inet_ntoa question

Funkster has asked for the wisdom of the Perl Monks concerning the following question:

Any correlation between me and reality, let alone my opinions and those of my employer, is entirely coincidental

I'm not worthy, I'm not worthy...but I do believe in the interconnectedness of all things...
I have a database that keeps ip addresses stored as 32 bit integers. I have to extract this and make an ascii string for a config file. If this were C, i'd stuff the address in the appropriate part of in_addr, and call inet_ntoa. Can't see how to get into the structures for Perl.. and all the references i find to inet_ntoa on web searches either
a. get a value using gethostbyname (not applicable)
b. talk about opaque values (which I don't understand)
c. seem to be using a structure, but are not clear how one manipulates the structure.
Here's what I'm trying to do:

use Socket;
#=================================================================
$var=0x0a0a0a01;   #simulate the value from the database
printf(STDERR  "DEBUG, var is %4.4x \n", $var);
print STDERR "DEBUG, var is $var\n";
$peer_addr = inet_ntoa($var);
print "DEBUG, $peer_addr";
[download]

which gives the infamous output of:

DEBUG, var is a0a0a01 
DEBUG, var is 168430081
Bad arg length for Socket::inet_ntoa, length is 9, should be 4
[download]

9. Hmmm is it relevant that that is the number of digits in the "print" value.. is it being stored in some format other than integer?

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Re: inet_ntoa question by esskar (Deacon) on Mar 04, 2004 at 20:46 UTC
`print inet_ntoa(pack("N", $var));`	[reply] [d/l]
Re: inet_ntoa question by Paladin (Vicar) on Mar 04, 2004 at 20:50 UTC
It is being stored as an int. The problem is that `inet_ntoa` takes a 4 character string as an argument. You need to do something like: `$var=chr(0x0a).chr(0x0a).chr(0x0a).chr(0x01); # OR $var=v10.10.10.1; #using the v-string notation if your perl is new en +ough # OR $var=pack "CCCC", 10, 10, 10, 1; # OR (probably best yet) $var=inet_aton 0x0a0a0a01;` [download] To get the proper string format to feed to `inet_ntoa`	[reply] [d/l] [select]
Re: Re: inet_ntoa question by Funkster (Initiate) on Mar 04, 2004 at 23:52 UTC
Any correlation between me and reality, let alone my opinions and those of my employer, is entirely coincedental Thankx, guys. I have a working solution.. (inet_ntoa(pack). and info that wasn't clear ntoa takes 4 chars). next task is to read up on pack and integer representation.... it's not clear to an old C guy why integer is different than the 4 concatenated characters you suggest.... if I cat the 4 1 byte chars x0a. 0xa . 0xa . 0x01 how is that different than the 32 bit value 0A0A0A01 that I had originally? mu la mi. guess I need to RTFM to figure out what really need to ask.	[reply]