test: find IPv6 address from localhost names

[thefourtheye]

Checklist

• make -j4 test (UNIX), or vcbuild test nosign (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

test

Description of change

Try all the possible hostnames listed in common.localIPv6Hosts to get
an IPv6 address. If none of them give a valid address, skip the tests.

cc @nodejs/testing

[thefourtheye]

CI Run: https://ci.nodejs.org/job/node-test-pull-request/3348/

CI Run: https://ci.nodejs.org/job/node-test-pull-request/3350/

[bnoordhuis]

Doesn't look like that approach works:

https://ci.nodejs.org/job/node-test-commit-linux-fips/2822/nodes=ubuntu1404-64/console
https://ci.nodejs.org/job/node-test-commit-linux/4251/nodes=ubuntu1204-64/console

[thefourtheye]

@bnoordhuis I found a way to fix that. Testing it in my local VMs. I'll update shortly.

[thefourtheye]

The current version looks like a partial win. https://ci.nodejs.org/job/node-test-pull-request/3351/.

Only two failures till now.

• https://ci.nodejs.org/job/node-test-commit-linux/4252/nodes=ubuntu1404-64/console
• https://ci.nodejs.org/job/node-test-commit-linux/4252/nodes=ubuntu1404-32/console

[thefourtheye]

Okay. All green now (Except Fedora 24, which keeps building and testing again and again). https://ci.nodejs.org/job/node-test-pull-request/3352/

[bnoordhuis]

I have to say that the changes to test/common.js don't look very appealing but I'll defer to @nodejs/testing.

[thefourtheye]

@bnoordhuis Any suggestions to make it better?

[thefourtheye]

@bnoordhuis Will this be better?

exports.getLocalIPv6Address = function getLocalIPv6Address(callback) {
  if (exports.localIPv6Hosts.length === 0 || localhostIPv6 === undefined) {
    localhostIPv6 = undefined;
    return process.nextTick(
      () => callback(new Error('Unable to determine IPv6 address'))
    );
  }
  (function processNextHost(current) {
    if (current < exports.localIPv6Hosts.length) {
      const host = exports.localIPv6Hosts[current];
      return dns.lookup(host, {family: 6}, (_, addr) => {
        if (addr && typeof addr === 'string') {
          localhostIPv6 = {hostname: host, address: addr};
          return callback(null, localhostIPv6);
        }
        return processNextHost(current + 1);
      });
    }
    localhostIPv6 = undefined;
    callback(new Error('Unable to determine IPv6 address'));
  })(0);
};

Edit: I probably can move the Error creation the recursive function and nextTick, so that the stacktrace will be better.

[Trott]

I have to say that the changes to test/common.js don't look very appealing but I'll defer to @nodejs/testing.

I feel the same, but would be curious how more people on @nodejs/testing felt.

This function seems to be only needed in two tests so it's not clear to me that common.js is the place for it.