made
Xup by two almost identical parts.
X
XThis is known as the basic Cristian's algorithm. One enhancement we make:
XWhen the measured roundtrip delay is higher than the smallest one
Xencountered so far, we discard the measured value and don't alterate
Xthe local clock.
XThe smallest roundtrip value is corrected using a factor containing
Xthe maximal amount two clocks can drift away from each other,
Xwhich is 2*DRIFT. (If we would not make this correction, then no more
Xclock adjustments would be performed when the minimal roundtrip delay is
Xreached.)
X
XSynclockd adjusts the local clock using adjtime(), hence
Xguaranteeing an always monotonically increasing local time.
Xadjtime() just speeds up, resp. slows down the local
Xclock by a few percents until the time value computed by our algorithm
Xis reached. Therefore it initially can take some time till
Xclocks are synchronized.
X
Xsynservd
X========
XSince services like time, daytime, rdate(), rtime() are not accurate
Xenough (these services usually provide a granularity of one second), the time
Xserver daemon synservd is also provided.
Xsynservd listens on a udp socket for incoming synclockd requests and
Xreturns the local time as obtained from gettimeofday(2).
X
XA possible way for synchronizing several clients is to choose
Xone host in the LAN known for his high availability and exact
Xlocal time clock as time-server. A synclockd is started on every client.
XA synservd is started only on the time-server host. (The time-server
Xitself needs no synclockd in this case).
X
XMultiple LANs can be synchronized by realizing a hierarchy of
Xtime-servers and time-clients.
X
Xsynmon
X======
Xsynmon is a simple monitor which helps in finding out how exact
Xa client clock is synchronized with the server.
X
Xsynmon servername 5
X
XDisplays information about the synchronization process every 5
Xseconds.
X
X
XEXACTNESS
X=========
XThe maximal accurateness af the synchronization depends on the true
Xexactness of gettimeofday(). For SPARCS running sunos 4, the logical
Xtick value is
X1/100 of a second, and therefore you cannot believe the microsecond values
Xreturned by gettimeofday().
XThus, the difference of local to remote can be up to
X1/99.999 seconds even when the daemons would provide for a 100%
Xexact synchronization, which is impossible to achieve anyway.
X
X
XINSTALLATION
X============
XInspect the Makefile and make changes if needed.
XCompile the daemons by typing ``make''.
X
XYou then need an entry for the synchronization service in
X/etc/services:
X
Xutime           8500/udp                        # time synch daemon
X
Xsynclockd must run under root privileges since you must be superuser to
Xuse adjtime(). The best way to start it
Xis from the /etc/rc.local file of the client using something like:
X
X# synchronize local clock with host.foo.bar.edu every hour:
X/usr/etc/synclockd host.foo.bar.edu 3600 &
X
Xor just
X/usr/etc/synclockd &
X
XIn the latter case, the two parameters are read from a configuration file.
X(something like /usr/local/etc/synclockd.conf. This filename is
X specified in the Makefile).
Xhost.foo.bar.edu is the name of the time-server on which synservd runs.
X
X
XSUGGESTED READING
X=================
X
XA.S. Tanenbaum, "Modern Operating Systems", Chapter 11.1
XD. Mills, Net Time Protocol (ntp), Articles on louie.udel.edu: pub/ntp/doc
X
X
XBUGS:
X=====
X
XThe daemons are used since a while over here to synchronize around
X30 clients (Sparcs, Silicon Graphics, RS6000, DecStation,...) in a LAN.
XA client clock normally differs by only
Xa few 0.001 sec from the server clock. We work with a synchronization
Xinterval of 1800 sec.
X
XNevertheless, some bugs surely exist. If you find some, please report them.
XPlease inform me of useful enhancements you make to the daemons.
