Re: advice needed: mod_perl reverse proxy

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hi stas

Stas Bekman wrote:
> allan juul wrote:
> [...]

>>> But if you use a mod_perl filter you will still hit the issue of 
>>> unknown content-length header.
>>
>>
>>
>> yes, of course that's true.
>> there goes caching (:
> 
> 
> Not really. Nothing prevents you from buffering up the response, process 
> it, set the content-length header and make the document cache-able.

ok, eh how do i that. you mean instead of printing to STDOUT, collect 
data in a buffer, then set the calculated Content-Length, then print data?

anyway, it's pretty strange. it seems i'm able to set the Content-Length 
when i use the mod_perl_filter and do *not* reverse proxy. see both 
headers below. the strange things is that i'm not allowed at all to set 
the standard Content-Length, but indeed allowed to set a custom one 
called Content-Length2. and even stranger is that this custom header 
presents a correct value when *not* proxying but "0" when proxying. i 
use the exact same mod_perl code, also supplied below. the actual 
filtering of data content works in both cases.

all this is on windows.


./allan


######### CODE ##############
# this is heavily based on
# http://search.cpan.org/~geoff/Apache-Clean-2.00_7/

package Apache::Clean;
use 5.008;
use Apache2::Filter ();
use Apache2::RequestRec ();
use Apache2::RequestUtil ();
use Apache2::Log ();
use APR::Table ();
use Apache2::Const -compile => qw(OK DECLINED);
use strict;
sub handler {
     my $f   = shift;
     my $r   = $f->r;
     my $log = $r->server->log;
     unless ($r->content_type =~ m!text/html!i) {
         $log->info('skipping request to ', $r->uri, ' (not an HTML 
document)');
         return Apache2::DECLINED;
     }
     my $context;
     unless ($f->ctx) {
         $r->headers_out->unset('Content-Length');
     }
     $context ||= $f->ctx;
     my $content_length = 0;
     while ($f->read(my $buffer, 1024)) {
         $buffer = $context->{extra} . $buffer if $context->{extra};
         if (($context->{extra}) = $buffer =~ m/(<[^>]*)$/) {
             $buffer = substr($buffer, 0, - length($context->{extra}));
         }
         my $str = $buffer;
         $str =~  s,OLD,NEW,igs;
         $content_length += length( $str );
         $f->print( ${str} );
     }
     if ($f->seen_eos) {
         $f->print($context->{extra}) if $context->{extra};
         $content_length += length( $context->{extra} );
     }
     else {
         $f->ctx($context);
     }
     $r->headers_out->set('Content-Length', $content_length);
     $r->headers_out->set('Content-Length2', $content_length);
     return Apache2::OK;
}
1;






######### HEADERS ##############

# no rev proxy
$ head localhost
200 OK
Connection: close
Date: Sat, 30 Apr 2005 20:02:17 GMT
Accept-Ranges: bytes
Server: Apache/2.0.54 (Win32) mod_ssl/2.0.53 OpenSSL/0.9.7f 
proxy_html/2.4 mod_perl/1.999.22-dev Perl/v5.8.6
Vary: negotiate,accept-language,accept-charset
Content-Language: en
Content-Length: 1773
Content-Location: index.html.en
Content-Type: text/html
Last-Modified: Sun, 21 Nov 2004 05:35:22 GMT
Client-Date: Sat, 30 Apr 2005 20:02:17 GMT
Client-Peer: 127.0.0.1:80
Client-Response-Num: 1
Content-Length2: 1773




# with rev proxy
$ head localhost
200 OK
Cache-Control: no-cache, no-store
Connection: close
Date: Sat, 30 Apr 2005 20:04:24 GMT
Pragma: no-cache
Server: Microsoft-IIS/6.0
Content-Type: text/html; charset=utf-8
Expires: -1
Client-Date: Sat, 30 Apr 2005 20:04:25 GMT
Client-Peer: 127.0.0.1:80
Client-Response-Num: 1
Content-Length2: 0
Set-Cookie: ASP.NET_SessionId=4nddnr453tjk0355flblp3fg; path=/
X-AspNet-Version: 1.1.4322
X-Powered-By: ASP.NET