all: log changes, imp docs

CHANGELOG.md

@@ -23,6 +23,13 @@ See also the [v0.107.50 GitHub milestone][ms-v0.107.50].
 NOTE: Add new changes BELOW THIS COMMENT.
 -->
 
+### Fixed
+
+- Broken private RDNS upstream servers validation causing update failures
+  ([#7013]).
+
+[#7013]: https://github.com/AdguardTeam/AdGuardHome/issues/7013
+
 <!--
 NOTE: Add new changes ABOVE THIS COMMENT.
 -->

internal/dnsforward/http.go

@@ -333,20 +333,21 @@ func (req *jsonDNSConfig) checkBootstrap() (err error) {
 	return nil
 }
 
+// containsPrivateRDNS returns true if req contains private RDNS settings and
+// should be validated.
+func (req *jsonDNSConfig) containsPrivateRDNS() (ok bool) {
+	return (req.UsePrivateRDNS != nil && *req.UsePrivateRDNS) ||
+		(req.LocalPTRUpstreams != nil && len(*req.LocalPTRUpstreams) > 0)
+}
+
 // checkPrivateRDNS returns an error if the configuration of the private RDNS is
 // not valid.
 func (req *jsonDNSConfig) checkPrivateRDNS(
 	ownAddrs addrPortSet,
 	sysResolvers SystemResolvers,
 	privateNets netutil.SubnetSet,
 ) (err error) {
-	switch {
-	case
-		req.UsePrivateRDNS != nil && *req.UsePrivateRDNS,
-		req.LocalPTRUpstreams != nil && len(*req.LocalPTRUpstreams) > 0:
-		// Only check the private RDNS servers if its usage has just been
-		// enabled or if it contains any addresses.
-	default:
+	if !req.containsPrivateRDNS() {
 		return nil
 	}