Club Drupal

<?php

/**

 * @file

 * Download via HTTP.

 *

 * Support caching, HTTP Basic Authentication, detection of RSS/Atom feeds,

 * redirects.

 */

/**

 * PCRE for finding the link tags in html.

 */

define('HTTP_REQUEST_PCRE_LINK_TAG', '/<link((?:[\x09\x0A\x0B\x0C\x0D\x20]+[^\x09\x0A\x0B\x0C\x0D\x20\x2F\x3E][^\x09\x0A\x0B\x0C\x0D\x20\x2F\x3D\x3E]*(?:[\x09\x0A\x0B\x0C\x0D\x20]*=[\x09\x0A\x0B\x0C\x0D\x20]*(?:"(?:[^"]*)"|\'(?:[^\']*)\'|(?:[^\x09\x0A\x0B\x0C\x0D\x20\x22\x27\x3E][^\x09\x0A\x0B\x0C\x0D\x20\x3E]*)?))?)*)[\x09\x0A\x0B\x0C\x0D\x20]*(>(.*)<\/link>|(\/)?>)/si');

/**

 * PCRE for matching all the attributes in a tag.

 */

define('HTTP_REQUEST_PCRE_TAG_ATTRIBUTES', '/[\x09\x0A\x0B\x0C\x0D\x20]+([^\x09\x0A\x0B\x0C\x0D\x20\x2F\x3E][^\x09\x0A\x0B\x0C\x0D\x20\x2F\x3D\x3E]*)(?:[\x09\x0A\x0B\x0C\x0D\x20]*=[\x09\x0A\x0B\x0C\x0D\x20]*(?:"([^"]*)"|\'([^\']*)\'|([^\x09\x0A\x0B\x0C\x0D\x20\x22\x27\x3E][^\x09\x0A\x0B\x0C\x0D\x20\x3E]*)?))?/');

/**

 * For cUrl specific errors.

 */

class HRCurlException extends Exception {}

/**

 * Discovers RSS or atom feeds at the given URL.

 *

 * If document in given URL is an HTML document, function attempts to discover

 * RSS or Atom feeds.

 *

 * @param string $url

 *   The url of the feed to retrieve.

 * @param array $settings

 *   An optional array of settings. Valid options are: accept_invalid_cert.

 *

 * @return bool|string

 *   The discovered feed, or FALSE if the URL is not reachable or there was an

 *   error.

 */

function http_request_get_common_syndication($url, $settings = NULL) {

  $accept_invalid_cert = isset($settings['accept_invalid_cert']) ? $settings['accept_invalid_cert'] : FALSE;

  $download = http_request_get($url, NULL, NULL, $accept_invalid_cert);

  // Cannot get the feed, return.

  // http_request_get() always returns 200 even if its 304.

  if ($download->code != 200) {

    return FALSE;

  }

  // Drop the data into a seperate variable so all manipulations of the html

  // will not effect the actual object that exists in the static cache.

  // @see http_request_get.

  $downloaded_string = $download->data;

  // If this happens to be a feed then just return the url.

  if (isset($download->headers['content-type']) && http_request_is_feed($download->headers['content-type'], $downloaded_string)) {

    return $url;

  }

  $discovered_feeds = http_request_find_feeds($downloaded_string);

  foreach ($discovered_feeds as $feed_url) {

    $absolute = http_request_create_absolute_url($feed_url, $url);

    if (!empty($absolute)) {

      // @TODO: something more intelligent?

      return $absolute;

    }

  }

}

/**

 * Get the content from the given URL.

 *

 * @param string $url

 *   A valid URL (not only web URLs).

 * @param string $username

 *   If the URL uses authentication, supply the username.

 * @param string $password

 *   If the URL uses authentication, supply the password.

 * @param bool $accept_invalid_cert

 *   Whether to accept invalid certificates.

 * @param integer $timeout

 *   Timeout in seconds to wait for an HTTP get request to finish.

 *

 * @return stdClass

 *   An object that describes the data downloaded from $url.

 */

function http_request_get($url, $username = NULL, $password = NULL, $accept_invalid_cert = FALSE, $timeout = NULL) {

  // Intra-pagedownload cache, avoid to download the same content twice within

  // one page download (it's possible, compatible and parse calls).

  static $download_cache = array();

  if (isset($download_cache[$url])) {

    return $download_cache[$url];

  }

  // Determine request timeout.

  $request_timeout = !empty($timeout) ? $timeout : variable_get('http_request_timeout', 30);

  if (!$username && valid_url($url, TRUE)) {

    // Handle password protected feeds.

    $url_parts = parse_url($url);

    if (!empty($url_parts['user'])) {

      $password = $url_parts['pass'];

      $username = $url_parts['user'];

    }

  }

  $curl = http_request_use_curl();

  // Only download and parse data if really needs refresh.

