===========
vmod_frozen
===========

---------------------
Varnish frozen Module
---------------------

DESCRIPTION
===========

This vmod makes available to VCL the _frozen_ JSON parser with low
overhead: By specifying a set of expected JSON paths, a callback to
the parser is used to track only paths of interest, which can then be
extracted.

Example
    ::

	import frozen;

	sub vcl_init {
	    new jwt_hdr = frozen.parser();
	    jwt_hdr.expect(".alg", type=STRING, null=false, required=true);
	    jwt_hdr.expect(".typ", type=STRING, null=false, required=true);

	    new jwt_payload = frozen.parser();
	    jwt_payload.expect(".attr");

	}

	sub vcl_recv {
	    if (! jwt_hdr.parse(...) ||
		jwt_hdr.extract(".alg") != "RS256" ||
		jwt_hdr.extract(".typ") != "JWT") {
		return (synth(400, "unsupported jwt alg/typ"));
	    }

	    if (! jwt_payload.parse(...)) {
		return (synth(400, "parse error"));
	    }

	    set req.http.something =
		jwt_payload.extract(".attr",
				    null = "<null>", undef = "<undef>");

	    # ...
	}

INSTALLATION
============

See `INSTALL.rst <INSTALL.rst>`_ in the source repository.

SEE ALSO
========

* vcl(7)
* varnishd(1)

COPYRIGHT
=========

::

  Copyright 2018 UPLEX Nils Goroll Systemoptimierung
  All rights reserved
 
  Author: Nils Goroll <nils.goroll@uplex.de>
 
  See LICENSE