get_headers 不一致[关闭]

Question

运行以下代码

var_dump(get_headers("http://www.domainnnnnnnnnnnnnnnnnnnnnnnnnnnn.com/CraxyFile.jpg"));

对于任何不存在的域或 URL，返回 HTTP 200 而不是 404

Array
(
    [0] => HTTP/1.1 200 OK
    [1] => Server: nginx/1.1.15
    [2] => Date: Mon, 08 Oct 2012 12:29:13 GMT
    [3] => Content-Type: text/html; charset=utf-8
    [4] => Connection: close
    [5] => Set-Cookie: PHPSESSID=3iucojet7bt2peub72rgo0iu21; path=/; HttpOnly
    [6] => Expires: Thu, 19 Nov 1981 08:52:00 GMT
    [7] => Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
    [8] => Pragma: no-cache
    [9] => Set-Cookie: bypassStaticCache=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; path=/; httponly
    [10] => Set-Cookie: bypassStaticCache=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; path=/; httponly
    [11] => Vary: Accept
)

如果你跑步

var_dump(get_headers("http://www.domain.com/CraxyFile.jpg"));

你得到

Array
(
    [0] => HTTP/1.1 404 Not Found
    [1] => Date: Mon, 08 Oct 2012 12:32:18 GMT
    [2] => Content-Type: text/html
    [3] => Content-Length: 8727
    [4] => Connection: close
    [5] => Server: Apache
    [6] => Vary: Accept-Encoding
)

在很多情况下，get_headers 已被证明是验证现有 URL 的解决方案

• What is the best way to check if a URL exists in PHP?
• How can I check if a URL exists via PHP?

这是一个错误还是 get_headers 不是验证 URL 的可靠方法

See Live Demo

更新 1

发现 CURL 也有同样的问题

$curl = curl_init();
curl_setopt_array($curl, array(CURLOPT_RETURNTRANSFER => true,CURLOPT_URL => 'idontexist.tld'));
curl_exec($curl);
$info = curl_getinfo($curl);
curl_close($curl);
var_dump($info);

Also returns the same result

Answer 1

问题与域名的长度无关，只是域名是否存在。

您正在使用将不存在的域解析为服务器的 DNS 服务，该服务器为您提供“友好”错误页面，并返回 200 响应代码。这意味着 get_headers() 也不是问题，它是任何潜在依赖于合理 DNS 查找的程序。

一种无需为您工作的每个环境硬编码变通的方法来处理此问题的方法可能如下所示：

// A domain that definitely does not exist. The easiest way to guarantee that
// this continues to work is to use an illegal top-level domain (TLD) suffix
$testDomain = 'idontexist.tld';

// If this resolves to an IP, we know that we are behind a service such as this
// We can simply compare the actual domain we test with the result of this
$badIP = gethostbyname($testDomain);

// Then when you want to get_headers()
$url = 'http://www.domainnnnnnnnnnnnnnnnnnnnnnnnnnnn.com/CraxyFile.jpg';

$host = parse_url($url, PHP_URL_HOST);
if (gethostbyname($host) === $badIP) {
  // The domain does not exist - probably handle this as if it were a 404
} else {
  // do the actual get_headers() stuff here
}

您可能希望以某种方式缓存对gethostbyname() 的第一次调用的返回值，因为您知道您正在查找一个不存在的名称，这通常需要几秒钟。