David
29ee1a315e
A broker that mirrors another delivers every message twice, and the bridge answered both copies of a discovery request. A request is now remembered by its messageId for 60 s, as a directive is, and its copy is dropped with a log line. The messageId is read from the header of the Discover directive or from the request itself when that is the header alone. A request without a messageId is answered every time, as before. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
401 lines
19 KiB
TypeScript
401 lines
19 KiB
TypeScript
// From a message on <root>/<endpointId>/alexaDirective to the handlers of the device, and to the one answer
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// Alex2MQTT takes for it. Every answer of the bridge passes through here, those of the 1.x message classes too, so
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// the dispatcher knows which directive is still waiting and answers for a handler that failed or stayed silent.
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import type { AnyCapability } from "./device/Capability.js";
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import type Device from "./device/Device.js";
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import { deferredResponse, errorResponse, response, sameProperty, stateReport } from "./messages/build.js";
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import { AlexaError } from "./messages/errors.js";
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import { StateBuilder } from "./messages/StateBuilder.js";
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import type { Property } from "./messages/types.js";
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import { SchemaError } from "./registry/schema.js";
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import * as topics from "./topics.js";
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import { asError } from "./transport.js";
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import type { Publisher, PublishResult } from "./transport.js";
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/** A directive as Alex2MQTT publishes it: the directive of Alexa without endpoint.scope, the token of the user. */
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export interface RawDirective {
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header: {
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namespace: string;
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name: string;
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instance?: string;
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messageId?: string;
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correlationToken?: string;
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payloadVersion?: string;
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};
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endpoint?: { endpointId?: string; cookie?: Record<string, string> };
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payload?: unknown;
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}
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/** Sets the properties of a message. */
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export type Fill = (state: StateBuilder) => void;
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/** One directive, and the ways to answer it. Each method resolves with what became of the publish, none rejects. */
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export interface DirectiveContext<T = unknown> {
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readonly endpointId: string;
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readonly namespace: string;
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readonly name: string;
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/** The instance of a generic controller, "" without one. */
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readonly instance: string;
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/** "" when the directive came without one; it can then not be answered. */
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readonly correlationToken: string;
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/** The payload, checked by the descriptor of the interface. As it arrived for an interface the library only names. */
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readonly payload: T;
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readonly raw: RawDirective;
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/** Date.now() when the directive arrived. */
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readonly receivedAt: number;
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/** A Response, a StateReport or an ErrorResponse was sent. */
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readonly answered: boolean;
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/** A DeferredResponse was sent: the answer goes to <root>/<endpointId>/deferredResponse. */
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readonly deferred: boolean;
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/**
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* Answer with a Response, or with the response the interface has of its own. The context is the state of
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* device.state(), and what fill sets replaces the same property of it.
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*/
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respond(fill?: Fill, options?: { payload?: Record<string, unknown> }): Promise<PublishResult>;
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/** Answer ReportState with a StateReport, its properties as for respond(). */
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report(fill?: Fill): Promise<PublishResult>;
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/** Send a DeferredResponse now, when the answer takes longer than the 7 s Alex2MQTT waits for it. */
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defer(estimatedDeferralInSeconds?: number): Promise<PublishResult>;
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/** Answer with an ErrorResponse. An error that is not an AlexaError is sent as INTERNAL_ERROR. */
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error(type: string, message: string, extra?: Record<string, unknown>): Promise<PublishResult>;
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error(err: Error): Promise<PublishResult>;
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}
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/** What a handler returns is awaited and otherwise ignored; what it throws answers the directive. */
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export type DirectiveHandler<T = unknown> = (ctx: DirectiveContext<T>) => unknown;
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/** The clock of the watchdog, replaced in tests. */
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export interface Timers {
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setTimeout(run: () => void, ms: number): unknown;
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clearTimeout(timer: unknown): void;
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}
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// unref: a directive that waits for its answer does not keep a process alive that is otherwise done
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const processTimers: Timers = {
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setTimeout(run, ms) {
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const timer = setTimeout(run, ms);
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timer.unref();
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return timer;
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},
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clearTimeout(timer) {
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clearTimeout(timer as ReturnType<typeof setTimeout>);
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},
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};
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/** What the dispatcher needs of its bridge. */
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export interface DispatcherOptions {
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rootTopic: string;
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/** Where the answers go. */
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publisher: Publisher;
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getDevice(endpointId: string): Device | undefined;
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log(message: string, detail?: unknown): void;
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/** Reports an error: the "error" event of the bridge. */
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fail(err: Error): void;
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emit(event: string, ...args: unknown[]): void;
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answerWithinMs?: number;
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answerUnknownEndpoints?: boolean;
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timers?: Timers;
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}
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/** Alex2MQTT gives up on a directive after DIRECTIVE_BUDGET_MS: the answer of the watchdog has to be there before. */
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export const ANSWER_WITHIN_MS = topics.DIRECTIVE_BUDGET_MS - 500;
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// How long a directive is remembered: its messageId, to drop the copy of a mirroring broker, and that it was
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// answered, to drop a second answer. A deferred answer may take this long and still find its directive.
