get_headers不一致 [英] get_headers Inconsistency

问题描述

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
)

如果您运行

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

您得到

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，已经证明get_headers是验证现有URL的解决方案

They are so many instances where get_headers has been proven to be a solution to validate existing URL

• 什么是最好的方法来检查PHP中是否存在URL?
• 如何通过PHP检查URL是否存在?

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

参见实时演示

发现CURL也存在相同的问题

Got to find out that CURL also has the same issue

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

也返回相同的结果

推荐答案

问题与域名的长度无关，只是域名是否存在.

The problem is nothing to do with the length of the domain name, it is simply whether the domain exists.

您正在使用DNS服务，该服务将不存在的域解析到服务器，该服务器为您提供友好的"错误页面，该页面返回200响应码.这意味着get_headers()也不是问题，具体来说，它是任何依赖于合理的DNS查找的过程.

You are using a DNS service that resolves non-existent domains to a server that gives you a "friendly" error page, which it returns with a 200 response code. This means it is also not a problem with get_headers() specifically, it is any procedure with an underlying reliance on sensible DNS lookups.

一种处理此问题的方法而无需对您工作的每个环境进行硬编码，如下所示:

A way to handle this without hardcoding a work around for every environment you work in might look something like this:

// 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第一次调用gethostbyname()的返回值，因为您知道自己正在查找一个不存在的名称，这通常可能需要几秒钟.

You may want to somehow cache the return value of the first call to gethostbyname(), since you know you are looking up a name that does not exist, and this can often take a few seconds.

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