[9fans] return of dns woes

[9fans] return of dns woes

[erik quanstrom]

i'm seeing dns break about every 6 hrs.  i can't leave
the process hanging about, so i have an automated dns killer.
unfortunately this results in no useful debugging information.
i'll upgrade the script (following) to snap the broken processes.

dennis      1206083    0:00   0:00      472K Await    dns [/net restarter]
dennis      1206084    0:00   0:00     6316K Pread    dns [636 /net/dns Twrites of 4798 9p rpcs read; 16754 alarms]
dennis      1206085    0:08   0:26     6316K Pread    dns [served 74205 udp; 16753 alarms]
dennis      1206087    0:00   0:00      388K Await    dns [/net.alt restarter]
dennis      1206088    0:00   0:00      616K Pread    dns [0 /net.alt/dns Twrites of 982 9p rpcs read; 177 alarms]
dennis      1206089    1:54   0:06      616K Pread    dns [served 7775 udp; 177 alarms]
dennis      1234972    0:00   0:00     6316K Pread    dns [reading inside reply from 208.122.22.2: some.name.com ip from 1.2.3.4]
dennis      1235413    0:00   0:00     6316K Broken   dns [netquery: a1040.b.akamai.net]

sorry for the anonomization.  and the current lack
of detail.

- erik

#!/bin/rc
rfork en
mailto=quanstro
dns = ndb/dns
extrec = ()
ext = ()

fflag=0
nl='
'
fn usage{
	echo 'usage: restartdns [-f]' >[1=2]
	exit usage
}

fn why{
	if(! ~ $#nbroken 0)
		echo getting mediæval on $#nbroken broken dns processes.
	if not{
		echo getting mediæval on $#nwait deadlocked dns processes.
		for(i in $nwait)
			echo $i
	}
}

for(i)switch($i){
case -f
	fflag=1
case *
	usage
}

if(~ $fflag 0){
	if(! ~ $sysname atlas baron rb2 atlas)
		exit 'wrong system'
	nbroken=`{ps -a | grep ' dns ' | grep Broken}
	ifs=$nl nwait=`{ps -a |sed -n 's/.* +dns \[query lock wait for(.*)\]/\1/gp' | sort | uniq -c | awk '$1>2'}

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

slaydns = `{echo $dns | sed 's:.*/::g'}
slay $slaydns | rc
$dns -s
if(~ $sysname $ext)
	$dns -sx /net.alt -f /lib/ndb/external
if(~ $sysname $extrec)
	$dns -Rrsx /net.alt -f /lib/ndb/external