package runtime import ( "context" "errors" "io" "net/http" "google.golang.org/grpc/codes" "google.golang.org/grpc/grpclog" "google.golang.org/grpc/status" ) // ErrorHandlerFunc is the signature used to configure error handling. type ErrorHandlerFunc func(context.Context, *ServeMux, Marshaler, http.ResponseWriter, *http.Request, error) // StreamErrorHandlerFunc is the signature used to configure stream error handling. type StreamErrorHandlerFunc func(context.Context, error) *status.Status // RoutingErrorHandlerFunc is the signature used to configure error handling for routing errors. type RoutingErrorHandlerFunc func(context.Context, *ServeMux, Marshaler, http.ResponseWriter, *http.Request, int) // HTTPStatusError is the error to use when needing to provide a different HTTP status code for an error // passed to the DefaultRoutingErrorHandler. type HTTPStatusError struct { HTTPStatus int Err error } func (e *HTTPStatusError) Error() string { return e.Err.Error() } // HTTPStatusFromCode converts a gRPC error code into the corresponding HTTP response status. // See: https://github.com/googleapis/googleapis/blob/master/google/rpc/code.proto func HTTPStatusFromCode(code codes.Code) int { switch code { case codes.OK: return http.StatusOK case codes.Canceled: return 499 case codes.Unknown: return http.StatusInternalServerError case codes.InvalidArgument: return http.StatusBadRequest case codes.DeadlineExceeded: return http.StatusGatewayTimeout case codes.NotFound: return http.StatusNotFound case codes.AlreadyExists: return http.StatusConflict case codes.PermissionDenied: return http.StatusForbidden case codes.Unauthenticated: return http.StatusUnauthorized case codes.ResourceExhausted: return http.StatusTooManyRequests case codes.FailedPrecondition: // Note, this deliberately doesn't translate to the similarly named '412 Precondition Failed' HTTP response status. return http.StatusBadRequest case codes.Aborted: return http.StatusConflict case codes.OutOfRange: return http.StatusBadRequest case codes.Unimplemented: return http.StatusNotImplemented case codes.Internal: return http.StatusInternalServerError case codes.Unavailable: return http.StatusServiceUnavailable case codes.DataLoss: return http.StatusInternalServerError default: grpclog.Warningf("Unknown gRPC error code: %v", code) return http.StatusInternalServerError } } // HTTPError uses the mux-configured error handler. func HTTPError(ctx context.Context, mux *ServeMux, marshaler Marshaler, w http.ResponseWriter, r *http.Request, err error) { mux.errorHandler(ctx, mux, marshaler, w, r, err) } // DefaultHTTPErrorHandler is the default error handler. // If "err" is a gRPC Status, the function replies with the status code mapped by HTTPStatusFromCode. // If "err" is a HTTPStatusError, the function replies with the status code provide by that struct. This is // intended to allow passing through of specific statuses via the function set via WithRoutingErrorHandler // for the ServeMux constructor to handle edge cases which the standard mappings in HTTPStatusFromCode // are insufficient for. // If otherwise, it replies with http.StatusInternalServerError. // // The response body written by this function is a Status message marshaled by the Marshaler. func DefaultHTTPErrorHandler(ctx context.Context, mux *ServeMux, marshaler Marshaler, w http.ResponseWriter, r *http.Request, err error) { // return Internal when Marshal failed const fallback = `{"code": 13, "message": "failed to marshal error message"}` var customStatus *HTTPStatusError if errors.As(err, &customStatus) { err = customStatus.Err } s := status.Convert(err) pb := s.Proto() w.Header().Del("Trailer") w.Header().Del("Transfer-Encoding") contentType := marshaler.ContentType(pb) w.Header().Set("Content-Type", contentType) if s.Code() == codes.Unauthenticated { w.Header().Set("WWW-Authenticate", s.Message()) } buf, merr := marshaler.Marshal(pb) if merr != nil { grpclog.Errorf("Failed to marshal error message %q: %v", s, merr) w.WriteHeader(http.StatusInternalServerError) if _, err := io.WriteString(w, fallback); err != nil { grpclog.Errorf("Failed to write response: %v", err) } return } md, ok := ServerMetadataFromContext(ctx) if !ok { grpclog.Error("Failed to extract ServerMetadata from context") } handleForwardResponseServerMetadata(w, mux, md) // RFC 7230 https://tools.ietf.org/html/rfc7230#section-4.1.2 // Unless the request includes a TE header field indicating "trailers" // is acceptable, as described in Section 4.3, a server SHOULD NOT // generate trailer fields that it believes are necessary for the user // agent to receive. doForwardTrailers := requestAcceptsTrailers(r) if doForwardTrailers { handleForwardResponseTrailerHeader(w, mux, md) w.Header().Set("Transfer-Encoding", "chunked") } st := HTTPStatusFromCode(s.Code()) if customStatus != nil { st = customStatus.HTTPStatus } w.WriteHeader(st) if _, err := w.Write(buf); err != nil { grpclog.Errorf("Failed to write response: %v", err) } if doForwardTrailers { handleForwardResponseTrailer(w, mux, md) } } func DefaultStreamErrorHandler(_ context.Context, err error) *status.Status { return status.Convert(err) } // DefaultRoutingErrorHandler is our default handler for routing errors. // By default http error codes mapped on the following error codes: // // NotFound -> grpc.NotFound // StatusBadRequest -> grpc.InvalidArgument // MethodNotAllowed -> grpc.Unimplemented // Other -> grpc.Internal, method is not expecting to be called for anything else func DefaultRoutingErrorHandler(ctx context.Context, mux *ServeMux, marshaler Marshaler, w http.ResponseWriter, r *http.Request, httpStatus int) { sterr := status.Error(codes.Internal, "Unexpected routing error") switch httpStatus { case http.StatusBadRequest: sterr = status.Error(codes.InvalidArgument, http.StatusText(httpStatus)) case http.StatusMethodNotAllowed: sterr = status.Error(codes.Unimplemented, http.StatusText(httpStatus)) case http.StatusNotFound: sterr = status.Error(codes.NotFound, http.StatusText(httpStatus)) } mux.errorHandler(ctx, mux, marshaler, w, r, sterr) }