HTTP response code after redirect

Question

There is a redirect to server for information and once response comes from server, I want to check HTTP code to throw an exception if there is any code starting with 4XX. For that I need to know how can I get only HTTP code from header? Also here redirection to server is involved so I afraid curl will not be useful to me.

So far I have tried this solution but it's very slow and creates script time out in my case. I don't want to increase script time out period and wait longer just to get an HTTP code.

Thanks in advance for any suggestion.

Answer 1

Your method with get_headers and requesting the first response line will return the status code of the redirect (if any) and more importantly, it will do a GET request which will transfer the whole file.

You need only a HEAD request and then to parse the headers and return the last status code. Following is a code example that does this, it's using $http_response_header instead of get_headers, but the format of the array is the same:

$url = 'http://example.com/';

$options['http'] = array(
    'method' => "HEAD",
    'ignore_errors' => 1,
);

$context = stream_context_create($options);

$body = file_get_contents($url, NULL, $context);

$responses = parse_http_response_header($http_response_header);

$code = $responses[0]['status']['code']; // last status code

echo "Status code (after all redirects): $code<br>\n";

$number = count($responses);

$redirects = $number - 1;

echo "Number of responses: $number ($redirects Redirect(s))<br>\n";

if ($redirects)
{
    $from = $url;

    foreach (array_reverse($responses) as $response)
    {
        if (!isset($response['fields']['LOCATION']))
            break;
        $location = $response['fields']['LOCATION'];
        $code = $response['status']['code'];

        echo " * $from -- $code --> $location<br>\n";
        $from = $location;
    }
    echo "<br>\n";
}

/**
 * parse_http_response_header
 *
 * @param array $headers as in $http_response_header
 * @return array status and headers grouped by response, last first
 */
function parse_http_response_header(array $headers)
{
    $responses = array();
    $buffer = NULL;
    foreach ($headers as $header)
    {
        if ('HTTP/' === substr($header, 0, 5))
        {
            // add buffer on top of all responses
            if ($buffer) array_unshift($responses, $buffer);
            $buffer = array();

            list($version, $code, $phrase) = explode(' ', $header, 3) + array('', FALSE, '');

            $buffer['status'] = array(
                'line' => $header,
                'version' => $version,
                'code' => (int) $code,
                'phrase' => $phrase
            );
            $fields = &$buffer['fields'];
            $fields = array();
            continue;
        }
        list($name, $value) = explode(': ', $header, 2) + array('', '');
        // header-names are case insensitive
        $name = strtoupper($name);
        // values of multiple fields with the same name are normalized into
        // a comma separated list (HTTP/1.0+1.1)
        if (isset($fields[$name]))
        {
            $value = $fields[$name].','.$value;
        }
        $fields[$name] = $value;
    }
    unset($fields); // remove reference
    array_unshift($responses, $buffer);

    return $responses;
}

For more information see: HEAD first with PHP Streams, at the end it contains example code how you can do the HEAD request with get_headers as well.

Related: How can one check to see if a remote file exists using PHP?

Answer 2

Something like:

  $ch = curl_init(); 
  $httpcode = curl_getinfo ($ch, CURLINFO_HTTP_CODE );

You should try the HttpEngine Class. Hope this helps.

--

EDIT

$ch = curl_init();
curl_setopt($ch, CURLOPT_USERAGENT, $your_agent_variable);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_REFERER, $your_referer);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_TIMEOUT, 5);
$output = curl_exec($ch);
$httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

if ($httpcode ...)

Answer 3

The solution you found looks good. If the server is not able to send you the http headers in time your problem is that the other server is broken or under very heavy load.