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-rw-r--r--engine/lib/actions.php83
1 files changed, 83 insertions, 0 deletions
diff --git a/engine/lib/actions.php b/engine/lib/actions.php
index 682e13b55..0779e5d6a 100644
--- a/engine/lib/actions.php
+++ b/engine/lib/actions.php
@@ -107,6 +107,89 @@
function actions_init($event, $object_type, $object) {
register_action("error");
return true;
+ }
+
+ /**
+ * Action gatekeeper.
+ * This function verifies form input for security features (like a generated token), and forwards
+ * the page if they are invalid.
+ *
+ * Place at the head of actions.
+ */
+ function action_gatekeeper()
+ {
+ $token = get_input('__elgg_token');
+ $action = get_input('__elgg_action');
+ $ts = get_input('__elgg_ts');
+ $session_id = session_id();
+
+ if (($token) && ($action) && ($ts) && ($session_id))
+ {
+ // generate token, check with input and forward if invalid
+ $generated_token = generate_action_token($action, $ts);
+
+ // Validate token
+ if (strcmp($token, $generated_token)==0)
+ {
+
+ // TODO: Validate time to ensure its not crazy
+
+
+ return true;
+ }
+ else
+ register_error(elgg_echo('actiongatekeeper:tokeninvalid'));
+ }
+ else
+ register_error(elgg_echo('actiongatekeeper:missingfields'));
+
+ forward();
+ exit;
+ }
+
+ /**
+ * Generate a token for the current user suitable for being placed in a hidden field in action forms.
+ *
+ * @param string $action The action being called
+ * @param int $timestamp Unix timestamp
+ */
+ function generate_action_token($action, $timestamp)
+ {
+ // Get input values
+ $site_secret = get_site_secret();
+
+ // Current session id
+ $session_id = session_id();
+
+ if (($site_secret) && ($session_id))
+ return md5($site_secret.$action.$timestamp.$session_id);
+
+ return false;
+ }
+
+ /**
+ * Initialise the site secret.
+ *
+ */
+ function init_site_secret()
+ {
+ $secret = md5(rand().microtime());
+ if (datalist_set('__site_secret__', $secret))
+ return $secret;
+
+ return false;
+ }
+
+ /**
+ * Retrieve the site secret.
+ *
+ */
+ function get_site_secret()
+ {
+ $secret = datalist_get('__site_secret__');
+ if (!$secret) $secret = init_site_secret();
+
+ return $secret;
}
// Register some actions ***************************************************