Add sing-box API service

daemon/errors.go

@@ -0,0 +1,42 @@
+package daemon
+
+import (
+	"context"
+	"errors"
+	"os"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func UnaryErrorInterceptor(ctx context.Context, request any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {
+	response, err := handler(ctx, request)
+	if err != nil {
+		return nil, mapStatusError(err)
+	}
+	return response, nil
+}
+
+func StreamErrorInterceptor(server any, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+	err := handler(server, stream)
+	if err != nil {
+		return mapStatusError(err)
+	}
+	return nil
+}
+
+func mapStatusError(err error) error {
+	if _, loaded := status.FromError(err); loaded {
+		return err
+	}
+	switch {
+	case errors.Is(err, os.ErrInvalid):
+		return status.Error(codes.FailedPrecondition, "service not started")
+	case errors.Is(err, os.ErrClosed):
+		return status.Error(codes.Unavailable, "service is closing")
+	case errors.Is(err, context.Canceled), errors.Is(err, context.DeadlineExceeded):
+		return status.FromContextError(err).Err()
+	}
+	return err
+}