diff --git CHANGELOG.txt CHANGELOG.txt
index 266e94e..02e1936 100644
--- CHANGELOG.txt
+++ CHANGELOG.txt
@@ -137,6 +137,13 @@ Drupal 7.0, xxxx-xx-xx (development version)
- Added RDF support:
* Modules can declare RDF namespaces which are serialized in the tag
for RDFa support.
+- Search engine optimization and web linking:
+ * Added a rel="canonical" link on node and comment pages to prevent
+ duplicate content indexing by search engines.
+ * Added default a rel="shortlink" link on node and comment pages
+ that advertises a short link as an alternative to third-party services.
+ * drupal_set_html_head now stores structured data for link, meta, and
+ other elements, allowing it to be altered by modules before rendering.
- Field API:
* Custom data fields may be attached to nodes, users, comments and taxonomy
terms.
diff --git includes/batch.inc includes/batch.inc
index f626e31..d481469 100644
--- includes/batch.inc
+++ includes/batch.inc
@@ -190,7 +190,14 @@ function _batch_progress_page_nojs() {
}
$url = url($batch['url'], array('query' => array('id' => $batch['id'], 'op' => $new_op)));
- drupal_add_html_head('');
+ $element = array(
+ '#tag' => 'meta',
+ '#attributes' => array(
+ 'http-equiv' => 'Refresh',
+ 'content' => '0; URL=' . $url,
+ ),
+ );
+ drupal_add_html_head($element, 'batch_progress_meta_refresh');
return theme('progress_bar', $percentage, $message);
}
diff --git includes/common.inc includes/common.inc
index 680683c..7d53b1d 100644
--- includes/common.inc
+++ includes/common.inc
@@ -281,22 +281,71 @@ function drupal_get_rdf_namespaces() {
* Add output to the head tag of the HTML page.
*
* This function can be called as long the headers aren't sent.
+ *
+ * @param $data
+ * A renderable array. If the '#type' key is not set then 'xhtml_tag' will be
+ * added as the default '#type'.
+ * @param $key
+ * A unique string key identifying the data. Required if $data is not NULL.
+ *
+ * @return
+ * An array of all the stored HEAD elements.
*/
-function drupal_add_html_head($data = NULL) {
- $stored_head = &drupal_static(__FUNCTION__, '');
+function drupal_add_html_head($data = NULL, $key = NULL) {
+ $stored_head = &drupal_static(__FUNCTION__);
- if (!is_null($data)) {
- $stored_head .= $data . "\n";
+ if (!isset($stored_head)) {
+ // Make sure the defaults, including Content-Type, come first.
+ $stored_head = _drupal_default_html_head();
+ }
+
+ if (isset($data) && isset($key)) {
+ if (!isset($data['#type'])) {
+ $data['#type'] = 'xhtml_tag';
+ }
+ $stored_head[$key] = $data;
}
return $stored_head;
}
/**
- * Retrieve output to be displayed in the head tag of the HTML page.
+ * Returns elements always displayed in the HEAD tag of the HTML page.
+ */
+function _drupal_default_html_head() {
+ // Add default elements. Make sure the Content-Type comes first because the
+ // IE browser may be vulnerable to XSS via encoding attacks from any content
+ // that comes before this META tag, such as a TITLE tag.
+ $elements['system_meta_content_type'] = array(
+ '#type' => 'xhtml_tag',
+ '#tag' => 'meta',
+ '#attributes' => array(
+ 'http-equiv' => 'Content-Type',
+ 'content' => 'text/html; charset=utf-8',
+ ),
+ );
+ // Get the major version.
+ list($version, ) = explode('.', VERSION);
+ // Show Drupal and the major version number in the META GENERATOR tag.
+ $elements['system_meta_generator'] = array(
+ '#type' => 'xhtml_tag',
+ '#tag' => 'meta',
+ '#attributes' => array(
+ 'name' => 'Generator',
+ 'content' => 'Drupal ' . $version . ' (http://drupal.org)',
+ ),
+ );
+ // Send Drupal and the major version number in the HTTP headers.
+ $elements['system_meta_generator']['#attached']['drupal_set_header'][] = array('X-Generator', 'Drupal ' . $version . ' (http://drupal.org)');
+ return $elements;
+}
+
+/**
+ * Retrieve output to be displayed in the HEAD tag of the HTML page.
