nodejs / nodejs/node

[DNS] add AD Flag support for DNSSEC to allow DANE usage

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feature request
Dominant language
JavaScript
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Merged PRs (30d)
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Description

What is the problem this feature will solve?

With ef91595e2fc1f96b7c8eb51bfcc1408a5adaa4a9 in PR https://github.com/nodejs/node/pull/52983 related to issue https://github.com/nodejs/node/issues/39569 you added support for TLSA resource records via dns.resolve .
This was done with the intention to support DANE.
However, to correctly make use of DANE, the records need to be DNSSEC validated.

Currently there is no possibility to validate DNSSEC via the given API.

As example, the following code (currently a nightly build)

dns.resolveTlsa("_443._tcp.fedoraproject.org", (error, result) => {
	console.log(result)
})

generates the following response

[
  {
    certUsage: 3,
    selector: 1,
    match: 1,
    data: ArrayBuffer {
      [Uint8Contents]: <09 ca 10 dd 09 f1 24 a2 26 3a a8 cc 49 12 fd a8 59 2f 40 cc ab 90 b6 10 ae 84 01 01 a9 1a eb c0>,
      byteLength: 32
    }
  }
]

Thus, as next step for the DANE implementation, this feature request aims to add information to above response of dns.resolve, about if the records have been validated by the resolver.
This allows to use technology relying on DNSSEC, such as TLSA records for DANE.

What is the feature you are proposing to solve the problem?

As DNSSEC does not protect the path between client and resolver by design, we can make use of the AD bit: RFC 6840 Section 5.7 and RFC 6840 Section 5.8

According to above mentioned RFC6840, the AD bit should be set in the query to indicate that node is going to honor the AD bit in the response. Then, the AD bit in the reply should be propagated to the returned contents of dns.resolve

If this request is included we can get to the next step of checking TLSA records within TLS certificate verification.

What alternatives have you considered?

In https://github.com/nodejs/node/issues/39569 @bradh352 mentioned the DO bit (RFC 6840 Section 5.6) and RFC 3225 Section 3, however as I read it, the setting the DO bit indicates that the client can understand DNSSEC related records. Thus, the resolver is going to attach RRSIG, etc. for validation on the client side.
In contrast, the DO bit should be set to 0 to indicate that node is unprepared to handle DNSSEC RR.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start from Node.js's dns.resolveTlsa API and the resolver behavior described in RFC 6840 Sections 5.7 and 5.8. Trace how the AD bit is sent and how the response is exposed, then define the returned validation information and verify it with DNSSEC-backed TLSA lookups; the issue names no source files or tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, node.js
Domain
api, networking
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Active
Clarity
Mostly clear
Newbie friendliness
48/100

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