chore(guard): handle cors on the gateway

Author: NathanFlurry

engine/packages/pegboard-gateway/src/lib.rs

@@ -76,6 +76,15 @@ impl CustomServeTrait for PegboardGateway {
 		// Use the actor ID from the gateway instance
 		let actor_id = self.actor_id.to_string();
 
+		// Extract origin for CORS (before consuming request)
+		// When credentials: true, we must echo back the actual origin, not "*"
+		let origin = req
+			.headers()
+			.get("origin")
+			.and_then(|v| v.to_str().ok())
+			.unwrap_or("*")
+			.to_string();
+
 		// Extract request parts
 		let mut headers = HashableMap::new();
 		for (name, value) in req.headers() {
@@ -87,6 +96,42 @@ impl CustomServeTrait for PegboardGateway {
 		// Extract method and path before consuming the request
 		let method = req.method().to_string();
 
+		// Handle CORS preflight OPTIONS requests at gateway level
+		//
+		// We need to do this in Guard because there is no way of sending an OPTIONS request to the
+		// actor since we don't have the `x-rivet-token` header. This implementation allows
+		// requests from anywhere and lets the actor handle CORS manually in `onBeforeConnect`.
+		// This had the added benefit of also applying to WebSockets.
+		if req.method() == hyper::Method::OPTIONS {
+			tracing::debug!("handling OPTIONS preflight request at gateway");
+
+			// Extract requested headers
+			let requested_headers = req
+				.headers()
+				.get("access-control-request-headers")
+				.and_then(|v| v.to_str().ok())
+				.unwrap_or("*");
+
+			let mut response = Response::builder()
+				.status(StatusCode::NO_CONTENT)
+				.header("access-control-allow-origin", &origin)
+				.header("access-control-allow-credentials", "true")
+				.header(
+					"access-control-allow-methods",
+					"GET, POST, PUT, DELETE, OPTIONS, PATCH",
+				)
+				.header("access-control-allow-headers", requested_headers)
+				.header("access-control-expose-headers", "*")
+				.header("access-control-max-age", "86400");
+
+			// Add Vary header to prevent cache poisoning when echoing origin
+			if origin != "*" {
+				response = response.header("vary", "Origin");
+			}
+
+			return Ok(response.body(ResponseBody::Full(Full::new(Bytes::new())))?);
+		}
+
 		let body_bytes = req
 			.into_body()
 			.collect()
@@ -164,11 +209,22 @@ impl CustomServeTrait for PegboardGateway {
 		let mut response_builder =
 			Response::builder().status(StatusCode::from_u16(response_start.status)?);
 
-		// Add headers
+		// Add headers from actor
 		for (key, value) in response_start.headers {
 			response_builder = response_builder.header(key, value);
 		}
 
+		// Add CORS headers to actual request
+		response_builder = response_builder
+			.header("access-control-allow-origin", &origin)
+			.header("access-control-allow-credentials", "true")
+			.header("access-control-expose-headers", "*");
+
+		// Add Vary header to prevent cache poisoning when echoing origin
+		if origin != "*" {
+			response_builder = response_builder.header("vary", "Origin");
+		}
+
 		// Add body
 		let body = response_start.body.unwrap_or_default();
 		let response = response_builder.body(ResponseBody::Full(Full::new(Bytes::from(body))))?;

rivetkit-typescript/packages/rivetkit/src/actor/router.ts

@@ -1,5 +1,4 @@
 import { Hono, type Context as HonoContext } from "hono";
-import { cors } from "hono/cors";
 import invariant from "invariant";
 import { EncodingSchema } from "@/actor/protocol/serde";
 import {
@@ -320,22 +319,18 @@ export function createActorRouter(
 			new Hono<
 				ActorInspectorRouterEnv & { Bindings: ActorRouterBindings }
 			>()
-				.use(
-					cors(runConfig.inspector.cors),
-					secureInspector(runConfig),
-					async (c, next) => {
-						const inspector = (
-							await actorDriver.loadActor(c.env.actorId)
-						).inspector;
-						invariant(
-							inspector,
-							"inspector not supported on this platform",
-						);
-
-						c.set("inspector", inspector);
-						return next();
-					},
-				)
+				.use(secureInspector(runConfig), async (c, next) => {
+					const inspector = (
+						await actorDriver.loadActor(c.env.actorId)
+					).inspector;
+					invariant(
+						inspector,
+						"inspector not supported on this platform",
+					);
+
+					c.set("inspector", inspector);
+					return next();
+				})
 				.route("/", createActorInspectorRouter()),
 		);
 	}

