#!/usr/bin/perl -w
# --*-perl-*-
;#
;# ntploopstat,v 3.1 1993/07/06 01:09:11 jbj Exp
;# 
;# Poll NTP server using NTP mode 7 loopinfo request.
;# Log info and timestamp to file for processing by ntploopwatch.
;#
;#
;# Copyright (c) 1992
;# Rainer Pruy Friedrich-Alexander Universitaet Erlangen-Nuernberg
;#
;#################################################################
;#
;# The format written to the logfile is the same as used by xntpd
;# for the loopstats file.
;# This script however allows to gather loop filter statistics from
;# remote servers where you do not have access to the loopstats logfile.
;#
;# Please note: Communication delays affect the accuracy of the
;#              timestamps recorded. Effects from these delays will probably
;#              not show up, as timestamps are recorded to the second only.
;#              (Should have implemented &gettimeofday()..)
;#

$0 =~ s!^.*/([^/]+)$!$1!;		# beautify script name

$ntpserver = 'localhost';		# default host to poll
$delay = 60;				# default sampling rate
				       ;# keep it shorter than minpoll (=64)
				       ;# to get all values

require "ctime.pl";
;# handle bug in early ctime distributions
$ENV{'TZ'} = 'MET' unless defined($ENV{'TZ'}) || $] > 4.010;

if (defined(@ctime'MoY))
{
    *MonthName = *ctime'MoY;
}
else
{
    @MonthName = ('Jan','Feb','Mar','Apr','May','Jun',
		  'Jul','Aug','Sep','Oct','Nov','Dec');
}

;# this routine can be redefined to point to syslog if necessary
sub msg
{
    return unless $verbose;

    print  STDERR "$0: ";
    printf STDERR @_;
}

;#############################################################
;#
;# process command line
$usage = <<"E-O-S";

usage:
  $0 [-d<delay>] [-t<timeout>] [-l <logfile>] [-v] [ntpserver]
E-O-S

while($_ = shift)
{
    /^-v(\d*)$/ && ($verbose=($1 eq '') ? 1 : $1,1) && next;
    /^-d(\d*)$/ &&
	do {
	    ($1 ne '') && ($delay = $1,1) && next;
	    @ARGV || die("$0: delay value missing after -d\n$usage");
	    $delay = shift;
	    ($delay  >= 0) || die("$0: bad delay value \"$delay\"\n$usage");
	    next;
	};
    /^-l$/ &&
	do {
	    @ARGV || die("$0: logfile missing after -l\n$usage");
	    $logfile = shift;
	    next;
	};
    /^-t(\d*(\.\d*)?)$/ &&
	do {
	    ($1 ne '') && ($timeout = $1,1) && next;
	    @ARGV || die("$0: timeout value missing after -t\n$usage\n");
	    $timeout = shift;
	    ($timeout > 0) ||
		die("$0: bad timeout value \"$timeout\"\n$usage");
	    next;
	};
    
    /^-/ && die("$0: unknown option \"$_\"\n$usage");

    ;# any other argument is server to poll
    $ntpserver = $_;
    last;
}

if (@ARGV)
{
    warn("unexpected arguments: ".join(" ",@ARGV).".\n");
    die("$0: too many servers specified\n$usage");
}

;# logfile defaults to include server name
;# The name of the current month is appended and
;# the file is opened and closed for each sample.
;#
$logfile = "loopstats:$ntpserver." unless defined($logfile);
$timeout = 12.0 unless defined($timeout); # wait $timeout seconds for reply

$MAX_FAIL = 60;				# give up after $MAX_FAIL failed polls


$MJD_1970 = 40587;

if (eval 'require "syscall.ph";')
{
    if (defined(&SYS_gettimeofday))
    {
	;# assume standard
 	;# gettimeofday(struct timeval *tp,struct timezone *tzp)
	;# syntax for gettimeofday syscall
 	;# tzp = NULL -> undef
	;# tp = (long,long)
	eval 'sub time { local($tz) = pack("LL",0,0);
              (&msg("gettimeofday failed: $!\n"),
	      return (time))
	      unless syscall(&SYS_gettimeofday,$tz,undef) == 0;
              local($s,$us) = unpack("LL",$tz);
              return $s + $us/1000000; }';
	local($t1,$t2,$t3);
	$t1 = time;
	eval '$t2 = &time;';
	$t3 = time;
	die("$0: gettimeofday failed: $@.\n") if defined($@) && $@;
	die("$0: gettimeofday inconsistency time=$t1,gettimeofday=$t2,time=$t2\n")
	    if (int($t1) != int($t2) && int($t3) != int($t2));
	&msg("Using gettimeofday for timestamps\n");
    }
    else
    {
	warn("No gettimeofday syscall found - using time builtin for timestamps\n");
        eval 'sub time { return time; }';
    }
}
else
{
    warn("No syscall.ph file found - using time builtin for timestamps\n");
    eval 'sub time { return time; }';
}


