linkchecker.install | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 linkchecker.module  | 31 +++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/linkchecker.install b/linkchecker.install
index 84686c0..9a467bf 100644
--- a/linkchecker.install
+++ b/linkchecker.install
@@ -6,6 +6,58 @@
  */
 
 /**
+ * Implements hook_requirements().
+ */
+function linkchecker_requirements($phase) {
+  $requirements = array();
+  if ($phase == 'runtime') {
+    $t = get_t();
+    module_load_include('module', 'linkchecker');
+    $links_all = db_query('SELECT COUNT(1) FROM {linkchecker_link} WHERE status = :status', array(':status' => 1))->fetchField();
+    $links_unchecked = db_query('SELECT COUNT(1) FROM {linkchecker_link} WHERE last_checked = :last_checked AND status = :status', array(':last_checked' => 0, ':status' => 1))->fetchField();
+    $query = _linkchecker_broken_links_query();
+    $links_broken = $query->countQuery()->execute()->fetchField();
+
+    $description = '';
+    if ($links_all > 0 && $links_broken == 0 && $links_unchecked == 0) {
+      $msg = format_plural($links_all,
+        '@count link in the database is checked OK.',
+        '@count links in the database are checked OK.'
+      );
+    }
+    else {
+      $msg = ($links_all > 0)
+        ? format_plural($links_all,
+            '@links_broken broken and @links_unchecked unchecked of total @count link in the database.',
+            '@links_broken broken and @links_unchecked unchecked of total @count links in the database.',
+            array(
+              '@links_unchecked' => $links_unchecked,
+              '@links_broken' => $links_broken,
+            ))
+        : $t('There are no links in the database.');
+      if ($links_unchecked > 0) {
+        $description .= $t('Please be patient until all links have been checked via cron.');
+        $description .= ' ' . $t('You can <a href="@cron">run cron manually</a>.', array('@cron' => url('admin/reports/status/run-cron')));
+      }
+      if ($links_broken > 0) {
+        if (!empty($description)) {
+          $description .= '<br />';
+        }
+        $description .=  $t('See <a href="@report">Broken links report</a>.', array('@report' => url('admin/reports/linkchecker')));
+      }
+    }
+
+    $requirements['linkchecker'] = array(
+      'value' => $msg,
+      'severity' => ($links_broken > 0) ? REQUIREMENT_INFO : REQUIREMENT_OK,
+      'description' => $description,
+      'title' => $t('Link Checker'),
+    );
+  }
+  return $requirements;
+}
+
+/**
  * Implements hook_install().
  */
 function linkchecker_install() {
diff --git a/linkchecker.module b/linkchecker.module
index a05d4c6..f1dceb3 100644
--- a/linkchecker.module
+++ b/linkchecker.module
@@ -2505,3 +2505,34 @@ function _linkchecker_array_values_recursive(array $array) {
 
   return $array_values;
 }
+
+function _linkchecker_broken_links_query() {
+  $ignore_response_codes = preg_split('/(\r\n?|\n)/', variable_get('linkchecker_ignore_response_codes', "200\n206\n302\n304\n401\n403"));
+
+  // Search for broken links in nodes and comments and blocks of all users.
+  // @todo Try to make UNION'ed subselect resultset smaller.
+  $subquery4 = db_select('linkchecker_node', 'ln')
+    ->distinct()
+    ->fields('ln', array('lid'));
+
+  $subquery3 = db_select('linkchecker_comment', 'lc')
+    ->distinct()
+    ->fields('lc', array('lid'));
+
+  $subquery2 = db_select('linkchecker_block_custom', 'lb')
+    ->distinct()
+    ->fields('lb', array('lid'));
+
+  // UNION all linkchecker type tables.
+  $subquery1 = db_select($subquery2->union($subquery3)->union($subquery4), 'q1')->fields('q1', array('lid'));
+
+  // Build query.
+  $query = db_select('linkchecker_link', 'll');
+  $query->innerJoin($subquery1, 'q2', 'q2.lid = ll.lid');
+  $query->fields('ll');
+  $query->condition('ll.last_checked', 0, '<>');
+  $query->condition('ll.status', 1);
+  $query->condition('ll.code', $ignore_response_codes, 'NOT IN');
+  return $query;
+}
+