fn follow_cnames(
rrs: &[ResourceRecord],
target: &DomainName,
qtype: QueryType,
) -> Option<(DomainName, HashMap<DomainName, DomainName>)>Expand description
Given a set of RRs and a domain name we’re looking for, follow
CNAMEs in the response and return the final name (which is the
name that will have the non-CNAME records associated with it).
Returns None if CNAMEs form a loop, or there is no RR which
matches the target name (a CNAME or one with the right type).