;#------------------+
;# from ntp_request.h
;#------------------+

;# NTP mode 7 packet format:
;#	Byte 1:     ResponseBit MoreBit Version(3bit) Mode(3bit)==7
;#      Byte 2:     AuthBit Sequence #   - 0 - 127 see MoreBit
;#      Byte 3:     Implementation #
;#      Byte 4:     Request Code
;#
;#      Short 1:    Err(3bit) NumItems(12bit)
;#      Short 2:    MBZ(3bit)=0 DataItemSize(12bit)
;#      0 - 500 byte Data 
;#  if AuthBit is set:
;#      Long:       KeyId
;#      2xLong:     AuthCode

;# 
$IMPL_XNTPD  = 2;
$REQ_LOOP_INFO = 8;


;# request packet for REQ_LOOP_INFO:
;#     B1:  RB=0 MB=0 V=2 M=7 
;#     B2:  S# = 0
;#     B3:  I# = IMPL_XNTPD
;#     B4:  RC = REQ_LOOP_INFO
;#     S1:  E=0 NI=0
;#     S2:  MBZ=0 DIS=0
;#     data:  32 byte 0 padding
;#            8byte timestamp if encryption, 0 padding otherwise
$loopinfo_reqpkt = 
    pack("CCCC nn x32 x8", 0x17, 0, $IMPL_XNTPD, $REQ_LOOP_INFO, 0, 0);

;# ignore any auth data in packets
$loopinfo_response_size =
    1+1+1+1+2+2			# header size like request pkt
    + 8				# l_fp last_offset
    + 8				# l_fp drift_comp
    + 4				# u_long compliance
    + 4				# u_long watchdog_timer
    ;
$loopinfo_response_fmt    = "C4n2N2N2NN"; 
$loopinfo_response_fmt_v2 = "C4n2N2N2N2N"; 

;#
;# prepare connection to server
;# 

;# workaround for broken socket.ph on dynix_ptx
eval 'sub INTEL {1;}' unless defined(&INTEL);
eval 'sub ATT {1;}'  unless defined(&ATT);

require "sys/socket.ph";

require 'netinet/in.ph';

;# if you do not have netinet/in.ph enable the following lines
;#eval 'sub INADDR_ANY { 0x00000000; }' unless defined(&INADDR_ANY);
;#eval 'sub IPPRORO_UDP { 17; }' unless defined(&IPPROTO_UDP);

if ($ntpserver =~ /^((0x?)?\w+)\.((0x?)?\w+)\.((0x?)?\w+)\.((0x?)?\w+)$/)
{
    local($a,$b,$c,$d) = ($1,$3,$5,$7);
    $a = oct($a) if defined($2);
    $b = oct($b) if defined($4);
    $c = oct($c) if defined($6);
    $d = oct($d) if defined($8);
    $server_addr = pack("C4", $a,$b,$c,$d);

    $server_mainname
	= (gethostbyaddr($server_addr,&AF_INET))[$[] || $ntpserver;
}
else
{
    ($server_mainname,$server_addr)
	= (gethostbyname($ntpserver))[$[,$[+4];

    die("$0: host \"$ntpserver\" is unknown\n")
	unless defined($server_addr);
}
&msg ("Address of server \"$ntpserver\" is \"%d.%d.%d.%d\"\n",
      unpack("C4",$server_addr));

$proto_udp = (getprotobyname('udp'))[$[+2] || &IPPROTO_UDP;
 
$ntp_port =
    (getservbyname('ntp','udp'))[$[+2] ||
    (warn "Could not get port number for service \"ntp/udp\" using 123\n"),
    ($ntp_port=123);
 
;# 
0 && &SOCK_DGRAM;		# satisfy perl -w ...
socket(S, &AF_INET, &SOCK_DGRAM, $proto_udp) ||
    die("Cannot open socket: $!\n");

bind(S, pack("S n N x8", &AF_INET, 0, &INADDR_ANY)) ||
    die("Cannot bind: $!\n");
 
($my_port, $my_addr) = (unpack("S n a4 x8",getsockname(S)))[$[+1,$[+2];

&msg("Listening at address %d.%d.%d.%d port %d\n",
     unpack("C4",$my_addr), $my_port);

$server_inaddr = pack("Sna4x8", &AF_INET, $ntp_port, $server_addr);

;############################################################
;#
;# the main loop:
;#	send request
;#      get reply
;#      wait til next sample time

undef($lasttime);
$lostpacket = 0;

while(1)
{
    $stime = &time;

    &msg("Sending request $stime...\n");

    $ret = send(S,$loopinfo_reqpkt,0,$server_inaddr);

    if (! defined($ret) || $ret < length($loopinfo_reqpkt))
    {
	warn("$0: send failed ret=($ret): $!\n");
	$fail++;
	next;
    }

    &msg("Waiting for reply...\n");

    $mask = ""; vec($mask,fileno(S),1) = 1;
    $ret = select($mask,undef,undef,$timeout);

    if (! defined($ret))
    {
	warn("$0: select failed: $!\n");
	$fail++;
	next;
    }
    elsif ($ret == 0)
    {
	warn("$0: request to $ntpserver timed out ($timeout seconds)\n");
	;# do not count this event as failure
	;# it usually this happens due to dropped udp packets on noisy and
	;# havily loaded lines, so just try again;
	$lostpacket = 1;
	next;
    }

