make local dns server better #54

Job	Run time
build-android	3m 41s
build-bin-local (macos-latest)	1m 3s
build-bin-cross (x86_64-unknown-linux-musl)	4m 57s
build-apple	13m 30s
build-bin-cross (i686-unknown-linux-musl)	5m 20s
test (macos-latest)	3m 22s
build-bin-cross (aarch64-unknown-linux-musl)	5m 12s
test (ubuntu-latest)	3m 42s
build-bin-cross (arm-unknown-linux-musleabi)	4m 58s
build-bin-cross (armv7-unknown-linux-musleabihf)	5m 1s
build-bin-cross (x86_64-pc-windows-gnu)	2m 11s
	52m 57s

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