Fix android DNS issues by using Go's built-in DNS resolver

[thehxdev]

On android devices (with termux) warp-plus fails to resolve the hostname in wireguard config file. By using a custom resolver and Go's built-in DNS resolver this bug have been fixed.

command:

./warp-plus --wgconf wg.conf --bind '127.0.0.1:10808' --cache-dir $PWD

[Lanius-collaris]

Building an elf file for android need two additional environment variables, CGO_ENABLED=1 and CC=/path/to/ndk/clang.
I think it can be fixed by editing .github/workflows/go-build.yaml.

warp-plus/.github/workflows/go-build.yaml

Lines 64 to 68 in b727aba

	GOOS: ${{ matrix.goos }}
	GOARCH: ${{ matrix.goarch }}
	GOARM: ${{ matrix.goarm }}
	GOMIPS: ${{ matrix.gomips }}
	CGO_ENABLED: 0

[thehxdev]

Building warp-plus for android devices with arm64 architecture does not require CGO. And the bug is not related to CGO. The problem is warp-plus could not resolve endpoint hostname in Wireguard config file because it uses net.DefaultResolver to resolve hostname to IP address.

[Lanius-collaris]

If the elf is not linked with bionic libc, it will attempt to read /etc/resolv.conf ( doesn't exist on android ) to find DNS servers, then fall back to [::1]:53 and 127.0.0.1:53.
@thehxdev

[thehxdev]

Yes that's the actual problem. But using Go's built-in DNS reaolver is a simple solution that solves the problem and does not need external C libraries. Also, the executable will be fully static and other users can build warp-plus for android arm64 without C dependencies.

[markpash]

This is interesting, I didn't know that Go was unable to resolve names on termux. I'm not a user of termux so these bugs always seem to exist.
I have plans for DNS in the future which will hopefully improve this situation, and your fix is good for that, so I'm happy to merge this.
Can you please squash your second commit into the first and then I'll happily merge this. ❤️

[thehxdev]

Thank you Mark! Is that ok now?