fix(rpc): improve handlers

rpc/src/core/base.ts

@@ -13,7 +13,6 @@ import {
 	type RPCState,
 } from '../utils/types'
 
-/** Shared plumbing of the server, client and webview instances */
 export class RPCInstanceBase {
 	protected readonly env: RPCEnvironment
 	protected readonly debug: boolean
@@ -26,9 +25,7 @@ export class RPCInstanceBase {
 		this._pending = new Pending(cfg.timeout ?? 5000)
 	}
 
-	// ===== LISTENERS =====
-
-	/** Registers `cb` for `event` on `emitter`; `method` is only used for logs */
+	/** Registers `cb` for `event` on `emitter`; `method` is only for logs */
 	protected listen(
 		emitter: Emitter,
 		method: string,
@@ -40,14 +37,13 @@ export class RPCInstanceBase {
 		return this
 	}
 	
+	/** Unregisters `cb` for `event` on `emitter`; `method` is only for logs */
 	protected unlisten(emitter: Emitter, method: string, event: string): this {
 		this.log(`${method} ${event}`)
 		emitter.off(event)
 		return this
 	}
 
-	// ===== OUTGOING =====
-
 	/** Builds an event payload sent from this environment to `to` */
 	protected request(
 		event: string,
@@ -89,8 +85,6 @@ export class RPCInstanceBase {
 		if (!found) this.logIgnored(response)
 	}
 
-	// ===== INCOMING =====
-
 	/**
 	 * Runs the listener for `request` and builds the response to send back.
 	 * Never throws: a missing listener or a thrown error ends up in `error`.
@@ -147,8 +141,6 @@ export class RPCInstanceBase {
 		})
 	}
 
-	// ===== LOGS =====
-
 	/** Debug-only log, prefixed with the environment */
 	protected log(message: string): void {
 		if (this.debug) console.log(`[RPC]:${this.env}:${message}`)

rpc/src/core/client.ts

@@ -2,7 +2,7 @@ import type * as s from '@entityseven/fivem-rpc-shared-types'
 
 import { Emitter } from '../utils/emitter'
 import { RPCError } from '../utils/errors'
-import { parse, stringify, stringifyWeb } from '../utils/funcs'
+import { stringify, stringifyWeb } from '../utils/funcs'
 import {
 	NATIVE_CLIENT_EVENTS,
 	NATIVE_CLIENT_NETWORK_EVENTS,
@@ -35,11 +35,14 @@ export class RPCInstanceClient extends RPCInstanceBase {
 		RegisterNuiCallbackType(RPCEvents.LISTENER_WEB)
 		on(
 			`__cfx_nui:${RPCEvents.LISTENER_WEB}`,
-			async (data: RPCState, callback: (res: unknown) => void) => {
+			async (data: unknown, callback: (res: unknown) => void) => {
+				const payload = this.accept(data)
+				if (!payload) return callback({ status: 'invalid' })
+
 				try {
-					callback(await this._handleWeb(data))
+					callback(await this._handleWeb(payload))
 				} catch (e) {
-					callback(this.errorResponse(data, e))
+					callback(this.errorResponse(payload, e))
 				}
 			},
 		)
@@ -48,16 +51,8 @@ export class RPCInstanceClient extends RPCInstanceBase {
 	// ===== HANDLERS =====
 
 	private async _handleServer(payloadRaw: RPCStateRaw) {
-		try {
-			parse(payloadRaw)
-		} catch {
-			throw new RPCError(RPCErrors.INVALID_DATA, RPCErrors.INVALID_DATA)
-		}
-		const payload = parse(payloadRaw)
-
-		this.log(
-			`accepted ${payload.type} ${payload.event} from ${payload.calledFrom}`,
-		)
+		const payload = this.accept(payloadRaw)
+		if (!payload) return
 
 		if (payload.type === 'event') {
 			if (payload.calledTo === 'client') {
@@ -86,10 +81,6 @@ export class RPCInstanceClient extends RPCInstanceBase {
 	}
 
 	private async _handleWeb(payload: RPCState): Promise<unknown> {
-		this.log(
-			`accepted ${payload.type} ${payload.event} from ${payload.calledFrom}`,
-		)
-
 		if (payload.type === 'event') {
 			if (payload.calledTo === 'client') {
 				return this.dispatch(this._emitterWeb, payload)

rpc/src/core/server.ts

@@ -2,7 +2,7 @@ import type * as s from '@entityseven/fivem-rpc-shared-types'
 
 import { Emitter } from '../utils/emitter'
 import { RPCError } from '../utils/errors'
-import { parse, stringify } from '../utils/funcs'
+import { stringify } from '../utils/funcs'
 import { NATIVE_SERVER_EVENTS } from '../utils/native'
 import {
 	type RPCConfig,
@@ -32,16 +32,8 @@ export class RPCInstanceServer extends RPCInstanceBase {
 	// ===== HANDLERS =====
 
 	private async _handleClient(payloadRaw: RPCStateRaw) {
-		try {
-			parse(payloadRaw)
-		} catch {
-			throw new RPCError(RPCErrors.INVALID_DATA, RPCErrors.INVALID_DATA)
-		}
-		const payload = parse(payloadRaw)
-
-		this.log(
-			`accepted ${payload.type} ${payload.event} from ${payload.calledFrom}`,
-		)
+		const payload = this.accept(payloadRaw)
+		if (!payload) return
 
