Personally, I'd use Date::Calc, which has given me good results in the past.

Here's a small program showing how you could pass a date string as dd-mm-yyyy, parse it into the corresponding day, month, and year, and test it with Date::Calc::check_date:

use strict;
use warnings;

use Date::Calc qw/check_date/;

check_this("28-02-2007");
check_this("31-02-2007");


sub check_this {
    my ($date) = @_;
    if ($date !~ /^(\d+)-(\d+)-(\d+)$/) {
        printf "Invalid date '$date'\n";
        return;
    }
    my ($day, $mon, $yr) = ($1, $2, $3);
    my $result = check_date($yr, $mon, $day);
    printf "Result for '$date' => %s\n", $result? "Okay": "Bad";
}
[download]

The output is:

Result for '28-02-2007' => Okay
Result for '31-02-2007' => Bad
[download]

Update:  Fixed mistyped method name.