[FS#400] odhcpd: lease file persistence per RFC2131 S-2.1 and S-3.1.4

[LEDE Bugs]

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

User who did this - Eric Luehrsen (EricLuehrsen) 

Attached to Project - LEDE Project
Summary - odhcpd: lease file persistence per RFC2131 S-2.1 and S-3.1.4
Task Type - Bug Report
Category - Packages
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - RFC2131 DHCPv4 expects that the DHCP leases and other configuration results are in persistent storage. For small embedded routers during a machine reboot, it has been accepted that read-write memory is RAM (not flash) and persistence may not be entirely upheld. That being said, odhcpd has no means to maintain the lease information even through an application only restart (example ifup event). The lease file odhcpd writes is not used to seed odhcpd, if it is restarted. (1) an interface reconnect that causes odhcpd to restart destroys the lease record, even if the network resumes as previously configured. (2) even if odhcpd lease file is directed to persistent storage (USB drive) it is not used to resume leases.


More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=400