Fixed: shortcodes prefix field now accepts special characters

Author: vanokhin

admin/class-shortcodes-ultimate-admin-settings.php

@@ -209,7 +209,7 @@ protected function get_plugin_settings() {
 
 			$this->plugin_settings[] = array(
 				'id'          => 'su_option_prefix',
-				'sanitize'    => 'sanitize_html_class',
+				'sanitize'    => array( $this, 'sanitize_prefix' ),
 				'title'       => __( 'Shortcodes prefix', 'shortcodes-ultimate' ),
 				'description' => __( 'This prefix will be used in shortcode names. For example: set <code>MY_</code> prefix and shortcodes will look like <code>[MY_button]</code>. Please note that this setting does not change shortcodes that have been inserted earlier. Change this setting very carefully.', 'shortcodes-ultimate' ),
 			);
@@ -228,4 +228,15 @@ protected function get_plugin_settings() {
 
 	}
 
+	/**
+	 * Callback function to sanitize prefix value.
+	 *
+	 * @since  5.0.1
+	 * @param string  $prefix Prefix value.
+	 * @return string          Sanitized string.
+	 */
+	public function sanitize_prefix( $prefix ) {
+		return preg_replace( '@[<>&/\[\]\x00-\x20="\']@', '', $prefix );
+	}
+
 }