#!/bin/bash
# Copyright (C) 2014 Timothe Litt litt at acm dot org
# This script may be freely copied, used and modified providing that
# this notice and the copyright statement are included in all copies
# and derivative works. No warranty is offered, and use is entirely at
# your own risk. Bugfixes and improvements would be appreciated by the
# author.
VERSION="1.003"
# leap-seconds file manager/updater
# Depends on:
# wget sed, tr, shasum, logger
# ########## Default configuration ##########
#
# Where to get the file
LEAPSRC="ftp://time.nist.gov/pub/leap-seconds.list"
# How many times to try to download new file
MAXTRIES=6
INTERVAL=10
# Where to find ntp config file
NTPCONF=/etc/ntp.conf
# How long before expiration to get updated file
PREFETCH="60 days"
# How to restart NTP - older NTP: service ntpd? try-restart | condrestart
# Recent NTP checks for new file daily, so there's nothing to do
RESTART=
# Where to put temporary copy before it's validated
TMPFILE="/tmp/leap-seconds.$$.tmp"
# Syslog facility
LOGFAC=daemon
# ###########################################
# Places to look for commands. Allows for CRON having path to
# old utilities on embedded systems
PATHLIST="/opt/sbin:/opt/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:"
REQUIREDCMDS=" wget logger tr sed shasum"
SELF="`basename $0`"
function displayHelp {
cat <<EOF
Usage: $SELF [options] [leapfile]
Verifies and if necessary, updates leap-second definition file
All arguments are optional: Default (or current value) shown:
-s Specify the URL of the master copy to download
$LEAPSRC
-4 Use only IPv4
-6 Use only IPv6
-p 4|6
Prefer IPv4 or IPv6 (as specified) addresses, but use either
-d Specify the filename on the local system
$LEAPFILE
-e Specify how long before expiration the file is to be refreshed
Units are required, e.g. "-e 60 days" Note that larger values
imply more frequent refreshes.
"$PREFETCH"
-f Specify location of ntp.conf (used to make sure leapfile directive is
present and to default leapfile)
$NTPCONF
-F Force update even if current file is OK and not close to expiring.
-c Command to restart NTP after installing a new file
<none> - ntpd checks file daily
-r Specify number of times to retry on get failure
$MAXTRIES
-i Specify number of minutes between retries
$INTERVAL
-l Use syslog for output (Implied if CRONJOB is set)
-L Don't use syslog for output
-P Specify the syslog facility for logging
$LOGFAC
-t Name of temporary file used in validation
$TMPFILE
-q Only report errors to stdout
-v Verbose output
-z Specify path for utilities
$PATHLIST
-Z Only use system path
$SELF will validate the file currently on the local system
Ordinarily, the file is found using the "leapfile" directive in $NTPCONF.
However, an alternate location can be specified on the command line.
If the file does not exist, is not valid, has expired, or is expiring soon,
a new copy will be downloaded. If the new copy validates, it is installed and
NTP is (optionally) restarted.
If the current file is acceptable, no download or restart occurs.
-c can also be used to invoke another script to perform administrative
functions, e.g. to copy the file to other local systems.
This can be run as a cron job. As the file is rarely updated, and leap
seconds are announced at least one month in advance (usually longer), it
need not be run more frequently than about once every three weeks.
For cron-friendly behavior, define CRONJOB=1 in the crontab.
