From: Fabian Keil <fk@fabiankeil.de>
Date: Mon, 2 Jun 2014 06:20:51 +0000 (+0000)
Subject: Add documentation for external filters
X-Git-Tag: v_3_0_22~136
X-Git-Url: http://www.privoxy.org/gitweb/user-manual/static/@default-cgi@toggle?a=commitdiff_plain;h=2b8bec1ba7fa010ae0aa6aadfae62261ca11dabd;p=privoxy.git
Add documentation for external filters
---
diff --git a/doc/source/p-config.sgml b/doc/source/p-config.sgml
index c1ef4d7b..d8d9fb3f 100644
--- a/doc/source/p-config.sgml
+++ b/doc/source/p-config.sgml
@@ -3,7 +3,7 @@
Purpose : Used with other docs and files only.
- $Id: p-config.sgml,v 2.103 2014/02/10 14:39:13 fabiankeil Exp $
+ $Id: p-config.sgml,v 2.104 2014/05/05 09:59:30 fabiankeil Exp $
Copyright (C) 2001-2011 Privoxy Developers http://www.privoxy.org/
See LICENSE.
@@ -97,7 +97,7 @@
Sample Configuration File for Privoxy &p-version;
</title>
<para>
- $Id: p-config.sgml,v 2.103 2014/02/10 14:39:13 fabiankeil Exp $
+ $Id: p-config.sgml,v 2.104 2014/05/05 09:59:30 fabiankeil Exp $
</para>
<para>
Copyright (C) 2001-2013 Privoxy Developers http://www.privoxy.org/
@@ -588,6 +588,55 @@ II. FORMAT OF THE CONFIGURATION FILE
</sect3>
+<!-- ~~~~~ New section ~~~~~ -->
+<sect3 renderas="sect4" id="temporary-directory"><title>temporary-directory</title>
+
+<variablelist>
+ <varlistentry>
+ <term>Specifies:</term>
+ <listitem>
+ <para>A directory where Privoxy can create temporary files.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Type of value:</term>
+ <listitem>
+ <para>Path name</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Default value:</term>
+ <listitem>
+ <para>unset</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Effect if unset:</term>
+ <listitem>
+ <para>No temporary files are created, external filters don't work.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Notes:</term>
+ <listitem>
+ <para>
+ To execute <literal><ulink url="actions-file.html#EXTERNAL-FILTER">external filters</ulink></literal>,
+ <application>Privoxy</application> has to create temporary files.
+ This directive specifies the directory the temporary files should
+ be written to.
+ </para>
+ <para>
+ It should be a directory only <application>Privoxy</application>
+ (and trusted users) can access.
+ </para>
+ </listitem>
+ </varlistentry>
+</variablelist>
+
+<![%config-file;[<literallayout>@@#temporary-directory .</literallayout>]]>
+</sect3>
+
+
<!-- ~~~~~ New section ~~~~~ -->
<sect3 renderas="sect4" id="logdir"><title>logdir</title>
diff --git a/doc/source/user-manual.sgml b/doc/source/user-manual.sgml
index 10d0add7..eb4fd30e 100644
--- a/doc/source/user-manual.sgml
+++ b/doc/source/user-manual.sgml
@@ -36,7 +36,7 @@
This file belongs into
ijbswa.sourceforge.net:/home/groups/i/ij/ijbswa/htdocs/
- $Id: user-manual.sgml,v 2.182 2014/05/05 10:08:43 fabiankeil Exp $
+ $Id: user-manual.sgml,v 2.183 2014/05/26 10:48:39 fabiankeil Exp $
Copyright (C) 2001-2013 Privoxy Developers http://www.privoxy.org/
See LICENSE.
@@ -62,7 +62,7 @@
</subscript>
</pubdate>
-<pubdate>$Id: user-manual.sgml,v 2.182 2014/05/05 10:08:43 fabiankeil Exp $</pubdate>
+<pubdate>$Id: user-manual.sgml,v 2.183 2014/05/26 10:48:39 fabiankeil Exp $</pubdate>
<!--
@@ -3601,6 +3601,92 @@ problem-host.example.com</screen>
</variablelist>
</sect3>
+<!-- ~~~~~ New section ~~~~~ -->
+<sect3 renderas="sect4" id="external-filter">
+<title>external-filter</title>
+
+<variablelist>
+ <varlistentry>
+ <term>Typical use:</term>
+ <listitem>
+ <para>Modify content using a programming language of your choice.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Effect:</term>
+ <listitem>
+ <para>
+ All instances of text-based type, most notably HTML and JavaScript, to which
+ this action applies, can be filtered on-the-fly through the specified external
+ filter.
+ By default plain text documents are exempted from filtering, because web
+ servers often use the <literal>text/plain</literal> MIME type for all files
+ whose type they don't know.)
