mwan3: default route src ip should be preferred over interface ip when get_src_ip

Package Name

mwan3

Maintainer

@feckert

OpenWrt Version

23.05.4

OpenWrt Target/Subtarget

mediatek/filogic

Steps to Reproduce

1. Set up a custom "wan" interface I with its IP being A;
2. Add a route with a src ip being B different to the interface IP A (e.g. ip route add default via X src B dev I metric 1000);
3. Add the interface I to mwan3;
4. Navigate to the mwan3 dianostics page (/cgi-bin/luci/admin/status/mwan3/diagnostics);
5. Select the interface I and run "ping track ip";

Actual Behaviour

The interface IP A is used as SRCIP for ping. And due to some configuration choices, ping sourcing from the interface IP won't work in my case.

Expected behaviour:

The src ip B listed in the default route is expected to be used as SRCIP.

Confirmation Checklist

• The package is maintained in this repository.
• I understand that issues related to the base OpenWrt repository or LuCI repository will be closed.
• I am reporting an issue for OpenWrt, not an unsupported fork.

Start at the mwan3 diagnostics page entry point (/cgi-bin/luci/admin/status/mwan3/diagnostics) and trace the “ping track ip” handling for the selected interface. Compare how the interface IP A and the default route source IP B are selected; done means ping uses B as SRCIP when the route provides it.