  // Based on "Last-Modified" and "If-Modified-Since".

  $headers = array();

  if ($cache = cache_get('feeds_http_download_' . md5($url))) {

    $last_result = $cache->data;

    $last_headers = array_change_key_case($last_result->headers);

    if (!empty($last_headers['etag'])) {

      if ($curl) {

        $headers[] = 'If-None-Match: ' . $last_headers['etag'];

      }

      else {

        $headers['If-None-Match'] = $last_headers['etag'];

      }

    }

    if (!empty($last_headers['last-modified'])) {

      if ($curl) {

        $headers[] = 'If-Modified-Since: ' . $last_headers['last-modified'];

      }

      else {

        $headers['If-Modified-Since'] = $last_headers['last-modified'];

      }

    }

    if (!empty($username) && !$curl) {

      $headers['Authorization'] = 'Basic ' . base64_encode("$username:$password");

    }

  }

  // Support the 'feed' and 'webcal' schemes by converting them into 'http'.

  $url = strtr($url, array('feed://' => 'http://', 'webcal://' => 'http://'));

  if ($curl) {

    $headers[] = 'User-Agent: Drupal (+http://drupal.org/)';

    $result = new stdClass();

    $result->headers = array();

    // Parse the URL and make sure we can handle the schema.

    // cURL can only support either http:// or https://.

    // CURLOPT_PROTOCOLS is only supported with cURL 7.19.4

    $uri = parse_url($url);

    if (!isset($uri['scheme'])) {

      $result->error = 'missing schema';

      $result->code = -1002;

    }

    else {

      switch ($uri['scheme']) {

        case 'http':

        case 'https':

          // Valid scheme.

          break;

        default:

          $result->error = 'invalid schema ' . $uri['scheme'];

          $result->code = -1003;

          break;

      }

    }

    // If the scheme was valid, continue to request the feed using cURL.

    if (empty($result->error)) {

      $download = curl_init($url);

      curl_setopt($download, CURLOPT_FOLLOWLOCATION, TRUE);

      if (!empty($username)) {

        curl_setopt($download, CURLOPT_USERPWD, "{$username}:{$password}");

        curl_setopt($download, CURLOPT_HTTPAUTH, CURLAUTH_ANY);

      }

      curl_setopt($download, CURLOPT_HTTPHEADER, $headers);

      curl_setopt($download, CURLOPT_HEADER, TRUE);

      curl_setopt($download, CURLOPT_RETURNTRANSFER, TRUE);

      curl_setopt($download, CURLOPT_ENCODING, '');

      curl_setopt($download, CURLOPT_TIMEOUT, $request_timeout);

      if ($accept_invalid_cert) {

        curl_setopt($download, CURLOPT_SSL_VERIFYPEER, 0);

      }

      $header = '';

      $data = curl_exec($download);

      if (curl_error($download)) {

        throw new HRCurlException(

          t('cURL error (@code) @error for @url', array(

            '@code' => curl_errno($download),

            '@error' => curl_error($download),

            '@url' => $url,

          )), curl_errno($download)

        );

      }

      $header_size = curl_getinfo($download, CURLINFO_HEADER_SIZE);

      $header = substr($data, 0, $header_size - 1);

      $result->data = substr($data, $header_size);

      $headers = preg_split("/(\r\n){2}/", $header);

      $header_lines = preg_split("/\r\n|\n|\r/", end($headers));

      // Skip HTTP response status.

      array_shift($header_lines);

      while ($line = trim(array_shift($header_lines))) {

        list($header, $value) = explode(':', $line, 2);

        // Normalize the headers.

        $header = strtolower($header);

        if (isset($result->headers[$header]) && $header == 'set-cookie') {

          // RFC 2109: the Set-Cookie response header comprises the token Set-

          // Cookie:, followed by a comma-separated list of one or more cookies.

          $result->headers[$header] .= ',' . trim($value);

        }

        else {

          $result->headers[$header] = trim($value);

        }

      }

      $result->code = curl_getinfo($download, CURLINFO_HTTP_CODE);

      curl_close($download);

    }

  }

  else {

    $result = drupal_http_request($url, array('headers' => $headers, 'timeout' => $request_timeout));

    $result->headers = isset($result->headers) ? $result->headers : array();

  }

  $result->code = isset($result->code) ? $result->code : 200;

  // In case of 304 Not Modified try to return cached data.

  if ($result->code == 304) {

    if (isset($last_result)) {

      $last_result->from_cache = TRUE;

      return $last_result;

    }

    else {

      // It's a tragedy, this file must exist and contain good data.

      // In this case, clear cache and repeat.

      cache_clear_all('feeds_http_download_' . md5($url), 'cache');

      return http_request_get($url, $username, $password, $accept_invalid_cert, $request_timeout);

    }

  }

  // Set caches.

  cache_set('feeds_http_download_' . md5($url), $result);

  $download_cache[$url] = $result;

  return $result;

}

/**

 * Decides if it's possible to use cURL or not.

