Looking for DNS/Operational experience

[Mike Leber]

Hehehe, that's pretty cool that you already submitted a patch for it! :)

Mike.

Bjørn Mork wrote:
> Mike Leber <mleber at he.net> writes:
>> Bjørn Mork wrote:
>>> Mike Leber <mleber at he.net> writes:
>>>
>>>> Since you mentioned Perl, here is a way to do it with Perl:
>>>>
>>>> $ perl -e 'use Net::IP;$ip=new Net::IP("2a02:c0:100::2/128");print
>>>> ($ip->reverse_ip()."\n");'
>>>>
>>>> 2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.c.0.0.2.0.a.2.ip6.arpa.
>>>>
>>>> You'll probably find Net::IP very useful.  You can use it to write
>>>> code that is nearly address family agnostic.
>>> No, you can't.  You can use it for IPv6, but it fails for IPv4 (CIDR):
>> To date, I'd bet Net::IP has been used in more IPv4 code than IPv6.
> 
> Sure.  You just can't use the reverse_ip function.  The rest of Net::IP
> is quite nice, and I certainly use it for IPv6.
> 
>> The documentation for the reverse_ip function is:
>>
>> QUOTE
>> Return the reverse IP for a given IP address (in.addr. format).
>> ENDQUOTE
>>
>> It says IP address (not prefix)
> 
> Oh, but it doesn't work any better with an IP address:
> 
> bjorn at nemi:/tmp$ perl -e 'use Net::IP;$ip=new Net::IP("192.168.4.0");print $ip->reverse_ip()."\n"'
> 4.168.192.in-addr.arpa.
> 
>> plus they probably didn't test for somebody using .0 of a prefix.
> 
> No, the probably didn't.  Which probably is why it doesn't work :-)
> 
>> This function is just one of 27.
>>
>> If you find a behavior in a package you don't agree with:
>>
>> 1) Find out how other people made it work correctly.  Read the
>> documentation and use Google.  Look at what how the module writer
>> actually wrote the function you are using.
> 
> I did.   I sent this patch to the author in february 2008:
> 
> diff -urN a/Net/IP.pm b/Net/IP.pm
> --- a/Net/IP.pm	2008-02-06 11:47:39.870067846 +0100
> +++ b/Net/IP.pm	2008-02-06 11:54:26.622068489 +0100
> @@ -1769,15 +1769,12 @@
>  
>      if ($ip_version == 4) {
>          my @quads    = split /\./, $ip;
> -        my $no_quads = ($len / 8);
> +        my $first_quad_index = $len ? 4 - (int($len / 8)) : 0;
>  
>          my @reverse_quads = reverse @quads;
>  
> -        while (@reverse_quads and $reverse_quads[0] == 0) {
> -            shift(@reverse_quads);
> -        }
> -
> -        return join '.', @reverse_quads, 'in-addr', 'arpa.';
> +        return join '.', @reverse_quads[ $first_quad_index .. $#reverse_quads ],
> +          'in-addr', 'arpa.';
>      }
>      elsif ($ip_version == 6) {
>          my @rev_groups = reverse split /:/, $ip;
> 
> 
>> 2) Write your own perl code to handle it.
> 
> I did.  It's not like it's a big problem.
> 
>> 3) Find another package that does what you want.
> 
> It's not that important to me. 
> 
>> 4) Fix the module, or write a fixed version of the function, and mail
>> the module writer.  Other people will probably run into the same
>> thing.
> 
> Oh, they already did.  See
> 
> http://rt.cpan.org/Public/Bug/Display.html?id=42793
> http://rt.cpan.org/Public/Bug/Display.html?id=25169
> 
> 
> Bjørn

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| Mike Leber        Wholesale IPv4 and IPv6 Transit      510 580 4100 |
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