1500863 - Use GetAddrInfoEx to resolve hosts on windows

Status: NEW

(Core :: Networking, enhancement, P3)

Description

[Valentin Gosu [:valentin] (he/him)]

As revealed in bug 1498782, it seems that the regular getaddrinfo tends to get stuck, and causes shutdown hangs.
It would be a good idea to switch to async methods on all platforms, but the windows API seems to be extra prone to get stuck.
It would be good to replace it with GetAddrInfoEx

https://docs.microsoft.com/en-us/windows/desktop/api/ws2tcpip/nf-ws2tcpip-getaddrinfoexa

Comment 1

[Valentin Gosu [:valentin] (he/him)]

I've got a rough WIP patch for this, but it seems it wouldn't be useful for all platforms.

As the description for `lpCompletionRoutine` says:
> On Windows 7 and Windows Server 2008 R2 or earlier, this parameter is currently reserved and must be set to NULL since asynchronous operations are not supported.

That means async DNS resolution using this API wouldn't work on Windows 7, which is still ~40% of our user base - we would still need to fall back to sync DNS resolution.

Comment 2

[Valentin Gosu [:valentin] (he/him)]

Don't have time to work on this right now. If anyone wants to take a shot at this, let me know.