This script depends on$REQUIREDCMDS
Version $VERSION
EOF
return 0
}
# Default: Use syslog for logging if running under cron
SYSLOG="$CRONJOB"
if [ "$1" = "--help" ]; then
displayHelp
exit 0
fi
# Parse options
while getopts 46p:P:s:e:f:Fc:r:i:lLt:hqvz:Z opt; do
case $opt in
4)
PROTO="-4"
;;
6)
PROTO="-6"
;;
p)
if [ "$OPTARG" = '4' -o "$OPTARG" = '6' ]; then
PREFER="--prefer-family=IPv$OPTARG"
else
echo "Invalid -p $OPTARG" >&2
exit 1;
fi
;;
P)
LOGFAC="$OPTARG"
;;
s)
LEAPSRC="$OPTARG"
;;
e)
PREFETCH="$OPTARG"
;;
f)
NTPCONF="$OPTARG"
;;
F)
FORCE="Y"
;;
c)
RESTART="$OPTARG"
;;
r)
MAXTRIES="$OPTARG"
;;
i)
INTERVAL="$OPTARG"
;;
t)
TMPFILE="$OPTARG"
;;
l)
SYSLOG="y"
;;
L)
SYSLOG=
;;
h)
displayHelp
exit 0
;;
q)
QUIET="Y"
;;
v)
VERBOSE="Y"
;;
z)
PATHLIST="$OPTARG:"
;;
Z)
PATHLIST=
;;
*)
echo "$SELF -h for usage" >&2
exit 1
;;
esac
done
shift $((OPTIND-1))
export PATH="$PATHLIST$PATH"
# Add to path to deal with embedded systems
#
for P in $REQUIREDCMDS ; do
if >/dev/null 2>&1 which "$P" ; then
continue
fi
[ "$P" = "logger" ] && continue
echo "FATAL: missing $P command, please install"
exit 1
done
# Handle logging
if ! LOGGER="`2>/dev/null which logger`" ; then
LOGGER=
fi
function log {
# "priority" "message"
#
# Stdout unless syslog specified or logger isn't available
#
if [ -z "$SYSLOG" -o -z "$LOGGER" ]; then
if [ -n "$QUIET" -a \( "$1" = "info" -o "$1" = "notice" -o "$1" = "debug" \) ]; then
return 0
fi
echo "`echo \"$1\" | tr a-z A-Z`: $2"
return 0
fi
# Also log to stdout if cron job && notice or higher
local S
if [ -n "$CRONJOB" -a \( "$1" != "info" \) -a \( "$1" != "debug" \) ] || [ -n "$VERBOSE" ]; then
S="-s"
fi
$LOGGER $S -t "$SELF[$$]" -p "$LOGFAC.$1" "$2"
}
# Verify interval
INTERVAL=$(( $INTERVAL *1 ))
# Validate a leap-seconds file checksum
#
# File format: (full description in files)
# # marks comments, except:
# #$ number : the NTP date of the last update
# #@ number : the NTP date that the file expires
# Date (seconds since 1900) leaps : leaps is the # of seconds to add for times >= Date
# Date lines have comments.
# #h hex hex hex hex hex is the SHA-1 checksum of the data & dates, excluding whitespace w/o leading zeroes
function verifySHA {
if [ ! -f "$1" ]; then
return 1
fi
# Remove comments, except those that are markers for last update, expires and hash
local RAW="`sed $1 -e'/^\\([0-9]\\|#[\$@h]\)/!d' -e'/^#[\$@h]/!s/#.*\$//g'`"
# Extract just the data, removing all whitespace
local DATA="`echo \"$RAW\" | sed -e'/^#h/d' -e's/^#[\$@]//g' | tr -d '[:space:]'`"
# Compute the SHA hash of the data, removing the marker and filename
# Computed in binary mode, which shouldn't matter since whitespace has been removed
# shasum comes in several flavors; a portable one is available in Perl (with Digest::SHA)
local DSHA="`echo -n \"$DATA\" | shasum | sed -e's/[? *].*$//'`"