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const REMEMBERED_MS = 60_000;
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// A directive on its way to its answer
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interface Exchange {
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readonly endpointId: string;
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readonly namespace: string;
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readonly name: string;
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readonly correlationToken: string;
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readonly receivedAt: number;
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answered: boolean;
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deferred: boolean;
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/** Set while the watchdog waits for the first answer. */
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watchdog?: unknown;
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}
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// A directive no handler can be called for. A device with a 1.x listener answers it by itself.
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class RoutingError extends AlexaError {}
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const key = (endpointId: string, id: string): string => `${endpointId}\n${id}`;
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class Context implements DirectiveContext<any> {
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payload: unknown;
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/** The capability the directive is for; none for ReportState. */
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capability?: AnyCapability;
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constructor(
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private readonly dispatcher: Dispatcher,
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private readonly device: Device,
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private readonly exchange: Exchange,
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readonly raw: RawDirective
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) {
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this.payload = raw.payload ?? {};
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}
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get endpointId(): string { return this.exchange.endpointId; }
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get namespace(): string { return this.exchange.namespace; }
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get name(): string { return this.exchange.name; }
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get instance(): string { return this.raw.header.instance ?? ""; }
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get correlationToken(): string { return this.exchange.correlationToken; }
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get receivedAt(): number { return this.exchange.receivedAt; }
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get answered(): boolean { return this.exchange.answered; }
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get deferred(): boolean { return this.exchange.deferred; }
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get reportState(): boolean { return this.namespace === "Alexa" && this.name === "ReportState"; }
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async respond(fill?: Fill, options: { payload?: Record<string, unknown> } = {}): Promise<PublishResult> {
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const { endpointId, correlationToken } = this;
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const own = this.capability?.descriptor.responseFor?.(this.name);
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const payload = own?.payload ? own.payload.parse(options.payload ?? {}, "payload") : options.payload;
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const context = this.state(fill);
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return this.answer(response({ endpointId, correlationToken, namespace: own?.namespace, name: own?.name, payload, context }));
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}
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async report(fill?: Fill): Promise<PublishResult> {
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if (!this.reportState) {
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throw new Error(`report() answers ReportState with a StateReport: answer ${this.namespace}.${this.name} with respond()`);
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}
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const { endpointId, correlationToken } = this;
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return this.answer(stateReport({ endpointId, correlationToken, context: this.state(fill) }));
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}
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defer(estimatedDeferralInSeconds?: number): Promise<PublishResult> {
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const { endpointId, correlationToken } = this;
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if (this.capability && !this.capability.descriptor.deferrable && !this.deferredByAnother()) this.dispatcher.noteDeferral(this.namespace);
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// Always where the first answer goes: a second DeferredResponse is refused there
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const topic = topics.response(this.dispatcher.rootTopic, endpointId);
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return this.dispatcher.send(topic, deferredResponse({ endpointId, correlationToken, estimatedDeferralInSeconds }));
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}
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error(typeOrError: string | Error, message = "", extra: Record<string, unknown> = {}): Promise<PublishResult> {
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const { endpointId, correlationToken } = this;
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let error: AlexaError;
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if (typeOrError instanceof AlexaError) error = typeOrError;
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else if (typeOrError instanceof Error) error = new AlexaError("INTERNAL_ERROR", typeOrError.message);
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else error = new AlexaError(typeOrError, message, extra);
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const { type, alexaMessage, namespace } = error;
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return this.answer(errorResponse({ endpointId, correlationToken, type, message: alexaMessage, extra: error.extra, namespace }));
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}
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// An interface of the device documents a DeferredResponse for this directive of another one
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private deferredByAnother(): boolean {
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const { namespace, name } = this;
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return this.device.getCapabilities().some(({ descriptor }) =>
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descriptor.defers?.some((directive) => directive.namespace === namespace && directive.name === name));
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}
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// The state of the device, and over it what the handler says about this directive
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private state(fill?: Fill): Property[] {
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const whole = new StateBuilder();
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this.device.stateProvider?.(whole);
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const own = new StateBuilder();
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fill?.(own);
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return [...whole.context.filter((property) => !own.context.some((other) => sameProperty(property, other))), ...own.context];
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}
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private answer(message: object): Promise<PublishResult> {
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const topic = this.deferred ? topics.deferred : topics.response;
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return this.dispatcher.send(topic(this.dispatcher.rootTopic, this.endpointId), message);
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}
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}
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export class Dispatcher {
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readonly rootTopic: string;
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/**
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* What the devices of the bridge publish through. An answer to a directive that waits is let through once, and a
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* DeferredResponse once before it; everything else passes.
