make the ipv4 subnet matching code work like the ipv6 code, fixes bug in...

make the ipv4 subnet matching code work like the ipv6 code, fixes bug in subnet matching on tun interfaces

(cherry picked from commit 07d2354a)
(cherry picked from commit b3bad8d2)

src/etc/inc/interfaces.lib.inc

@@ -246,8 +246,15 @@ function legacy_interfaces_details($intf = null)
             $result[$current_interface]["macaddr"] = $line_parts[1];
         } elseif (strpos($line, "\tinet ") !== false) {
             // IPv4 information
-            $mask = substr_count(base_convert(hexdec($line_parts[3]), 10, 2), '1');
-            $result[$current_interface]["ipv4"][] = array("ipaddr" => $line_parts[1], "subnetbits" => $mask);
+            unset($mask);
+            for ($i = 0; $i < count($line_parts) - 1; ++$i) {
+                if ($line_parts[$i] == 'netmask') {
+                    $mask = substr_count(base_convert(hexdec($line_parts[($i + 1)]), 10, 2), '1');
+                }
+            }
+            if (isset($mask)) {
+                $result[$current_interface]["ipv4"][] = array("ipaddr" => $line_parts[1], "subnetbits" => $mask);
+            }
         } elseif (strpos($line, "\tinet6 ") !== false) {
             // IPv6 information
             $addr = strtok($line_parts[1], '%');