# Extract the file's hash. Restore any leading zeroes in hash segments.
# The sed [] includes a tab (\t) and space; #h is followed by a tab and space
local FSHA="`echo \"$RAW\" | sed -e'/^#h/!d' -e's/^#h//' -e's/[ ] */ 0x/g'`"
FSHA=`printf '%08x%08x%08x%08x%08x' $FSHA`
if [ -n "$FSHA" -a \( "$FSHA" = "$DSHA" \) ]; then
if [ -n "$2" ]; then
log "info" "Checksum of $1 validated"
fi
else
log "error" "Checksum of $1 is invalid:"
[ -z "$FSHA" ] && FSHA="(no checksum record found in file)"
log "error" "EXPECTED: $FSHA"
log "error" "COMPUTED: $DSHA"
return 1
fi
# Check the expiration date, converting NTP epoch to Unix epoch used by date
EXPIRES="`echo \"$RAW\" | sed -e'/^#@/!d' -e's/^#@//' | tr -d '[:space:]'`"
EXPIRES="$(($EXPIRES - 2208988800 ))"
if [ $EXPIRES -lt `date -u +%s` ]; then
log "notice" "File expired on `date -u -d \"Jan 1, 1970 00:00:00 +0000 + $EXPIRES seconds\"`"
return 2
fi
}
# Verify ntp.conf
if ! [ -f "$NTPCONF" ]; then
log "critical" "Missing ntp configuration $NTPCONF"
exit 1
fi
# Parse ntp.conf for leapfile directive
LEAPFILE="`sed $NTPCONF -e'/^ *leapfile *.*$/!d' -e's/^ *leapfile *//'`"
if [ -z "$LEAPFILE" ]; then
log "error" "$NTPCONF does not specify a leapfile"
fi
# Allow placing the file someplace else - testing
if [ -n "$1" ]; then
if [ "$1" != "$LEAPFILE" ]; then
log "notice" "Requested install to $1, but $NTPCONF specifies $LEAPFILE"
fi
LEAPFILE="$1"
fi
# Verify the current file
# If it is missing, doesn't validate or expired
# Or is expiring soon
# Download a new one
if [ -n "$FORCE" ] || ! verifySHA $LEAPFILE "$VERBOSE" || [ $EXPIRES -lt `date -d "NOW + $PREFETCH" +%s` ] ; then
TRY=0
while true; do
TRY=$(( $TRY + 1 ))
if [ -n "$VERBOSE" ]; then
log "info" "Attempting download from $LEAPSRC, try $TRY.."
fi
if wget $PROTO $PREFER -o ${TMPFILE}.log $LEAPSRC -O $TMPFILE ; then
log "info" "Download of $LEAPSRC succeeded"
if [ -n "$VERBOSE" ]; then
cat ${TMPFILE}.log
fi
if ! verifySHA $TMPFILE "$VERBOSE" ; then
# There is no point in retrying, as the file on the server is almost
# certainly corrupt.
log "warning" "Downloaded file $TMPFILE rejected -- saved for diagnosis"
cat ${TMPFILE}.log
rm -f ${TMPFILE}.log
exit 1
fi
rm -f ${TMPFILE}.log
# Set correct permissions on temporary file
REFFILE="$LEAPFILE"
if [ ! -f $LEAPFILE ]; then
log "notice" "$LEAPFILE was missing, creating new copy - check permissions"
touch $LEAPFILE
# Can't copy permissions from old file, copy from NTPCONF instead
REFFILE="$NTPCONF"
fi
chmod --reference $REFFILE $TMPFILE
chown --reference $REFFILE $TMPFILE
( which selinuxenabled && selinuxenabled && which chcon ) >/dev/null 2>&1
if [ $? == 0 ] ; then
chcon --reference $REFFILE $TMPFILE
fi
# Replace current file with validated new one
if mv -f $TMPFILE $LEAPFILE ; then
log "notice" "Installed new $LEAPFILE from $LEAPSRC"
else
log "error" "Install $TMPFILE => $LEAPFILE failed -- saved for diagnosis"
exit 1
fi
# Restart NTP (or whatever else is specified)
if [ -n "$RESTART" ]; then
if [ -n "$VERBOSE" ]; then
log "info" "Attempting restart action: $RESTART"
fi
R="$( 2>&1 $RESTART )"
if [ $? -eq 0 ]; then
log "notice" "Restart action succeeded"
if [ -n "$VERBOSE" -a -n "$R" ]; then
log "info" "$R"
fi
else
log "error" "Restart action failed"
if [ -n "$R" ]; then
log "error" "$R"
fi
exit 2
fi
fi
exit 0
fi
# Failed to download. See about trying again
rm -f $TMPFILE
if [ $TRY -ge $MAXTRIES ]; then
break;
fi
if [ -n "$VERBOSE" ]; then
cat ${TMPFILE}.log
log "info" "Waiting $INTERVAL minutes before retrying..."
fi
sleep $(( $INTERVAL * 60))
done
# Failed and out of retries
log "warning" "Download from $LEAPSRC failed after $TRY attempts"
if [ -f ${TMPFILE}.log ]; then
cat ${TMPFILE}.log
rm -f ${TMPFILE}.log $TMPFILE
fi
exit 1
fi
log "info" "Not time to replace $LEAPFILE"
exit 0
# EOF