X
XSilvano Maffeis, [e-mail]
X
END_OF_FILE
if test 4392 -ne `wc -c <'README'`; then
    echo shar: \"'README'\" unpacked with wrong size!
fi
# end of 'README'
fi
if test -f 'getrtime.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'getrtime.c'\"
else
echo shar: Extracting \"'getrtime.c'\" \(1236 characters\)
sed "s/^X//" >'getrtime.c' <<'END_OF_FILE'
X/* (C) Silvano Maffeis, [e-mail]
X * University of Zurich, Switzerland 1992
X *
X * getrtime.c: read time from remote host using udp
X */
X
X#include <stdio.h>
X#include <sys/time.h>
X#include <sys/types.h>
X#include <sys/socket.h>
X#include <sys/errno.h>
X#include <netinet/in.h>
X
Xextern errno;
X
Xvoid sclose(s)
X     int s;
X{
X  int save;
X
X  save = errno;
X  (void) close(s);
X  errno = save;
X}
X
Xgetrtime(addrp, timep)
X     struct sockaddr_in *addrp;
X     struct timeval *timep;
X{
X  int s;
X  int res;
X  char thetime[2*sizeof(long)];
X  struct timeval *rtime = (struct timeval *)thetime;
X  struct sockaddr_in from;
X  int fromlen;
X
X  s = socket(AF_INET, SOCK_DGRAM, 0);
X  if (s < 0) {
X    return(-1);
X  }
X  addrp->sin_family = AF_INET;
X  res = sendto(s, (char *)thetime, 2*sizeof(long), 0,
X           (struct sockaddr *)addrp, sizeof(*addrp));
X  if (res < 0) {
X    sclose(s);
X    return(-1);
X  }
X  fromlen = sizeof(from);
X  res = recvfrom(s, (char *)thetime, 2*sizeof(long), 0,
X         (struct sockaddr *)&from, &fromlen);
X  sclose(s);
X  if (res < 0) {
X    return(-1);
X  }
X  if (res != sizeof(thetime)) {
X    errno = EIO;
X    return(-1);
X  }
X  timep->tv_sec  = ntohl(rtime->tv_sec);
X  timep->tv_usec = ntohl(rtime->tv_usec);
X  return(0);
X}
X
END_OF_FILE
if test 1236 -ne `wc -c <'getrtime.c'`; then
    echo shar: \"'getrtime.c'\" unpacked with wrong size!
fi
# end of 'getrtime.c'
fi
if test -f 'synclockd.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'synclockd.c'\"
else
echo shar: Extracting \"'synclockd.c'\" \(9596 characters\)
sed "s/^X//" >'synclockd.c' <<'END_OF_FILE'
X/* (C) Silvano Maffeis, [e-mail]
X * University of Zurich, Switzerland 1992
X */
X
X#include <stdio.h>
X#include <string.h>
X#include <sys/types.h>
X#include <sys/time.h>
X#include <sys/socket.h>
X#include <errno.h>
X#include <signal.h>
X#include <netinet/in.h>
X#include <netdb.h>
X#include <values.h>
X#include <malloc.h>
X
X#define DRIFT      0.00001    /* Drift of the hardware clock compared to "real time" */
X#define MIN_RT       1500       /* Shortest roundtrip measured in an ethernet lan      */
X#define AVG_RT       2500       /* Average roundtrip measured in an ethernet lan       */
X#define SUSPICIOUS 100000     /* Log time deviations > SUSPICIOUS microsec           */
X#define VERSION    "V1.0"
X
X
Xextern getrtime();
X
X
X/* .......................globals.................................*/
Xchar **Argv;
Xextern char *sys_errlist[];
Xextern int errno;
Xshort synmon = 0;
Xchar *host;
Xchar *localHost;
X/* ...............................................................*/
X
X/* log an event
X */
Xvoid LOG(str)
X     char *str;
X{
X  FILE *logF;
X  struct tm *tm;
X  struct timeval tv;
X  char *date;
X
X  if (gettimeofday(&tv, 0) < 0){
X    fprintf(stderr, "%s: gettimeofday: %s\n", Argv[0], sys_errlist[errno]);
