# usual strict and warnings and such

use Date::Parse;        # to parse the entry date
use Text::ParseWords;   # to handled quoted entries

# $logfile defined in skipped code

open DF, $logfile or die $!;
while (<DF>) {
    chomp;
    # the following conversion is so the date can be
    #   captured intact
    s/(\[|\])/"/g;
    my @part = Text::ParseWords::quotewords( '\s+', 0, $_ );
    $part[3] = str2time( $part[3] );

    # deal with whatever part 
    #   of the log entry here you need

}
close DF;