HostResolver shouldn't return IPv6 addresses by default

They don't work over the SLIRP interface, and sometimes don't
even work over a bridged vmnet interface.

Signed-off-by: Jan Dubois <jan.dubois@suse.com>

Author: jandubois

cmd/limactl/debug.go

@@ -27,22 +27,27 @@ func newDebugDNSCommand() *cobra.Command {
 		Args:  cobra.RangeArgs(1, 2),
 		RunE:  debugDNSAction,
 	}
+	cmd.Flags().BoolP("ipv6", "6", false, "lookup IPv6 addresses too")
 	return cmd
 }
 
 func debugDNSAction(cmd *cobra.Command, args []string) error {
+	ipv6, err := cmd.Flags().GetBool("ipv6")
+	if err != nil {
+		return err
+	}
 	udpLocalPort, err := strconv.Atoi(args[0])
 	if err != nil {
 		return err
 	}
 	tcpLocalPort := 0
-	if len(args) > 2 {
+	if len(args) > 1 {
 		tcpLocalPort, err = strconv.Atoi(args[1])
 		if err != nil {
 			return err
 		}
 	}
-	srv, err := dns.Start(udpLocalPort, tcpLocalPort)
+	srv, err := dns.Start(udpLocalPort, tcpLocalPort, ipv6)
 	if err != nil {
 		return err
 	}

pkg/cidata/cidata.go

@@ -138,7 +138,7 @@ func GenerateISO9660(instDir, name string, y *limayaml.LimaYAML, udpDNSLocalPort
 	if err != nil {
 		return err
 	}
-	if *y.UseHostResolver {
+	if *y.HostResolver.Enabled {
 		args.UDPDNSLocalPort = udpDNSLocalPort
 		args.TCPDNSLocalPort = tcpDNSLocalPort
 		args.DNSAddresses = append(args.DNSAddresses, qemu.SlirpDNS)

pkg/hostagent/dns/dns.go

@@ -18,6 +18,7 @@ const truncateSize = 512
 type Handler struct {
 	clientConfig *dns.ClientConfig
 	clients      []*dns.Client
+	IPv6         bool
 }
 
 type Server struct {
@@ -43,7 +44,7 @@ func newStaticClientConfig(ips []net.IP) (*dns.ClientConfig, error) {
 	return dns.ClientConfigFromReader(r)
 }
 
-func newHandler() (dns.Handler, error) {
+func newHandler(IPv6 bool) (dns.Handler, error) {
 	cc, err := dns.ClientConfigFromFile("/etc/resolv.conf")
 	if err != nil {
 		fallbackIPs := []net.IP{net.ParseIP("8.8.8.8"), net.ParseIP("1.1.1.1")}
@@ -60,6 +61,7 @@ func newHandler() (dns.Handler, error) {
 	h := &Handler{
 		clientConfig: cc,
 		clients:      clients,
+		IPv6:         IPv6,
 	}
 	return h, nil
 }
@@ -78,7 +80,12 @@ func (h *Handler) handleQuery(w dns.ResponseWriter, req *dns.Msg) {
 			Ttl:    5,
 		}
 		switch q.Qtype {
-		case dns.TypeCNAME, dns.TypeA, dns.TypeAAAA:
+		case dns.TypeAAAA:
+			if !h.IPv6 {
+				break
+			}
+			fallthrough
+		case dns.TypeCNAME, dns.TypeA:
 			cname, err := net.LookupCNAME(q.Name)
 			if err != nil {
 				break
@@ -212,8 +219,8 @@ func (h *Handler) ServeDNS(w dns.ResponseWriter, req *dns.Msg) {
 	}
 }
 
-func Start(udpLocalPort, tcpLocalPort int) (*Server, error) {
-	h, err := newHandler()
+func Start(udpLocalPort, tcpLocalPort int, IPv6 bool) (*Server, error) {
+	h, err := newHandler(IPv6)
 	if err != nil {
 		return nil, err
 	}

pkg/hostagent/hostagent.go

@@ -92,7 +92,7 @@ func New(instName string, stdout io.Writer, sigintCh chan os.Signal, opts ...Opt
 	}
 
 	var udpDNSLocalPort, tcpDNSLocalPort int
-	if *y.UseHostResolver {
+	if *y.HostResolver.Enabled {
 		udpDNSLocalPort, err = findFreeUDPLocalPort()
 		if err != nil {
 			return nil, err
@@ -248,8 +248,8 @@ func (a *HostAgent) Run(ctx context.Context) error {
 		a.emitEvent(ctx, exitingEv)
 	}()
 
-	if *a.y.UseHostResolver {
-		dnsServer, err := dns.Start(a.udpDNSLocalPort, a.tcpDNSLocalPort)
+	if *a.y.HostResolver.Enabled {
+		dnsServer, err := dns.Start(a.udpDNSLocalPort, a.tcpDNSLocalPort, *a.y.HostResolver.IPv6)
 		if err != nil {
 			return fmt.Errorf("cannot start DNS server: %w", err)
 		}

pkg/limayaml/default.yaml

@@ -236,9 +236,14 @@ propagateProxyEnv: null
 # The host agent implements a DNS server that looks up host names on the host
 # using the local system resolver. This means changing VPN and network settings
 # are reflected automatically into the guest, including conditional forward,
-# and mDNS lookup:
-# Default: true
-useHostResolver: null
+# and mDNS lookup. By default only IPv4 addresses will be returned. IPv6 addresses
+# can only work when using a vmnet network interface and the host has working
+# IPv6 configured as well.
+hostResolver:
+  # Default: true
+  enabled: null
+  # Default: false
+  ipv6: null
 