X    LOG("panic: gettimeofday failed!");
X    exit(1);
X  };
X
X  tm = localtime(&tv.tv_sec);
X  date = (char*)malloc(25);
X  strcpy(date, asctime(tm));
X  date[24] = '\0';   /* overwrite '\n' */
X
X  if(!synmon){
X    logF = fopen(LOG_FILE, "a");
X    if(logF == NULL){ free(date); return;}
X
X    fprintf(logF, "%s: %s: %s\n", date, localHost, str);
X    fclose(logF);
X    free(date);
X  }
X}
X
X/*
X * trap SIGINT:
X */
X#if defined(SYSV)
Xvoid term_fcn(sig)
X#else
X     term_fcn(sig)
X#endif SYSV
X     int sig;
X{
X  if(signal(sig, SIG_IGN) == SIG_ERR){
X    fprintf(stderr, "%s: term_fcn %s\n", Argv[0], sys_errlist[errno]);
X    exit(1);
X  }
X
X  LOG("Got a kill signal!");
X
X  exit(1);
X}
X
X/*
X * handle signals:
X */
Xint handle_sigs(){
X  if(signal(SIGHUP, SIG_IGN) == SIG_ERR)
X    return(0);
X
X  if(signal(SIGINT, SIG_IGN) == SIG_ERR)
X    return(0);
X
X  if(signal(SIGQUIT, SIG_IGN) == SIG_ERR)
X    return(0);
X
X  if(signal(SIGTERM, term_fcn) == SIG_ERR)
X    return(0);
X
X  return(1);
X}
X
X/*
X * read time of day:
X */
Xvoid  time_get(seconds, usecs)
X     long *seconds;
X     long *usecs;
X{
X  struct timeval tv;
X
X  if (gettimeofday(&tv, 0) < 0){
X    fprintf(stderr, "%s: gettimeofday: %s\n", Argv[0], sys_errlist[errno]);
X    LOG("panic: gettimeofday failed!");
X    exit(1);
X  };
X  *seconds = tv.tv_sec;
X  *usecs   = tv.tv_usec;
X}
X
X/*
X * calculate roundtrip
X * starttime must be <= endtime
X */
Xlong calc_roundtrip(start_s, start_u, end_s, end_u)
X     long start_s;
X     long start_u;
X     long end_s;
X     long end_u;
X{
X
X  end_s -= start_s;
X  if ((end_u -= start_u) < 0) {
X    end_u += 1000000;
X    --end_s;
X  }
X  return(end_u + end_s * 1000000);
X};
X
X/*
X * calculate delta
X * starttime can also be > endtime
X */
Xlong calc_delta(start_s, start_u, end_s, end_u)
X     long start_s;
X     long start_u;
X     long end_s;
X     long end_u;
X{
X  if(start_s < end_s || ( start_s == end_s && start_u < end_u ))
X    return calc_roundtrip(start_s, start_u, end_s, end_u);
X
X  return 0-calc_roundtrip(end_s, end_u, start_s, start_u);
X};
X
X/*
X * set up connection to remote hosts
X */
Xvoid init_connection(addrp)
X     struct sockaddr_in *addrp;
X{
X  struct servent *servent;
X  long address;
X  struct hostent *ph;
X
X
X  if(isdigit(host[0])){
X    if((address=inet_addr(host))==-1){
X      fprintf(stderr, "%s: invalid inet number %s\n", Argv[0], host);
X      exit(1);
X    }
X    addrp->sin_addr.s_addr=address;
X    addrp->sin_family=AF_INET;
X  }
X  else{
X    addrp->sin_family = AF_INET;
X    if((ph = gethostbyname(host)) == 0){
X      fprintf(stderr, "%s: unknown host %s\n", Argv[0], host);
X      exit(1);
X    }
X    bcopy(ph->h_addr, &addrp->sin_addr, ph->h_length);
X  }
X
X#ifndef PORT
X  servent = getservbyname("utime", "udp");
X  if(servent == NULL){
X    fprintf(stderr, "%s: getservbyname: %s\n", Argv[0], sys_errlist[errno]);
X    exit(1);
X  };
X
X  addrp->sin_port = htons(servent->s_port);
X#else
X  addrp->sin_port = htons(PORT);
X#endif PORT
X
X};
X
X/* read parameters from config file
X */
Xvoid loadParams(file, sleept)
X     char *file;
X     int *sleept;
X{
X  FILE *conf;
X  static unsigned char is_loaded = 0;
X
X  conf = fopen(file, "r");
X  if(conf == NULL){