*/
function drupal_get_html_head() {
- $output = "\n";
- return $output . drupal_add_html_head();
+ $head_elements = drupal_add_html_head();
+ drupal_alter('html_head', $head_elements);
+ return drupal_render($head_elements);
}
/**
@@ -319,7 +368,7 @@ function drupal_clear_path_cache() {
function drupal_add_feed($url = NULL, $title = '') {
$stored_feed_links = &drupal_static(__FUNCTION__, array());
- if (!is_null($url) && !isset($stored_feed_links[$url])) {
+ if (isset($url)) {
$stored_feed_links[$url] = theme('feed_icon', $url, $title);
drupal_add_link(array('rel' => 'alternate',
@@ -2481,6 +2530,28 @@ function url($path = NULL, array $options = array()) {
}
/**
+ * Format an attribute string for a HTTP header.
+ *
+ * @param $attributes
+ * An associative array of attributes.
+ *
+ * @return
+ * A ; separated string ready for insertion in a HTTP header. No escaping is
+ * performed for HTML entities, so this string is not safe to be printed.
+ *
+ * @see drupal_set_header()
+ */
+function drupal_header_attributes(array $attributes = array()) {
+ foreach ($attributes as $attribute => &$data) {
+ if (is_array($data)) {
+ $data = implode(' ', $data);
+ }
+ $data = $attribute . '="' . $data . '"';
+ }
+ return $attributes ? ' ' . implode('; ', $attributes) : '';
+}
+
+/**
* Format an attribute string to insert in a tag.
*
* Each array key and its value will be formatted into an HTML attribute string.
@@ -2692,12 +2763,31 @@ function base_path() {
}
/**
- * Add a tag to the page's HEAD.
+ * Add a LINK tag with a distinct REL attribute to the page's HEAD.
*
- * This function can be called as long the HTML header hasn't been sent.
- */
-function drupal_add_link($attributes) {
- drupal_add_html_head('\n");
+ * This function can be called as long the HTML header hasn't been sent,
+ * which on normal pages is up through the preprocess step of theme('html').
+ * Adding a link will overwrite a prior link with the exact same REL and HREF
+ * attributes.
+ *
+ * @param $attributes
+ * Associative array of element attributes including 'href' and 'rel'.
+ * @param $header
+ * Optional flag to determine if a HTTP Link: header should be sent.
+ */
+function drupal_add_link($attributes, $header = FALSE) {
+ $element = array(
+ '#tag' => 'link',
+ '#attributes' => $attributes,
+ );
+
+ if ($header) {
+ // Set a HTTP Link: header also.
+ $href = '<' . check_plain($attributes['href']) . '>;';
+ unset($attributes['href']);
+ $element['#attached']['drupal_set_header'][] = array('Link', $href . drupal_header_attributes($attributes), TRUE);
+ }
+ drupal_add_html_head($element, 'drupal_add_link:' . $attributes['rel'] . ':' . $attributes['href']);
}
/**
@@ -2910,7 +3000,16 @@ function drupal_get_css($css = NULL) {
break;
case 'external':
// Preprocessing for external CSS files is ignored.
- $external_css .= '' . "\n";
+ $element = array(
+ '#tag' => 'link',
+ '#attributes' => array(
+ 'type' => "text/css",
+ 'rel' => "stylesheet",
+ 'media' => $item['media'],
+ 'href' => $item['data'],
+ ),
+ );
+ $external_css .= theme('xhtml_tag', $element) . "\n";
break;
}
}
@@ -2921,7 +3020,16 @@ function drupal_get_css($css = NULL) {
// starting with "ad*".
$filename = 'css_' . md5(serialize($items) . $query_string) . '.css';
$preprocess_file = file_create_url(drupal_build_css_cache($items, $filename));
- $rendered_css['preprocess'] .= '' . "\n";
+ $element = array(
+ '#tag' => 'link',
+ '#attributes' => array(
+ 'type' => "text/css",
+ 'rel' => "stylesheet",
+ 'media' => $media,
+ 'href' => $preprocess_file,
+ ),
+ );
+ $rendered_css['preprocess'] .= theme('xhtml_tag', $element) . "\n";
}
}
// Enclose the inline CSS with the style tag if required.
