Pull request: 2508 ip conversion vol.2

Merge in DNS/adguard-home from 2508-ip-conversion-vol2 to master

Closes #2508.

Squashed commit of the following:

commit 5b9d33f9cd352756831f63e34c4aea48674628c1
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Wed Jan 20 17:15:17 2021 +0300

    util: replace net.IPNet with pointer

commit 680126de7d59464077f9edf1bbaa925dd3fcee19
Merge: d3ba6a6c 5a50efad
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Wed Jan 20 17:02:41 2021 +0300

    Merge branch 'master' into 2508-ip-conversion-vol2

commit d3ba6a6cdd01c0aa736418fdb86ed40120169fe9
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Jan 19 18:29:54 2021 +0300

    all: remove last conversion

commit 88b63f11a6c3f8705d7fa0c448c50dd646cc9214
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Jan 19 14:12:45 2021 +0300

    all: improve code quality

commit 71af60c70a0dbaf55e2221023d6d2e4993c9e9a7
Merge: 98af3784 9f75725d
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon Jan 18 17:13:27 2021 +0300

    Merge branch 'master' into 2508-ip-conversion-vol2

commit 98af3784ce44d0993d171653c13d6e83bb8d1e6a
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon Jan 18 16:32:53 2021 +0300

    all: log changes

commit e99595a172bae1e844019d344544be84ddd65e4e
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon Jan 18 16:06:49 2021 +0300

    all: fix or remove remaining net.IP <-> string conversions

commit 7fd0634ce945f7e4c9b856684c5199f8a84a543e
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Jan 15 15:36:17 2021 +0300

    all: remove redundant net.IP <-> string converions

commit 5df8af030421237d41b67ed659f83526cc258199
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Jan 14 16:35:25 2021 +0300

    stats: remove redundant net.IP <-> string conversion

commit fbe4e3fc015e6898063543a90c04401d76dbb18f
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Thu Jan 14 16:20:35 2021 +0300

    querylog: remove redundant net.IP <-> string conversion

internal/home/options.go

@@ -2,6 +2,7 @@ package home
 
 import (
 	"fmt"
+	"net"
 	"os"
 	"strconv"
 
@@ -13,7 +14,7 @@ type options struct {
 	verbose        bool   // is verbose logging enabled
 	configFilename string // path to the config file
 	workDir        string // path to the working directory where we will store the filters data and the querylog
-	bindHost       string // host address to bind HTTP server on
+	bindHost       net.IP // host address to bind HTTP server on
 	bindPort       int    // port to serve HTTP pages on
 	logFile        string // Path to the log file. If empty, write to stdout. If "syslog", writes to syslog
 	pidFile        string // File name to save PID to
@@ -54,10 +55,19 @@ type arg struct {
 // against its zero value and return nil if the parameter value is
 // zero otherwise they return a string slice of the parameter
 
+func ipSliceOrNil(ip net.IP) []string {
+	if ip == nil {
+		return nil
+	}
+
+	return []string{ip.String()}
+}
+
 func stringSliceOrNil(s string) []string {
 	if s == "" {
 		return nil
 	}
+
 	return []string{s}
 }
 
@@ -65,6 +75,7 @@ func intSliceOrNil(i int) []string {
 	if i == 0 {
 		return nil
 	}
+
 	return []string{strconv.Itoa(i)}
 }
 
@@ -72,6 +83,7 @@ func boolSliceOrNil(b bool) []string {
 	if b {
 		return []string{}
 	}
+
 	return nil
 }
 
@@ -96,8 +108,8 @@ var workDirArg = arg{
 var hostArg = arg{
 	"Host address to bind HTTP server on",
 	"host", "h",
-	func(o options, v string) (options, error) { o.bindHost = v; return o, nil }, nil, nil,
-	func(o options) []string { return stringSliceOrNil(o.bindHost) },
+	func(o options, v string) (options, error) { o.bindHost = net.ParseIP(v); return o, nil }, nil, nil,
+	func(o options) []string { return ipSliceOrNil(o.bindHost) },
 }
 
 var portArg = arg{