Emulator

On dolphin's end a new BBA option needs to be added that has a UDP socket to connect to the XLink Kai client on port 34523 (Config for the BBA should have a box for the IP address of the device running the xlink client [default to localhost])

Simple protocol to communicate with XLink client:

• Dolphin sends 'c;uniquename;' to connect where uniquename is a....unique name to identify this dolphin process in case of multiple Dolphin instances connected to one XLink client (like at a LAN party/tournament night [This ability has been requested by the XLink gamecube community]) Name needs to be unique to the individual XLink client, not globally) (Could use the BBA's MAC address as the name!) Gets 'connectok;' in response
• Dolphin sends 'e;e;ethernetframebinary' where ethernetframebinary is literally an entire Ethernet frame that the BBA would normally be sending (MAC address of the BBA must be using Nintendo's OUI [the current BBA implementation does])
• Dolphin receives Ethernet frames back the same way; 'e;e;ethernetframebinary'
• Dolphin sends 'd;thesameuniquename;' to disconnect cleanly from the client (otherwise the XLink client will stop sending LAN traffic to that socket after 30 minutes of inactivity) Gets 'disconnectok;' in response
• If traffic is not expected to be sent for a while Dolphin can send 'k;' as a keepalive to reset the counter. Gets 'k;' in response.

Connect/disconnect responses have been changed to "connected;" and disconnected;"

This new UDP socket is not in the current public release (7.4.36); you'll need a beta client to test with.

This could be seen as a derivative of this PR by tommy1019 https://github.com/dolphin-emu/dolphin/pull/8754

I've started working on this myself :)

Dolphin can now communicate with XLink properly and multiple dolphin instances can do LAN play locally via XLink client and against remote players
Still need to get dolphin <-> local LAN cubes working via XLink, packet injection isn't working for some reason.

This has only been tested on Ubuntu so far; need to do macOS and Windows still.

The following traffic patterns now work with Dolphin via XLink:

• Dolphin and remote gamecube
• Dolphin and remote dolphin
• Dolphin and local gamecube (XLink handling the Ethernet bridging!)
• Dolphin and another Dolphin
• Dolphin, another local dolphin, a local cube, and remote dolphin

Dolphin <-> XLink Kai comms protocol has changed since #1 was written. Do NOT use it as a protocol reference.
I'll provide proper docs when everything is done.

Currently roadblocked by https://github.com/dolphin-emu/dolphin/pull/8841 and unknown QT errors on MacOS (Catalina)

Can now compile on macOS, XLink Integration working perfectly :)

Now for windows!

Now working on macOS/Windows/Linux with the same codebase!

Up next: Rewrites to conform to dolphin's coding style, performance tweaks, and fixing a couple crashes in XLink

Everything now works on the dolphin end of things. I need to pull in some testers over the next couple days to make sure I haven't broken TAP adapters and that the drastic changes to XLink's frame handling code haven't broken other platforms.

Added OSD messages for BBA connect/disconnect and added chat messages in OSD (can be turned off in the config file)
In testing we got 7 dolphins and one cube connected in MKDD!

Now adding the final polish before submitting the PR :D

PR opened https://github.com/dolphin-emu/dolphin/pull/8853

Play testing is going very well. Testers are reporting improved FPS compared to TAP adapters and no stability problems.

XLink Kai 7.4.37 (support for this addition) is now ready for release and will be out in a couple hours.

XLink Kai 7.4.37 has now been released for:

• CentOS 7 x86
• CentOS 7 x86_64
• Debian 9 x86
• Debian 9 x86_64
• Ubuntu 16 x86
• Ubuntu 16 x86_64
• Raspbian/Raspberry Pi OS - Raspberry Pi (ARMHF)
• Windows
• macOS (including on brew!)