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From Martin Gerdes <>
Subject [users@httpd] using ProxyHTMLEnable On, mod_proxy_html or xml2enc segfaults
Date Thu, 29 Oct 2009 13:27:31 GMT
2009/10/29 Nick Kew <>

> 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. :-)
> Hmmm,  I thought I advised getting me a test case that could reproduce
> the crash, and your email on Oct 26th said the problem had gone.

Alright, so I simplified a bit :-)
The problem IS gone with the new version. I just failed to check whether the
conversion was still happening - which it turns out it wasn't. That should
have no bearing on the crash though, as the conversion back to ISO-8859-1
happens after the links are replaced.

> 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).
> Precisely the same configuration would be incorrect.  You need to switch
> from using apache's generic filter configuration to the new
> ProxyHTMLEnable directive.  Hence the bold
> *Important Note*: Configuration has changed:
> on its front page.
> But maybe you've found a docs bug, and I need to add the note
> in more places, for existing users who don't check what you
> already know about!  Where did you check?
> I just went to to get the
source code. But I did not reread the page, but just fetched the archive
I did look within the archive for any kind of info, like build instructions,
a readme or changelog, but there wasn't any.
I also distinctly remember looking on the website for a changelog, so an
entry there would have reached me. Other than than: Mea Culpa.

However, I still do not have it working:

Relevant configuration in /etc/apache/apache2.conf:
ProxyHTMLEnable On
ProxyHTMLCharsetOut *
ProxyHTMLExtended On
ProxyHTMLMeta On
ProxyHTMLLogVerbose On
LogLevel info

(the line "SetOutputFilter proxy-html" has been commented out)

>grep -i charset /var/log/apache2/error.log
[Thu Oct 29 13:52:34 2009] [info] [client] Got charset
ISO-8859-1 from HTTP headers
multiple times, no other charset is recognized, so that is fine

I can load the login page of the webapp, though it is returned in utf8.
Once I send of the login data, it segfaults. It did NOT do that when I used
SetOutputFilter instead of ProxyHTMLEnable, so I assume that xml2enc
crashes, though that is only conjecture.

Line in apache error log:
"[Thu Oct 29 14:18:22 2009] [notice] child pid 29443 exit signal
Segmentation fault (11)"

It makes me cry, it really does :-(

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