#!/bin/sh
#
# qtest: queries a set of DNS name servers and report the fastest ones
# 
# Usage: qtest query server...
# Example: qtest -n 3 "SOA fr" $(dig +short NS fr.)
#
# From: Joe Abley <jabley@isc.org>
# Modified-by: Stephane Bortzmeyer <bortzmeyer@nic.fr>

# Settings 
max=1
verbose=0

# Some Unices like NetBSD are crazy enough to ship a dinosaurian
# version of getopt, which cannot handle arguments with spaces! So, we
# have a lot of work to work around this pre-babylonian limit.
test_getopt() 
{
    getopt=$1
    if [ ! -x $getopt ] && ! which $getopt > /dev/null 2>&1; then
	return 1
    fi
    if [ "$($getopt -o '' -- 'a b')" = " -- 'a b'" ]; then
	return 0
    else
	return 1
    fi
}
if test_getopt getopt; then
    GETOPT=getopt
else 
    if test_getopt ggetopt; then
	GETOPT=ggetopt
    else 
	if test_getopt /usr/pkg/bin/getopt; then # Last resort for NetBSD
	    GETOPT=/usr/pkg/bin/getopt
	else
	    echo "Cannot find a working getopt on this machine"  > /dev/stderr
	    exit 1
	fi
    fi
fi

TEMP=$($GETOPT -o "n:v" -- "$@")
if [ $? != 0 ]; then
    echo "Usage: $0 [-n MAX] [-v] query server..." > /dev/stderr
    exit 1
fi
eval set -- "$TEMP"
while true ; do
        case "$1" in
                -n) max=$2; shift 2;;
                -v) verbose=1; shift;;
                --) shift ; break ;;
                *) echo "Internal error!" > /dev/stderr ; exit 1 ;;
        esac
done

query=$1
shift
servers=""
for server in $*; do
    addresses=$(dig +short A $server ; dig +short AAAA $server)
    if [ -z "$addresses" ]; then # Let's hope it was an IP address
	addresses=$server
    fi
    for address in $addresses; do
	servers="$servers $server/$address"
    done
done
for i in 0 1 2; do
     for server in $servers; do
	 address=$(echo $server | cut -d/ -f 2)
	 # TODO: if the box has no IPv6 connectivity, or if it is an
	 # old dig without IPv6, we get something like "dig: couldn't
	 # get address for '2001:4f8:0:2::8': address family not
	 # supported". Should we do something?
	 echo "TEST: $server"
	 dig @${address} ${query}
     done
done | \
   awk '/^TEST: / { server = $2; } \
     /^;; Query time:/ { query_time = $4; } \
     /^;; SERVER: / { sum[server] += query_time; num[server]++; } \
     END { for (ns in sum) { print int(sum[ns]/num[ns]), ns; } }' | \
   sort -n | head -${max}