Merge pull request #1512 from josephschorr/cursor-errors

Have invalid cursors return a proper error

internal/services/v1/relationships_test.go

@@ -1383,6 +1383,39 @@ func TestReadRelationshipsWithTimeout(t *testing.T) {
 	}
 }
 
+func TestReadRelationshipsInvalidCursor(t *testing.T) {
+	require := require.New(t)
+
+	conn, cleanup, _, revision := testserver.NewTestServer(require, 0, memdb.DisableGC, true, tf.StandardDatastoreWithData)
+	client := v1.NewPermissionsServiceClient(conn)
+	t.Cleanup(cleanup)
+
+	stream, err := client.ReadRelationships(context.Background(), &v1.ReadRelationshipsRequest{
+		Consistency: &v1.Consistency{
+			Requirement: &v1.Consistency_AtLeastAsFresh{
+				AtLeastAsFresh: zedtoken.MustNewFromRevision(revision),
+			},
+		},
+		RelationshipFilter: &v1.RelationshipFilter{
+			ResourceType:       "folder",
+			OptionalResourceId: "auditors",
+			OptionalRelation:   "viewer",
+			OptionalSubjectFilter: &v1.SubjectFilter{
+				SubjectType:       "user",
+				OptionalSubjectId: "jeshk",
+			},
+		},
+		OptionalLimit:  42,
+		OptionalCursor: &v1.Cursor{Token: "someinvalidtoken"},
+	})
+	require.NoError(err)
+
+	_, err = stream.Recv()
+	require.Error(err)
+	require.ErrorContains(err, "error decoding cursor")
+	grpcutil.RequireStatus(t, codes.InvalidArgument, err)
+}
+
 func readOfType(require *require.Assertions, resourceType string, client v1.PermissionsServiceClient, token *v1.ZedToken) map[string]struct{} {
 	got := make(map[string]struct{})
 	stream, err := client.ReadRelationships(context.Background(), &v1.ReadRelationshipsRequest{

pkg/cursor/cursor.go

@@ -13,25 +13,13 @@ import (
 	"github.com/authzed/spicedb/pkg/spiceerrors"
 )
 
-// Public facing errors
-const (
-	errEncodeError = "error encoding cursor: %w"
-	errDecodeError = "error decoding cursor: %w"
-)
-
-// ErrNilCursor is returned as the base error when nil is provided as the
-// cursor argument to Decode
-var ErrNilCursor = errors.New("cursor pointer was nil")
-
-// ErrHashMismatch is returned as the base error when a mismatching hash was given to the decoder.
-var ErrHashMismatch = errors.New("the cursor provided does not have the same arguments as the original API call; please ensure you are making the same API call, with the exact same parameters (besides the cursor)")
-
 // Encode converts a decoded cursor to its opaque version.
 func Encode(decoded *impl.DecodedCursor) (*v1.Cursor, error) {
 	marshalled, err := decoded.MarshalVT()
 	if err != nil {
-		return nil, fmt.Errorf(errEncodeError, err)
+		return nil, NewInvalidCursorErr(fmt.Errorf(errEncodeError, err))
 	}
+
 	return &v1.Cursor{
 		Token: base64.StdEncoding.EncodeToString(marshalled),
 	}, nil
@@ -40,17 +28,19 @@ func Encode(decoded *impl.DecodedCursor) (*v1.Cursor, error) {
 // Decode converts an encoded cursor to its decoded version.
 func Decode(encoded *v1.Cursor) (*impl.DecodedCursor, error) {
 	if encoded == nil {
-		return nil, fmt.Errorf(errDecodeError, ErrNilCursor)
+		return nil, NewInvalidCursorErr(errors.New("cursor pointer was nil"))
 	}
 
 	decodedBytes, err := base64.StdEncoding.DecodeString(encoded.Token)
 	if err != nil {
-		return nil, fmt.Errorf(errDecodeError, err)
+		return nil, NewInvalidCursorErr(fmt.Errorf(errDecodeError, err))
 	}
+
 	decoded := &impl.DecodedCursor{}
 	if err := decoded.UnmarshalVT(decodedBytes); err != nil {
-		return nil, fmt.Errorf(errDecodeError, err)
+		return nil, NewInvalidCursorErr(fmt.Errorf(errDecodeError, err))
 	}
+
 	return decoded, nil
 }
 
@@ -87,11 +77,11 @@ func DecodeToDispatchCursor(encoded *v1.Cursor, callAndParameterHash string) (*d
 
 	v1decoded := decoded.GetV1()
 	if v1decoded == nil {
-		return nil, ErrNilCursor
+		return nil, NewInvalidCursorErr(ErrNilCursor)
 	}
 
 	if v1decoded.CallAndParametersHash != callAndParameterHash {
-		return nil, ErrHashMismatch
+		return nil, NewInvalidCursorErr(ErrHashMismatch)
 	}
 
 	return &dispatch.Cursor{

pkg/cursor/errors.go

@@ -0,0 +1,46 @@
+package cursor
+
+import (
+	"errors"
+
+	v1 "github.com/authzed/authzed-go/proto/authzed/api/v1"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	"github.com/authzed/spicedb/pkg/spiceerrors"
+)
+
+// Public facing errors
+const (
+	errEncodeError = "error encoding cursor: %w"
+	errDecodeError = "error decoding cursor: %w"
+)
+
+// ErrNilCursor is returned as the base error when nil is provided as the
+// cursor argument to Decode
+var ErrNilCursor = errors.New("cursor pointer was nil")
+
+// ErrHashMismatch is returned as the base error when a mismatching hash was given to the decoder.
+var ErrHashMismatch = errors.New("the cursor provided does not have the same arguments as the original API call; please ensure you are making the same API call, with the exact same parameters (besides the cursor)")
+
+// ErrInvalidCursor occurs when a cursor could not be decoded.
+type ErrInvalidCursor struct {
+	error
+}
+
+// GRPCStatus implements retrieving the gRPC status for the error.
+func (err ErrInvalidCursor) GRPCStatus() *status.Status {
+	return spiceerrors.WithCodeAndDetails(
+		err,
+		codes.InvalidArgument,
+		spiceerrors.ForReason(
+			v1.ErrorReason_ERROR_REASON_INVALID_CURSOR,
+			nil,
+		),
+	)
+}
+
+// NewInvalidCursorErr creates and returns a new invalid cursor error.
+func NewInvalidCursorErr(err error) error {
+	return ErrInvalidCursor{err}
+}