@@ -4868,6 +4976,9 @@ function drupal_common_theme() {
'indentation' => array(
'arguments' => array('size' => 1),
),
+ 'xhtml_tag' => array(
+ 'arguments' => array('element' => NULL),
+ ),
// from pager.inc
'pager' => array(
'arguments' => array('tags' => array(), 'element' => 0, 'parameters' => array(), 'quantity' => 9),
diff --git includes/theme.inc includes/theme.inc
index e300eb6..6156882 100644
--- includes/theme.inc
+++ includes/theme.inc
@@ -1869,6 +1869,20 @@ function theme_feed_icon($url, $title) {
}
/**
+ * Generate the output for a generic XHTML tag with attributes.
+ *
+ * @ingroup themeable
+ */
+function theme_xhtml_tag(array $element) {
+ if (!isset($element['#value'])) {
+ return '<' . $element['#tag'] . drupal_attributes($element['#attributes']) . " />\n";
+ }
+ else {
+ return '<' . $element['#tag'] . drupal_attributes($element['#attributes']) . '>' . $element['#value'] . '\n";
+ }
+}
+
+/**
* Returns code that emits the 'more' link used on blocks.
*
* @param $url
@@ -2158,7 +2172,7 @@ function template_preprocess_html(&$variables) {
if (theme_get_setting('toggle_favicon')) {
$favicon = theme_get_setting('favicon');
$type = theme_get_setting('favicon_mimetype');
- drupal_add_html_head('');
+ drupal_add_link(array('rel' => 'shortcut icon', 'href' => check_url($favicon), 'type' => $type));
}
// Construct page title.
@@ -2327,7 +2341,7 @@ function template_preprocess_maintenance_page(&$variables) {
if (theme_get_setting('toggle_favicon')) {
$favicon = theme_get_setting('favicon');
$type = theme_get_setting('favicon_mimetype');
- drupal_add_html_head('');
+ drupal_add_link(array('rel' => 'shortcut icon', 'href' => check_url($favicon), 'type' => $type));
}
global $theme;
diff --git modules/comment/comment.module modules/comment/comment.module
index 0f94475..0ed8a4d 100644
--- modules/comment/comment.module
+++ modules/comment/comment.module
@@ -349,9 +349,6 @@ function comment_permalink($comment) {
$_GET['q'] = 'node/' . $node->nid;
$_GET['page'] = $page;
- // Set the node path as the canonical URL to prevent duplicate content.
- drupal_add_link(array('rel' => 'canonical', 'href' => url('node/' . $node->nid)));
-
// Return the node view, this will show the correct comment in context.
return menu_execute_active_handler('node/' . $node->nid);
}
diff --git modules/node/node.module modules/node/node.module
index 8de33ee..2bd1a6a 100644
--- modules/node/node.module
+++ modules/node/node.module
@@ -1986,6 +1986,10 @@ function node_page_default() {
*/
function node_page_view($node) {
drupal_set_title($node->title);
+ // Set the node path as the canonical URL to prevent duplicate content.
+ drupal_add_link(array('rel' => 'canonical', 'href' => url('node/' . $node->nid)), TRUE);
+ // Set the non-aliased path as a default shortlink.
+ drupal_add_link(array('rel' => 'shortlink', 'href' => url('node/' . $node->nid, array('alias' => TRUE))), TRUE);
return node_show($node);
}
diff --git modules/openid/tests/openid_test.module modules/openid/tests/openid_test.module
index a2891f2..4a20ded 100644
--- modules/openid/tests/openid_test.module
+++ modules/openid/tests/openid_test.module
@@ -97,7 +97,14 @@ function openid_test_yadis_x_xrds_location() {
* Menu callback; regular HTML page with element.
*/
function openid_test_yadis_http_equiv() {
- drupal_add_html_head('');
+ $element = array(
+ '#tag' => 'meta',
+ '#attributes' => array(
+ 'http-equiv' => 'X-XRDS-Location',
+ 'content' => url('openid-test/yadis/xrds', array('absolute' => TRUE)),
+ ),
+ );
+ drupal_add_html_head($element, 'openid_test_yadis_http_equiv');
return t('This page includes a <meta equiv=...> element containing the URL of an XRDS document.');
}
@@ -105,7 +112,7 @@ function openid_test_yadis_http_equiv() {
* Menu callback; regular HTML page with OpenID 1.0 element.
