#!/bin/sh

# Quick and dirty script around dig +trace

# Stop on any uncaucht error
set -e

# Initialization
OUTPUT_EXIT_STATUS=0
OUTPUT_DETAIL_OK=""
OUTPUT_DETAIL_CRITICAL=""
OUTPUT_DETAIL_UNKNOWN=""
OUTPUT_PERFDATA=""
LOGGER=""
TIMEOUT=3

#
# Help function
#
usage() {
	cat <<EOF
Usage:
  $0 -d example.net
  $0 -h            (this help output)
EOF
}

if ! which dig >/dev/null 2>&1; then
	echo "UNKNOWN 'dig' not found."
	exit 3
fi

if [ -z "$LOGGER" ] && which logger >/dev/null 2>&1; then
	LOGGER="logger"
fi

#
# Gestion des paramètres
#
while getopts hd: f; do
	case "$f" in
		'h')
			usage
			exit
			;;

		'd')
			# Let's chronometer the resolution
			CHRONO="$(( $( date +%s%N ) / 1000000 ))"
			OUTPUT="$( dig +trace +all +timeout=$TIMEOUT "$OPTARG" )"
			DIG_STATUS_CODE="$?"
			CHRONO="$(( $( date +%s%N ) / 1000000 - $CHRONO ))"

			# Store the perfdata for each domain
			OUTPUT_PERFDATA="$OUTPUT_PERFDATA 't_$( echo $OPTARG | tr -cd 'a-zA-Z0-9. ' )'=$CHRONO""ms;;;0"

			if [ "$DIG_STATUS_CODE" -ne "0" ]; then
				# 'dig' output an error -> status unknown.
				OUTPUT_DETAIL_UNKNOWN=" dig returned error code $DIG_STATUS_CODE"
				OUTPUT_EXIT_STATUS=3
				break  # I don't feel like we should go on, should we ?
			else
				# Unfortunately, I couldn't get a proper way to know if the resolution
				# was successful. So parsing the output it is...
				# We're looking for a line like 'www.kernel.org.    3600   IN  ...'
				if ! echo "$OUTPUT" | egrep "^$OPTARG.?[[:space:]]+[0-9]+[[:space:]]+IN[[:space:]]+" >/dev/null 2>&1; then
					[ -z "$LOGGER" ] || echo "$OUTPUT" | $LOGGER
					OUTPUT_DETAIL_CRITICAL="$OUTPUT_DETAIL_CRITICAL $OPTARG"
					OUTPUT_EXIT_STATUS=2
				else
					OUTPUT_DETAIL_OK="$OUTPUT_DETAIL_OK $OPTARG"
				fi
			fi
			;;

		\?)
			usage
			exit 1
			;;
	esac
done


case "$OUTPUT_EXIT_STATUS" in
	'0')
		if [ -z "$OUTPUT_DETAIL_OK" ]; then
			OUTPUT_DETAIL_OK=" (no domains tested)"
		fi
		# Trick for the perfdata : convert the first space to the separator '|'
		printf "OK%s%s\n" "$OUTPUT_DETAIL_OK" "$( echo "$OUTPUT_PERFDATA" | sed 's/^ /|/' )"
		;;

	'2')
		printf "CRITICAL%s\n" "$OUTPUT_DETAIL_CRITICAL"
		;;

	'3')
		printf "UNKOWN%s\n" "$OUTPUT_DETAIL_CRITICAL"
		;;
esac

exit "$OUTPUT_EXIT_STATUS"