Darold Gilles > Apache2-ModProxyPerlHtml-3.5 > Apache2::ModProxyPerlHtml

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Module Version: 3.5   Source   Latest Release: Apache2-ModProxyPerlHtml-3.6

DESCRIPTION ^

Apache2::ModProxyPerlHtml is the most advanced Apache output filter to rewrite HTTP headers and HTML links for reverse proxy usage. It is written in Perl and exceeds all mod_proxy_html.c limitations without performance lost.

Apache2::ModProxyPerlHtml is very simple and has far better parsing/replacement of URL than the original C code. It also support meta tag, CSS, and javascript URL rewriting and can be use with compressed HTTP. You can now replace any code by other, like changing images name or anything else. mod_proxy_html can't do all of that. Since release 3.x ModProxyPerlHtml is also able to rewrite HTTP headers with Refresh url redirection and Referer.

The replacement capability concern only the following HTTP content type:

        text/javascript
        text/html
        text/css
        text/xml
        application/.*javascript
        application/.*xml

other kind of file, will be left untouched (or see ProxyHTMLContentType and ProxyHTMLExcludeContentType).

AVAIBILITY ^

You can get the latest version of Apache2::ModProxyPerlHtml from CPAN (http://search.cpan.org/).

PREREQUISITES ^

You must have Apache2, mod_perl2 and IO::Compress::Zlib perl modules installed on your system.

You also need to install the mod_proxy Apache modules. See documentation at http://httpd.apache.org/docs/2.0/mod/mod_proxy.html

INSTALLATION ^

        % perl Makefile.PL
        % make && make install

APACHE CONFIGURATION ^

In your Apache configuration file you have to load the following DSO modules:

    LoadModule deflate_module modules/mod_deflate.so
    LoadModule headers_module modules/mod_headers.so
    LoadModule proxy_module modules/mod_proxy.so
    LoadModule proxy_connect_module modules/mod_proxy_connect.so
    LoadModule proxy_ftp_module modules/mod_proxy_ftp.so
    LoadModule proxy_http_module modules/mod_proxy_http.so
    LoadModule ssl_module modules/mod_ssl.so
    LoadModule perl_module  modules/mod_perl.so

Then in your Apache site or virtualhost configuration file use ModProxyPerlHtml* as follow:

    ProxyRequests Off
    ProxyPreserveHost Off
    ProxyPass       /webcal/  http://webcal.domain.com/

    PerlInputFilterHandler Apache2::ModProxyPerlHtml
    PerlOutputFilterHandler Apache2::ModProxyPerlHtml
    SetHandler perl-script
    PerlSetVar ProxyHTMLVerbose "On"
    LogLevel Info


    <Location /webcal/>
        ProxyPassReverse /
        PerlAddVar ProxyHTMLURLMap "/ /webcal/"
        PerlAddVar ProxyHTMLURLMap "http://webcal.domain.com /webcal"
    </Location>

Note that here FilterHandlers are set globally, you can also set them in any <Location> part to set it locally and avoid calling this Apache module globally.

If you want to rewrite some code on the fly, like changing images filename you can use the perl variable ProxyHTMLRewrite under the location directive as follow:

    <Location /webcal/>
        ...
        PerlAddVar ProxyHTMLRewrite "/logo/image1.png /images/logo1.png"
        # Or more complicated to handle space in the code as space is the
        # pattern / substitution separator character internally in ModProxyPerlHtml
        PerlAddVar ProxyHTMLRewrite "ajaxurl[\s\t]*=[\s\t]*'/blog' ajaxurl = '/www2.mydom.org/blog'"
        ...
    </Location>

this will replace each occurence of '/logo/image1.png' by '/images/logo1.png' in the entire stream (html, javascript or css). Note that this kind of substitution is done after all other proxy related replacements.

