This change improves compatibility with newer UniFi OS versions while
maintaining backward compatibility with UniFi OS 4.2 and earlier.
The refactoring also reduces code duplication and improves maintainability
by centralizing dnsmasq configuration path logic.
Generally, using /jffs/scripts/dnsmasq.postconf is the right way to add
custom configuration to dnsmasq on Merlin. However, we have seen many
reports that the postconf does not work on their devices.
This commit changes how dnsmasq config manipulation is done on Merlin,
so it's expected to work on all Merlin devices:
- Writing /jffs/scripts/dnsmasq.postconf script
- Copy current dnsmasq.conf to /jffs/configs/dnsmasq.conf
- Run postconf script directly on /jffs/configs/dnsmasq.conf
- Restart dnsmasq
This way, the /jffs/configs/dnsmasq.conf will contain both current
dnsmasq config, and also custom config added by ctrld, without worrying
about conflicting, because configuration was added by postconf.
See (1) for more details about custom config files on Merlin.
(1) https://github.com/RMerl/asuswrt-merlin.ng/wiki/Custom-config-files
Since ctrld now supports MAC rules, the client's mac and ip must always
be sent to ctrld. Otherwise, the mac policy won't work when ctrld is an
upstream of dnsmasq.
On some routers, dnsmasq config may change cache-size dynamically after
ctrld starts, causing dnsmasq crashes.
Fixing this by using max-cache-ttl, which have the same effect with
setting cache-size=0 but won't conflict with existing routers config.
The dnsmasq cache-size setting on EdgeOS could be re-generated anytime
by vyatta router/dhcp components. This conflicts with setting generated
by ctrld, causing dnsmasq fails to start.
It's better to keep dnsmasq cache enabled on EdgeOS, we can turn it off
again once we find a reliable way to control cache-size setting.
So ctrld can record the raw/original client IP instead of looking up
from MAC to IP, which may not the right choice in some network setup
like using wireguard/vpn on Merlin router.
Config fetching/generating in cd mode is currently weird, error prone,
and easy for user to break ctrld when using custom config.
This commit reworks the flow:
- Fetching config from Control D API.
- No custom config, use the current default config.
- If custom config presents, but there's no listener, use 0.0.0.0:53.
- Try listening on current ip+port config, if ok, ctrld could be a
direct listener with current setup, moving on.
- If failed, trying 127.0.0.1:53.
- If failed, trying current ip + port 5354
- If still failed, pick a random ip:port pair, retry until listening ok.
With this flow, thing is more predictable/stable, and help removing the
Config interface for router.
