Display returnto URL above the login form if present to further mitigate CSRF issues

Changelog.md

@@ -4,6 +4,9 @@ This file holds the changelog for Pepperminty Wiki. This is the master list of t
 
 ## v0.24-dev
 
+### Changed
+ - Display returnto URL above the login form if present to further mitigate CSRF issues
+
 ### Fixed
  - [security] Fixed an XSS vulnerability in the `format` GET parameter of the `stats` action (thanks, @JamieSlome)
  - [security] Ensured that the `returnto` GET parameter leads you only to another place on your Pepperminty Wiki instance (thanks, @JamieSlome)

modules/page-login.php

@@ -53,6 +53,8 @@ register_module([
 				$content .= "\t\t<p><em>Login failed.</em></p>\n";
 			if(isset($_GET["required"]))
 				$content .= "\t\t<p><em>$settings->sitename requires that you login before continuing.</em></p>\n";
+			if(isset($_GET["returnto"]))
+				$content .= "\t\t<p>Login to be redirected to <code>".htmlentities($_GET["returnto"])."</code>.</p>";
 			$content .= "\t\t<form method='post' action='$login_form_action_url'>
 				<label for='user'>Username:</label>
 				<input type='text' name='user' id='user' autofocus />