[ ijbswa-Bugs-3423782 ] Clarify about filtering compressed content

Bugs item #3423782, was opened at 2011-10-14 08:55
Message generated for change (Comment added) made by fabiankeil
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Category: documentation
Group: version 3.0.17
>Status: Closed
Resolution: Accepted
Priority: 5
Private: No
Submitted By: dg1727 (dg1727)
Assigned to: Fabian Keil (fabiankeil)
Summary: Clarify about filtering compressed content

Initial Comment:
Privoxy 3.0.17

Under http://config.privoxy.org/user-manual/actions-file.html#FILTER there is a "Notes" section which says, in part:  

Inappropriate MIME types, such as zipped files, are not filtered at all. ...
Compressed content can't be filtered either, unless Privoxy is compiled with zlib support (requires at least Privoxy 3.0.7), in which case Privoxy will decompress the content before filtering it. 

At first glance, this seems self-contradictory (compressed content is never filtered, but sometimes it is filtered).  Can it be clarified in the HTML file for the sake of readers who are not quite technically adept enough to understand this apparent contradiction themselves?  Thanks in advance.  

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>Comment By: Fabian Keil (fabiankeil)
Date: 2012-12-15 05:31

Message:
I believe Privoxy users who care about the details of HTTP compression will
have no trouble looking it up elsewhere.

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Comment By: dg1727 (dg1727)
Date: 2011-10-15 15:28

Message:
Thanks for updating the text.  I originally submitted this issue because
the ability of web servers to provide text files in compressed form may not
be known to some Privoxy users.  

The following is my attempt at a patch (to be copied, pasted, & edited
manually) to resolve this issue.  The suggested patch would replace the
paragraph of the Privoxy 3.0.17 user manual starting with "Compressed
content can't be filtered either."  

=====

A different matter is HTTP compression, in which files are sent compressed
by the web server according to the Accept-Encoding client header and the
Content-Encoding server header.  Files of any MIME type can be sent with
HTTP compression (although usually only text files are sent
HTTP-compressed, because most picture formats are inherently compressed). 
HTTP-compressed content will be decompressed and filtered by &my-app; if: 

1.  &my-app; is compiled with zlib support, and
2.  the appropriate compression library exists on the computer that
&my-app; is running on, and is loadable by &my-app;, and 
3.  a supported compression algorithm is used (gzip or deflate).  

To find out whether an installed copy of &my-app; was compiled with zlib
support:  First, browse to http://config.privoxy.org/show-status (which can
also be reached by browsing to http://p.p/, then clicking "View & change
the current configuration").  Then, look in the "Conditional #defines"
section for FEATURE_ZLIB to be marked as Yes.  

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Comment By: Fabian Keil (fabiankeil)
Date: 2011-10-14 09:59

Message:
Thanks for the suggestion.

Should be fixed in the SGML file now:
http://ijbswa.cvs.sourceforge.net/viewvc/ijbswa/current/doc/source/user-manual.sgml?r1=2.135&r2=2.136

The HTML file will get the fix the next time it's regenerated.

----------------------------------------------------------------------

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