Pull request: 2757 fix OpenWRT detection

Merge in DNS/adguard-home from 2757-openwrt to master

Updates #2757.

Squashed commit of the following:

commit 8e94e6a67ae702bd1b281b306555a4ce9ecc6391
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon Mar 1 17:02:24 2021 +0300

    util: convert only once

commit f1c74f4d18898f286d70c58f93b2fa21de6b5780
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon Mar 1 16:22:51 2021 +0300

    util: log changes, imp docs

commit 0a4558d044602058255db71f825a730642cc9b07
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon Mar 1 15:53:26 2021 +0300

    util: imp os detection

CHANGELOG.md

@@ -14,11 +14,12 @@ and this project adheres to
 -->
 
 <!--
-## [v0.105.2] - 2021-02-24
+## [v0.105.2] - 2021-03-04
 -->
 
 ### Fixed
 
+- Incomplete OpenWRT detection ([#2757]).
 - DHCP lease's `expired` field incorrect time format ([#2692]).
 - Incomplete DNS upstreams validation ([#2674]).
 - Wrong parsing of DHCP options of the `ip` type ([#2688]).
@@ -26,6 +27,7 @@ and this project adheres to
 [#2674]: https://github.com/AdguardTeam/AdGuardHome/issues/2674
 [#2688]: https://github.com/AdguardTeam/AdGuardHome/issues/2688
 [#2692]: https://github.com/AdguardTeam/AdGuardHome/issues/2692
+[#2757]: https://github.com/AdguardTeam/AdGuardHome/issues/2757
 
 
 

internal/util/helpers.go

@@ -5,10 +5,12 @@
 package util
 
 import (
+	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"runtime"
 	"strings"
 )
@@ -64,16 +66,43 @@ func SplitNext(str *string, splitBy byte) string {
 	return strings.TrimSpace(s)
 }
 
-// IsOpenWRT checks if OS is OpenWRT.
+// IsOpenWRT returns true if host OS is OpenWRT.
 func IsOpenWRT() bool {
 	if runtime.GOOS != "linux" {
 		return false
 	}
 
-	body, err := ioutil.ReadFile("/etc/os-release")
+	const etcDir = "/etc"
+
+	// TODO(e.burkov): Take care of dealing with fs package after updating
+	// Go version to 1.16.
+	fileInfos, err := ioutil.ReadDir(etcDir)
 	if err != nil {
 		return false
 	}
 
-	return strings.Contains(string(body), "OpenWrt")
+	// fNameSubstr is a part of a name of the desired file.
+	const fNameSubstr = "release"
+	osNameData := []byte("OpenWrt")
+
+	for _, fileInfo := range fileInfos {
+		if fileInfo.IsDir() {
+			continue
+		}
+
+		if !strings.Contains(fileInfo.Name(), fNameSubstr) {
+			continue
+		}
+
+		body, err := ioutil.ReadFile(filepath.Join(etcDir, fileInfo.Name()))
+		if err != nil {
+			continue
+		}
+
+		if bytes.Contains(body, osNameData) {
+			return true
+		}
+	}
+
+	return false
 }