use strict;
use warnings;
use CGI;

my $q    = CGI->new();
my $id   = $q->param('id')   || 0;
my $name = $q->param('name') || '';

my $all_valid = 1;
# Apply your rules for parameter validation.
# If some is not valid then $all_valid = 0

if(! $all_valid) {
    # log the information somewhere, file, DB ...
    # redirect
    print redirect(-uri => 'xyz.com/index.html',
                   -status => 303
                  );
    exit;
}

# all is well. Continue processing