php - 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>
";

$number = count($responses);

$redirects = $number - 1;

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

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>
";
        $from = $location;
    }
    echo "<br>
";
}

/**
 * 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.

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