Command for resolving DNSaddr

[lidel]

dnsaddr is a protocol that instructs the resolver to lookup multiaddr(s) in DNS TXT records for the domain name in it's value section.

Current state

• We have ipfs dns which resolves DNSLink
• We don't have anything for /dnsaddr/ addresses.
• ipfs swarm connect /dnsaddr/fooo works, but requires online mode and then trying to analyze ipfs swarm peers list is a guessing game will only show a subset of addrs that are actively utilized.

Proposed enhancement

We are missing a utility command for resolving /dnsaddr/example.com and getting the list of multiaddrs published as TXT records on _dnsaddr.example.com

Design TBD, could be a dedicated command, or just like with DNSLink, we could collapse it into ipfs resolve.

Value to the ecosystem

This would be highly useful in browser and other contexts where DHT is not fast enough.
For example, gateways could announce own peers and links to public gateway could trigger DNSaddr resolution and act as an opportunistic content routing hint.

[BigLep]

@lidel : is this a good candidate for @schomatis ?