PHP library to parse and generate Extensible Resource Descriptor (XRD) Version 1.0 files. It supports loading and saving XML (XRD) and JSON (JRD) markup.
XRD and JRD files are used for .well-known/host-meta files as standardized
in RFC 6415: Web Host Metadata.
Webfinger, based on JRD, can be used to discover information about users by just their e-mail address, e.g. their OpenID provider URL.
The XRD format supercedes the XRDS format defined in XRI 2.0, which is used in the Yadis communications protocol.
Contents
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
try {
$xrd->loadFile('/path/to/my.xrd', 'xml');
} catch (XML_XRD_Exception $e) {
die('Loading XRD file failed: ' . $e->getMessage());
}
<?php
$myxrd = <<<XRD
<?xml version="1.0"?>
<XRD>
...
XRD;
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
try {
$xrd->loadString($myxrd, 'xml');
} catch (XML_XRD_Exception $e) {
die('Loading XRD string failed: ' . $e->getMessage());
}
Check if the XRD file really describes the resource/URL that we requested the XRD for:
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
$xrd->loadFile('http://example.org/.well-known/host-meta');
if (!$xrd->describes('http://example.org/')) {
die('XRD document is not the correct one for http://example.org/');
}
The <subject> and all <alias> tags are checked.
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
$xrd->loadFile('http://example.org/.well-known/host-meta');
foreach ($xrd as $link) {
echo $link->rel . ': ' . $link->href . "\n";
}
Returns the first link that has the given relation:
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
$xrd->loadFile('http://example.org/.well-known/host-meta');
$idpLink = $xrd->get('lrdd');
echo $idpLink->rel . ': ' . $idpLink->href . "\n";
If no link with the given type is found, the first link with the correct
relation and an empty type will be returned:
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
$xrd->loadFile('http://example.org/.well-known/host-meta');
$link = $xrd->get('lrdd', 'application/xrd+xml');
echo $link->rel . ': ' . $link->href . "\n";
The relation and the type both need to match exactly:
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
$xrd->loadFile('http://example.org/.well-known/host-meta');
$link = $xrd->get('lrdd', 'application/xrd+xml', false);
echo $link->rel . ': ' . $link->href . "\n";
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
$xrd->loadFile('http://example.org/.well-known/host-meta');
foreach ($xrd->getAll('lrdd') as $link) {
echo $link->rel . ': ' . $link->href . "\n";
}
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
$xrd->loadFile('http://example.org/.well-known/host-meta');
if (isset($xrd['http://spec.example.net/type/person'])) {
echo $xrd['http://spec.example.net/type/person'] . "\n";
}
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
$xrd->loadFile('http://example.org/.well-known/host-meta');
foreach ($xrd->getProperties() as $property) {
echo $property->type . ': ' . $property->value . "\n";
}
<?php
require_once 'XML/XRD.php';
$xrd = new XML_XRD();
$xrd->loadFile('http://example.org/.well-known/host-meta');
foreach ($xrd->getProperties('http://spec.example.net/type/person') as $property) {
echo $property->type . ': ' . $property->value . "\n";
}
<?php
$link = $xrd->get('http://specs.openid.net/auth/2.0/provider');
$title = $link->getTitle('de');
$url = $link->href;
$urlTemplate = $link->template;
$mimetype = $link->type;
Works just like properties in the XRD document:
<?php
$link = $xrd->get('http://specs.openid.net/auth/2.0/provider');
$prop = $link['foo'];
As described by RFC 6415:
<?php
require_once 'XML/XRD.php';
$x = new XML_XRD();
$x->subject = 'example.org';
$x->aliases[] = 'example.com';
$x->links[] = new XML_XRD_Element_Link(
'lrdd', 'http://example.org/gen-lrdd.php?a={uri}',
'application/xrd+xml', true
);
echo $x->to('xml');
?>
If you want a JSON file for JRD:
echo $x->to('json');
<?php require_once 'XML/XRD.php'; $x = new XML_XRD(); $x->subject = '[email protected]'; //add link to the user's OpenID $x->links[] = new XML_XRD_Element_Link( 'http://specs.openid.net/auth/2.0/provider', 'http://id.example.org/user' ); //add link to user's home page $x->links[] = new XML_XRD_Element_Link( 'http://xmlns.com/foaf/0.1/homepage', 'http://example.org/~user/' ); echo $x->to('jrd'); ?>
When loading a file, exceptions of type XML_XRD_Exception may be thrown.
All other parts of the code do not throw exceptions but fail gracefully by returning
null, e.g. when a property does not exist.
Using loadFile() may result in PHP warnings like:
Warning: simplexml_load_file(https://example.org/) failed to open stream: Connection refused
This cannot be prevented properly, so you either have to silence it with @
or fetch the file manually and use loadString().
- XML signature verification
- (very optional) XRDS (multiple XRD)?