reset listening state for each secondary server

[cjihrig]

The listenCallback() function is called for each secondary address that a server should listen on. However, each call sets the listening state to true, so subsequent addresses fail with FST_ERR_REOPENED_SERVER. This commit resets the state on each call.

Note:
I had a bit of trouble creating a test for this. The existing tests all have plan() calls expecting the number of listening addresses to match the number of addresses on the system. This is an incorrect assumption. The listening logic in multipleBindings() in lib/server.js ignores errors encountered when trying to listen. For example, on my machine, I have 3 interfaces, but Fastify can only listen on two of them.

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[cjihrig]

ping @mcollina

[climba03003]

Should L107 be removed? and move the comment to new place?

[metcoder95]

The listenCallback is the one that turns on the switch as soon as the returned callback is called. As is reused across the multipleBindings I believe it is what's causing the issues.

Maybe we can isolate the listenCallback and make a new function that just handles the new instances and waits until all of them are listening (or failed, does not matter), before calling marking the server as already listening.

fastify/lib/server.js

Line 169 in f6a0ff3

function listenCallback (server, listenOptions) {

[cjihrig]

The listenCallback is the one that turns on the switch as soon as the returned callback is called. As is reused across the multipleBindings I believe it is what's causing the issues.

Yes, that's what I was saying in the OP. If you want to take this over and implement your suggestion, I'm fine with that.

[cjihrig]

I've moved this to #4810 since the node-20 branch was merged.

Should L107 be removed? and move the comment to new place?

I'm not sure about that because it's possible that the if statement on line 122 will not be entered, depending on the user's machine setup.