Allow binding to IPv6 (if present)

[deavmi]

If an interface has an IPv6 address record associated with it then, and only then, prefer that.

Otherwise AF_INET is used (Ipv4 address)

• get_address_for_if(string) done
• get_broadcast_for_if(string)

[deavmi]

Need to probably do get_broadcast_for_if(string) @markqvist ?

[deavmi]

Okay, all prepped. Need to figure out why the test failing tho :), doesn't seem to be related to the other PR me thinks.

[deavmi]

@markqvist Not sure why but a unittest fails

[deavmi]

Reverted changes to see if CI passes, looks like it didn't. I am even more
confused.

Added changes back anyways.

[deavmi]

Nvm it is passing

[deavmi]

Should be good to merge @markqvist

[rlaneth]

Hi everyone,

I've noticed that rnsd doesn't seem to support binding TCP server interfaces to IPv6 addresses. Upon searching the repository to see if someone else had the same demand, I came across this PR. After reviewing the changes, I have observed:

1. It appears that this PR does not enable binding to IPv6 via the listen_ip option. Instead, it only works when specifying a network interface with the device option; and

2. If the device option is used and the specified interface has at least one IPv6 address, the TCP server interface will bind to the first available IPv6 address, and will not bind to the IPv4 address at all.

Am I understanding this correctly?

If so, I have some concerns about merging this. It seems to change the behavior of an existing configuration option in an unexpected way, which could potentially break many existing setups. For instance, consider a case where someone binds to an interface with both a public IPv4 and an IPv6 address, but the IPv6 address isn't actually usable for internet connectivity.

In fact, I believe the current behavior of the device option is already a bit counterintuitive. I would expect it to listen on all IP addresses — both IPv4 and IPv6 — associated with the specified interface. However, the code suggests that it only selects the first available address, which seems limiting.

From my perspective, there are a few key issues here that could be improved:

1. When a device is specified, the server should listen on all addresses associated with the network interface, including both IPv4 and IPv6.

2. The listen_ip option should support specifying an IPv6 address directly for the TCP server interface.

3. Ideally, the TCP server configuration would allow multiple IP addresses, enabling bindings to both IPv4 and IPv6 in the same block (e.g., listen_ip = 0.0.0.0, ::0).

I would really appreciate @markqvist’s thoughts on this since he’s the project maintainer. If he agrees and you, @deavmi, don’t plan to implement these changes, I’d be happy to take this on myself and submit a PR.

Thanks!

[deavmi]

Agreed, listening on all associated IP addresses (of both families) would be ideal and also what I would like.