liminix/modules/dhcp6c/acquire-delegated-prefix.fnl
Daniel Barlow 16e4b05653 dhcp6c: set preferred and valid address lifetimes
also workaround a bug in rebinding/updates where we get an error
from "ip addr add" trying to add an address that's already present
2024-02-13 13:49:12 +00:00

40 lines
1.5 KiB
Fennel

(local { : system } (require :anoia))
(local svc (require :anoia.svc))
(fn changes [old-addresses new-addresses]
(let [added {}
deleted {}]
(each [n address (pairs new-addresses)]
(if (not (. old-addresses n))
(table.insert added address)))
(each [n address (pairs old-addresses)]
(if (not (. new-addresses n))
(table.insert deleted address)))
(values added deleted)))
(fn update-prefixes [device prefixes new-prefixes]
(let [(added deleted) (changes prefixes new-prefixes)]
;; if some address has changed (e.g. preferred/valid lifetime)
;; then we don't want to delete it before re-adding it because
;; the kernel will drop any routes that go through it. On the
;; other hand, we can't add it _before_ deleting it as we'll
;; get an error that it already exists. Therefore, use "change"
;; instead of "add", it works a bit more like an upsert
(each [_ p (ipairs added)]
(system
(.. "ip address change " p.address "1/" p.len " dev " device
" valid_lft " p.valid
" preferred_lft " p.preferred
)))
(each [_ p (ipairs deleted)]
(system
(.. "ip address del " p.address "1/" p.len " dev " device)))))
(fn run []
(let [[state-directory lan-device] arg
dir (svc.open state-directory)]
(accumulate [addresses []
v (dir:events)]
(update-prefixes lan-device addresses (v:output "prefix")))))
{ : changes : run }