Module dns 

A real DNS client behind the RFC 3263 Resolver trait.

crate::resolve() implements every selection rule and knows nothing about DNS; this is the part that actually asks. The split is what lets the selection logic — where the bugs are — be tested against fixtures with no network.

Two things here are not just plumbing.

A failure is not an empty answer. “There is no such record” is a final answer and the next candidate should be tried; “the resolver did not respond” is a transient condition and retrying later is right. Conflating them turns a thirty-second DNS blip into a permanent routing failure, because the negative gets cached and nothing ever asks again.

Nothing here may block the endpoint loop. A lookup can take seconds; the loop it would block owns every transaction timer.

Structs

DnsResolver

A DNS-backed resolver with a TTL-respecting cache.

Prefetched

Blocking adapter so DnsResolver can satisfy the synchronous Resolver trait.

Enums

Answer

What a lookup produced.

Functions

resolve_uri

Resolve a URI to an ordered candidate list, in one await (RFC 3263).