###
# dnswrapper.pl to transmit dsn lines (usernames,passwords) to applica
+tions
###

#!/usr/bin/perl

use strict;
use Storable qw(freeze);
use vars qw($configfile %config $caller $dbi);

$configfile="dsn.conf";

open(C,$configfile) || die("$!: $configfile");
while(<C>) {$config{$1}=$2 if(/^\[([^\[|^\]]+)\]=\[([^\[|^\]]+)\]/)}
close(C);

die("No DSN Line !\n") if (!exists $config{DSN});
die("No USER Line !\n") if (!exists $config{USER});
die("No CALLER Line !\n") if (!exists $config{CALLER});
die("What Iam my own parent !") if($$==getppid());

open(P,'/proc/'.getppid().'/cmdline') || die("$!: PARENT CMDLINE");
$caller=<P>;
close(P);

$caller=$1 if ($caller=~/^perl\0([^\0]+)/);

if (getpwuid($<) eq $config{USER} and $caller eq $config{CALLER}) {
        print freeze({DSN=>$config{DSN}});
} else {
        die("Something went wroung !\n");
}
[download]

and the config

[USER]=[jason]
[DSN]=[DBI:mysql:dbname;user=dbuser]
[CALLER]=[/usr/local/bin/caller.pl]
[download]

and my example caller script

#!/usr/bin/perl

open(P,"perl ./dsnwrapper.pl|");
binmode(P);
my($dsn)=${(thaw(join('',<P>)))[0]}{DSN};
close(P);
my($dbh)=DBI->connect($dsn) || die(DBI->errstr);
[download]