[Dnsmasq-discuss] [PATCH] ubus: add lease management methods

[Bergamote]

Hi!

The attached patch adds three ubus methods to dnsmasq: add_lease, delete_lease and get_leases.  These are the ubus equivalent of the existing dbus AddDhcpLease/DeleteDhcpLease, plus get_leases which has no dbus counterpart.

The use case is HA DHCP on OpenWrt: when a dnsmasq instance creates or removes a lease, an external daemon replicates it to peer nodes via the new ubus methods, so that all instances share a consistent lease database.

The implementation follows the same internal APIs as the dbus path (lease4_allocate, lease_set_hwaddr, lease_set_expires, etc.) with a few improvements: hostname validation via legal_hostname(), IPv6 domain lookup with get_domain6(), and script-triggering flag suppression for injected leases (preventing dhcp-script ping-pong).

No extra per-lease storage is required.  get_leases iterates the existing lease linked list on demand.

I am aware of the 2021 discussion around Eduardo Aguilar's lease method proposal.  This takes a different approach: it hooks directly into the ubus method table (not log_packet()), stores no extra data, and mirrors the existing dbus design rather than introducing a new one.

The patch is tested on an OpenWrt HA cluster.  If there is interest, I also have a self-contained contrib daemon (contrib/lease-sync/) that uses these methods, which I could submit separately.

Browsable code: https://github.com/pgaufillet/dnsmasq/tree/submission/lease-sync-patches, and for information https://github.com/pgaufillet/openwrt-ha-feed 

N.B. This work has been performed using Claude Code, among other tools.

Pierre Gaufillet

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