Panic when solving URI with mDNS

[ODCA117]

I tried to enable the following feature in embassy-net #[cfg(feature = "socket-mdns")] to be able to resolve this URI homeassistant.local in rp pico. I was able to enable mdns feature but when trying to resolve the URI smoltcp panics with

smoltcp-0.11.0/src/iface/interface/mod.rs:882:14:
called `Option::unwrap()` on a `None` value

[Dirbaio]

panic is here https://github.com/smoltcp-rs/smoltcp/blob/v0.11.0/src/iface/interface/mod.rs#L882

it happens because you haven't configured any ipv6 address in the interface. Are you actually intending to use IPv6? if no, disable it. if yes, configure an address.

(we should probably look into preventing mDNS from trying to use ipv6 if you have no ipv6 addr, or at least not panic...)

[aurelj]

Note that the panic seems to already be fixed in the current git tree.

You can try the git version adding this in your Cargo.toml:

[patch.crates-io]
smoltcp = { git = "https://github.com/smoltcp-rs/smoltcp.git" }

[thvdveld]

The panic is still there, but in a different place:

smoltcp/src/socket/dns.rs

Line 615 in 8025752

let src_addr = cx.get_source_address(&dst_addr).unwrap(); // TODO remove unwrap

There is a panic when there is no IPv4 or IPv6 address configured when sending to an IPv4 or IPv6 address respectively. We should handle this case differently.