php 如何仅从 $_SERVER['HTTP_REFERER']; 中选择根域？
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How do I select only the root domain from $_SERVER['HTTP_REFERER'];?
提问by Nathan Bunn
I want to have a 404 page that can detect if a user has come to that page either via my site, via my shortened URL or via another site, and I am making it using PHP. I am slowly getting to grips with PHP and this may well be a simple question, but I am quite tired to be honest and have no caffeine in my system, and I am wanting to tie up any loose ends in my portfolio as soon as possible.
我想要一个 404 页面，它可以检测用户是否通过我的站点、我的缩短 URL 或其他站点访问了该页面，并且我正在使用 PHP 进行访问。我正在慢慢掌握 PHP，这很可能是一个简单的问题，但老实说我很累，我的系统中没有咖啡因，我想尽快解决我的投资组合中的任何松散问题.
I have found the $_SERVER['HTTP_REFERER'];PHP variable gives me the entire URL, which is a start. Is there a way that this can give me only the root domain, either via another variable or a function, bearing in mind that some referrers may be using http:// and some https:// (so simply starting from the seventh character would not always work)? That way, I can match the URL based on two (or more) predefined addresses and produce the content that relates to that domain.
我发现$_SERVER['HTTP_REFERER'];PHP 变量给了我整个 URL，这是一个开始。有没有办法通过另一个变量或函数只给我根域，记住一些引用者可能使用 http:// 和一些 https:// （所以简单地从第七个字符开始并不总是有效）？这样，我可以根据两个（或多个）预定义地址匹配 URL，并生成与该域相关的内容。
回答by deceze
parse_url($_SERVER['HTTP_REFERER'], PHP_URL_HOST)
See http://php.net/manual/en/function.parse-url.php.
请参阅http://php.net/manual/en/function.parse-url.php。
Note though that the referer is terrifically easy to spoof, so it's hardly reliable.
请注意，referer 非常容易被欺骗，因此它几乎不可靠。
回答by Dan LaManna
http://php.net/manual/en/function.parse-url.phpmay be your best bet, although you could use a regular expression to achieve what you're looking for easily as well.
http://php.net/manual/en/function.parse-url.php可能是您最好的选择，尽管您也可以使用正则表达式轻松实现您正在寻找的内容。
回答by Matoeil
this should do :
这应该做：
$_SERVER['SERVER_NAME']
