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NAME Interchange::Link -- mod_perl 1.99/2.0 module for linking to Interchange SYNOPSIS <Location /foundation> SetHandler perl-script PerlResponseHandler Interchange::Link PerlOptions +GlobalRequest PerlSetVar InterchangeServer /var/run/interchange/socket PerlSetVar OrdinaryFileList "/foundation/images/ /foundation/dl/" </Location> DESCRIPTION Interchange::Link is designed to replace the vlink and tlink programs that come with Interchange. The Interchange link protocol has been implemented via an Apache mod_perl modules which saves us the (small) overhead of the execution of a CGI program. In addition, it will deliver downloadable files in a streaming fashion without keeping Interchange open, which cuts overhead dramatically for large downloadable files. See FileDeliveryBase. Note that this module is not compatible with Apache 1. PREREQUISITES You must have mod_perl 1.99 or higher installed on your Apache. On a Red Hat-style Linux system, it is as simple as: rpm -i mod_perl-1.99.XX-X.rpm service httpd restart Installation of mod_perl will vary from system to system. Consult the mod_perl documentation. Sometimes it is as easy as perl -MCPAN -e 'install ModPerl::Registry' but often it is not. Usually you can download the package from http://perl.apache.org/ and follow those instructions. INSTALLATION You must specify that Apache use mod_perl, and you must tell it where to find the Perl modules you want to use. On a Red Hat Linux system you might copy this file to /usr/lib/httpd/perl/ via this procedure: mkdir -p /usr/lib/httpd/perl/Interchange cp Link.pm /usr/lib/httpd/perl/Interchange If you have mod_perl2 1.999_21 or earlier, you should instead do: mkdir -p /usr/lib/httpd/perl/Interchange cp Link.pm.mod_perl-1.999_21_and_before /usr/lib/httpd/perl/Interchange Then you provide a startup script that tells mod_perl where its libraries are: cd /usr/lib/httpd/perl echo "use lib qw(/usr/lib/httpd/perl);1;" > startup.pl Then you can put in your /etc/httpd/conf/httpd.conf: PerlModule Apache2 PerlRequire /usr/lib/httpd/perl/startup.pl Finally, you specify a location like: <Location /foundation> SetHandler perl-script PerlResponseHandler Interchange::Link PerlOptions +GlobalRequest # Make sure you set SocketPerms to 0666 (or 0660 with appropriate # setgid group ownership of the directory) PerlSetVar InterchangeServer /var/run/interchange/socket PerlSetVar OrdinaryFileList "/foundation/images/ /foundation/dl/" </Location> Note: The Apache <Location> path should not contain a dot (.) or any other characters except A-Z, a-z, 0-9 or a hyphen (-), so: <Location /shop.name> is invalid, whereas: <Location /shop-name> is valid. The specifics of the configuration are discussed in the next section. CONFIGURATION The module understands directives set via the mod_perl "PerlSetVar" directive. InterchangeServer This specifies the way to contact the primary and possibly additio- nial Interchange servers. The InterchangeServer directive takes either a pathname to the Interchange UNIX socket or a host:port specification if you want to use INET mode. Normally this takes the form of: PerlSetVar InterchangeServer /var/run/interchange/socket Note that your file permissions for the socket file need to allow the Apache User uid to read and write it. This usually means "Sock- etPerms 0666" or in interchange.cfg. You can also do "SocketPerms 0660" if you set the group of the containing directory to the Apache Group value, and change the directory permissions to enable the setgid bit. (That is accomplished with "chmod g+s <directory>".) If you want to specify more than one so that a backup server can provide request support in case of failure: PerlSetVar InterchangeServer "/var/run/interchange/socket 10.1.1.1:7786" The optional InterchangeServerBackup directive takes the same argu- ments, but should obviously point to a different Interchange server than the primary. The InterchangeServerBackup directive is only of any use if you have multiple Interchange servers configured in a clustered environment. If you want to randomly select from a series of clustered servers, do: PerlSetVar InterchangeServer "10.1.1.1:7786 10.1.1.2:7786 10.1.1.3:7786" PerlSetVar RandomServer 1 Note: The Apache <Location> path should not contain a dot (.) or any other characters except A-Z, a-z, 0-9 or a hyphen (-), so: <Location /shop.name> is invalid, whereas: <Location /shop-name> is valid. Example of a UNIX mode local connection: <Location /shop> SetHandler perl-script PerlResponseHandler Interchange::Link PerlSetVar