 *

 * @return bool

 *   TRUE if cURL is available, FALSE otherwise.

 */

function http_request_use_curl() {

  // Allow site administrators to choose to not use cURL.

  if (variable_get('feeds_never_use_curl', FALSE)) {

    return FALSE;

  }

  // Check availability of cURL on the system.

  $basedir = ini_get("open_basedir");

  return function_exists('curl_init') && !ini_get('safe_mode') && empty($basedir);

}

/**

 * Clear cache for a specific URL.

 */

function http_request_clear_cache($url) {

  cache_clear_all('feeds_http_download_' . md5($url), 'cache');

}

/**

 * Returns if the provided $content_type is a feed.

 *

 * @param string $content_type

 *   The Content-Type header.

 *

 * @param string $data

 *   The actual data from the http request.

 *

 * @return bool

 *   Returns TRUE if this is a parsable feed.

 */

function http_request_is_feed($content_type, $data) {

  $pos = strpos($content_type, ';');

  if ($pos !== FALSE) {

    $content_type = substr($content_type, 0, $pos);

  }

  $content_type = strtolower($content_type);

  if (strpos($content_type, 'xml') !== FALSE) {

    return TRUE;

  }

  // @TODO: Sometimes the content-type can be text/html but still be a valid

  // feed.

  return FALSE;

}

/**

 * Finds potential feed tags in the HTML document.

 *

 * @param string $html

 *   The html string to search.

 *

 * @return array

 *   An array of href to feeds.

 */

function http_request_find_feeds($html) {

  $matches = array();

  preg_match_all(HTTP_REQUEST_PCRE_LINK_TAG, $html, $matches);

  $links = $matches[1];

  $valid_links = array();

  // Build up all the links information.

  foreach ($links as $link_tag) {

    $attributes = array();

    $candidate = array();

    preg_match_all(HTTP_REQUEST_PCRE_TAG_ATTRIBUTES, $link_tag, $attributes, PREG_SET_ORDER);

    foreach ($attributes as $attribute) {

      // Find the key value pairs, attribute[1] is key and attribute[2] is the

      // value.

      if (!empty($attribute[1]) && !empty($attribute[2])) {

        $candidate[drupal_strtolower($attribute[1])] = drupal_strtolower(decode_entities($attribute[2]));

      }

    }

    // Examine candidate to see if it s a feed.

    // @TODO: could/should use http_request_is_feed ??

    if (isset($candidate['rel']) && $candidate['rel'] == 'alternate') {

      if (isset($candidate['href']) && isset($candidate['type']) && strpos($candidate['type'], 'xml') !== FALSE) {

        // All tests pass, its a valid candidate.

        $valid_links[] = $candidate['href'];

      }

    }

  }

  return $valid_links;

}

/**

 * Create an absolute url.

 *

 * @param string $url

 *   The href to transform.

 * @param string $base_url

 *   The url to be used as the base for a relative $url.

 *

 * @return string

 *   An absolute url

 */

function http_request_create_absolute_url($url, $base_url) {

  $url = trim($url);

  if (valid_url($url, TRUE)) {

    // Valid absolute url already.

    return $url;

  }

  // Turn relative url into absolute.

  if (valid_url($url, FALSE)) {

    // Produces variables $scheme, $host, $user, $pass, $path, $query and

    // $fragment.

    $parsed_url = parse_url($base_url);

    $path = dirname($parsed_url['path']);

    // Adding to the existing path.

    if ($url{0} == '/') {

      $cparts = array_filter(explode("/", $url));

    }

    else {

      // Backtracking from the existing path.

      $cparts = array_merge(array_filter(explode("/", $path)), array_filter(explode("/", $url)));

      foreach ($cparts as $i => $part) {

        if ($part == '.') {

          $cparts[$i] = NULL;

        }

        if ($part == '..') {

          $cparts[$i - 1] = NULL;

          $cparts[$i] = NULL;

        }

      }

      $cparts = array_filter($cparts);

    }

    $path = implode("/", $cparts);

    // Build the prefix to the path.

    $absolute_url = '';

    if (isset($parsed_url['scheme'])) {

      $absolute_url = $parsed_url['scheme'] . '://';

    }

    if (isset($parsed_url['user'])) {

      $absolute_url .= $parsed_url['user'];

      if (isset($pass)) {

        $absolute_url .= ':' . $parsed_url['pass'];

      }

      $absolute_url .= '@';

    }

    if (isset($parsed_url['host'])) {

      $absolute_url .= $parsed_url['host'] . '/';

    }

    $absolute_url .= $path;

    if (valid_url($absolute_url, TRUE)) {

      return $absolute_url;

    }

  }

  return FALSE;

}