nsupdate returns error but is successfull

Question

I'm running Bind and Apache on Debian and im doing dynamic updates on one of my zones with nsupdate via php script

The update Function:

function nsupdate($subdomain, $ip) {
 $domain = escapeshellcmd($subdomain . '.example.com');
 $ip = escapeshellcmd($ip);
 $data = "<<EOF
 server localhost
 zone example.com
 update delete $domain A
 update add $domain 10 A $ip
 send
 EOF";
 exec("/usr/bin/nsupdate -k /var/bind/keys/Kexample.com.+157+40387.private $data", $cmdout, $ret);
 return $ret;
}

I call this function (sub = 'test', ip = random valid IPv4 IP):

$ret = nsupdate($sub, $ip);
if ($ret != 0) {
    $msg = "Error! Code: $ret";
}else {
     $msg = "Success!";
}

The value of $ret is '1' and the $msg is 'Error! Code: 1', but the syslog shows

client ::1#9726/key example.com: signer "example.com" approved
client ::1#9726/key example.com: updating zone 'example.com/IN': deleting rrset at 'test.example.com' A
client ::1#9726/key example.com: updating zone 'example.com/IN': adding an RR at 'test.example.com' A

i can ping the subdomain and it returns the new IP. But i'd still like to know why the nsupdate call returns 1 and not the expected 0 on a succesful update.

update 1 here the $cmdout with debugging enabled for nsupdate

array(13) { 
[0]=> string(22) "Outgoing update query:" 
[1]=> string(59) ";; ->>HEADER<<- opcode: UPDATE, status: NOERROR, id: 58402" 
[2]=> string(55) ";; flags:; ZONE: 1, PREREQ: 0, UPDATE: 2, ADDITIONAL: 1" 
[3]=> string(16) ";; ZONE SECTION:" 
[4]=> string(22) ";example.com. IN SOA" 
[5]=> string(0) "" 
[6]=> string(18) ";; UPDATE SECTION:" 
[7]=> string(33) "test.example.com. 0 ANY A" 
[8]=> string(45) "test.example.com. 10 IN A 22.22.22.22" 
[9]=> string(0) "" 
[10]=> string(22) ";; TSIG PSEUDOSECTION:"
[11]=> string(109) "example.com. 0 ANY TSIG hmac-md5.sig-alg.reg.int. 1439217988 300 16 kaHm1/GbMf0+cuIJO62lgw== 58402 NOERROR 0" 
[12]=> string(0) "" }

score 2 · Answer 1 · answered Mar 01 '17 at 22:18

2

I had the same "problem" bothering me for a while now. When I tried the above nsupdate commands on the command line everything was fine and the exit status (type in console directly after nsupdate -> echo $? returned 0) but called from php it was 1.

Until I realized that while being on the console I typed quit to end my nsupdate session. As soon as I added this line to the php script everything was fine aka exit code 0.

So change $data to $data = "<<EOF server localhost zone example.com update delete $domain A update add $domain 10 A $ip send quit EOF";

answered Mar 01 '17 at 22:18

Arigion

3,267
31
41

I have tested with quit, but still I got $ret = 2 – developer Oct 05 '17 at 22:13
The question is about $ret=1. Exit code 2 is about some other error. Try updating the record manually and/or check your log files. Probably the format or the access rights are incorrect. – Arigion Oct 12 '17 at 14:16

score 1 · Answer 2 · answered Aug 10 '15 at 12:31

1

Try adding var_dump($cmdout);var_dump($ret); before return $ret. $msg is irrelevant.

answered Aug 10 '15 at 12:31

Voro

66
2

$cmdout is just an empty Array, $ret is int(1) ( see Update 1 for $cmdout with debugging enabled ) – Wipfelgilm Aug 10 '15 at 14:57
Maybe the error is not related to the update operation itself but because of a "local" problem (writing to a local file like logs, locks or status). Check the user / permissions or try to run it as root. Also, attaching strace or gdb may be useful. – Voro Aug 10 '15 at 17:08

nsupdate returns error but is successfull

2 Answers2