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Bug #47035 dns_get_record returns a garbage byte at the end of a TXT record
Submitted: 2009-01-08 09:07 UTC Modified: 2009-01-15 12:44 UTC
Votes:1
Avg. Score:4.0 ± 0.0
Reproduced:1 of 1 (100.0%)
Same Version:1 (100.0%)
Same OS:1 (100.0%)
From: valli at icsurselva dot ch Assigned: felipe (profile)
Status: Closed Package: Network related
PHP Version: 5.2.8 OS: gentoo
Private report: No CVE-ID: None
View Developer Edit
 [2009-01-08 09:07 UTC] valli at icsurselva dot ch 
Description:
------------
The last byte of a TXT record returned by dns_get_record
is garbage.


Reproduce code:
---------------
$rt = dns_get_record('82.19.186.195.countries.blackholes.us', DNS_TXT);
$txt = $rt[0]['txt'];
print $txt." (".strlen($txt).")\n";
foreach(str_split($txt) as $char) {
    print "$char\t".ord($char)."\n";
}


Expected result:
----------------
ch (2)
c       99
h       104


Actual result:
--------------
ch (3)
c       99
h       104
        128

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 [2009-01-08 09:31 UTC] valli at icsurselva dot ch 
Here's my current workaround:

$rt = @dns_get_record($lookuphost, DNS_ANY);
// workaround for http://bugs.php.net/bug.php?id=47035
if (substr(PHP_VERSION,0,strpos(PHP_VERSION, '-')) == '5.2.8') {
    for($i = 0, $rts = sizeof($rt); $i < $rts; ++$i) {
        if ($rt[$i]['type'] == 'TXT') {
            // remove last byte
            $rt[$i]['txt'] = substr($rt[$i]['txt'], 0, -1);
        }
    }
}
 [2009-01-08 10:45 UTC] pajoye@php.net 
Felipe, can you give it a try please?

http://cvs.php.net/viewvc.cgi/php-src/ext/standard/dns.c?r1=1.70.2.7&r2=1.70.2.7.2.7&pathrev=PHP_5_2
 [2009-01-08 17:20 UTC] felipe@php.net 
This bug has been fixed in CVS.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
Thank you for the report, and for helping us make PHP better.

Thanks.
 [2009-01-09 11:36 UTC] valli at icsurselva dot ch 
Hello again,
I just dicovered that the garbage chars not
only appear at the end of a TXT record.
Example:
 nslookup -type=TXT 82.19.186.195.aspath.routeviews.org
 Returns: text = "13237 3303 44038" "195.186.0.0" "17"

This DNS request returns 3 Strings.
If I do this with dns_get_record the strings are concatenated
(containing a garbage char between the strings)

BTW: Is it really a good idea to concatenate this strings?
     Wouldn't it better to return a array containing this strings?
     Example: the anwers from routeviews.org are really
              hard (if not impossible) to parse in this way:
              "13237 3303 44038195.186.0.017"
              it would be better in this way:
              array("13237 3303 44038","195.186.0.0","17")
 [2009-01-09 12:52 UTC] pajoye@php.net 
I agree, it would be more logical to return an array of strings.

Comments?
 [2009-01-12 20:40 UTC] felipe@php.net 
Sure, it's right to do.

We add a new entry in the array returned, on 5.3+ we get:

array(6) {
  ["host"]=>
  string(35) "82.19.186.195.aspath.routeviews.org"
  ["type"]=>
  string(3) "TXT"
  ["txt"]=>
  string(31) "13237 3303 44038195.186.0.017"
  ["entries"]=>
  array(3) {
    [0]=>
    string(16) "13237 3303 44038"
    [1]=>
    string(11) "195.186.0.0"
    [2]=>
    string(2) "17"
  }
  ["class"]=>
  string(2) "IN"
  ["ttl"]=>
  int(592)
}
 
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