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Type:</term>
+ <!-- boolean, parameterized, Multi-value -->
+ <listitem>
+ <para>Parameterized.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Parameter:</term>
+ <listitem>
+ <para>
+ The name of an external content filter, as defined in the
+ <link linkend="filter-file">filter file</link>.
+ External filters can be defined in one or more files as defined by the
+ <literal><link linkend="filterfile">filterfile</link></literal>
+ option in the <link linkend="config">config file</link>.
+ </para>
+ <para>
+ When used in its negative form,
+ and without parameters, <emphasis>all</emphasis> filtering with external
+ filters is completely disabled.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Notes:</term>
+ <listitem>
+ <para>
+ External filters are scripts or programs that can modify the content in
+ case common <literal><link linkend="filter">filters</link></literal>
+ aren't powerful enough.
+ </para>
+ <warning>
+ <para>
+ Currently external filters are executed with &my-app;'s privileges.
+ Only use external filters you understand and trust.
+ </para>
+ </warning>
+ <para>
+ This feature is experimental, the <literal><link
+ linkend="external-filter-syntax">syntax</link></literal>
+ may change in the future.
+ </para>
+
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Example usage:</term>
+ <listitem>
+ <para>
+ <screen>+external-filter{fancy-filter}</screen>
+ </para>
+ </listitem>
+ </varlistentry>
+</variablelist>
+</sect3>
+
<!-- ~~~~~ New section ~~~~~ -->
<sect3 renderas="sect4" id="fast-redirects">
<title>fast-redirects</title>
@@ -6453,7 +6539,7 @@ stupid-server.example.com/</screen>
</para>
<para>
- &my-app; supports three different filter actions:
+ &my-app; supports three different pcrs-based filter actions:
<literal><link linkend="filter">filter</link></literal> to
rewrite the content that is send to the client,
<literal><link linkend="client-header-filter">client-header-filter</link></literal>
@@ -6473,6 +6559,13 @@ stupid-server.example.com/</screen>
applying actions through sections with <link linkend="tag-pattern">tag-patterns</link>.
</para>
+<para>
+ Finally &my-app; supports the
+ <literal><link linkend="external-filter">external-filter</link></literal> action
+ to enable <literal><link linkend="external-filter-syntax">external filters</link></literal>
+ written in proper programming languages.
+</para>
+
<para>
Multiple filter files can be defined through the <literal> <link
@@ -7290,6 +7383,72 @@ pre-defined filters for your convenience:
</variablelist>
</sect2>
+
+<!-- ~~~~~~~~ New section Header ~~~~~~~~~ -->
+<sect2 id="external-filter-syntax"><title>External filter syntax</title>
+<para>
+ External filters are scripts or programs that can modify the content in
+ case common <literal><link linkend="filter">filters</link></literal>
+ aren't powerful enough.
+</para>
+<para>
+ External filters can be written in any language the platform &my-app; runs
+ on supports.
+</para>
+<para>
+ They are controlled with the
+ <literal><link linkend="external-filter">external-filter</link></literal> action
+ and have to be defined in the <literal><link linkend="filterfile">filterfile</link></literal>
+ first.
+</para>
+<para>
+ The header looks like any other filter, but instead of pcrs jobs, external
+ filters contain a single job which can be a program or a shell script (which
+ may call other scripts or programs).
+</para>
+<para>
+ External filters read the content from STDIN and write the rewritten
+ content to STDOUT. The environment variables PRIVOXY_URL, PRIVOXY_PATH,
+ PRIVOXY_HOST, PRIVOXY_ORIGIN can be used to get some details about the
+ client request.
+</para>
+<para>
+ &my-app; will temporary store the content to filter in the
+ <literal><link linkend="temporary-directory">temporary-directory</link></literal>.
+</para>
+<para>
+ <screen>
+EXTERNAL-FILTER: cat Pointless example filter that doesn't actually modify the content
+/bin/cat
+
+# Incorrect reimplementation of the filter above in POSIX shell.
+#
+# Note that it's a single job that spans multiple lines, the line
+# breaks are not passed to the shell, thus the semicolons are required.
+#
+# If the script isn't trivial, it is recommended to put it into an external file.
+#
+# In general, writing external filters entirely in POSIX shell is not
+# considered a good idea.
+EXTERNAL-FILTER: cat2 Pointless example filter that despite its name may actually modify the content
+while read line; \
+do \
+ echo "$line"; \
+done
+</screen>
+</para>
+
+<warning>
+ <para>
+ Currently external filters are executed with &my-app;'s privileges!
+ Only use external filters you understand and trust.
+ </para>
+</warning>
+<para>
+ External filters are experimental and the syntax may change in the future.
+</para>
+</sect2>
+
</sect1>
<!-- ~ End section ~ -->