    &msg("Receiving reply...\n");

    $len = 520;				# max size of a mode 7 packet
    $reply = "";			# just make it defined for -w
    $ret = recv(S,$reply,$len,0);

    if (!defined($ret))
    {
	warn("$0: recv failed: $!\n");
	$fail++;
	next;
    }

    $etime = &time;
    &msg("Received at\t$etime\n");

    ;#$time = ($stime + $etime) / 2; # symmetric delay assumed
    $time = $etime;		# the above assumption breaks for X25
			       ;# so taking etime makes timestamps be a
			       ;# little late, but keeps them increasing
			       ;# monotonously

    &msg(sprintf("Reply from %d.%d.%d.%d took %f seconds\n",
		 (unpack("SnC4",$ret))[$[+2 .. $[+5], ($etime - $stime)));

    if ($len < $loopinfo_response_size)
    {
	warn("$0: short packet ($len bytes) received ($loopinfo_response_size bytes expected\n");
	$fail++;
	next;
    }
    
    ($b1,$b2,$b3,$b4,$s1,$s2,
     $offset_i,$offset_f,$drift_i,$drift_f,$compl,$watchdog)
	= unpack($loopinfo_response_fmt,$reply);

    ;# check reply
    if (($s1 >> 12) != 0)	      # error !
    {
	die("$0: got error reply ".($s1>>12)."\n");
    }
    if (($b1 != 0x97 && $b1 != 0x9f) || # Reply NotMore V=2 M=7
	($b2 != 0 && $b2 != 0x80) ||	# S=0 Auth no/yes
	$b3 != $IMPL_XNTPD ||		# ! IMPL_XNTPD
	$b4 != $REQ_LOOP_INFO ||	# Ehh.. not loopinfo reply ?
	$s1 != 1 ||			# ????
	($s2 != 24 && $s2 != 28)	# 
	)
    {
	warn("$0: Bad/unexpected reply from server:\n");
	warn("  \"".unpack("H*",$reply)."\"\n");
	warn("   ".sprintf("b1=%x b2=%x b3=%x b4=%x s1=%d s2=%d\n",
			   $b1,$b2,$b3,$b4,$s1,$s2));
	$fail++;
	next;
    }
    elsif ($s2 == 28)
    {
      ;# seems to be a version 2 xntpd
      ($b1,$b2,$b3,$b4,$s1,$s2,
       $offset_i,$offset_f,$drift_i,$drift_f,$compl_i,$compl_f,$watchdog)
	  = unpack($loopinfo_response_fmt_v2,$reply);
      $compl = &lfptoa($compl_i, $compl_f);
    }

    $time -= $watchdog;

    $offset = &lfptoa($offset_i, $offset_f);
    $drift  = &lfptoa($drift_i, $drift_f);

    &log($time,$offset,$drift,$compl) && ($fail = 0);;
}
continue
{
    die("$0: Too many failures - terminating\n") if $fail > $MAX_FAIL;
    &msg("Sleeping " . ($lostpacket ? ($delay / 2) : $delay) . " seconds...\n");

    sleep($lostpacket ? ($delay / 2) : $delay);
    $lostpacket = 0;
}

sub log
{
    local($time,$offs,$freq,$cmpl) = @_;
    local($y,$m,$d);
    local($fname,$suff) = ($logfile);


    ;# silently drop sample if distance to last sample is too low
    if (defined($lasttime) && ($lasttime + 2) >= $time)
    {
      &msg("Dropped packet - old sample\n");
      return 1;
    }

    ;# $suff determines which samples end up in the same file
    ;# could have used $year (;-) or WeekOfYear, DayOfYear,....
    ;# Change it to your suit...

    ($d,$m,$y) = (localtime($time))[$[+3 .. $[+5];
    $suff = sprintf("%04d%02d%02d",$y+1900,$m+1,$d);
    $fname .= $suff;
    if (!open(LOG,">>$fname"))
    {
	warn("$0: open($fname) failed: $!\n");
	$fail++;
	return 0;
    }
    else
    {
	;# file format
	;#          MJD seconds offset drift compliance
	printf LOG ("%d %.3lf %.8lf %.7lf %d\n",
		    int($time/86400)+$MJD_1970,
		    $time - int($time/86400) * 86400,
		    $offs,$freq,$cmpl);
	close(LOG);
	$lasttime = $time;
    }
    return 1;
}

;# see ntp_fp.h to understand this
sub lfptoa
{
    local($i,$f) = @_;
    local($sign) = 1;

    
    if ($i & 0x80000000)
    {
	if ($f == 0)
	{
	    $i = -$i;
	}
	else
	{
	    $f = -$f;
	    $i = ~$i;
	    $i += 1;			# 2s complement
	}
	$sign = -1;
	;#print "NEG: $i $f\n";
    }
    else
    {
	;#print "POS: $i $f\n";
    }
    ;# unlike xntpd I have perl do the dirty work.
    ;# Using floats here may affect precision, but
    ;# currently these bits aren't significant anyway
    return $sign * ($i + $f/2**32);    
}