dns: fix custom servers support and extend tests #22

	# Copyright 2021 The forwarder Authors. All rights reserved.
	# Use of this source code is governed by a MIT
	# license that can be found in the LICENSE file.

	---
	# Forwarder hacks the net package to support overriding internal DNS config.
	# This action checks the net package dns code for changes.
	name: dns

	on:
	pull_request:
	branches: [main]

	jobs:
	assert:
	runs-on: ubuntu-latest
	steps:
	- name: Checkout code
	uses: actions/checkout@v3

	- name: Set version env variables
	run: \|
	cat .version >> $GITHUB_ENV

	- name: Setup Go
	uses: actions/setup-go@v3
	with:
	go-version: "${{env.GO_VERSION}}"

	- name: Check Hash
	run: \|
	GOROOT_VALUE=$(go env \| awk -F'=' '/^GOROOT=/{gsub("\"", "", $2); print $2}')
	$GOROOT_VALUE/src/net/dnsclient_unix.go \| awk '{print $1}' \| md5sum -c 516cf174c57f20905997b74529c6542f
	$GOROOT_VALUE/src/net/dnsconfig.go \| awk '{print $1}' \| md5sum -c 52dd7dea88dfce956c3de0b6f6513b76

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