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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 in-
       stance 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  ex-
	      pression	regex,	then replace it	with the result	of a substitu-
	      tion 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  refer	 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
	      native 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() ap-
	      plies to the entire header  line,	 including  the	 header	 name,
	      colon separator, and header value. Take care that	your substitu-
	      tions  result in valid headers, since ill-formed headers can in-
	      terfere with the HTTP protocol.

	      Consider case sensitivity	in the regex match. The	standard  dic-
	      tates  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	 arbi-
	      trary 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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