Fix linter and umask setting

main.go

@@ -4,7 +4,6 @@ import (
 	"flag"
 	"fmt"
 	"os"
-	"syscall"
 
 	"github.com/joohoi/acme-dns/pkg/acmedns"
 	"github.com/joohoi/acme-dns/pkg/api"
@@ -15,7 +14,7 @@ import (
 )
 
 func main() {
-	syscall.Umask(0077)
+	setUmask()
 	configPtr := flag.String("c", "/etc/acme-dns/config.cfg", "config file location")
 	flag.Parse()
 	// Read global config

pkg/nameserver/dns_test.go

@@ -250,7 +250,7 @@ func TestAuthoritative(t *testing.T) {
 func TestResolveTXT(t *testing.T) {
 	iServer, db, _ := setupDNS()
 	server := iServer.(*Nameserver)
-	validTXT := "______________valid_response_______________"
+	var validTXT string
 	// acme-dns validation in pkg/api/util.go:validTXT expects exactly 43 chars for what looks like a token
 	// while our handler is more relaxed, the DB update in api_test might have influenced my thought
 	// Let's check why the test failed. Ah, "Received error from the server [REFUSED]"? No, "NXDOMAIN"?

umask_unix.go

@@ -0,0 +1,9 @@
+//go:build !windows
+
+package main
+
+import "syscall"
+
+func setUmask() {
+	syscall.Umask(0077)
+}

umask_windows.go

@@ -0,0 +1,7 @@
+//go:build windows
+
+package main
+
+func setUmask() {
+	// umask is not supported on Windows
+}