Merge: + DNS: use rules from /etc/hosts

- fix filtering logic: don't do DNS response check for Rewrite rules

Close #1478

Squashed commit of the following:

commit 1206b94881289ff664b7c8998ea97c1455da1ff8
Merge: c462577a 5fe98474
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Mar 20 15:00:25 2020 +0300

    Merge remote-tracking branch 'origin/master' into 1478-auto-records

commit c462577ad84754f5b3ea4cd58339838af817fe36
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Mar 20 14:33:17 2020 +0300

    minor

commit 7e824ba5f432648a976bc4b8076a645ba875ef70
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Mar 20 14:29:54 2020 +0300

    more tests

commit a22b62136c5cfd84cd0450897aef9e7d2e20585a
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Mar 20 14:09:52 2020 +0300

    rename, move

commit 9e5ed49ad3c27c57d540edf18b78d29e56afb067
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Thu Mar 19 15:33:27 2020 +0300

    fix logic - don't do DNS response check for Rewrite rules

commit 6cfabc0348a41883b8bba834626a7e8760b76bf2
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Thu Mar 19 11:35:07 2020 +0300

    minor

commit 4540aed9327566078e5087d43c30f4e8bffab7b9
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Thu Mar 19 11:03:24 2020 +0300

    fix

commit 9ddddf7bded812da48613cc07084e360c15ddd0e
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Thu Mar 19 10:49:13 2020 +0300

    fix

commit c5f8ef745b6f2a768be8a2ab23ad80b01b0aa54f
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Thu Mar 19 10:37:26 2020 +0300

    fix

commit f4be00947bf0528c9a7cd4f09c4090db444c4694
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Mon Mar 16 20:13:00 2020 +0300

    + auto DNS records from /etc/hosts

dnsfilter/dnsfilter.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/AdguardTeam/AdGuardHome/util"
 	"github.com/AdguardTeam/dnsproxy/upstream"
 	"github.com/AdguardTeam/golibs/cache"
 	"github.com/AdguardTeam/golibs/log"
@@ -53,6 +54,9 @@ type Config struct {
 	// Per-client settings can override this configuration.
 	BlockedServices []string `yaml:"blocked_services"`
 
+	// IP-hostname pairs taken from system configuration (e.g. /etc/hosts) files
+	AutoHosts *util.AutoHosts `yaml:"-"`
+
 	// Called when the configuration is changed by HTTP request
 	ConfigModified func() `yaml:"-"`
 
@@ -139,6 +143,9 @@ const (
 
 	// ReasonRewrite - rewrite rule was applied
 	ReasonRewrite
+
+	// RewriteEtcHosts - rewrite by /etc/hosts rule
+	RewriteEtcHosts
 )
 
 var reasonNames = []string{
@@ -154,6 +161,7 @@ var reasonNames = []string{
 	"FilteredBlockedService",
 
 	"Rewrite",
+	"RewriteEtcHosts",
 }
 
 func (r Reason) String() string {
@@ -303,6 +311,15 @@ func (d *Dnsfilter) CheckHost(host string, qtype uint16, setts *RequestFiltering
 		return result, nil
 	}
 
+	if d.Config.AutoHosts != nil {
+		ips := d.Config.AutoHosts.Process(host)
+		if ips != nil {
+			result.Reason = RewriteEtcHosts
+			result.IPList = ips
+			return result, nil
+		}
+	}
+
 	// try filter lists first
 	if setts.FilteringEnabled {
 		result, err = d.matchHost(host, qtype, setts.ClientTags)

dnsfilter/dnsfilter_test.go

@@ -3,6 +3,7 @@ package dnsfilter
 import (
 	"fmt"
 	"net"
+	"os"
 	"path"
 	"runtime"
 	"testing"
@@ -621,6 +622,13 @@ func TestRewrites(t *testing.T) {
 	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
 }
 
+func prepareTestDir() string {
+	const dir = "./agh-test"
+	_ = os.RemoveAll(dir)
+	_ = os.MkdirAll(dir, 0755)
+	return dir
+}
+
 // BENCHMARKS
 
 func BenchmarkSafeBrowsing(b *testing.B) {