map GRPC error codes to REVA errors (#2140)

changelog/unreleased/map-grpc-error-codes.md

@@ -0,0 +1,5 @@
+Bugfix: Map GRPC error codes to REVA errors
+
+We've fixed the error return behaviour in the gateway which would return GRPC error codes from the auth middleware. Now it returns REVA errors which other parts of REVA are also able to understand.
+
+https://github.com/cs3org/reva/pull/2140

pkg/rgrpc/status/status.go

@@ -29,6 +29,8 @@ import (
 	"github.com/cs3org/reva/pkg/appctx"
 	"github.com/cs3org/reva/pkg/errtypes"
 	"go.opentelemetry.io/otel/trace"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 )
 
 // NewOK returns a Status with CODE_OK.
@@ -169,6 +171,28 @@ func NewStatusFromErrType(ctx context.Context, msg string, err error) *rpc.Statu
 	case errtypes.BadRequest:
 		return NewInvalidArg(ctx, "gateway: "+msg+":"+err.Error())
 	}
+
+	// map GRPC status codes coming from the auth middleware
+	grpcErr := err
+	for {
+		st, ok := status.FromError(grpcErr)
+		if ok {
+			switch st.Code() {
+			case codes.NotFound:
+				return NewNotFound(ctx, "gateway: "+msg+": "+err.Error())
+			case codes.Unauthenticated:
+				return NewUnauthenticated(ctx, err, "gateway: "+msg+": "+err.Error())
+			case codes.PermissionDenied:
+				return NewPermissionDenied(ctx, err, "gateway: "+msg+": "+err.Error())
+			}
+		}
+		// the actual error can be wrapped multiple times
+		grpcErr = errors.Unwrap(grpcErr)
+		if grpcErr == nil {
+			break
+		}
+	}
+
 	return NewInternal(ctx, err, "gateway: "+msg+":"+err.Error())
 }