test: test-net-dns-error.js fails on SunOS

[batrla]

Test test-net-dns-error.js causes assertion failure on SunOS,
test expects ENOTFOUND, but OS returns EAI_FAIL.

Maximum length of a host name is 63 characters. Test test-net-dns-error.js
makes a connection attempt to invalid host name (longer than maximum by 1).
Such connection attempt on SunOS returns permanent failure (EAI_FAIL)
as invalid hostname won't be ever resolved.

Checklist

• make -j4 test (UNIX)
• commit message follows commit guidelines

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/29171/

[batrla]

Sorry, the suggested fix caused test regression in CI on SmartOS, where
the same test got ENOTFOUND instead of expected EAI_FAIL.
My testing was on Solaris 11.4 OS.

Test regression was either due to:

• divergency between Solaris and SmartOS (both are being SunOS derivates)
• difference in name services configuration on my machine and CI (perhaps
  nsswitch.conf(5) or resolv.conf(5))

I don't know exact cause. It seems to me it's not trivial to determine whether
the OS returns EAI_FAIL or ENOTFOUND. My proposal is to:

• Allow both EAI_FAIL and ENOTFOUND in test-net-dns-error.js

  Let's assume that it is OS specific or resolver configuration specific
  whether the system actually returns EAI_FAIL or ENOTFOUND in response to
  attempt to resolve an illegal hostname using getaddrinfo(3C). EAI_FAIL
  indicates permanent failure:

  EAI_FAIL Non-recoverable failure in name resolution has occurred.

The proposal is dup of recent PR by @cjihrig in test-http-dns-error.js:
test: allow EAI_FAIL in test-http-dns-error.js #27500

[Trott]

• Allow both EAI_FAIL and ENOTFOUND in test-net-dns-error.js

Yes, I think that would be the thing to do.

[Trott]

• Allow both EAI_FAIL and ENOTFOUND in test-net-dns-error.js

Yes, I think that would be the thing to do.

You might also want to include a comment explaining why both are being allowed and linking to this pull request/discussion. Otherwise, someone might subsequently remove the allowance for EAI_FAIL (and CI will pass when they do).

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/29248/

[batrla]

You might also want to include a comment explaining why both are being allowed and linking to this pull request/discussion. Otherwise, someone might subsequently remove the allowance for EAI_FAIL (and CI will pass when they do).

I added following comment:

// Resolving hostname > 63 characters may return EAI_FAIL (permanent failure).

If the comment is insufficient, I'll be happy to make it more explicit next time the test breaks.

[Trott]

If the comment is insufficient, I'll be happy to make it more explicit next time the test breaks.

That's good, but perhaps we should also mention specifically that it fails that way on SunOS and what version of SunOS? (This is just a suggestion though. I'm not blocking this from landing or anything.)

[addaleax]

Landed in 077f9dc