How can I return HTTP 403 from a template?

Question

I'm building a rough JSON API using normal Craft templates (i.e. rendering the JSON with Twig) but would like to be able to return HTTP 403 to unauthenticated requests.

For example:

{% if not user %}
    {% respond 403 %}
{% endif %}

Is something like this built in?

Answer 1

Exit tag is what you're looking for.

{% exit 403 %}

Answer 2

Bit of a shot in the dark here, but it might be worth having a look at the header tag, see if you can get that to do what you need...