 # If useHostResolver is false, then the following rules apply for configuring dns:
 # Explicitly set DNS addresses for qemu user-mode networking. By default qemu picks *one*

pkg/limayaml/defaults.go

@@ -217,14 +217,36 @@ func FillDefault(y, d, o *LimaYAML, filePath string) {
 		// After defaults processing the singular HostPort and GuestPort values should not be used again.
 	}
 
-	if y.UseHostResolver == nil {
-		y.UseHostResolver = d.UseHostResolver
+	// If both `useHostResolved` and `HostResolver.Enabled` are defined in the same config,
+	// then the deprecated `useHostResolved` setting is silently ignored.
+	if y.HostResolver.Enabled == nil {
+		y.HostResolver.Enabled = y.UseHostResolver
 	}
-	if o.UseHostResolver != nil {
-		y.UseHostResolver = o.UseHostResolver
+	if d.HostResolver.Enabled == nil {
+		d.HostResolver.Enabled = d.UseHostResolver
 	}
-	if y.UseHostResolver == nil {
-		y.UseHostResolver = pointer.Bool(true)
+	if o.HostResolver.Enabled == nil {
+		o.HostResolver.Enabled = o.UseHostResolver
+	}
+
+	if y.HostResolver.Enabled == nil {
+		y.HostResolver.Enabled = d.HostResolver.Enabled
+	}
+	if o.HostResolver.Enabled != nil {
+		y.HostResolver.Enabled = o.HostResolver.Enabled
+	}
+	if y.HostResolver.Enabled == nil {
+		y.HostResolver.Enabled = pointer.Bool(true)
+	}
+
+	if y.HostResolver.IPv6 == nil {
+		y.HostResolver.IPv6 = d.HostResolver.IPv6
+	}
+	if o.HostResolver.IPv6 != nil {
+		y.HostResolver.IPv6 = o.HostResolver.IPv6
+	}
+	if y.HostResolver.IPv6 == nil {
+		y.HostResolver.IPv6 = pointer.Bool(false)
 	}
 
 	if y.PropagateProxyEnv == nil {

pkg/limayaml/defaults_test.go

@@ -67,7 +67,10 @@ func TestFillDefault(t *testing.T) {
 		Video: Video{
 			Display: pointer.String("none"),
 		},
-		UseHostResolver:   pointer.Bool(true),
+		HostResolver: HostResolver{
+			Enabled: pointer.Bool(true),
+			IPv6:    pointer.Bool(false),
+		},
 		PropagateProxyEnv: pointer.Bool(true),
 	}
 
@@ -186,7 +189,10 @@ func TestFillDefault(t *testing.T) {
 		Video: Video{
 			Display: pointer.String("cocoa"),
 		},
-		UseHostResolver:   pointer.Bool(false),
+		HostResolver: HostResolver{
+			Enabled: pointer.Bool(false),
+			IPv6:    pointer.Bool(true),
+		},
 		PropagateProxyEnv: pointer.Bool(false),
 
 		Mounts: []Mount{
@@ -298,7 +304,10 @@ func TestFillDefault(t *testing.T) {
 		Video: Video{
 			Display: pointer.String("cocoa"),
 		},
-		UseHostResolver:   pointer.Bool(false),
+		HostResolver: HostResolver{
+			Enabled: pointer.Bool(false),
+			IPv6:    pointer.Bool(false),
+		},
 		PropagateProxyEnv: pointer.Bool(false),
 
 		Mounts: []Mount{

pkg/limayaml/limayaml.go

@@ -25,7 +25,8 @@ type LimaYAML struct {
 	Network           NetworkDeprecated `yaml:"network,omitempty" json:"network,omitempty"` // DEPRECATED, use `networks` instead
 	Env               map[string]string `yaml:"env,omitempty" json:"env,omitempty"`
 	DNS               []net.IP          `yaml:"dns,omitempty" json:"dns,omitempty"`
-	UseHostResolver   *bool             `yaml:"useHostResolver,omitempty" json:"useHostResolver,omitempty"`
+	HostResolver      HostResolver      `yaml:"hostResolver,omitempty" json:"hostResolver,omitempty"`
+	UseHostResolver   *bool             `yaml:"useHostResolver,omitempty" json:"useHostResolver,omitempty"` // DEPRECATED, use `HostResolver.Enabled` instead
 	PropagateProxyEnv *bool             `yaml:"propagateProxyEnv,omitempty" json:"propagateProxyEnv,omitempty"`
 }
 
@@ -132,6 +133,11 @@ type Network struct {
 	Interface  string `yaml:"interface,omitempty" json:"interface,omitempty"`
 }
 
+type HostResolver struct {
+	Enabled *bool `yaml:"enabled,omitempty" json:"enabled,omitempty"`
+	IPv6    *bool `yaml:"ipv6,omitempty" json:"ipv6,omitempty"`
+}
+
 // DEPRECATED types below
 
 // Types have been renamed to turn all references to the old names into compiler errors,

pkg/limayaml/validate.go

@@ -194,8 +194,8 @@ func Validate(y LimaYAML, warn bool) error {
 		// processed sequentially and the first matching rule for a guest port determines forwarding behavior.
 	}
 
-	if y.UseHostResolver != nil && *y.UseHostResolver && len(y.DNS) > 0 {
-		return fmt.Errorf("field `dns` must be empty when field `useHostResolver` is true")
+	if y.HostResolver.Enabled != nil && *y.HostResolver.Enabled && len(y.DNS) > 0 {
+		return fmt.Errorf("field `dns` must be empty when field `HostResolver.Enabled` is true")
 	}
 
 	if err := validateNetwork(y, warn); err != nil {