Optimize registration payload size for DNS registrar (#163)

* Stop anypb from reading type url during unmarshal

* Fix test

* Add tests

* Check non-nil typeurl

* Check err

Author: mingyech

application/transports/anypb_nourl.go

@@ -0,0 +1,26 @@
+package transports
+
+import (
+	"fmt"
+
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/types/known/anypb"
+)
+
+// UnmarshalAnypbTo unmarshals the src anypb to dst without reading the src type url.
+// Used to unmarshal TransportParams in the registration message for saving space from
+// the type url so that the registration payload is small enough for the DNS registrar.
+func UnmarshalAnypbTo(src *anypb.Any, dst protoreflect.ProtoMessage) error {
+	expected, err := anypb.New(dst)
+	if err != nil {
+		return fmt.Errorf("error reading src type: %v", err)
+	}
+
+	if src.TypeUrl != "" && src.TypeUrl != expected.TypeUrl {
+		return fmt.Errorf("incorrect non-empty TypeUrl: %v != %v", src.TypeUrl, expected.TypeUrl)
+	}
+
+	src.TypeUrl = expected.TypeUrl
+	return anypb.UnmarshalTo(src, dst, proto.UnmarshalOptions{})
+}

application/transports/anypb_nourl_test.go

@@ -0,0 +1,57 @@
+package transports_test
+
+import (
+	"math/rand"
+	"testing"
+
+	"github.com/refraction-networking/conjure/application/transports"
+	pb "github.com/refraction-networking/gotapdance/protobuf"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/known/anypb"
+)
+
+func TestUnmarshall(t *testing.T) {
+	src, err := anypb.New(&pb.GenericTransportParams{RandomizeDstPort: proto.Bool(true)})
+	require.Nil(t, err)
+	src.TypeUrl = ""
+
+	dst := &pb.GenericTransportParams{}
+	err = transports.UnmarshalAnypbTo(src, dst)
+	require.Nil(t, err)
+
+	require.True(t, dst.GetRandomizeDstPort())
+}
+
+func TestMissingTypeURL(t *testing.T) {
+	src, err := anypb.New(&pb.GenericTransportParams{RandomizeDstPort: proto.Bool(true)})
+	require.Nil(t, err)
+	src.TypeUrl = ""
+
+	dst := &pb.GenericTransportParams{}
+	err = anypb.UnmarshalTo(src, dst, proto.UnmarshalOptions{})
+	require.NotNil(t, err)
+}
+
+func TestWrongType(t *testing.T) {
+	src, err := anypb.New(&pb.ClientToStation{Padding: []byte{0, 1}})
+	require.Nil(t, err)
+
+	dst := &pb.GenericTransportParams{}
+	err = transports.UnmarshalAnypbTo(src, dst)
+	require.NotNil(t, err)
+}
+
+func TestGarbage(t *testing.T) {
+	src, err := anypb.New(&pb.GenericTransportParams{RandomizeDstPort: proto.Bool(true)})
+	require.Nil(t, err)
+	garbagebytes, err := proto.Marshal(src)
+	require.Nil(t, err)
+	_, err = rand.Read(garbagebytes)
+	require.Nil(t, err)
+
+	dstAnypb := &anypb.Any{}
+
+	err = proto.Unmarshal(garbagebytes, dstAnypb)
+	require.NotNil(t, err)
+}

application/transports/wrapping/min/min.go

@@ -8,7 +8,6 @@ import (
 	dd "github.com/refraction-networking/conjure/application/lib"
 	"github.com/refraction-networking/conjure/application/transports"
 	pb "github.com/refraction-networking/gotapdance/protobuf"
-	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/types/known/anypb"
 )
 
@@ -65,7 +64,7 @@ func (Transport) ParseParams(libVersion uint, data *anypb.Any) (any, error) {
 	}
 
 	var m = &pb.GenericTransportParams{}
-	err := anypb.UnmarshalTo(data, m, proto.UnmarshalOptions{})
+	err := transports.UnmarshalAnypbTo(data, m)
 	return m, err
 }
 

application/transports/wrapping/obfs4/obfs4.go

@@ -12,7 +12,6 @@ import (
 	"gitlab.com/yawning/obfs4.git/common/drbg"
 	"gitlab.com/yawning/obfs4.git/common/ntor"
 	"gitlab.com/yawning/obfs4.git/transports/obfs4"
-	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/types/known/anypb"
 )
 
@@ -62,7 +61,7 @@ func (Transport) ParseParams(libVersion uint, data *anypb.Any) (any, error) {
 	}
 
 	var m = &pb.GenericTransportParams{}
-	err := anypb.UnmarshalTo(data, m, proto.UnmarshalOptions{})
+	err := transports.UnmarshalAnypbTo(data, m)
 	return m, err
 }