mod_perl 2.0 and PerlTransHandler content rewriting problems

choocroot has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

I'm beginning with mod_perl (mod_perl-1.99_05 + Apache-2.0.40 from Linux RedHat 8.0) and I would like to write a module that rewrite the documents that passes through the Apache proxy module.
I found an Apache::AdBlocker module but it is for mod_perl 1.0 and do not seems to work with mod_perl 2.0.
So I tried to follow it and write my own module. Here is the test code I wrote, its goal is to intercept the request, fetch the real document with LWP, modify the html document, then send the modified document back to the client . It almost work but I get a SEGFAULT when sending the modified document back to the client :

package Apache::Plop;

use strict;
use Apache::RequestRec;
use Apache::RequestIO;
use Apache::RequestUtil;
use Apache::Const;
use Apache::ServerUtil;
use Apache::Response;
use APR::Table;
use LWP::UserAgent;

my $ua = LWP::UserAgent->new();

sub handler {
    my $r = shift;

    if( ! $r->proxyreq ) {
        return Apache::DECLINED;
    }
    print STDERR "Good, this is a proxyreq ...\n";

# -->
# if I use this push_handlers, I never reach the "proxy_handler" sub
# So I commented it out and tried to do the work directly in "handler"

#    $r->handler("perl-script"); #ok, let's do it               
#    $r->push_handlers(PerlHandler => \&proxy_handler);         
#}
#
#sub proxy_handler {
#    my $r = shift;

# <--

    if( $r->method ne "GET" ) {
        return Apache::DECLINED;
    }
    print STDERR "Good, this is a GET method ...\n";

    # prepare the "real" request
    my $request = HTTP::Request->new( $r->method, $r->uri );

    # copy headers from client request
    my %headers_in;
    print STDERR "-- client headers --\n";
    $r->headers_in()->do(
        sub {
            print STDERR "$_[0]: $_[1]\n";
            $headers_in{$_[0]} = $_[1];
            $request->header( {$_[0]}, $_[0] );
        }
    );
    print STDERR "-- end --\n";

    # make the "real" request myself
    $ua->agent( $headers_in{ 'User-Agent' } );
    my $response = $ua->request( $request );

    if( ! $response->is_success() ) {
        print STDERR "== ERROR ==\n";
        return Apache::DECLINED;
    }

    print STDERR "-- server headers --\n";
    my %headers_out;
    $response->headers()->scan(
        sub {
            print STDERR "$_[0]: $_[1]\n";
            $headers_out{$_[0]} = $_[1];
        }
    );
    print STDERR "-- end --\n";

    # simply override the content
    my $content = $response->content;
    $content = "<html><body>plop</body></html>";

    # adjust the headers for the new content
    $headers_out{ 'Content-length' } = length( $content );
    $headers_out{ 'Content-type' } = 'text/html';

    # copy the modified response headers back to Apache
    foreach (keys %headers_out) {
        $r->headers_out->{$_} = $headers_out{$_};
    }
    $r->content_type( $headers_out{ 'Content-type' } );

    print STDERR "-- send/print --\n";

# -->
# here is where the SEGFAULT occurs

    $r->send_http_header();
    $r->print( $content );

# I don't know how to write a content back to the client
# <--

    print STDERR "-- end --\n";

    return Apache::OK;
}

1;
[download]

This module is registered with a "PerlTransHandler Apache::Plop" and is correctly launched but I'm facing two problems with this code :
- First, if I use the $r->push_handlers() mecanism I never reach the proxy_handler subroutine ...
- Second, if I do the work directly in handler(), I can get the request, make the real request, modify the content but I don't know how to write back a document to the client. I get a SEGFAULT when it reach the $r->send_http_header/$r->print statement. If I remove the send_http_header it SEGFAULT on the print ...

Any hints ?

Thanks for your help

Comment on mod_perl 2.0 and PerlTransHandler content rewriting problems Download Code

Replies are listed 'Best First'.
Re: mod_perl 2.0 and PerlTransHandler content rewriting problems by Aristotle (Chancellor) on Jan 12, 2003 at 16:11 UTC
I have no idea, and since you didn't get any replies, even after I frontpaged the node for greater visibility to Anonymonks and the like who may only take a cursory look at the site, I thought I should at least give a token reply: You will probably have better luck on the mod_perl Users mailing list. Sorry I can't be more helpful - I hope someone can help you along there. `:)` Makeshifts last the longest.	[reply]
Re: Re: mod_perl 2.0 and PerlTransHandler content rewriting problems by choocroot (Friar) on Jan 12, 2003 at 19:07 UTC
You're right, I also think I should ask this question on the mod_perl mailing list. I'll subscribe to it and see what happens. Meanwhile I fetched the source of mod_perl 1.99 and it seems that some methods are not yet fully implemented/funtional. So, this could explain my problems ... Thanks again ;)	[reply]