Net::DNS objects

Hello, I'm using Net:NS to do
a dns lookup against a specific server,
following on the instructions in the Net:NS man
page, I have created a
lookup object:-
  my $lookup = Net:NS::Reso
lver->new(
        nameservers => [$nameserver],
        recurse     => 0,
        debug       => 0,
  );

and I can do a lookup with :-
  my $packet = $lookup->send($query);

Taking $packet apart with Data:umper
reveals the structure but I cannot
get the syntax correct to extract the lookup result from
$packet. I am
assuming that $packet is an object so:-
my $reply = $packet-> ; (amongst other tries)

Clearly this is not correct but I cannot see why. The first
part of the
structure of $packet is:-
DataDumper of $packet is
$VAR1 = bless( {
                 'answer' => [
                               bless( {
                                        'rdlength' =>
4,
                                        'ttl' => 10800,
                                        'name' =>
'ns0.brm.pri',
                                        'address' =>
'10.79.0.100',
                                        'class' =>
'IN',
                                        'type' =>
'A',
                                        'rdata' => '
Od'
                                      }, 'Net:NS::RR::
A' )
                             ],


Can anyone put me on the right track?

Regards,
Andrew



"If the SOFTWARE is not accompanied by HARDWARE, you
may not use the
SOFTWARE."
 Win eXPerimantal EULA.  Really....?

$packet->answer should return a list of Net:NS::RR
objects.  In your case,
one Net:NS::RR::
A object so you should be able to access the object by
using : (Though the data dump suggests it is not a list)

$packet->answer->[0]->address;

If it is not a list then $packet->answer->address
should work.

Cheers

Ben


-----Original Message-----
From: birmingham-pm-bounces+bellis=i2q.co.ukpm.org
[mailto:birmingham-pm-bounces+bellis=i2q.co.ukpm.org]
On Behalf Of Andrew
Stringer
Sent: 29 March 2006 09:54
To: birmingham-pmpm.org
Subject: Net:NS
objects

Hello, I'm using Net:NS to do
a dns lookup against a specific server,
following on the instructions in the Net:NS man
page, I have created a
lookup object:-
  my $lookup = Net:NS::Reso
lver->new(
        nameservers => [$nameserver],
        recurse     => 0,
        debug       => 0,
  );

and I can do a lookup with :-
  my $packet = $lookup->send($query);

Taking $packet apart with Data:umper
reveals the structure but I cannot
get the syntax correct to extract the lookup result from
$packet. I am
assuming that $packet is an object so:-
my $reply = $packet-> ; (amongst other tries)

Clearly this is not correct but I cannot see why. The first
part of the
structure of $packet is:-
DataDumper of $packet is
$VAR1 = bless( {
                 'answer' => [
                               bless( {
                                        'rdlength' =>
4,
                                        'ttl' => 10800,
                                        'name' =>
'ns0.brm.pri',
                                        'address' =>
'10.79.0.100',
                                        'class' =>
'IN',
                                        'type' =>
'A',
                                        'rdata' => '
Od'
                                      }, 'Net:NS::RR::
A' )
                             ],


Can anyone put me on the right track?

Regards,
Andrew



"If the SOFTWARE is not accompanied by HARDWARE, you
may not use the
SOFTWARE."
 Win eXPerimantal EULA.  Really....?

Hello.

On Wed, 2006-03-29 at 09:53 +0100, Andrew Stringer wrote:
> Hello, I'm using Net:NS to do
a dns lookup against a specific server,
> following on the instructions in the Net:NS man
page, I have created a
> lookup object:-
>   my $lookup = Net:NS::Reso
lver->new(
>         nameservers => [$nameserver],
>         recurse     => 0,
>         debug       => 0,
>   );
> 
> and I can do a lookup with :-
>   my $packet = $lookup->send($query);
> 
> Taking $packet apart with Data:umper
reveals the structure but I cannot
> get the syntax correct to extract the lookup result
from $packet. I am
> assuming that $packet is an object so:-
> my $reply = $packet-> ; (amongst other
tries)
[snip]

Not used this module, but from "perldoc Net:NS::Reso
lver":

"Returns a "Net:NS::Pack
et" object whether there were any answers or
not.  Use "$packet->header->ancount" or
"$packet->answer" to find out if
there were any records in the answer section.  Returns
"undef" if there
was an error."

"perldoc Net:NS::Pack
et" shows:

"answer, pre, prerequisite

answer = $packet->answer;

Returns a list of "Net:NS::RR&
quot; objects representing the answer sec-
tion of the packet."

I guess you want something like this:

my $answer;
if (defined($packet->answer) &&
defined($packet->answer->[0]))
{
  $answer = $packet->answer->[0]->;
}

...assuming you want only the first A record.

(Completely untested code. May be broken!)

Bye, Rich

-- 
Richard Dawe
Senior Software Engineer
MessageLabs - Be Certain


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Thanks to Ben & Richard, but I'm still confused.

If I do:-
my answer=$packet->answer ;

I get:-
$answer[0] is Net:NS::RR::
A=HASH(0x8410f5c)

This suggests to me that $packet->answer->[0] contains
a hash reference,
and I should be able to use -> as the key to get
the value.

But the result from:-
print $packet->answer->[0]->,
"\n\n";

is:-
Use of uninitialized value in print at ./test.pl line 29

Is uninitialized the same as undef?

If it is, I think I am asking for the value from a non
existant key, but I
cannot see how to craft the  correct question to a key value
which exists.

Regards,
Andrew


"If the SOFTWARE is not accompanied by HARDWARE, you
may not use the
SOFTWARE."
 Win eXPerimental EULA.  Really....?

Andrew,

So am I.  Have you tried $packet->answer->?.

Alternatively break it down :

$answer = =$packet->answer;
$address = $answer->;

And see if that helps.

Cheers

Ben

-----Original Message-----
From: birmingham-pm-bounces+bellis=i2q.co.ukpm.org
[mailto:birmingham-pm-bounces+bellis=i2q.co.ukpm.org]
On Behalf Of Andrew
Stringer
Sent: 30 March 2006 11:07
To: birmingham-pmpm.org
Subject: Re: Net:NS
objects

Thanks to Ben & Richard, but I'm still confused.

If I do:-
my answer=$packet->answer ;

I get:-
$answer[0] is Net:NS::RR::
A=HASH(0x8410f5c)

This suggests to me that $packet->answer->[0] contains
a hash reference,
and I should be able to use -> as the key to get
the value.

But the result from:-
print $packet->answer->[0]->,
"\n\n";

is:-
Use of uninitialized value in print at ./test.pl line 29

Is uninitialized the same as undef?

If it is, I think I am asking for the value from a non
existant key, but I
cannot see how to craft the  correct question to a key value
which exists.

Regards,
Andrew


"If the SOFTWARE is not accompanied by HARDWARE, you
may not use the
SOFTWARE."
 Win eXPerimental EULA.  Really....?