Fix parsing of IPv4 addresses with certain symbols

Add some extra checks to the parser to make sure that addresses
like "300-05" aren't interpreted as valid IPv4 addresses.

Change-Id: I12475eebc9452e060779bb05e2b4ad9512a28281
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>