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VMOD_HEADER(3)		    Library Functions Manual		  VMOD_HEADER(3)

NAME
     vmod_header - Header VMOD for Varnish

SYNOPSIS
	import header [as name] [from "path"]

	VOID append(HEADER, STRING)

	VOID copy(HEADER, HEADER)

	STRING get(HEADER header, REGEX regex)

	VOID remove(HEADER header, REGEX regex)

	VOID regsub(HTTP, REGEX regex, STRING sub, BOOL all)

	HEADER dyn(HTTP, STRING)

DESCRIPTION
     Varnish  Module  for  manipulation of duplicated HTTP headers, for instance
     multiple Set-Cookie headers.

     Example:

	vcl 4.0;
	import header;

	backend default { .host = "192.0.2.11"; .port = "8080"; }

	sub vcl_backend_response {
	    if (beresp.http.Set-Cookie) {
		# Add another line of Set-Cookie in the response.
		header.append(beresp.http.Set-Cookie, "VSESS=abbabeef");

		# CMS always set this, but doesn't really need it.
		header.remove(beresp.http.Set-Cookie, "JSESSIONID=");
	    }
	}

   VOID append(HEADER, STRING)
     Description
	    Append an extra occurrence to an existing header.

     Example
	    :: header.append(beresp.http.Set-Cookie, "foo=bar")

   VOID copy(HEADER, HEADER)
     Description
	    Copy all source headers to a new header.

     Example
	    :: header.copy(beresp.http.set-cookie, beresp.http.x-old-cookie);

   STRING get(HEADER header, REGEX regex)
     Description
	    Fetches the value of the first header that matches the given regular
	    expression regex.

     Example
	    ::		     set	       beresp.http.xusr 	       =
	    header.get(beresp.http.set-cookie,"user=");

   VOID remove(HEADER header, REGEX regex)
     Description
	    Remove all occurrences of header that matches regex.

     Example
	    :: header.remove(beresp.http.set-cookie,"^(?!(funcookie=))");

   VOID regsub(HTTP, REGEX regex, STRING sub, BOOL all=0)
     Description
	    For  every	header line in the HTTP object, which can be one of req,
	    resp, bereq or beresp, if the line matches	the  regular  expression
	    regex,  then  replace it with the result of a substitution using the
	    string sub. sub may include backreferences of the  form  \1  through
	    \9,  which refer to capturing expressions in the regex, or \0 to re-
	    fer to the entire matched portion of the header line.

	    If all is false, replace the first matched	portion  of  the  header
	    line  with	sub. This is the same operation performed by the VCL na-
	    tive function regsub(). all is false by default.

	    If all is true, replace each non-overlapping matched portion of  the
	    header line with sub. This is the same operation performed by native
	    regsuball().

	    Note  that unlike the other functions in this VMOD, regsub() applies
	    to the entire header line, including the header name, colon  separa-
	    tor,  and  header value. Take care that your substitutions result in
	    valid headers, since ill-formed headers can interfere with the  HTTP
	    protocol.

	    Consider  case sensitivity in the regex match. The standard dictates
	    that header names are case insensitive, but header values  are  not.
	    The  VMOD  function  does not take care of that for you, but you can
	    express it in the regex using the (?i) flag, as shown in the example
	    below (use (?-i) to turn it off).

	    Consider using the ^ starting anchor in regex to be sure to match  a
	    header  name (and not the same string somewhere in the middle of the
	    line).

     Example
	    :: header.regsub(req, "^(?i)Foo(\d): (?-i)bar=(.*)$", "Bar\1: \2")

   HEADER dyn(HTTP, STRING)
     Description
	    Return a dynamic header name.

	    Most other functions of this vmod require a HEADER	argument,  which
	    usually is a VCL-defined header like req.http.foo.

	    This  function  allows  to construct a header name from an arbitrary
	    string, which may also be dynamically created, for	example  from  a
	    variable.

	    Notice  that there are no syntactic checks on the STRING argument by
	    purpose in order to support exotic use cases. It is entirely  up  to
	    the user and at their own risk to supply a string which represents a
	    valid HTTP header name (or not).

     Example
	    ::	#  create  this  request  header  # 42: is the answer header.ap-
	    pend(header.dyn(req, 35 + 7), "is the answer");

ACKNOWLEDGEMENTS
     The development of this plugin was made  possible	by  the  sponsorship  of
     Softonic,	<http://en.softonic.com/>  .

     Also thanks to Imo Klabun and Anders Nordby for bug reports.

BUGS
     You can't use dynamic regular expressions, which also holds true for normal
     regular expressions in regsub().

								  VMOD_HEADER(3)

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