X    if(is_loaded) return;
X
X    fprintf(stderr, "%s: cannot open %s: %s\n", Argv[0], file,
X        sys_errlist[errno]);
X    exit(1);
X  };
X  is_loaded = 1;
X
X  if(fscanf(conf, "%s %d\n", host, sleept) != 2){
X    fprintf(stderr, "%s: syntax error in %s\n", Argv[0], file);
X    exit(1);
X  };
X  fclose(conf);
X}
X
Xshort rt_is_lower(rt, now_sec, now_usec)
X     double rt;
X     double now_sec;
X     double now_usec;
X{
X  static double llast = -1.0;
X  static double shortest = MAXDOUBLE;
X  double elapsed, tmp;
X
X  if(llast==-1.0) llast = now_sec * 1000000.0 + now_usec;
X
X  elapsed = (now_sec * 1000000.0 + now_usec) - llast;
X
X  if(synmon){
X    printf("now = %0.f, %0.f\n", now_sec, now_usec);
X    printf("last = %0.f\n", llast);
X    if(shortest != MAXDOUBLE)
X      printf("shortest roundtrip so far = %.0f usec\n", shortest);
X    printf("last adjustement          = %.0f usec ago\n", elapsed);
X  };
X
X  tmp = now_sec*1000000.0 + now_usec;
X
X  if(rt < shortest + 2*DRIFT * elapsed){
X    shortest = rt;
X    llast = tmp;
X    return 1;
X  }
X
X  return 0;
X}
X
X/******************************************************************************/
Xmain(argc, argv)
X     int argc;
X     char **argv;
X{
X  struct sockaddr_in addr;
X  struct timeval time, ltime, ntime;
X  int ret;
X  long start_sec, start_usec, end_sec, end_usec, rt, delta;
X  int sleept;
X  char buf[64], str[32];
X
X  Argv = argv;
X
X  if(argc != 3 && argc != 1){
X    fprintf(stderr, "usage: %s remotehost timeinterval\n", Argv[0]);
X    exit(1);
X  };
X
X  if( argc == 1 ){
X    host = (char*)malloc(64);
X    loadParams(CONF, &sleept);
X  }
X  else{
X    if(sscanf(Argv[2], "%d", &sleept) != 1){
X      fprintf(stderr, "%s: parameter 2 must be an integer value\n", Argv[0]);
X      exit(1);
X    };
X    host = Argv[1];
X  }
X
X  localHost = (char*)malloc(64);
X  gethostname(localHost, 64);
X
X  if(strcmp(argv[0], "synmon") == 0) synmon = 1;
X  init_connection(&addr, host);
X
X  sprintf(str, "synclockd %s started", VERSION);
X  LOG(str);
X
X  if(synmon){
X    printf("remote host   = %s\n", host);
X    printf("time interval = %d\n", sleept);
X  }
X  else
X    handle_sigs();
X
X  while(1){
X    if(synmon)
X      printf("\npolling %s:\n", host);
X
X    time_get(&start_sec, &start_usec);
X    ret = getrtime(&addr, &time);
X    time_get(&end_sec, &end_usec);
X
X    if(ret != 0){  /* rtimel timed stderr. Retry later */
X      if(synmon)
X        fprintf(stderr, "%s: connection to %s timed out\n", Argv[0], host);
X      else
X    LOG("connection to time server timed out");
X      sleep(sleept);
X      continue;
X    }
X
X    ret = gettimeofday(<ime, (struct timezone*)0);
X    if(ret != 0){
X      fprintf(stderr, "%s: gettimeofday: %s\n", Argv[0], sys_errlist[errno]);
X      LOG("panic: gettimeofday failed!");
X      exit(1);
X    }
X
X    rt = calc_roundtrip(start_sec, start_usec, end_sec, end_usec);
X
X    /*
X     * since gettimeofday()'s _real_ exactness is around 1/60 second,
X     * most rountripdelays in a LAN will become 0 if we rely on
X     * gettimeofday().
X     * Too small values ( < MIN_RT ) are corrected to AVG_RT. Both values
X     * derive from measurements using an exact timer we undertook
X     * in a Ethernet LAN.
