PHP:fopen 失败 "HTTP Request Failed"，但响应 header 的状态代码为 200

Question

我有一个 PHP 脚本，它应该连接到一个从代理列表中选择的代理并下载一个文件。一些代理(在 200-400 个工作代理中)工作完美，但其他的则不能，我无法找出原因。

这里是通过代理连接的代码:

    $proxy = determine_proxy ($proxyList);
 $proxyString = 'tcp://' . $proxy['ip'] . ':' . $proxy['port'];

 $userAgent = $userAgents [rand (0, $agentsCount - 1)];

 // set up our headers
 $hdrs = array( 'http' => array(
     'method' => "GET",
     'header'=> "Host: www.example.net\r\n" .
      // "User-Agent: $userAgent\r\n" .
      "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n" .
      "Accept-Language: en-us,en;q=0.5\r\n" .
      "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7\r\n" . 
      "Keep-Alive: 115\r\n" .
      "Proxy-Connection: keep-alive\r\n" .
  "Referer: http://$url",     // Setting the http-referer
     'proxy' => "$proxyString",
     'request_fulluri' => true
     )
 );

 echo "Using proxy: "; print_r ($proxy); echo '<br>';

 $context = stream_context_create ($hdrs);  // set up the context

 $timeout = 3;
 $oldTimeout = ini_set('default_socket_timeout', $timeout);
 $oldAgent = ini_set ('user_agent', $userAgent);

 $fp = fopen ("http://www.example.net$file", 'r', false, $context); // open the file

 if (!$fp) {
  echo 'fopen failed! Skipping this proxy for now...<br>';
  print_r ($http_response_header); echo '<br />';
  unset ($http_response_header);
  flush(); @ob_flush();
  ini_set ('user_agent', $oldAgent);
  ini_set('default_socket_timeout', $oldTimeout);
  continue;
 }

 print_r ($http_response_header); echo '<br />';
 unset ($http_response_header);

奇怪的是，失败尝试的响应头有时是空的，有时是这样的:

   Array (
 [0] => HTTP/1.0 200 OK
 [1] => Server: falcon
 [2] => Date: Sun, 16 Jan 2011 14:06:37 GMT
 [3] => Content-Type: application/x-bittorrent
 [4] => Cache-Control: must-revalidate, post-check=0, pre-check=0
 [5] => Content-Disposition: attachment; filename="example.torrent"
 [6] => Vary: Accept-Encoding,User-Agent
 [7] => Connection: close
)

有时，是这样的:

   Array ( 
 [0] => HTTP/1.0 200 OK 
 [1] => Server: falcon 
 [2] => Date: Sun, 16 Jan 2011 14:06:47 GMT 
 [3] => Content-Type: application/x-bittorrent 
 [4] => Cache-Control: must-revalidate, post-check=0, pre-check=0 
 [5] => Content-Disposition: attachment; filename="example2.torrent" 
 [6] => Vary: Accept-Encoding,User-Agent 
 [7] => X-Cache: MISS from proxy 
 [8] => Proxy-Connection: close
)

这是来自成功尝试的响应 header :

HTTP/1.0 200 OK
Server: falcon
Date: Fri, 21 Jan 2011 18:53:00 GMT
Content-Type: application/x-bittorrent
Cache-Control: must-revalidate, post-check=0, pre-check=0
Content-Disposition: attachment; filename="example3.torrent"
Vary: Accept-Encoding,User-Agent
X-Cache: MISS from www.example.com
X-Cache-Lookup: MISS from www.example.com:3128
Via: 1.0 www.example.com (squid/3.0.STABLE23-BZR)
Proxy-Connection: close

我正在将用户代理设置为有效的用户代理字符串，我已检查 allow_url_fopen 并将其设置为开。

来自 RFC-2616，第 10 节:

200 OK

The request has succeeded. The information returned with the response is dependent on the method used in the request, for example:

GET an entity corresponding to the requested resource is sent in the response;

怎么可能，服务器通过代理返回状态 200，而 fopen 仍然失败？有人知道这个问题以及如何解决吗？

Answer 1

问题在于，我设置的套接字超时在某些情况下对于 fopen 来说太低，无法管理和下载所有数据。超时时间结束后，fopen 仍未下载数据，它返回 FALSE 并抛出“HTTP 请求失败”错误。