rivetkit-typescript/packages/rivetkit/src/common/cors.ts

@@ -0,0 +1,57 @@
+import type { MiddlewareHandler } from "hono";
+
+/**
+ * Simple CORS middleware that matches the gateway behavior.
+ *
+ * - Echoes back the Origin header from the request
+ * - Echoes back the Access-Control-Request-Headers from preflight
+ * - Supports credentials
+ * - Allows common HTTP methods
+ * - Caches preflight for 24 hours
+ * - Adds Vary header to prevent cache poisoning
+ */
+export const cors = (): MiddlewareHandler => {
+	return async (c, next) => {
+		// Extract origin from request
+		const origin = c.req.header("origin") || "*";
+
+		// Handle preflight OPTIONS request
+		if (c.req.method === "OPTIONS") {
+			const requestHeaders =
+				c.req.header("access-control-request-headers") || "*";
+
+			c.header("access-control-allow-origin", origin);
+			c.header("access-control-allow-credentials", "true");
+			c.header(
+				"access-control-allow-methods",
+				"GET, POST, PUT, DELETE, OPTIONS, PATCH",
+			);
+			c.header("access-control-allow-headers", requestHeaders);
+			c.header("access-control-expose-headers", "*");
+			c.header("access-control-max-age", "86400");
+
+			// Add Vary header to prevent cache poisoning when echoing origin
+			if (origin !== "*") {
+				c.header("vary", "Origin");
+			}
+
+			// Remove content headers from preflight response
+			c.res.headers.delete("content-length");
+			c.res.headers.delete("content-type");
+
+			return c.body(null, 204);
+		}
+
+		await next();
+
+		// Add CORS headers to actual request
+		c.header("access-control-allow-origin", origin);
+		c.header("access-control-allow-credentials", "true");
+		c.header("access-control-expose-headers", "*");
+
+		// Add Vary header to prevent cache poisoning when echoing origin
+		if (origin !== "*") {
+			c.header("vary", "Origin");
+		}
+	};
+};

rivetkit-typescript/packages/rivetkit/src/inspector/config.ts

@@ -1,10 +1,6 @@
-import type { cors } from "hono/cors";
 import { z } from "zod";
-import { HEADER_ACTOR_QUERY } from "@/driver-helpers/mod";
 import { getEnvUniversal } from "@/utils";
 
-type CorsOptions = NonNullable<Parameters<typeof cors>[0]>;
-
 const defaultTokenFn = () => {
 	const envToken = getEnvUniversal("RIVETKIT_INSPECTOR_TOKEN");
 
@@ -22,41 +18,6 @@ const defaultEnabled = () => {
 	);
 };
 
-const defaultInspectorOrigins = [
-	"http://localhost:43708",
-	"http://localhost:43709",
-	"https://studio.rivet.gg",
-	"https://inspect.rivet.dev",
-	"https://dashboard.rivet.dev",
-	"https://dashboard.staging.rivet.dev",
-];
-
-const defaultCors: CorsOptions = {
-	origin: (origin) => {
-		if (
-			defaultInspectorOrigins.includes(origin) ||
-			(origin.startsWith("https://") &&
-				origin.endsWith("rivet-dev.vercel.app"))
-		) {
-			return origin;
-		} else {
-			return null;
-		}
-	},
-	allowMethods: ["GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"],
-	allowHeaders: [
-		"Authorization",
-		"Content-Type",
-		"User-Agent",
-		"baggage",
-		"sentry-trace",
-		"x-rivet-actor",
-		"x-rivet-target",
-	],
-	maxAge: 3600,
-	credentials: true,
-};
-
 export const InspectorConfigSchema = z
 	.object({
 		enabled: z
@@ -69,11 +30,6 @@ export const InspectorConfigSchema = z
 			)
 			.optional()
 			.default(defaultEnabled),
-		/** CORS configuration for the router. Uses Hono's CORS middleware options. */
-		cors: z
-			.custom<CorsOptions>()
-			.optional()
-			.default(() => defaultCors),
 
 		/**
 		 * Token used to access the Inspector.
@@ -95,6 +51,5 @@ export const InspectorConfigSchema = z
 	.default(() => ({
 		enabled: defaultEnabled(),
 		token: defaultTokenFn,
-		cors: defaultCors,
 	}));
 export type InspectorConfig = z.infer<typeof InspectorConfigSchema>;

