[client] Add reverse dns zone (#3217)

client/internal/dns/host.go

@@ -9,6 +9,11 @@ import (
 	nbdns "github.com/netbirdio/netbird/dns"
 )
 
+const (
+	ipv4ReverseZone = ".in-addr.arpa"
+	ipv6ReverseZone = ".ip6.arpa"
+)
+
 type hostManager interface {
 	applyDNSConfig(config HostDNSConfig, stateManager *statemanager.Manager) error
 	restoreHostDNS() error
@@ -94,9 +99,10 @@ func dnsConfigToHostDNSConfig(dnsConfig nbdns.Config, ip string, port int) HostD
 	}
 
 	for _, customZone := range dnsConfig.CustomZones {
+		matchOnly := strings.HasSuffix(customZone.Domain, ipv4ReverseZone) || strings.HasSuffix(customZone.Domain, ipv6ReverseZone)
 		config.Domains = append(config.Domains, DomainConfig{
 			Domain:    strings.TrimSuffix(customZone.Domain, "."),
-			MatchOnly: false,
+			MatchOnly: matchOnly,
 		})
 	}
 

client/internal/dns/server.go

@@ -395,12 +395,12 @@ func (s *DefaultServer) applyConfiguration(update nbdns.Config) error {
 
 	localMuxUpdates, localRecordsByDomain, err := s.buildLocalHandlerUpdate(update.CustomZones)
 	if err != nil {
-		return fmt.Errorf("not applying dns update, error: %v", err)
+		return fmt.Errorf("local handler updater: %w", err)
 	}
 
 	upstreamMuxUpdates, err := s.buildUpstreamHandlerUpdate(update.NameServerGroups)
 	if err != nil {
-		return fmt.Errorf("not applying dns update, error: %v", err)
+		return fmt.Errorf("upstream handler updater: %w", err)
 	}
 	muxUpdates := append(localMuxUpdates, upstreamMuxUpdates...) //nolint:gocritic
 
@@ -447,7 +447,8 @@ func (s *DefaultServer) buildLocalHandlerUpdate(
 
 	for _, customZone := range customZones {
 		if len(customZone.Records) == 0 {
-			return nil, nil, fmt.Errorf("received an empty list of records")
+			log.Warnf("received a custom zone with empty records, skipping domain: %s", customZone.Domain)
+			continue
 		}
 
 		muxUpdates = append(muxUpdates, handlerWrapper{
@@ -460,7 +461,8 @@ func (s *DefaultServer) buildLocalHandlerUpdate(
 		for _, record := range customZone.Records {
 			var class uint16 = dns.ClassINET
 			if record.Class != nbdns.DefaultClass {
-				return nil, nil, fmt.Errorf("received an invalid class type: %s", record.Class)
+				log.Warnf("received an invalid class type: %s", record.Class)
+				continue
 			}
 
 			key := buildRecordKey(record.Name, class, uint16(record.Type))

client/internal/dns/server_test.go

@@ -266,7 +266,7 @@ func TestUpdateDNSServer(t *testing.T) {
 			shouldFail: true,
 		},
 		{
-			name:            "Invalid Custom Zone Records list Should Fail",
+			name:            "Invalid Custom Zone Records list Should Skip",
 			initLocalMap:    make(registrationMap),
 			initUpstreamMap: make(registeredHandlerMap),
 			initSerial:      0,
@@ -285,7 +285,11 @@ func TestUpdateDNSServer(t *testing.T) {
 					},
 				},
 			},
-			shouldFail: true,
+			expectedUpstreamMap: registeredHandlerMap{generateDummyHandler(".", nameServers).id(): handlerWrapper{
+				domain:   ".",
+				handler:  dummyHandler,
+				priority: PriorityDefault,
+			}},
 		},
 		{
 			name:         "Empty Config Should Succeed and Clean Maps",