PEAR2 Services_Linkback

Pingback and webmention client and server implementation for PHP 5.3+.

Glossary:

• source URL: Remote URL that links to the local target URL
• target URL: Local URL that gets linked by the source URL

Linkback server

The package provides a basic pingback+webmention server implementation that can be customized easily via callbacks.

Usage:

$srv = new \PEAR2\Services\Linkback\Server();
$srv->addCallback(new PingbackLogger());
$srv->run();

Customization via callbacks

The server provides 4 types of callbacks to modify its behaviour. Each callback needs to implement one of the four interfaces:

ServicesLinkbackServerCallbackITarget

Verifies that the target URL exists in the local system. Useful to filter out pingbacks for non-existant URLs.

FIXME: Default implementation

ServicesLinkbackServerCallbackISource

Fetches the source URL for further verification. Used to determine if the source URL really exists.

Services_Pingback provides the Services\Linkback\Server\Callback\FetchSource callback class that is automatically registered with the server.

ServicesLinkbackServerCallbackILink

Verifies that the source URL content really links to the target URL. Used to filter out fake pingbacks that do not actually provide links.

Services_Pingback provides the Services\Linkback\Server\Callback\LinkExists callback class that is automatically registered with the server.

ServicesLinkbackServerCallbackIStorage

After all verifications have been done, the storage finally handles the pingback - it could e.g. log it to a file or a database.

Services_Pingback does not provide a default storage implementation; you have to write it yourself.

TODO

See what we can learn from http://www.acunetix.com/blog/web-security-zone/wordpress-pingback-vulnerability/