X     */
X    if(rt < MIN_RT) rt = AVG_RT;
X
X    /*
X     * Next we look if the actual roundtrip is smaller than the corrected,
X     * shortest roundtrip so far:
X     * rt < rt_min + 2 * (1+DRIFT) * elapsed_time.
X     * With rt being the actual roundtrip, rt_min the shortest roundtrip
X     * encountered so far and the rest a parameter taking into
X     * account the maximal drift of two clocks.
X     */
X    if( rt_is_lower((double)rt, (double)start_sec, (double)start_usec, synmon) ){
X      if(synmon){
X        printf("roundtrip is lower       : %ld usec\n", rt);
X        printf("remote time: %ld sec, %ld usec\n", time.tv_sec, time.tv_usec);
X        printf("local time : %ld sec, %ld usec\n", ltime.tv_sec, ltime.tv_usec);
X      }
X
X      /* compute time-delta between remote and local:
X       * roundtrip/2 + remote - local .
X       * If delta is positive, then speed up clock, else slow down.
X       */
X      delta =  rt/2 +
X          calc_delta(ltime.tv_sec, ltime.tv_usec, time.tv_sec, time.tv_usec);
X
X      if(delta != 0){
X
X        ntime.tv_sec  = delta/1000000;
X        ntime.tv_usec = delta - ntime.tv_sec * 1000000;
X
X    if(!synmon){
X          ret = adjtime(&ntime, 0);
X          if(ret != 0){
X            fprintf(stderr, "%s: adjtime: %s\n", Argv[0], sys_errlist[errno]);
X        LOG("panic: adjtime failed");
X            exit(1);
X          }
X        }
X
X    /* Look if the difference between local and remote clock
X     * is "suspiciously" high. If so, log it.
X         */
X    rt = calc_delta(time.tv_sec, time.tv_usec, ltime.tv_sec,
X            ltime.tv_usec);
X
X    if(abs(rt) > SUSPICIOUS){
X      sprintf(buf, "suspicious time difference: %ld", rt);
X      LOG(buf);
X        }
X      }
X
X      if(synmon){
X        printf("advancing local clock by %ld sec, %ld usec\n",
X           ntime.tv_sec, ntime.tv_usec);
X      }
X    }
X    else
X      if(synmon)
X    printf("roundtrip is *not* lower : %d usec\n", rt);
X
X    sleep(sleept);
X
X    /* allows to configure synclockd at runtime:
X     */
X    if(argc == 1)
X      loadParams(CONF, host, &sleept);
X  }
X}
END_OF_FILE
if test 9596 -ne `wc -c <'synclockd.c'`; then
    echo shar: \"'synclockd.c'\" unpacked with wrong size!
fi
# end of 'synclockd.c'
fi
if test -f 'synclockd.conf' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'synclockd.conf'\"
else
echo shar: Extracting \"'synclockd.conf'\" \(26 characters\)
sed "s/^X//" >'synclockd.conf' <<'END_OF_FILE'
Xhost.foo.bar.edu   1800
X
END_OF_FILE
if test 26 -ne `wc -c <'synclockd.conf'`; then
    echo shar: \"'synclockd.conf'\" unpacked with wrong size!
fi
# end of 'synclockd.conf'
fi
if test -f 'synservd.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'synservd.c'\"
else
echo shar: Extracting \"'synservd.c'\" \(3072 characters\)
sed "s/^X//" >'synservd.c' <<'END_OF_FILE'
X/* (C) Silvano Maffeis, [e-mail]
X * University of Zurich, Switzerland 1992
X *
X * synservd.c: server daemon that listens on udp socket and quickly
X *             returns the local time using gettimeofday().
