dns/dnsmessage: add RFC3597-inspired UnknownResource type

Currently, dnsmessage is not capable of parsing messages that contain
unknown records. Specifically, unpackResourceType returns an error
stating "invalid resource type".

This makes it tricky to use dnsmessage for applications such as
recursive resolvers or DNS forwarders. (I was bitten already, which is
why I'm writing this!)

RFC3597 indicates that name servers and resolvers must treat unknown RRs
as binary data. Quoting the first paragraph from section 3 below:

>   To enable new RR types to be deployed without server changes, name
>   servers and resolvers MUST handle RRs of unknown type transparently.
>   That is, they must treat the RDATA section of such RRs as
>   unstructured binary data, storing and transmitting it without change
>   [RFC1123].

Fixes #42128

Change-Id: I2a203177e6e6cf51d70c63568c0465fc36a49afe
Reviewed-on: https://go-review.googlesource.com/c/net/+/262037
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Dmitri Shuralyov <dmitshur@golang.org>
2 files changed
tree: 798d471fbbc43a40945d43a8c8c8429ea74226d8
  1. .gitattributes
  2. .gitignore
  3. AUTHORS
  4. CONTRIBUTING.md
  5. CONTRIBUTORS
  6. LICENSE
  7. PATENTS
  8. README.md
  9. bpf/
  10. codereview.cfg
  11. context/
  12. dict/
  13. dns/
  14. go.mod
  15. go.sum
  16. html/
  17. http/
  18. http2/
  19. icmp/
  20. idna/
  21. internal/
  22. ipv4/
  23. ipv6/
  24. lif/
  25. nettest/
  26. netutil/
  27. proxy/
  28. publicsuffix/
  29. route/
  30. trace/
  31. webdav/
  32. websocket/
  33. xsrftoken/
README.md

Go Networking

Go Reference

This repository holds supplementary Go networking libraries.

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