*/
function openid_test_html_openid1() {
- drupal_add_html_head('');
+ drupal_add_link(array('rel' => 'openid.server', 'href' => url('openid-test/endpoint', array('absolute' => TRUE))));
return t('This page includes a <link rel=...> element containing the URL of an OpenID Provider Endpoint.');
}
@@ -113,7 +120,7 @@ function openid_test_html_openid1() {
* Menu callback; regular HTML page with OpenID 2.0 element.
*/
function openid_test_html_openid2() {
- drupal_add_html_head('');
+ drupal_add_link(array('rel' => 'openid2.provider', 'href' => url('openid-test/endpoint', array('absolute' => TRUE))));
return t('This page includes a <link rel=...> element containing the URL of an OpenID Provider Endpoint.');
}
diff --git modules/simpletest/tests/browser_test.module modules/simpletest/tests/browser_test.module
index f433312..df5a265 100644
--- modules/simpletest/tests/browser_test.module
+++ modules/simpletest/tests/browser_test.module
@@ -57,7 +57,14 @@ function browser_test_print_post_form_submit($form, &$form_state) {
function browser_test_refresh_meta() {
if (!isset($_GET['refresh'])) {
$url = url('browser_test/refresh/meta', array('absolute' => TRUE, 'query' => array('refresh' => 'true')));
- drupal_add_html_head('');
+ $element = array(
+ '#tag' => 'meta',
+ '#attributes' => array(
+ 'http-equiv' => 'Refresh',
+ 'content' => '0; URL=' . $url,
+ )
+ );
+ drupal_add_html_head($element, 'browser_test_refresh_meta');
return '';
}
echo 'Refresh successful';
diff --git modules/system/system.api.php modules/system/system.api.php
index 1ebd7fe..20f3a83 100644
--- modules/system/system.api.php
+++ modules/system/system.api.php
@@ -2256,6 +2256,27 @@ function hook_drupal_goto_alter(array $args) {
}
/**
+ * Alter XHTML HEAD tags before they are rendered by drupal_get_html_head().
+ *
+ * Elements available to be altered are only those added using
+ * drupal_add_link() or drupal_add_html_head(). CSS and JS files are handled
+ * using drupal_add_css() and drupal_add_js(), so the head links for those
+ * files will not appear in the $head_elements array.
+ *
+ * @param $head_elements
+ * An array of renderable elements. Generally the values of the #attributes
+ * array will be the most likely target for changes.
+ */
+function hook_html_head_alter(&$head_elements) {
+ foreach($head_elements as $key => $element) {
+ if (isset($element['#attributes']['rel']) && $element['#attributes']['rel'] == 'canonical') {
+ // I want a custom canonical url.
+ $head_elements[$key]['#attributes']['href'] = mymodule_canonical_url();
+ }
+ }
+}
+
+/**
* Alter MIME type mappings used to determine MIME type from a file extension.
*
* This hook is run when file_mimetype_mapping() is called. It is used to
diff --git modules/system/system.module modules/system/system.module
index b617862..aee96f6 100644
--- modules/system/system.module
+++ modules/system/system.module
@@ -194,12 +194,6 @@ function system_theme() {
'system_powered_by' => array(
'arguments' => array('image_path' => NULL),
),
- 'meta_generator_html' => array(
- 'arguments' => array('version' => NULL),
- ),
- 'meta_generator_header' => array(
- 'arguments' => array('version' => NULL),
- ),
'system_compact_link' => array(),
'system_run_cron_image' => array(
'arguments' => array('image_path' => NULL),
@@ -300,6 +294,12 @@ function system_element_info() {
'#items' => array(),
);
+ $types['xhtml_tag'] = array(
+ '#theme' => 'xhtml_tag',
+ '#attributes' => array(),
+ '#value' => NULL,
+ );
+
// Input elements.
$types['submit'] = array(
'#input' => TRUE,
@@ -2715,24 +2715,6 @@ function theme_system_compact_link() {
}
/**
- * Send Drupal and the major version number in the META GENERATOR HTML.
- *
- * @ingroup themeable
- */
-function theme_meta_generator_html($version = VERSION) {
- drupal_add_html_head('');
-}
-
-/**
- * Send Drupal and the major version number in the HTTP headers.
- *
- * @ingroup themeable
- */
-function theme_meta_generator_header($version = VERSION) {
- drupal_add_http_header('X-Generator', 'Drupal ' . $version . ' (http://drupal.org)');
-}
-
-/**
* Implement hook_image_toolkits().
*/
function system_image_toolkits() {