Bun `dns.resolve6` returns IPv4-mapped IPv6 address on macOS but IPv6 address on Linux

[adam12]

What version of Bun is running?

1.1.22-debug+e585f900c

What platform is your computer?

Darwin 23.5.0 arm64 arm

What steps can reproduce the bug?

$ bun repl
> require('dns').resolve6('example.com', console.log)
> null ::ffff:93.184.215.14 6

What is the expected behavior?

$ bun repl
> require('dns').resolve6('example.com', console.log)
> null 2606:2800:21f:cb07:6820:80da:af6b:8b2c 6

What do you see instead?

No response

Additional information

Nodejs appears to return the correct result on macOS.

$ node
> require('dns').resolve6('example.com', console.log)
QueryReqWrap {
  bindingName: 'queryAaaa',
  callback: [Function: log],
  hostname: 'example.com',
  oncomplete: [Function: onresolve],
  ttl: false
}
> null [ '2606:2800:21f:cb07:6820:80da:af6b:8b2c' ]

Switching to c-ares backend and using dns.lookup directly seems to be correct.

$ bun repl
> dns.lookup('example.com', {family: 6, backend: 'c-ares'}, console.log)
> null 2606:2800:21f:cb07:6820:80da:af6b:8b2c 6

[RiskyMH]

@adam12 are you still running into this discrepancy?

[adam12]

Still observed, using 1.1.31.

[RiskyMH]

Thanks for sharing! That’s really interesting—I’m not sure why this is happening. I've checked with a few others using macOS, and they’ve observed the correct behavior, so there might be something unusual going on with Bun in this case.