最近，我开始编写自己的 PHP OpenID 消费类，以便更好地理解 openID。作为指导，我一直在引用 [LightOpenID 类][1]。在大多数情况下，我了解代码以及 OpenID 的工作原理。在查看作者的discover功能时，我感到困惑：
function discover($url)
{
if(!$url) throw new ErrorException('No identity supplied.');
# We save the original url in case of Yadis discovery failure.
# It can happen when we'll be lead to an XRDS document
# which does not have any OpenID2 services.
$originalUrl = $url;
# A flag to disable yadis discovery in case of failure in headers.
$yadis = true;
# We'll jump a maximum of 5 times, to avoid endless redirections.
for($i = 0; $i < 5; $i ++) {
if($yadis) {
$headers = explode("\n",$this->request($url, 'HEAD'));
$next = false;
foreach($headers as $header) {
if(preg_match('#X-XRDS-Location\s*:\s*(.*)#', $header, $m)) {
$url = $this->build_url(parse_url($url), parse_url(trim($m[1])));
$next = true;
}
if(preg_match('#Content-Type\s*:\s*application/xrds\+xml#i', $header)) {
# Found an XRDS document, now let's find the server, and optionally delegate.
$content = $this->request($url, 'GET');
# OpenID 2
# We ignore it for MyOpenID, as it breaks sreg if using OpenID 2.0
$ns = preg_quote('http://specs.openid.net/auth/2.0/');
if (preg_match('#<Service.*?>(.*)<Type>\s*'.$ns.'(.*?)\s*</Type>(.*)</Service>#s', $content, $m)
&& !preg_match('/myopenid\.com/i', $this->identity)) {
$content = $m[1] . $m[3];
if($m[2] == 'server') $this->identifier_select = true;
$content = preg_match('#<URI>(.*)</URI>#', $content, $server);
$content = preg_match('#<LocalID>(.*)</LocalID>#', $content, $delegate);
if(empty($server)) {
return false;
}
# Does the server advertise support for either AX or SREG?
$this->ax = preg_match('#<Type>http://openid.net/srv/ax/1.0</Type>#', $content);
$this->sreg = preg_match('#<Type>http://openid.net/sreg/1.0</Type>#', $content);
$server = $server[1];
if(isset($delegate[1])) $this->identity = $delegate[1];
$this->version = 2;
$this->server = $server;
return $server;
}
# OpenID 1.1
$ns = preg_quote('http://openid.net/signon/1.1');
if(preg_match('#<Service.*?>(.*)<Type>\s*'.$ns.'\s*</Type>(.*)</Service>#s', $content, $m)) {
$content = $m[1] . $m[2];
$content = preg_match('#<URI>(.*)</URI>#', $content, $server);
$content = preg_match('#<.*?Delegate>(.*)</.*?Delegate>#', $content, $delegate);
if(empty($server)) {
return false;
}
# AX can be used only with OpenID 2.0, so checking only SREG
$this->sreg = preg_match('#<Type>http://openid.net/sreg/1.0</Type>#', $content);
$server = $server[1];
if(isset($delegate[1])) $this->identity = $delegate[1];
$this->version = 1;
$this->server = $server;
return $server;
}
$next = true;
$yadis = false;
$url = $originalUrl;
$content = null;
break;
}
}
if($next) continue;
# There are no relevant information in headers, so we search the body.
$content = $this->request($url, 'GET');
if($location = $this->htmlTag($content, 'meta', 'http-equiv', 'X-XRDS-Location', 'value')) {
$url = $this->build_url(parse_url($url), parse_url($location));
continue;
}
}
if(!$content) $content = $this->request($url, 'GET');
# At this point, the YADIS Discovery has failed, so we'll switch
# to openid2 HTML discovery, then fallback to openid 1.1 discovery.
$server = $this->htmlTag($content, 'link', 'rel', 'openid2.provider', 'href');
$delegate = $this->htmlTag($content, 'link', 'rel', 'openid2.local_id', 'href');
$this->version = 2;
# Another hack for myopenid.com...
if(preg_match('/myopenid\.com/i', $server)) {
$server = null;
}
if(!$server) {
# The same with openid 1.1
$server = $this->htmlTag($content, 'link', 'rel', 'openid.server', 'href');
$delegate = $this->htmlTag($content, 'link', 'rel', 'openid.delegate', 'href');
$this->version = 1;
}
if($server) {
# We found an OpenID2 OP Endpoint
if($delegate) {
# We have also found an OP-Local ID.
$this->identity = $delegate;
}
$this->server = $server;
return $server;
}
throw new ErrorException('No servers found!');
}
throw new ErrorException('Endless redirection!');
}
[1]: http://gitorious.org/lightopenid
好的，这是我理解的逻辑（基本上）：
- 检查是否
$url向您发送了有效的 XRDS 文件，然后您对其进行解析以找出 OpenID 提供者的端点。- 据我了解，这称为 Yadis 认证方式。
- 如果未找到 XRDS 文件，请检查响应正文中是否存在包含端点 url 的 HTML <link> 标记。
什么。这。见鬼。
我的意思是认真的？本质上是屏幕抓取响应并希望您找到具有适当属性值的链接？
现在，不要误会我的意思，这门课就像一个魅力，太棒了。我只是无法理解用于发现端点的两种不同方法：XRDS (yadis) 和 HTML。
我的问题
- 这些是发现过程中使用的仅有的两种方法吗？
- 一个只在 OpenID 1.1 版中使用，而另一个在 2 版中使用？
- 支持这两种方法是否至关重要？
- 我遇到 HTML 方法的站点是 Yahoo。他们疯了吗？
再次感谢你们的时间。如果我听起来有点吃惊，我深表歉意，但是当我开始了解正在采取哪些措施来寻找终点时，我真的对这种方法感到震惊。