X */
X
X#include <stdio.h>
X#include <sys/types.h>
X#include <sys/socket.h>
X#include <netinet/in.h>
X#include <arpa/inet.h>
X#include <netdb.h>
X#include <ctype.h>
X#include <errno.h>
X#include <signal.h>
X#include <sys/time.h>
X
X#define BUFFERSIZE sizeof(struct timeval)
X
Xextern errno;
Xextern char *sys_errlist[];
Xstruct sockaddr_in sin;
Xint sock;
Xchar  **Argv;
X
Xint setup_connection(){
X  int s;
X  int length;
X  struct hostent *gethostbyname();
X  struct servent *servent;
X
X  s = socket(AF_INET, SOCK_DGRAM, 0);
X  if (s < 0) {
X    fprintf(stderr, "%s: opening udp socket\n", Argv[0]);
X    exit(1);
X  }
X
X  /* Connect socket using name specified by command line. */
X  sin.sin_family = AF_INET;
X  sin.sin_addr.s_addr = INADDR_ANY;
X
X#ifndef PORT
X  servent = getservbyname("utime", "udp");
X  if(servent == NULL){
X    fprintf(stderr, "%s: getservbyname: %s\n", Argv[0], sys_errlist[errno]);
X    exit(1);
X  };
X  sin.sin_port = htons(servent->s_port);
X#else
X  sin.sin_port = htons(PORT);
X#endif PORT
X
X  if(bind(s, (struct sockaddr *) &sin, sizeof(sin)) < 0){
X    fprintf(stderr, "%s: cannot bind\n", Argv[0]);
X    exit(1);
X  }
X
X  /* find socket# */
X
X  length = sizeof(sin);
X  if (getsockname(s, &sin, &length)) {
X    fprintf(stderr, "%s: getsockname\n", Argv[0]);
X    exit(1);
X  }
X  fprintf(stderr, "Socket has port #%d\n", ntohs(sin.sin_port));
X
X  listen(s, 5);
X  return(s);
X}
X
X#if defined(SYSV)
Xvoid term_fcn(sig)
X#else
X     term_fcn(sig)
X#endif SYSV
X     int sig;
X{
X  if(signal(sig, SIG_IGN) == SIG_ERR){
X    fprintf(stderr, "%s: signal\n", Argv[0]);
X    exit(1);
X  }
X
X  fprintf(stderr, "%s: Got a kill signal!\n\n", Argv[0]);
X
X  shutdown(sock,2);
X  close(sock);
X  exit(1);
X}
X
Xint handle_sigs(){
X  if(signal(SIGHUP, SIG_IGN) == SIG_ERR)
X    return(0);
X
X  if(signal(SIGINT, SIG_IGN) == SIG_ERR)
X    return(0);
X
X  if(signal(SIGQUIT, SIG_IGN) == SIG_ERR)
X    return(0);
X
X  if(signal(SIGTERM, term_fcn) == SIG_ERR)
X    return(0);
X
X  return(1);
X}
X
X
Xmain(argc, argv)
X     int argc;
X     char *argv[];
X{
X  char in[BUFFERSIZE], out[BUFFERSIZE];
X  struct timeval tv;
X  struct sockaddr sa;
X  int size = sizeof(sa);
X
X  Argv = argv;
X
X  if(! handle_sigs()){
X    fprintf(stderr, "%s: handle sigs\n", Argv[0]);
X    exit(1);
X  };
X
X  sock=setup_connection();
X
X  while(1){
X
X    if (recvfrom(sock, in, BUFFERSIZE, 0, &sa, &size) < 0){
X      fprintf(stderr, "%s: recvfrom udp socket\n", Argv[0]);
X      exit(1);
X    };
X
X    if (gettimeofday(&tv, 0) < 0){
X      fprintf(stderr, "%s: gettimeofday: %s\n", Argv[0], sys_errlist[errno]);
X      exit(1);
X    };
X
X    memcpy(out, &tv.tv_sec, sizeof(long));
X    memcpy(&out[sizeof(long)], &tv.tv_usec, sizeof(long));
X
X    if(sendto(sock, out, BUFFERSIZE, 0, &sa, size) < 0){
X      fprintf(stderr, "%s: sendto udp socket\n", Argv[0]);
X      exit(1);
X    };
X  }
X}
X
X
END_OF_FILE
if test 3072 -ne `wc -c <'synservd.c'`; then
    echo shar: \"'synservd.c'\" unpacked with wrong size!
fi
# end of 'synservd.c'
fi
echo shar: End of shell archive.
exit 0
--
Silvano Maffeis       CS Dept. University of Zurich, Switzerland
   RFC822: [e-mail]            voice: [phone]
   X.400: /S=maffeis/OU=ifi/O=unizh/PRMD=SWITCH/ADMD=ARCOM/C=CH/