use strict;
use warnings;

my ($sec, %config);
while (<DATA>) {
   $sec = $1 and next if /^\[([^\]]+)\]/;
   $config{$sec}{$1} = $2 if /^\s*([^=]+)\s*=\s*"([^"]+)"/;
}

=cut
we now have ths following structure:

%config = (
   client => {
      host = 'localhost',
      port = '8080'
   },

   server => {
      host    => 'localhost',
      port    => '8900',
      timeout => '60'
   }
);
=cut

__DATA__
[client]
host="localhost"
port="8080"

[server]
host="localhost"
port="8900"
timeout="60"