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From Martin Gerdes <>
Subject [users@httpd] Re: xml2enc does not appear to be functional with mod-proxy-html 3.1.2
Date Thu, 29 Oct 2009 08:53:01 GMT
I think I now know what is going wrong in principle:

>ldd -r /usr/lib/apache2/modules/
undefined symbol: ap_filter_flush
undefined symbol: apr_bucket_type_eos
undefined symbol: apr_bucket_type_flush
undefined symbol: ap_strcasestr (/usr/lib/apache2/modules/
undefined symbol: ap_register_output_filter_protocol
undefined symbol: apr_brigade_write
undefined symbol: ap_pass_brigade
undefined symbol: apr_array_push
undefined symbol: ap_regexec    (/usr/lib/apache2/modules/
undefined symbol: apr_brigade_create
undefined symbol: apr_brigade_partition
undefined symbol: apr_dynamic_fn_register
undefined symbol: apr_brigade_length
undefined symbol: apr_xlate_conv_buffer
undefined symbol: apr_pstrndup  (/usr/lib/apache2/modules/
undefined symbol: ap_check_cmd_context
undefined symbol: ap_add_output_filter
undefined symbol: apr_palloc    (/usr/lib/apache2/modules/
undefined symbol: apr_brigade_cleanup
undefined symbol: ap_pregcomp   (/usr/lib/apache2/modules/
undefined symbol: ap_fflush     (/usr/lib/apache2/modules/
undefined symbol: xmlDetectCharEncoding
undefined symbol: xmlGetCharEncodingName
undefined symbol: xmlAddEncodingAlias
undefined symbol: apr_pstrdup   (/usr/lib/apache2/modules/
undefined symbol: xmlParseCharEncoding
undefined symbol: ap_remove_output_filter
undefined symbol: apr_pstrcat   (/usr/lib/apache2/modules/
undefined symbol: apr_brigade_flatten
undefined symbol: ap_log_rerror (/usr/lib/apache2/modules/
undefined symbol: apr_array_make
undefined symbol: apr_optional_hook_get
undefined symbol: apr_xlate_open
undefined symbol: apr_bucket_transient_create
(/usr/lib/apache2/modules/ =>  (0x00007ffff61fe000) => /lib/ (0x00007f32edc1e000)
        /lib64/ (0x00007f32ee17b000)

If I understand the output correctly, the sybols provided by libxml2 are
undefined, and it does not depend on libxml2 as it should.
Furthermore, of the 3 referenced libraries, only exists
(/lib/ does, but /lib64/ does not).

I did get warnings about the missing symbols when building the .deb package.
But I ignored them thinking that a used but undefined symbol would throw an
error somewhere along the line...!?

Not sure which of these problems is the decisive on, or how to solve them (I
do have package libxml2-dev installed, which defines all these symbols under
/usr/include/libxml2/, and contains /usr/lib/, but I will try to
get those symbols defined. Hopefully that will do it.

All help and suggestions appreciated.


2009/10/28 Martin Gerdes <>

> Background:
> I am running Apache as provided for Debian Lenny (2.2.9-10+lenny4) as
> a reverse proxy. To that end, I installed libapache2-mod-proxy-html
> (3.0.0-1) for URL rewriting.
> As the original content is in charset ISO-8859-1, I set the option
> "ProxyHTMLCharsetOut *" to get the webpage output as ISO-8859 instead
> of UTF-8.
> Everything worked just fine, except that a certain packet crashed the
> proxy-html module (Paket went into the proxy, no paket came out;
> according to the log, a process crashed at precisely that time...)
> I emailed the developer, who advised me to try the most recent version
> (3.1.2) for which unfortunately no debian package exists. So I spent
> half a day figuring out how to update the source debian archive with
> the most recent source code. I managed it, installed it, and it
> worked, and the module did not crash anymore. :-)
> However, after continuing to play around with mod-proxy-html I noticed
> that the output stays as utf-8 (having been converted from ISO-8859-1)
> instead of being converted back to ISO-8859-1.
> Note that 3.0.0 worked with precisely the same configuration (except
> that it did not need xml2enc).
> I am loading xml2enc, and mod-proxy-html notices that I do: If I
> comment the line "LoadModule xml2enc_module
> /usr/lib/apache2/modules/" out, I get Lines "[Wed Oct 28
> 10:42:04 2009] [warn] [client] No i18n support found.
> Install mod_xml2enc if required , referer: ...".
> Loading the module xml2enc, I am not getting error messages of any
> kind in the apache log file.
> If I turn on verbose Logging, and set log level to info, I get Lines
> "[Wed Oct 28 11:04:22 2009] [info] [client] H: matched
> /dwhfe/, substituting /testdwh/, referer: ...", "[Wed Oct 28 11:04:30
> 2009] [info] [client] No content-type; bailing out of
> proxy-html filter, referer: ..." and similar entries, so the logging
> works.
> However, if I grep the file for "charset" (cat
> /var/log/apache2/error.log | grep -i "charset") I don't get any
> matches, although according to the documention I should.
> I have tried changing the value of ProxyHTMLCharsetOut from * to
> ISO-8859-1, and to set "ProxyHTMLMeta On". No change.
> Unless I have compiled the module incorrectly (I have used the command
> "apxs2 -c -I/usr/include/libxml2 mod_xml2enc.c") I conclude that the
> output conversion just plainly is not working anymore.
> If I have compiled it incorrectly, I would appreciate being given the
> proper command to use, as I could not find any documentation to do so
> (thus I adjusted the command the debian module used to build
> mod_html_proxy).
> Any help or suggestions would be much appreciated. :-(
> Martin

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