Async DNS seeder lookups

[oxarbitrage]

Motivation

I am trying to replace to_socket_addrs() with my crated function resolve(). This is work in progress for #1613.

So i basically will want to replace https://github.com/oxarbitrage/zebra/blob/8a9a32b2f4f3e1e735def4ade717884885184243/zebra-network/src/config.rs#L46 with https://github.com/oxarbitrage/zebra/blob/8a9a32b2f4f3e1e735def4ade717884885184243/zebra-network/src/config.rs#L42 where replace is a new custom function that should return the same data.

to_socket_addrs() returns Result<Iterator> but replace() returns Option<Iterator> which are not the same. This can be a first issue.

Additionally i think there is something else, according to some hints i got from @teor2345 in discord something like this will need to be added to the combination:

zebra/zebrad/src/components/inbound.rs

Line 257 in 4f172ab

.collect::<futures::stream::FuturesOrdered<_>>()

Which makes the implementation even more complicated for my skills. Looking for some additional hints to make more progress here.

Solution

Share the problem with others.

The code in this pull request has:

• Documentation Comments
• Unit Tests and Property Tests

Review

I will like @yaahc or @teor2345 to take a look.

Related Issues

Closes #1613

Note: #1613 is about DNS seeders, #1631 is about listener ports. This PR fixes the DNS seeders.

Follow Up Work

None by now.

[teor2345]

Hi @oxarbitrage I've made some suggestions to help move you forward.

I've also tagged @yaahc in some questions that she's better able to answer.

[teor2345]

I'm good with this now, but I'd like @oxarbitrage to check the changes I just made.

[oxarbitrage]

Changes looks good to me.