#!/bin/rc
rfork en
nl='
'
mailto=(quanstro)
allow=(ladd)
recursive=()
gcidr = (
	# only blocks that can map to google's a records
	72.14.192.0/18
	74.125.0.0/16
	209.85.128.0/17
	216.239.32.0/19
	173.194.0.0/16
)

if(! ~ `{cat /dev/user} `{cat /dev/hostowner}){
	echo 'restartdns: must be hostowner' >[1=2];
	exit user
}

9fs other

fn syslog{
	echo $sysname `{date} restartdns: $* > /sys/log/dns
}

fn pgroup{
	ifs=$nl g=`{cat /proc/$1/noteid}
	for(i in `{grep -l $g /proc/*/noteid | sed 's:/proc/([^/]+)/noteid:\1:g'})
		if(test -d /proc/$i)
			echo $i
}

fn reaper{
	nbroken=()
	for(i in `{ps | awk '$6 == "Broken" && $7 == "dns" {print $2}'}){
		r = /n/other/$user/dnssnap/$sysname.$i.`{date -n}
		snap -o $r `{pgroup $i}
		nbroken = ($nbroken $r)
	}
}

fn getips{
	ndb/dnsquery $* | sed 's/.*[ 	]//g'
}

fn google{
	google=()
	if(! ip/cidr -rf <{getips google.com} <{echo $gcidr})
		google=1
	if(ip/cidr -f /lib/badcidr <{getips 9fans.net} )
		google=($google 2)
}

fn why{
	if(! ~ $#nbroken 0){
		echo getting mediæval on $#nbroken broken dns processes.
		for(i in $nbroken)
			echo $i
	}
	if(! ~ $#nwait 0){
		echo getting mediæval on $#nwait deadlocked dns processes.
		for(i in $nwait)
			echo $i
	}
	if(! ~ $#google 0){
		echo google broken
		ndb/dnsquery google.com
		ndb/dnsquery 9fans.net any
	}
}

flagfmt='p,f'
args=()
if(! ifs=() eval `{aux/getflags $*} || ! ~ $#* 0){
	aux/usage
	exit usage
}

if(~ $#flagf 0){
	if(! ~ $sysname $allow)
		exit 'wrong system'
	reaper
	ifs=$nl nwait=`{ps -a |sed -n 's/.* +dns \[query lock wait for(.*)\]/\1/gp' | sort | uniq -c | awk '$1>2'}
	google

	if(~ $#nbroken 0 && ~ $#nwait 0 && ~ $#google 0)
		exit 'none broken'
	why
	if(~ $service rx)
		{date; echo; why; echo; ps -a | grep ' dns ' }| mail -s 'restartdns: '^$sysname $mailto
}

if(~ $flagp 1)
	exit ''

syslog slaying broken $#nbroken nwait $#nwait google $#google

dns = ndb/dns
slaydns = `{echo $dns | sed 's:.*/::g'}
slay $slaydns | rc
unmount '#s/dns' /net/dns >[2=]
unmount '#s/dns_net.alt' /net.alt/dns >[2=]
rm -f '#s/dns'  '#s/dns_net.alt'

$dns -N 20000 -s
if(~ $sysname $recursive)
	$dns -sx /net.alt -f /lib/ndb/external
if not
	$dns -Rrsx /net.alt -f /lib/ndb/external