6.0.0

CHANGES:

• use Cstruct.length instead of deprecated Cstruct.len

• avoid deprecated fmt functions

• dns-client: send EDNS tcp keepalive with a timeout of 120 seconds if TCP
  is used (@reynir @hannesm)

• BREAKING dns: Rr_map.get_ttl is now ttl, and takes 'a key -> 'a -> int32
  (instead of b -> int32), Rr_map.with_ttl now is 'a key -> 'a -> int32 -> 'a
  (instead of b -> int32 -> b) (#264 @hannesm)

• BREAKING dns: Rr_map.A now uses Ipaddr.V4.Set.t, Aaaa uses Ipaddr.V6.Set.t
  (requires ipaddr 5.2.0) (#268 @hannesm)

• BREAKING dns.cache: type entry now is polymorphic ('a entry = Entry of 'a ...) (instead of Entry of Rr_map.b) (#263 @reynir and @hannesm)

• BREAKING dns.cache: use a LRU.F.t instead of LRU.M.t (#256 @hannesm)

• dns.cache: provide get_or_cname and get_any function (#256 #257 @hannesm)

• BUGFIX dns.cache: update if time to live of cached entry expired
  (reported in #259 by @dinosaure, fix by @reynir and @hannesm)

• dns-client support DNS-over-TLS (RFC 7858): the type io_addr is now a variant
  of Plaintext (Ipaddr.t * int) or Tls (Tls.Config.client * Ipaddr.t * int)
  By default, ca-certs (ca-certs-nss for MirageOS) are used as trust anchors,
  and the certificate is expected to contain the IP address of the resolver.
  The default resolver (anycast.uncensoreddns.org) certificate is verified by
  hostname, since the let's encrypt certificate does not include an IP address
  in SubjectAlternativeNames (#270 @hannesm)

• BREAKING dns-client.mirage.Make is extended by a Mirage_clock.PCLOCK
  (#270 @hannesm)

• BREAKING dns-client, dns-stub: use Dns.proto instead of custom [TCP|UDP]
  (#266 @hannesm)

• dns-client: use a mutable timeout_ns : int64 instead of
  timeout_ns : int64 ref (#269 @hannesm)

• BREAKING dns-client: remove ?nameserver from
  getaddrinfo/gethostbyname/gehostbyname6/get_resource_record - if a custom
  nameserver should be queried, a distinct Dns_client.t can be constructed
  (#269 @reynir and @hannesm)

• dns-client: multiplex over TCP connections (#269 @reynir and @hannesm)

• dns-client: use happy-eyeballs to connect to all nameservers from
  /etc/resolv.conf sequentially (lwt and mirage) (#269 @reynir and @hannesm)

• BREAKING dns-client remove UDP support from lwt (#270 @reynir and @hannesm)

• BREAKING dns-resolver.mirage add DNS-over-TLS support (@reynir @hannesm)

• BREAKING dns-resolver remove "mode" from codebase, default to recursive
  (a stub resolver is available as dns-stub) (#260 @hannesm)

• dns-resolver: use dns.cache instead of copy in Dns_resolver_cache
  (#256 @hannesm)

• BUGFIX dns-resolver: fix responses to queries (reported in #255 by @dinosaure,
  fix in #258 by @reynir and @hannesm)

• dns-resolver: refactor and cleanup code, remove statistics, remove dead code
  (#258 #261 @reynir @hannesm)

• dns-stub: reconnect to resolver, resend all outstanding queries
  (#269 @hannesm)