In some conditions javascript code can be replaced by error, for example:

        imgUp.src = '/images/' + varPath + '/' + 'up.png';

will be rewritten like this:

        imgUp.src = '/URL/images/' + varPath + '/URL/' + 'up.png';

To avoid the second replacement, write your JS code like that:

        imgUp.src = '/images/' + varPath + unescape('%2F') + 'up.png';

ModProxyPerlHTML replacement is activated on certain HTTP Content Type. If you experienced that replacement is not activated for your file type, you can use the ProxyHTMLContentType configuration directive to redefined the HTTP Content Type that should be parsed by ModProxyPerlHTML. The default value is the following Perl regular expresssion:

        PerlAddVar ProxyHTMLContentType    (text\/javascript|text\/html|text\/css|text\/xml|application\/.*javascript|application\/.*xml)

If you know exactly what you are doing by editing this regexp fill free to add the missing Content-Type that must be parsed by ModProxyPerlHTML. Otherwise drop me a line with the content type, I will give you the rigth expression. If you don't know about the content type, with FireFox simply type Ctrl+i on the web page.

Some MS Office files may conflict with the above ProxyHTMLContentType regex like .docx or .xlsx files. The result is that there could suffer of replacement inside and the file will be corrupted. to prevent this you have the ProxyHTMLExcludeContentType configuration directive to exclude certain content-type. Here is the default value:

        ProxyHTMLExcludeContentType     (application\/vnd\.openxml)

If you have problem with other content-type, use this directive. For example, as follow:

        ProxyHTMLExcludeContentType     (application\/vnd\.openxml|application\/vnd\..*text)

this regex will prevent any MS Office XML or text document to be parsed.

LIVE EXAMPLE ^

Here is the reverse proxy configuration I use to give access to Internet users to internal applications:

    ProxyRequests Off
    ProxyPreserveHost Off
    ProxyPass       /webmail/  http://webmail.domain.com/
    ProxyPass       /webcal/  http://webcal.domain.com/
    ProxyPass       /intranet/  http://intranet.domain.com/


    PerlInputFilterHandler Apache2::ModProxyPerlHtml
    PerlOutputFilterHandler Apache2::ModProxyPerlHtml
    SetHandler perl-script
    PerlSetVar ProxyHTMLVerbose "On"
    LogLevel Info


    # URL rewriting
    RewriteEngine   On
    #RewriteLog      "/var/log/apache/rewrite.log"
    #RewriteLogLevel 9
    # Add ending '/' if not provided
    RewriteCond     %{REQUEST_URI}  ^/mail$
    RewriteRule     ^/(.*)$ /$1/    [R]
    RewriteCond     %{REQUEST_URI}  ^/planet$
    RewriteRule     ^/(.*)$ /$1/    [R]
    # Add full path to the CGI to bypass the index.html redirect that may fail
    RewriteCond     %{REQUEST_URI}  ^/calendar/$
    RewriteRule     ^/(.*)/$ /$1/cgi-bin/wcal.pl    [R]
    RewriteCond     %{REQUEST_URI}  ^/calendar$
    RewriteRule     ^/(.*)$ /$1/cgi-bin/wcal.pl     [R]


    <Location /webmail/>
        ProxyPassReverse /
        PerlAddVar ProxyHTMLURLMap "/ /webmail/"
        PerlAddVar ProxyHTMLURLMap "http://webmail.domain.com /webmail"
        # Use this to disable compressed HTTP
        #RequestHeader   unset   Accept-Encoding
    </Location>


    <Location /webcal/>
        ProxyPassReverse /
        PerlAddVar ProxyHTMLURLMap "/ /webcal/"
        PerlAddVar ProxyHTMLURLMap "http://webcal.domain.com /webcal"
    </Location>


    <Location /intranet/>
        ProxyPassReverse /
        PerlAddVar ProxyHTMLURLMap "/ /intranet/"
        PerlAddVar ProxyHTMLURLMap "http://intranet.domain.com /intranet"
        # Rewrite links that give access to the two previous location 
        PerlAddVar ProxyHTMLURLMap "/intranet/webmail /webmail"
        PerlAddVar ProxyHTMLURLMap "/intranet/webcal /webcal"
    </Location>

This gives access two a webmail and webcal application hosted internally to all authentified users through their own Internet acces. There's also one acces to an Intranet portal that have links to the webcal and webmail application. Those links must be rewritten twice to works.

BUGS ^

Apache2::ModProxyPerlHtml is still under development and is pretty stable. Please send me email to submit bug reports or feature requests.

COPYRIGHT ^

Copyright (c) 2005-2012 - Gilles Darold

All rights reserved. This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.

AUTHOR ^

Apache2::ModProxyPerlHtml was created by :

        Gilles Darold
        <gilles at darold dot net>

and is currently maintain by me.

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