 		if (payload.calledFrom === 'client') {
 			if (payload.type === 'event') {
@@ -71,16 +63,8 @@ export class RPCInstanceServer extends RPCInstanceBase {
 	}
 
 	private async _handleWeb(payloadRaw: RPCStateRaw) {
-		try {
-			parse(payloadRaw)
-		} catch {
-			throw new RPCError(RPCErrors.INVALID_DATA, RPCErrors.INVALID_DATA)
-		}
-		const payload = parse(payloadRaw)
-
-		this.log(
-			`accepted ${payload.type} ${payload.event} from ${payload.calledFrom}`,
-		)
+		const payload = this.accept(payloadRaw)
+		if (!payload) return
 
 		if (payload.calledFrom === 'webview') {
 			if (payload.type === 'event') {

rpc/src/core/webview.ts

@@ -23,23 +23,30 @@ export class RPCInstanceWebview extends RPCInstanceBase {
 
 		console.log('[RPC] Initialized Webview')
 
-		window.addEventListener('message', (e: MessageEvent<RPCStateWeb>) => {
-			if (e.data.origin === RPCEvents.LISTENER_CLIENT) {
-				this._handleClient(e.data.data)
+		window.addEventListener(
+			'message',
+			(e: MessageEvent<Partial<RPCStateWeb> | null>) => {
+				const origin = e.data?.origin
+				// not ours, e.g. the resource's own SendNUIMessage calls
+				if (
+					origin !== RPCEvents.LISTENER_CLIENT &&
+					origin !== RPCEvents.LISTENER_SERVER
+				) {
+					return
 				}
-			if (e.data.origin === RPCEvents.LISTENER_SERVER) {
-				this._handleServer(e.data.data)
-			}
-		})
+
+				const payload = this.accept(e.data?.data)
+				if (!payload) return
+
+				if (origin === RPCEvents.LISTENER_CLIENT) this._handleClient(payload)
+				else this._handleServer(payload)
+			},
+		)
 	}
 
 	// ===== HANDLERS =====
 
 	private async _handleClient(payload: RPCState) {
-		this.log(
-			`accepted ${payload.type} ${payload.event} from ${payload.calledFrom}`,
-		)
-
 		if (payload.calledFrom === 'client' && payload.type === 'event') {
 			const response = await this.dispatch(this._emitterClient, payload)
 
@@ -48,10 +55,6 @@ export class RPCInstanceWebview extends RPCInstanceBase {
 	}
 
 	private async _handleServer(payload: RPCState) {
-		this.log(
-			`accepted ${payload.type} ${payload.event} from ${payload.calledFrom}`,
-		)
-
 		if (payload.calledFrom === 'server' && payload.type === 'event') {
 			const response = await this.dispatch(this._emitterServer, payload)
 
@@ -156,7 +159,10 @@ export class RPCInstanceWebview extends RPCInstanceBase {
 	private _request<R>(payload: RPCState): Promise<R> {
 		const response = this._pending.wait<R>(payload)
 		this._createHttpClientRequest<RPCState>(payload).then(
-			res => this.settle(res),
+			res => {
+				const reply = this.accept(res)
+				if (reply) this.settle(reply)
+			},
 			(error: Error) => this._pending.reject(payload.uuid, error),
 		)
 		return response

rpc/src/utils/funcs.ts

@@ -1,17 +1,48 @@
 import type {
+	RPCEnvironment,
 	RPCState,
 	RPCStateRaw,
 	RPCStateWeb,
 	RPCStateWebRaw,
 } from './types'
 
+const ENVIRONMENTS: readonly unknown[] = [
+	'server',
+	'client',
+	'webview',
+] satisfies RPCEnvironment[]
+
 /**
  * **Internal**
  *
- * Typed data parser
+ * Checks the shape of an incoming payload. Payloads come from the network or
+ * another runtime, so nothing about them is trusted.
  */
-export function parse(data: RPCStateRaw): RPCState {
-	return JSON.parse(data)
+export function isRPCState(value: unknown): value is RPCState {
+	if (typeof value !== 'object' || value === null) return false
+	const v = value as Record<string, unknown>
+	return (
+		typeof v.event === 'string' &&
+		typeof v.uuid === 'string' &&
+		(v.type === 'event' || v.type === 'response') &&
+		ENVIRONMENTS.includes(v.calledFrom) &&
+		ENVIRONMENTS.includes(v.calledTo) &&
+		(v.data === null || Array.isArray(v.data))
+	)
+}
+
+/**
+ * **Internal**
+ *
+ * Parses a raw payload, `null` if it is not JSON or not an RPC payload
+ */
+export function parse(data: RPCStateRaw): RPCState | null {
+	try {
+		const value: unknown = JSON.parse(data)
+		return isRPCState(value) ? value : null
+	} catch {
+		return null
+	}
 }
 
 /**

rpc/src/utils/types.ts

@@ -94,7 +94,6 @@ export enum RPCEvents {
  */
 export enum RPCErrors {
 	EVENT_NOT_REGISTERED = 'Event not registered',
-	INVALID_DATA = 'Invalid data (possibly broken JSON)',
 	NO_PLAYER = 'No player (failed to resolve from local index)',
 	UNKNOWN_NATIVE = 'Unknown native event (if you are sure this exists - use native handler)',
 	UNKNOWN_ENVIRONMENT = 'Unknown environment (must be either "server", "client" or "webview")',