NAME
    Apache::Filter::HTTPHeadersFixup - Manipulate Apache 2 HTTP Headers

Synopsis
      # MyApache/FixupInputHTTPHeaders.pm
      package MyApache::FixupInputHTTPHeaders;
  
      use strict;
      use warnings FATAL => 'all';
  
      use base qw(Apache::Filter::HTTPHeadersFixup);
  
      sub manip {
          my ($class, $ra_headers) = @_;
  
          # modify a header
          for (@$ra_headers) {
              s/^(Foo).*/$1: Moahaha/;
          }
  
          # push header (don't forget "\n"!)
          push @$ra_headers, "Bar: MidBar\n";
      }
      1;

      # httpd.conf
      <VirtualHost Zoot>
          PerlModule MyApache::FixupInputHTTPHeaders
          PerlInputFilterHandler MyApache::FixupInputHTTPHeaders
      </VirtualHost>

      # similar for output headers

Description
    "Apache::Filter::HTTPHeadersFixup" is a super class which provides an
    easy way to manipulate HTTP headers without invoking any mod_perl HTTP
    handlers. This is accomplished by using input and/or output connection
    filters.

    It supports KeepAlive connections.

    This class cannot be used as is. It has to be sub-classed. Read on.

Usage
    A new class inheriting from "Apache::Filter::HTTPHeadersFixup" needs to
    be created. That class needs to include a single function "manip()".
    This function is invoked with two arguments, the package it was invoked
    from and a reference to an array of headers, each terminated with a new
    line.

    That function can manipulate the values in that array. It shouldn't
    return anything. That means you can't assign to the reference itself or
    the headers will be lost.

    Now you can modify, add or remove headers.

    The function works identically for input and output HTTP headers.

    See the Synopsis section for an example. More examples can be seen in
    the test suite.

Debug
    "Apache::Filter::HTTPHeadersFixup" includes internal tracing calls,
    which make it easy to debug the parsing of the headers.

    First change the constant DEBUG to 1 in
    "Apache::Filter::HTTPHeadersFixup". Then enable Apache-Test debug
    tracing. For example to run a test with tracing enabled do:

      % t/TEST -trace=debug -v manip/out_append

    Or you can set the "APACHE_TEST_TRACE_LEVEL" environment variable to
    *debug* at the server startup:

      APACHE_TEST_TRACE_LEVEL=debug apachectl start

    All the tracing goes into *error_log*.

Bugs
See Also
    Apache2, mod_perl, Apache::Filter

Authors
    Stas Bekman <stas@stason.org>

Copyright
    The "Apache::Filter::HTTPHeadersFixup" module is free software; you can
    redistribute it and/or modify it under the same terms as Perl itself.