fix: serve public assets on self-hosted deployments

apps/web/__tests__/unit/proxy-self-hosted.test.ts

@@ -1,10 +1,81 @@
 import { readFileSync } from "node:fs";
 import { join } from "node:path";
-import { describe, expect, it } from "vitest";
+import { NextRequest } from "next/server";
+import { describe, expect, it, vi } from "vitest";
+import { proxy } from "../../proxy";
+
+vi.mock("@cap/database", () => ({
+	db: () => {
+		throw new Error("Database should not be reached on self-hosted routes");
+	},
+}));
+
+vi.mock("@cap/database/schema", () => ({ organizations: {} }));
+
+vi.mock("@cap/env", () => ({
+	buildEnv: { NEXT_PUBLIC_IS_CAP: "false" },
+	serverEnv: () => ({
+		WEB_URL: "https://cap.example.com",
+		VERCEL_URL_HOST: undefined,
+		VERCEL_BRANCH_URL_HOST: undefined,
+		VERCEL_PROJECT_PRODUCTION_URL_HOST: undefined,
+	}),
+}));
+
+const request = (path: string) =>
+	proxy(new NextRequest(`https://cap.example.com${path}`));
+
+const expectServed = async (path: string) => {
+	const response = await request(path);
+	expect(response.status).toBe(200);
+	expect(response.headers.get("location")).toBeNull();
+};
+
+const expectLoginRedirect = async (path: string) => {
+	const response = await request(path);
+	expect(response.status).toBe(307);
+	expect(response.headers.get("location")).toBe(
+		"https://cap.example.com/login",
+	);
+};
 
 describe("self-hosted proxy routes", () => {
 	it("allows browser-based CLI authorization pages", () => {
 		const source = readFileSync(join(process.cwd(), "proxy.ts"), "utf8");
 		expect(source).toContain('path.startsWith("/cli/")');
 	});
+
+	it.each([
+		"/logos/browsers/google-chrome.svg",
+		"/illustrations/app.webp",
+		"/sounds/start-recording.ogg",
+		"/rive/main.riv",
+		"/fonts/Geist-Regular.woff2",
+		"/site.webmanifest",
+		"/.well-known/atproto-did",
+	])("serves the public asset %s instead of redirecting", (path) =>
+		expectServed(path),
+	);
+
+	it("still redirects page routes to /login", () =>
+		expectLoginRedirect("/pricing"));
+
+	it("still redirects extension-suffixed route handlers to /login", () =>
+		expectLoginRedirect("/install-cli.sh"));
+
+	it("does not let a missing file through", () =>
+		expectLoginRedirect("/logos/missing.svg"));
+
+	it("does not let a directory through", () => expectLoginRedirect("/logos"));
+
+	it("rejects path traversal out of public/", () =>
+		expectLoginRedirect("/logos/..%2F..%2Fproxy.ts"));
+
+	it.each(["/%00", "/favicon.ico/nested.svg", `/${"a".repeat(5000)}.svg`])(
+		"treats a filesystem lookup failure for %s as not an asset",
+		(path) => expectLoginRedirect(path),
+	);
+
+	it("does not treat a share link as an asset", () =>
+		expectServed("/s/video123"));
 });

apps/web/proxy.ts

@@ -1,3 +1,5 @@
+import { statSync } from "node:fs";
+import { resolve, sep } from "node:path";
 import { db } from "@cap/database";
 import { organizations } from "@cap/database/schema";
 import { buildEnv, serverEnv } from "@cap/env";
@@ -11,6 +13,18 @@ const addHttps = (s?: string) => {
 	return `https://${s}`;
 };
 
+const publicDir = resolve(process.cwd(), "public");
+
+const isPublicAsset = (path: string) => {
+	try {
+		const file = resolve(publicDir, `.${decodeURIComponent(path)}`);
+		if (!file.startsWith(`${publicDir}${sep}`)) return false;
+		return statSync(file, { throwIfNoEntry: false })?.isFile() ?? false;
+	} catch {
+		return false;
+	}
+};
+
 const mainOrigins = [
 	"https://cap.so",
 	"https://cap.link",
@@ -54,8 +68,11 @@ export async function proxy(request: NextRequest) {
 	const hostname = url.hostname;
 
 	if (buildEnv.NEXT_PUBLIC_IS_CAP !== "true") {
+		// Files under public/ have no route of their own, so without this every
+		// <img src="/logos/..."> on a self-hosted instance redirects to /login.
 		if (
 			!(
+				isPublicAsset(path) ||
 				path.startsWith("/s/") ||
 				path.startsWith("/c/") ||
 				path.startsWith("/cli/") ||