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*/
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readonly publisher: Publisher = { publish: (topic, message) => this.publish(topic, message) };
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private readonly answerWithinMs: number;
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private readonly timers: Timers;
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// Both oldest first. The directives by endpoint and correlationToken, when they arrived by endpoint and messageId.
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private readonly exchanges = new Map<string, Exchange>();
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private readonly arrived = new Map<string, number>();
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private readonly deferralNoted = new Set<string>();
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constructor(private readonly options: DispatcherOptions) {
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const { answerWithinMs = ANSWER_WITHIN_MS } = options;
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if (typeof answerWithinMs !== "number" || !(answerWithinMs >= 0)) {
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throw new Error(`answerWithinMs is ${String(answerWithinMs)}: pass the milliseconds a handler has to answer in, or 0 for no limit`);
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}
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this.rootTopic = options.rootTopic;
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this.answerWithinMs = answerWithinMs;
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this.timers = options.timers ?? processTimers;
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}
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/** Publish an answer; one that is not published is reported to the bridge. */
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async send(topic: string, message: object): Promise<PublishResult> {
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const result = await this.publish(topic, message);
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if (!result.ok) this.options.fail(result.error);
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return result;
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}
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/** defer() for an interface Amazon documents no DeferredResponse for: said once, the DeferredResponse is sent. */
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noteDeferral(namespace: string): void {
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if (this.deferralNoted.has(namespace)) return;
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this.deferralNoted.add(namespace);
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this.options.log(`warning: Amazon documents no DeferredResponse for ${namespace}, Alexa may not wait for the answer`);
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}
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/**
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* true for a message that came before, within REMEMBERED_MS: a broker that mirrors another delivers each message
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* twice. endpointId is "" for a message to the root, a discovery request.
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*/
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arrivedBefore(endpointId: string, messageId: string, now = Date.now()): boolean {
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this.forget(now);
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const id = key(endpointId, messageId);
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if (this.arrived.has(id)) return true;
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this.arrived.set(id, now);
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return false;
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}
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/** The text of a message on the directive topic of endpointId. Resolves when the handlers are done. */
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async dispatch(endpointId: string, text: string): Promise<void> {
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const { log, emit } = this.options;
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let raw: RawDirective;
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try {
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raw = JSON.parse(text);
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} catch (err) {
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// Without a correlationToken there is nothing to answer
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log(`the directive for ${endpointId} is dropped: it is not JSON`, err);
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return;
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}
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if (typeof raw !== "object" || raw === null || typeof raw.header !== "object" || raw.header === null) {
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log(`the directive for ${endpointId} is dropped: it has no header`);
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return;
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}
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const { namespace, name, messageId } = raw.header;
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const correlationToken = typeof raw.header.correlationToken === "string" ? raw.header.correlationToken : "";
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const receivedAt = Date.now();
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if (typeof messageId === "string" && this.arrivedBefore(endpointId, messageId, receivedAt)) {
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log(`the directive ${messageId} for ${endpointId} is dropped: it arrived before`);
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return;
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}
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const device = this.options.getDevice(endpointId);
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if (!device) {
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log(`No device found for endpointId: ${endpointId}`);
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emit("unknownEndpoint", { endpointId, namespace, name });
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// Off by default: the endpoint may belong to another bridge on the same root topic
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if (this.options.answerUnknownEndpoints) {
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const message = `${endpointId} is not an endpoint of this bridge`;
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await this.send(topics.response(this.rootTopic, endpointId), errorResponse({ endpointId, correlationToken, type: "NO_SUCH_ENDPOINT", message }));
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}
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return;
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}
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const exchange: Exchange = { endpointId, namespace, name, correlationToken, receivedAt, answered: false, deferred: false };
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if (correlationToken) {
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this.exchanges.set(key(endpointId, correlationToken), exchange);
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this.watch(exchange);
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}
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const ctx = new Context(this, device, exchange, raw);
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emit("directive", { endpointId, namespace, name });
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// The 1.x listeners first, called one by one: emit() would let what one of them throws out, and lose what an
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// async one rejects with
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const event = ctx.reportState ? "ReportState" : "Event";
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const listeners = device.rawListeners(event);
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const running = listeners.map((listener) => this.isolated(ctx, () => listener.call(device, raw, ...(ctx.reportState ? [] : [namespace]))));
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running.push(this.isolated(ctx, () => this.route(device, ctx)(ctx), listeners.length > 0));
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await Promise.all(running);
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}
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// The handler for the directive, the payload of ctx checked for it
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private route(device: Device, ctx: Context): DirectiveHandler<any> {
