TunTap has recently become unmaintained, and it seems Apple wants developers to move away from kexts in general. TunTap currently takes some finagling to work on Catalina, and it may not work at all on Big Sur, necessitating a non-kext-based solution. Fortunately, fake Ethernet devices were introduced in Sierra and can be used similarly to tap adapters. This commit adds a new type of BBA interface implementation which uses fake Ethernet devices via tapserver (https://github.com/fuzziqersoftware/tapserver) to communicate with the host. This implementation was tested with PSO Episodes I & II, which can successfully connect to a private server running locally.
This implementation is only available on macOS, since that's the only place it's needed - Windows/Linux/Unix are unaffected by TunTap being deprecated.
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