tree 87f9d6676ff2fbf59e4532dd4b9f87495b4e3ef8
parent 5262ffb7587817a6428bb6419823d4a259ec0cc2
author David Crawshaw <crawshaw@google.com> 1489158074 -0500
committer David Crawshaw <crawshaw@google.com> 1489167424 -0500

dhcp: send 'server identifier' on request

The 'server identifier' option on a DHCPREQUEST must be the value of
the option sent by the server on the DHCPOFFER. Before this CL, we
were mistakenly using the siaddr field of the packet as the
identifier.

To cover this case in our unit tests, we fix our server to always
provide an siaddr of 0, and then require the client to send the
correct 'server identifier' option. (Just the server changes from
this CL cause the tests to fail.)

Also allow the DNS option to be any multiple of four, as DHCP
servers can send more than DNS server.

Change-Id: I40ff359f739c1129558e316edcee50de13e56446