http://www.perlmonks.org?node_id=704425

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

I've got an issue with redirection failing from my CGI::Application when running under mod_perl.

I'm very new to mod_perl so I could well believe that I've done something wrong. My configuration for Apache2 + mod_perl is very minimal:

ServerName ...

Alias /cgi-bin/ /mf/cgi-bin/
<Location /cgi-bin>
        SetHandler      perl-script
        PerlHandler     ModPerl::Registry
        PerlSendHeader  On
        Options         +ExecCGI
</Location>

[download]

This works for most of my application, and appears to improve response time significantly - however there is one problem. My redirections, as coded in the CGI::Application do not work.

I've pared this down to a minimal clone of my code - I have a base class implementing a redirect method, and I have a subclass which uses that to redirect a few times.

In plain CGI-mode this works. In mod_perl it gives me the following output direct to my browser:

redirect<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>200 OK</title>
</head><body>
<h1>OK</h1>
<p>The document has moved 
<a href="http://example.com/">here</a>.</p>
<hr>
<address>Apache/2.2.9 (Debian) PHP/5.2.6-2+b1 with
 Suhosin-Patch mod_ssl/2.2.9
 OpenSSL/0.9.8g mod_musicindex/1.2.2
 mod_perl/2.0.4 Perl/v5.10.0
 Server at mail-scanning.com Port 80</address>
</body></html>

Now here is my example code which exhibits the same problem:

#!/usr/bin/perl -w

use strict;
use warnings;
use CGI::Application;

#
#  Base package
#
package Base;
use base 'CGI::Application';

sub redirectPage
{
    my ( $self, $url ) = (@_);
    $self->header_add( -location => $url );
    $self->header_type('redirect');
}

#
#  Derived package
#
package Derived;
use base 'Base';


sub setup
{
    my( $self ) = ( @_ );
    $self->run_modes( homepage => 'homepage' );

    $self->start_mode('homepage');
    $self->mode_param('mode');
}

#
#  Dummy method to redirect to an external site.
#
sub homepage
{
    my( $self ) = ( @_ );
    return ( $self->redirectPage("http://example.com/") );

}


#
#  Instance script
#
package main;

my $derived = new Derived();
$derived->run();

[download]

Any clues, or tips are most welcome. Any more details I can provide just ask - this is all running upon libapache2-mod-perl2, as included in Debian.

Update: - Strangly using CGI::Application::Plugin::Redirect works correctly if I change my code:


package Base;
use base 'CGI::Application';
use CGI::Application::Plugin::Redirect;

sub redirectPage
{
    my ( $self, $url ) = (@_);

    return( $self->redirect( $url ) );
}

[download]
Steve
--

Replies are listed 'Best First'.
Re: Failure to redirect when my CGI::Application powered site is used under mod_perl2
by Anonymous Monk on Aug 14, 2008 at 21:13 UTC
    In plain CGI-mode this works. In mod_perl it gives me the following output direct to my browser:

    Try 

    lwp-request -m get -USsexd http://whatever/cgi/
lwp-request -m get -USsex http://whatever/cgi/

    [download]
[reply]
[d/l]

      I'm not familiar with those commands, but here is what they produce:

      (Please excuse the formatting.)

      lwp-request -m get -USsexd http://mail-scanning/cgi-bin/temp.cgi 
      skx@gold:~$ lwp-request -m get -USsexd http://mail-scanning/cgi-bin/te
+mp.cgi
LWP::UserAgent::new: ()
LWP::UserAgent::request: ()
LWP::UserAgent::send_request: GET http://mail-scanning/cgi-bin/temp.cg
+i
LWP::UserAgent::_need_proxy: Not proxied
LWP::Protocol::http::request: ()
LWP::Protocol::collect: read 8 bytes
LWP::Protocol::collect: read 387 bytes
LWP::UserAgent::request: Simple response: OK
GET http://mail-scanning/cgi-bin/temp.cgi
User-Agent: lwp-request/5.810

GET http://mail-scanning/cgi-bin/temp.cgi --> 200 OK
Connection: close
Date: Thu, 14 Aug 2008 21:15:16 GMT
Location: http://example.com/
Server: Apache/2.2.9 (Debian) PHP/5.2.6-2+b1 with Suhosin-Patch mod_ss
+l/2.2.9 OpenSSL/0.9.8g mod_musicindex/1.2.2 mod_perl/2.0.4 Perl/v5.10
+.0
Content-Type: text/plain
Client-Date: Thu, 14 Aug 2008 21:15:16 GMT
Client-Peer: 192.168.1.10:80
Client-Response-Num: 1
Client-Transfer-Encoding: chunked

      [download]

      The second  lwp-request -m get -USsex http://mail-scanning/cgi-bin/temp.cgi 

      LWP::UserAgent::new: ()
LWP::UserAgent::request: ()
LWP::UserAgent::send_request: GET http://mail-scanning/cgi-bin/temp.cg
+i
LWP::UserAgent::_need_proxy: Not proxied
LWP::Protocol::http::request: ()
LWP::Protocol::collect: read 8 bytes
LWP::Protocol::collect: read 387 bytes
LWP::UserAgent::request: Simple response: OK
GET http://mail-scanning/cgi-bin/temp.cgi
User-Agent: lwp-request/5.810

GET http://mail-scanning/cgi-bin/temp.cgi --> 200 OK
Connection: close
Date: Thu, 14 Aug 2008 21:16:29 GMT
Location: http://example.com/
Server: Apache/2.2.9 (Debian) PHP/5.2.6-2+b1 with Suhosin-Patch mod_ss
+l/2.2.9 OpenSSL/0.9.8g mod_musicindex/1.2.2 mod_perl/2.0.4 Perl/v5.10
+.0
Content-Type: text/plain
Client-Date: Thu, 14 Aug 2008 21:16:29 GMT
Client-Peer: 192.168.1.10:80
Client-Response-Num: 1
Client-Transfer-Encoding: chunked

redirect<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>200 OK</title>
</head><body>
<h1>OK</h1>
<p>The document has moved <a href="http://example.com/">here</a>.</p>
<hr>
<address>Apache/2.2.9 (Debian) PHP/5.2.6-2+b1 with Suhosin-Patch mod_s
+sl/2.2.9 OpenSSL/0.9.8g mod_musicindex/1.2.2 mod_perl/2.0.4 Perl/v5.1
+0.0 Server at mail-scanning Port 80</address>
</body></html>

      [download]
      Steve
      --
[reply]
[d/l]
[select]

        To reply to myself it seems that I have two solutions:

        • Use CGI::Application::Plugin::Redirect
        • Update my code:
        sub redirectURL
{
    my ( $self, $url ) = (@_);
    $self->header_type('redirect');
    $self->header_add( -url => $url ,
                       -status => 301 );
    return;
}

        [download]

        That redundent "return" seems to make things work properly in my demo and real application.

        I guess the return value of "header_add" is causing problems ..

        Steve
        --
[reply]
[d/l]

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