InterchangeServer /opt/interchange/etc/socket </Location> Example of INET mode local connection: <Location /shop> SetHandler perl-script PerlResponseHandler Interchange::Link PerlSetVar InterchangeServer localhost:7786 </Location> UNIX mode local primary connection and INET mode remote backup connection: <Location /shop> SetHandler perl-script PerlResponseHandler Interchange::Link PerlSetVar InterchangeServer /opt/interchange/etc/socket PerlSetVar InterchangeServerBackup another.server.com:7786 </Location> The default if not set is "127.0.0.1:7786". ConnectTries and ConnectRetryDelay The ConnectTries parameter specifies the number of connection attempts to make before giving up. ConnectRetryDelay specifies the delay, in seconds, between each retry attempt. The ConnectTries default is 10 and the ConnectRetryDelay default is 2 seconds. Here is an example: <Location /shop> SetHandler perl-script PerlResponseHandler Interchange::Link PerlSetVar ConnectTries 10 PerlSetVar ConnectRetryDelay 1 </Location> DropRequestList The DropRequestList allows a list of space-separated URI components to be specified. If one of the list entries is found anywhere in the requested URI, the request will be dropped with a 404 (not found) error, without the request being passed to Interchange. This parameter is useful for blocking known Microsoft IIS attacks like "Code Red", so that we don't waste any more time processing the (bogus) requests than we have to. <Location /shop> SetHandler perl-script PerlResponseHandler Interchange::Link PerlSetVar DropRequestList "/default.ida /x.ida /cmd.exe /root.exe" </Location> OrdinaryFileList The OrdinaryFileList allows a list of space-separated URI path com- ponents to be specified. If one of the list entries is found at the start of any request then that request will not be passed to Interchange. Instead, the file will be directly served by Apache. For example: <Location /> SetHandler perl-script PerlResponseHandler Interchange::Link PerlSetVar OrdinaryFileList "/foundation/ /interchange-5/ /robots.txt" </Location> This will result in the following: www.example.com/index.html (handled by Interchange) www.example.com/ord/basket.html (handled by Interchange) www.example.com/foundation/images/somefile.gif (served by Apache) www.example.com/robots.txt (served by Apache) You should add a trailing slash to directory names to prevent, for instance, "/images/foo.gif" from being confused with the likes of "/images.html". If OrdinaryFileList was set to "/images" then both of those requests would be handled by Apache. If OrdinaryFileList was set to "/images/" then "/images/foo.gif" would be handled by Apache and "/images.html" would be handled by Interchange. If you're using "<Location />" then you will need a dummy "index.html" file in your VirtualHost's DocumentRoot directory to avoid permission problems assocated with the Apache directory index creation code. InterchangeScript The InterchangeScript parameter allows the SCRIPT_NAME to be dif- ferent from the <Location>. For example: <Location /shop> ... </Location> The above will set the SCRIPT_NAME to "/shop". <Location /shop> ... PerlSetVar InterchangeScript /foo </Location> The above will set the SCRIPT_NAME to "/foo", instead of "/shop" before passing the request to Interchange. The appropriate SCRIPT_NAME must be configured into the "Catalog" directive in your interchange.cfg file. FileDeliveryBase Interchange::Link can deliver files without needing to keep Inter- change open. To do this, you set the HTTP Status: header to "httpd_deliver". In Interchange 5.0 or higher you can do this by putting in a page: [deliver status=httpd_deliver location=directory/file.ext type=application/octet-stream ] The "FileDeliveryBase" setting determines where the file will be relative to. While you can set it to "/", that is not recommended as files like "/etc/passwd" could be delivered. The default is the document root of the Apache server. To protect files from being served directly by Apache, you can either put them under a directory at the Interchange location, or you can use nor- mal Apache exclusions. BUGS Send bug reports and suggestions to the Interchange users list, <email@example.com>. COPYRIGHT AND LICENSE Copyright (C) 1996-2002 Red Hat, Inc. Copyright (C) 2002-2007 Interchange Development Group This program is free software. You can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation. You may refer to either version 2 of the License or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MER- CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.