Failed to check for empty public IP and/or private IP

[hwdsl2]

A bug was introduced in a previous commit 21629ae on Jan 14, 2016. It removed checks for empty public/private IP strings, in favor of checking against the correct IP regular expression. However, the grep command used in the IP regex checks had an error (the "-v" switch was used instead of negating the exit code). As a result, undefined or empty IP variables would pass the check, which is incorrect.

This bug has been fixed in commit b610351 on Jan 21, 2016. GitHub users @bjzhush and @Geoferry please update your forks to the latest version. Thanks!