tree a3c82c5f0ff94904da15a7281f883d8a7c50e793
parent e08a3977a0afdcc5d935993e9ca4a5eaf769e523
author Lorenzo Colitti <lorenzo@google.com> 1425918760 +0900
committer Lorenzo Colitti <lorenzo@google.com> 1426489656 +0900

Add two utility methods for IPv4 netmasks.

1. Add a validating method to convert a netmask to a prefix length.
2. Add a function to get the implicit netmask of an IPv4 address.
3. Add a unit test.

Bug: 19704592
Change-Id: Icb9f58d3903ea01df9e3720383c9bd5db6dd8f26