Logging only DHCPACK

[Daniel Manser]

> A bit of experimentation may be required to test for the exact phase,
> but something like:
>
> if option dhcp-message-type = 5 {
>    log ( info, concat ( "Lease: ",
>        binary-to-ascii (10, 8, ".", leased-address)));
> }

well yeah, but for some reason, you won't get an entry in your log,
just for DHCPDISCOVER, DHCPREQUEST or (I believe) any DHCP packet that
came from the client TO the server, but not from the server to the
client. I needed this too, but then resigned. I'm sorry I haven't a
solution for this.