Fix some LDAP URIs failing is_valid_domain_name check

src/authorizer/class-authentication.php

@@ -575,10 +575,12 @@ protected function custom_authenticate_ldap( $auth_settings, $username, $passwor
 			// the form ldap://hostname:port or ldaps://hostname:port.
 			$ldap_port   = intval( $auth_settings['ldap_port'] );
 			$parsed_host = wp_parse_url( $ldap_host );
-			// Fail (fall back to WordPress auth) if invalid host is specified.
-			if ( false === $parsed_host || ! Helper::is_valid_domain_name( $ldap_host ) ) {
+
+			// Fail if invalid host is specified.
+			if ( false === $parsed_host ) {
 				continue;
 			}
+
 			// If a scheme is in the LDAP host, use full LDAP URI instead of just hostname.
 			if ( array_key_exists( 'scheme', $parsed_host ) ) {
 				// If the port isn't in the LDAP URI, use the one in the LDAP port field.
@@ -588,11 +590,18 @@ protected function custom_authenticate_ldap( $auth_settings, $username, $passwor
 				$ldap_host = Helper::build_url( $parsed_host );
 			}
 
-			// Establish LDAP connection.
+			// Create LDAP connection.
 			$ldap = ldap_connect( $ldap_host, $ldap_port );
 			ldap_set_option( $ldap, LDAP_OPT_PROTOCOL_VERSION, 3 );
-			if ( 1 === intval( $auth_settings['ldap_tls'] ) ) {
-				if ( ! ldap_start_tls( $ldap ) ) {
+
+			// Fail if we don't have a plausible LDAP URI.
+			if ( false === $ldap ) {
+				continue;
+			}
+
+			// Attempt to start TLS if that setting is checked and we're not using ldaps protocol.
+			if ( 1 === intval( $auth_settings['ldap_tls'] ) && false === strpos( $ldap_host, 'ldaps://' ) ) {
+				if ( ! @ldap_start_tls( $ldap ) ) {
 					continue;
 				}
 			}

src/authorizer/class-helper.php

@@ -381,24 +381,6 @@ public static function build_url( $parts = array() ) {
 	}
 
 
-	/**
-	 * Determine whether a domain name is valid.
-	 *
-	 * @param  string  $domain_name Name to test.
-	 * @return boolean              Whether the domain is valid.
-	 */
-	public static function is_valid_domain_name($domain_name) {
-		return (
-			// Valid characters check.
-			preg_match("/^([a-z\d](-*[a-z\d])*)(\.([a-z\d](-*[a-z\d])*))*$/i", $domain_name) &&
-			// Overall length check.
-			preg_match("/^.{1,253}$/", $domain_name) &&
-			// Length of each label check.
-			preg_match("/^[^\.]{1,63}(\.[^\.]{1,63})*$/", $domain_name)
-		);
-	}
-
-
 	/**
 	 * Helper function to get a single user info array from one of the access
 	 * control lists (pending, approved, or blocked).