[gh-438] Replace file_get_contents with a wrapper (unl_url_get_contents) that...

[gh-438] Replace file_get_contents with a wrapper (unl_url_get_contents) that will cache the results based on the requested URL's cache headers.

sites/all/modules/unl/includes/common.php

@@ -180,3 +180,80 @@ function unl_user_is_administrator() {
 
   return FALSE;
 }
+
+/**
+ * Fetch the contents at the given URL and cache the result using
+ * drupal's cache for as long as the response headers allow.
+ * @param string $url
+ * @param resource $context
+ */
+function unl_url_get_contents($url, $context = NULL)
+{
+  // get some per-request static storage
+  $static = &drupal_static(__FUNCTION__);
+  if (!isset($static)) {
+    $static = array();
+  }
+  
+  // If cached in the static array, return it.
+  if (array_key_exists($url, $static)) {
+    return $static[$url];
+  }
+  
+  // If cached in the drupla cache, return it.
+  $data = cache_get(__FUNCTION__ . $url);
+  if ($data && time() < $data->data['expires']) {
+    return $data->data['body'];
+  }
+
+  // Make the request
+  $http_response_header = array();
+  $body = file_get_contents($url, NULL, $context);
+  $headers = array();
+  foreach ($http_response_header as $rawHeader) {
+    $headerName = strtolower(trim(substr($rawHeader, 0, strpos($rawHeader, ':'))));
+    $headerValue = trim(substr($rawHeader, strpos($rawHeader, ':') + 1));
+    if ($headerName && $headerValue) {
+      $headers[$headerName] = $headerValue;
+    }
+  }
+  
+  $cacheable = NULL;
+  $expires = 0;
+  
+  // Check for a Cache-Control header and the max-age and/or private headers.
+  if (array_key_exists('cache-control', $headers)) {
+    $cacheControl = strtolower($headers['cache-control']);
+    $matches = array();
+    if (preg_match('/max-age=([0-9]+)/', $cacheControl, $matches)) {
+      $expires = time() + $matches[1];
+      $cacheable = TRUE;
+    }
+    if (strpos($cacheControl, 'private') !== FALSE) {
+      $cacheable = FALSE;
+    }
+    if (strpos($cacheControl, 'no-cache') !== FALSE) {
+      $cacheable = FALSE;
+    }
+  }
+  // If there was no Cache-Control header, or if it wasn't helpful, check for an Expires header.
+  if ($cacheable === NULL && array_key_exists('expires', $headers)) {
+    $cacheable = TRUE;
+    $expires = DateTime::createFromFormat(DateTime::RFC1123, $headers['expires'])->getTimestamp();
+  }
+  
+  // Save to the drupal cache if caching is ok
+  if ($cacheable && time() < $expires) {
+    $data = array(
+      'body' => $body,
+      'expires' => $expires,
+    );
+    cache_set(__FUNCTION__ . $url, $data, 'cache', $expires);
+  }
+  // Otherwise just save to the static per-request cache
+  else {
+    $static[$url] = $body;
+  }
+  
+  return $body;
+}

sites/all/modules/unl/unl.module

@@ -155,7 +155,7 @@ function unl_field_attach_view_alter(&$output, $context) {
     $element = isset($output[$field_name]['#field_name']) ? $output[$field_name]['#field_name'] : '';
     switch ($element) {
       case 'field_hrorgunit':
-        $result = file_get_contents('http://directory.unl.edu/departments/?view=deptlistings&org_unit='.$element['#items'][0]['value'].'&format=partial');
+        $result = unl_url_get_contents('http://directory.unl.edu/departments/?view=deptlistings&org_unit='.$element['#items'][0]['value'].'&format=partial');
         if (!empty($result) && $result != '<div id="all_employees"></div>') {
           drupal_add_css('http://directory.unl.edu/css/peoplefinder_default.css', 'external');
           drupal_add_js('http://directory.unl.edu/scripts/peoplefinder.js', 'external');
@@ -1626,7 +1626,7 @@ function unl_filter_ssi_process($text, $filter, $format, $langcode, $cache, $cac
       $url .= '#' . $parts['fragment'];
     }
 
-    $content = file_get_contents($url);
+    $content = unl_url_get_contents($url);
     $replacements[$full_match] = PHP_EOL
                                . '<!-- Begin content from ' . $url . ' -->' . PHP_EOL
                                . $content . PHP_EOL

sites/all/themes/unl_wdn/template.php

@@ -160,7 +160,12 @@ function unl_wdn_username_alter(&$name, $account) {
   $context = stream_context_create(array(
     'http' => array('timeout' => 1)
   ));
-  $result = json_decode(@file_get_contents('http://directory.unl.edu/service.php?format=json&uid='.$name, 0, $context));
+  if (function_exists('unl_url_get_contents')) {
+    $result = json_decode(@unl_url_get_contents('http://directory.unl.edu/service.php?format=json&uid='.$name, $context));
+  }
+  else {
+    $result = json_decode(@file_get_contents('http://directory.unl.edu/service.php?format=json&uid='.$name, 0, $context));
+  }
   if (!empty($result) && $result->sn) {
     $zero = '0';
     $firstname = ($result->eduPersonNickname ? $result->eduPersonNickname->$zero : $result->givenName->$zero);