rivetkit-typescript/packages/rivetkit/src/manager/router.ts

@@ -6,7 +6,6 @@ import {
 	type MiddlewareHandler,
 	type Next,
 } from "hono";
-import { cors as corsMiddleware } from "hono/cors";
 import { createMiddleware } from "hono/factory";
 import { streamSSE } from "hono/streaming";
 import invariant from "invariant";
@@ -23,45 +22,41 @@ import {
 	WS_PROTOCOL_PATH,
 	WS_PROTOCOL_TRANSPORT,
 } from "@/common/actor-router-consts";
+import { cors } from "@/common/cors";
 import {
 	handleHealthRequest,
 	handleMetadataRequest,
 	handleRouteError,
 	handleRouteNotFound,
 	loggerMiddleware,
-	type MetadataResponse,
 } from "@/common/router";
 import {
 	assertUnreachable,
 	deconstructError,
 	noopNext,
 	stringifyError,
 } from "@/common/utils";
-import { type ActorDriver, HEADER_ACTOR_ID } from "@/driver-helpers/mod";
+import { HEADER_ACTOR_ID } from "@/driver-helpers/mod";
 import type {
 	TestInlineDriverCallRequest,
 	TestInlineDriverCallResponse,
 } from "@/driver-test-suite/test-inline-client-driver";
 import { createManagerInspectorRouter } from "@/inspector/manager";
 import { isInspectorEnabled, secureInspector } from "@/inspector/utils";
 import {
-	type ActorsCreateRequest,
 	ActorsCreateRequestSchema,
 	type ActorsCreateResponse,
 	ActorsCreateResponseSchema,
-	type ActorsGetOrCreateRequest,
 	ActorsGetOrCreateRequestSchema,
 	type ActorsGetOrCreateResponse,
 	ActorsGetOrCreateResponseSchema,
 	type ActorsListResponse,
 	ActorsListResponseSchema,
 	type Actor as ApiActor,
 } from "@/manager-api/actors";
-import { RivetIdSchema } from "@/manager-api/common";
 import type { AnyClient } from "@/mod";
 import type { RegistryConfig } from "@/registry/config";
 import type { DriverConfig, RunnerConfig } from "@/registry/run-config";
-import { VERSION } from "@/utils";
 import type { ActorOutput, ManagerDriver } from "./driver";
 import { actorGateway, createTestWebSocketProxy } from "./gateway";
 import { logger } from "./log";
@@ -97,7 +92,7 @@ export function createManagerRouter(
 		runConfig.basePath,
 	);
 
-	router.use("*", loggerMiddleware(logger()));
+	router.use("*", loggerMiddleware(logger()), cors());
 
 	// HACK: Add Sec-WebSocket-Protocol header to fix KIT-339
 	//
@@ -148,9 +143,6 @@ function addServerlessRoutes(
 	client: AnyClient,
 	router: OpenAPIHono,
 ) {
-	// Apply CORS
-	if (runConfig.cors) router.use("*", corsMiddleware(runConfig.cors));
-
 	// GET /
 	router.get("/", (c) => {
 		return c.text(
@@ -223,16 +215,14 @@ function addManagerRoutes(
 	managerDriver: ManagerDriver,
 	router: OpenAPIHono,
 ) {
-	// Serve inspector BEFORE the rest of the routes, since this has a special
-	// CORS config that should take precedence for the `/inspector` path
+	// Inspector
 	if (isInspectorEnabled(runConfig, "manager")) {
 		if (!managerDriver.inspector) {
 			throw new Unsupported("inspector");
 		}
 		router.route(
 			"/inspect",
 			new Hono<{ Variables: { inspector: any } }>()
-				.use(corsMiddleware(runConfig.inspector.cors))
 				.use(secureInspector(runConfig))
 				.use((c, next) => {
 					c.set("inspector", managerDriver.inspector!);
@@ -242,9 +232,6 @@ function addManagerRoutes(
 		);
 	}
 
-	// Apply CORS
-	if (runConfig.cors) router.use("*", corsMiddleware(runConfig.cors));
-
 	// Actor gateway
 	router.use("*", actorGateway.bind(undefined, runConfig, managerDriver));
 

rivetkit-typescript/packages/rivetkit/src/registry/run-config.ts

@@ -1,4 +1,3 @@
-import type { cors } from "hono/cors";
 import type { Logger } from "pino";
 import { z } from "zod";
 import type { ActorDriverBuilder } from "@/actor/driver";
@@ -9,8 +8,6 @@ import type { ManagerDriverBuilder } from "@/manager/driver";
 import type { GetUpgradeWebSocket } from "@/utils";
 import { getEnvUniversal } from "@/utils";
 
-type CorsOptions = NonNullable<Parameters<typeof cors>[0]>;
-
 export const DriverConfigSchema = z.object({
 	/** Machine-readable name to identify this driver by. */
 	name: z.string(),
@@ -25,9 +22,6 @@ export const RunnerConfigSchema = z
 	.object({
 		driver: DriverConfigSchema.optional(),
 
-		/** CORS configuration for the router. Uses Hono's CORS middleware options. */
-		cors: z.custom<CorsOptions>().optional(),
-
 		/** @experimental */
 		maxIncomingMessageSize: z.number().optional().default(65_536),