[FS#406] odhcpd: enable IPv6 unicast relay

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Martin Garbe (monomartin) 

Attached to Project - LEDE Project
Summary - odhcpd: enable IPv6 unicast relay
Task Type - Feature Request
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - We want to use Prefix Delegation in a large layer3 mesh network. Currently odhcpd only supports DHCPv6-Relay by forwarding the incoming request to the master interface with multicast all-routers-destination address.

In a mesh network we do not have master/uplink interfaces. But we have the IP of the DHCP server which is X hops away and the routing protocol knows which way to send the packet.

Is it possible to add dhcp relay via unicast? An additional config parameter for the IP of the DHCP server is then also needed.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=406