Pull request: * all: move internal Go packages to internal/

Merge in DNS/adguard-home from 2234-move-to-internal to master

Squashed commit of the following:

commit d26a288cabeac86f9483fab307677b1027c78524
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Oct 30 12:44:18 2020 +0300

    * all: move internal Go packages to internal/

    Closes #2234.

internal/util/auto_hosts_test.go

@@ -0,0 +1,112 @@
+package util
+
+import (
+	"io/ioutil"
+	"net"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/miekg/dns"
+	"github.com/stretchr/testify/assert"
+)
+
+func prepareTestDir() string {
+	const dir = "./agh-test"
+	_ = os.RemoveAll(dir)
+	_ = os.MkdirAll(dir, 0755)
+	return dir
+}
+
+func TestAutoHostsResolution(t *testing.T) {
+	ah := AutoHosts{}
+
+	dir := prepareTestDir()
+	defer func() { _ = os.RemoveAll(dir) }()
+
+	f, _ := ioutil.TempFile(dir, "")
+	defer func() { _ = os.Remove(f.Name()) }()
+	defer f.Close()
+
+	_, _ = f.WriteString("  127.0.0.1   host  localhost # comment \n")
+	_, _ = f.WriteString("  ::1   localhost#comment  \n")
+
+	ah.Init(f.Name())
+
+	// Existing host
+	ips := ah.Process("localhost", dns.TypeA)
+	assert.NotNil(t, ips)
+	assert.Equal(t, 1, len(ips))
+	assert.Equal(t, net.ParseIP("127.0.0.1"), ips[0])
+
+	// Unknown host
+	ips = ah.Process("newhost", dns.TypeA)
+	assert.Nil(t, ips)
+
+	// Unknown host (comment)
+	ips = ah.Process("comment", dns.TypeA)
+	assert.Nil(t, ips)
+
+	// Test hosts file
+	table := ah.List()
+	name, ok := table["127.0.0.1"]
+	assert.True(t, ok)
+	assert.Equal(t, "host", name)
+
+	// Test PTR
+	a, _ := dns.ReverseAddr("127.0.0.1")
+	a = strings.TrimSuffix(a, ".")
+	assert.True(t, ah.ProcessReverse(a, dns.TypePTR) == "host")
+	a, _ = dns.ReverseAddr("::1")
+	a = strings.TrimSuffix(a, ".")
+	assert.True(t, ah.ProcessReverse(a, dns.TypePTR) == "localhost")
+}
+
+func TestAutoHostsFSNotify(t *testing.T) {
+	ah := AutoHosts{}
+
+	dir := prepareTestDir()
+	defer func() { _ = os.RemoveAll(dir) }()
+
+	f, _ := ioutil.TempFile(dir, "")
+	defer func() { _ = os.Remove(f.Name()) }()
+	defer f.Close()
+
+	// Init
+	_, _ = f.WriteString("  127.0.0.1   host  localhost  \n")
+	ah.Init(f.Name())
+
+	// Unknown host
+	ips := ah.Process("newhost", dns.TypeA)
+	assert.Nil(t, ips)
+
+	// Stat monitoring for changes
+	ah.Start()
+	defer ah.Close()
+
+	// Update file
+	_, _ = f.WriteString("127.0.0.2   newhost\n")
+	_ = f.Sync()
+
+	// wait until fsnotify has triggerred and processed the file-modification event
+	time.Sleep(50 * time.Millisecond)
+
+	// Check if we are notified about changes
+	ips = ah.Process("newhost", dns.TypeA)
+	assert.NotNil(t, ips)
+	assert.Equal(t, 1, len(ips))
+	assert.Equal(t, "127.0.0.2", ips[0].String())
+}
+
+func TestIP(t *testing.T) {
+	assert.Equal(t, "127.0.0.1", DNSUnreverseAddr("1.0.0.127.in-addr.arpa").String())
+	assert.Equal(t, "::abcd:1234", DNSUnreverseAddr("4.3.2.1.d.c.b.a.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa").String())
+	assert.Equal(t, "::abcd:1234", DNSUnreverseAddr("4.3.2.1.d.c.B.A.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa").String())
+
+	assert.Nil(t, DNSUnreverseAddr("1.0.0.127.in-addr.arpa."))
+	assert.Nil(t, DNSUnreverseAddr(".0.0.127.in-addr.arpa"))
+	assert.Nil(t, DNSUnreverseAddr(".3.2.1.d.c.b.a.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa"))
+	assert.Nil(t, DNSUnreverseAddr("4.3.2.1.d.c.b.a.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0..ip6.arpa"))
+	assert.Nil(t, DNSUnreverseAddr("4.3.2.1.d.c.b. .0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa"))
+}