under sub { validate_cookie() };
get "/foo" => sub {
    my $c = shift;
    ...
};
get "/bar" => sub {
    my $c = shift;
    ...
};

##</code><code>##

get "/foo" => sub {
    validate_cookie() or return;
    my $c = shift;
    ...
};
get "/bar" => sub {
    validate_cookie() or return;
    my $c = shift;
    ...
};