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const { endpointId, namespace, name, instance } = ctx;
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const refused = (type: string, problem: string): RoutingError => new RoutingError(type, problem);
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if (ctx.reportState) {
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if (device.reportStateHandler) return device.reportStateHandler;
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if (device.stateProvider) return (context) => context.report();
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throw refused("INVALID_DIRECTIVE", `${endpointId} has no handler for ReportState: register one with onReportState() or state() of the device`);
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}
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const capability = device.capability(namespace, instance);
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const declared = `${namespace}${instance ? ` "${instance}"` : ""}`;
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if (!capability) throw refused("INVALID_DIRECTIVE", `${declared} is not declared on ${endpointId}`);
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ctx.capability = capability;
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const directive = capability.descriptor.directives[name];
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// An interface the library only names describes no directive: its handlers get the payload as it arrived
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if (!directive && capability.descriptor.tier !== 3) throw refused("INVALID_DIRECTIVE", `${name} is not a directive of ${namespace}`);
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if (directive?.when && !directive.when(capability)) {
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throw refused("INVALID_DIRECTIVE", `${declared} as ${endpointId} declares it does not take ${name}`);
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}
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const handler = capability.handlerFor(name) ?? device.directiveHandler;
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if (!handler) {
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throw refused("INVALID_DIRECTIVE", `${endpointId} has no handler for ${namespace}.${name}: register one with on("${name}", handler) of the capability`);
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}
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try {
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if (directive) ctx.payload = directive.payload.parse(ctx.payload, "payload");
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} catch (err) {
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throw err instanceof SchemaError ? refused("INVALID_VALUE", err.message) : err;
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}
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return handler;
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}
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// Runs a listener or a handler. What it throws or rejects with answers the directive and goes no further.
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private async isolated(ctx: Context, run: () => unknown, answersItself = false): Promise<void> {
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try {
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await run();
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} catch (thrown) {
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if (thrown instanceof RoutingError && answersItself) return;
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const err = asError(thrown);
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// An AlexaError is the answer the handler chose. Anything else is a fault in it, and so is an answer too many.
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if (!(err instanceof AlexaError) || ctx.answered) this.options.fail(err);
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if (!ctx.answered) await ctx.error(err);
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}
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}
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private watch(exchange: Exchange): void {
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const within = this.answerWithinMs;
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if (within === 0) return;
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exchange.watchdog = this.timers.setTimeout(() => {
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exchange.watchdog = undefined;
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const { endpointId, namespace, name, correlationToken } = exchange;
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const message = `no answer within ${within / 1000} s`;
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this.options.emit("unanswered", { endpointId, namespace, name, correlationToken });
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this.options.fail(new Error(
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`${endpointId}: ${namespace}.${name} got ${message} and is answered with INTERNAL_ERROR. `
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+ "Answer in the handler, or defer() first when the device takes longer"
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));
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void this.send(topics.response(this.rootTopic, endpointId), errorResponse({ endpointId, correlationToken, type: "INTERNAL_ERROR", message }));
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}, within);
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}
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private publish(topic: string, message: object): Promise<PublishResult> {
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const { event } = message as { event?: { header?: { name?: string; correlationToken?: unknown }; endpoint?: { endpointId?: string } } };
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const token = event?.header?.correlationToken;
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const exchange = typeof token === "string" ? this.exchanges.get(key(event?.endpoint?.endpointId ?? "", token)) : undefined;
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if (exchange) {
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const deferral = event?.header?.name === "DeferredResponse";
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const { endpointId, namespace, name } = exchange;
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if (exchange.answered || (deferral && exchange.deferred)) {
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const was = exchange.answered ? "answered" : "deferred";
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const error = new Error(`nothing was published to ${topic}: ${namespace}.${name} for ${endpointId} was ${was} before, and Alex2MQTT takes one answer`);
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return Promise.resolve({ ok: false, topic, error });
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}
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if (deferral) exchange.deferred = true;
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else exchange.answered = true;
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if (exchange.watchdog !== undefined) {
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this.timers.clearTimeout(exchange.watchdog);
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exchange.watchdog = undefined;
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}
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}
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return this.options.publisher.publish(topic, message);
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}
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// Drops what is older than REMEMBERED_MS. A directive the watchdog still waits for is kept.
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private forget(now: number): void {
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const old = (since: number): boolean => now - since > REMEMBERED_MS;
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for (const [id, since] of this.arrived) {
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if (!old(since)) break;
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this.arrived.delete(id);
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}
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for (const [id, exchange] of this.exchanges) {
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if (!old(exchange.receivedAt)) break;
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if (exchange.watchdog === undefined) this.exchanges.delete(id);
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}
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}
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}
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