fix(review-followup-feb): block raw Markdown fetch vectors and guard preview

1 files changed, 105 insertions, 0 deletions

diff --git a/scripts/vite-network-guard.test.ts b/scripts/vite-network-guard.test.ts
new file mode 100644
index 0000000..651b635
--- /dev/null
+++ b/scripts/vite-network-guard.test.ts
@@ -0,0 +1,105 @@
+import { EventEmitter } from "node:events";
+import type { IncomingMessage, ServerResponse } from "node:http";
+import type { Connect, Plugin, PreviewServer, ViteDevServer } from "vite";
+import { describe, expect, it, vi } from "vitest";
+import { applyViteNetworkPolicy, devNetworkGuard } from "./vite-network-guard";
+
+const policy = {
+  allowedHosts: new Set(["localhost", "127.0.0.1", "::1", "node.ts.net", "100.64.0.10"]),
+  allowedAddresses: new Set(["127.0.0.1", "::1", "100.64.0.10"]),
+};
+
+function install(mode: "dev" | "preview") {
+  let middleware: Connect.NextHandleFunction | undefined;
+  const http = new EventEmitter();
+  const upgrade = vi.fn();
+  http.on("upgrade", upgrade);
+  const server = {
+    middlewares: {
+      use: (handler: Connect.NextHandleFunction) => {
+        middleware = handler;
+      },
+    },
+    httpServer: http,
+  };
+  const plugin = devNetworkGuard(policy);
+  const hook = mode === "dev" ? plugin.configureServer : plugin.configurePreviewServer;
+  if (typeof hook !== "function") throw new Error(`Missing ${mode} guard hook`);
+  // Hooks only need the injected middleware stack and HTTP event emitter.
+  hook.call({} as never, server as unknown as ViteDevServer & PreviewServer);
+  if (!middleware) throw new Error(`Missing ${mode} middleware`);
+  return { middleware, http, upgrade };
+}
+
+function request(localAddress: string | undefined, host?: string, origin?: string) {
+  return { socket: { localAddress }, headers: { host, origin } } as IncomingMessage;
+}
+
+const cases = [
+  ["loopback", "127.0.0.1", "localhost", undefined, 200],
+  ["IPv6 loopback", "::1", "[::1]:34204", undefined, 200],
+  ["mapped address / canonical Host", "::ffff:127.0.0.1", "LOCALHOST.:34204", undefined, 200],
+  ["tailnet", "100.64.0.10", "node.ts.net", "https://node.ts.net:34204", 200],
+  ["unselected interface with trusted Host", "172.17.0.1", "localhost", undefined, 403],
+  ["missing interface", undefined, "localhost", undefined, 403],
+  ["arbitrary IP Host", "127.0.0.1", "127.0.0.2", undefined, 421],
+  ["rebinding Host", "127.0.0.1", "evil.example", undefined, 421],
+  ["missing Host", "127.0.0.1", undefined, undefined, 421],
+  ["disallowed Origin", "127.0.0.1", "localhost", "https://evil.example", 403],
+  ["opaque Origin", "127.0.0.1", "localhost", "null", 403],
+  ["Host before Origin", "127.0.0.1", "evil.example", "null", 421],
+] as const;
+
+describe.each(["dev", "preview"] as const)("%s HTTP guard", (mode) => {
+  it.each(cases)("%s", (_label, local, host, origin, status) => {
+    const { middleware } = install(mode);
+    const req = request(local, host, origin);
+    const writeHead = vi.fn();
+    const end = vi.fn();
+    const next = vi.fn();
+    middleware(req, { writeHead, end } as unknown as ServerResponse, next);
+    if (status === 200) {
+      expect(next).toHaveBeenCalledExactlyOnceWith();
+      expect(writeHead).not.toHaveBeenCalled();
+      if (host === "LOCALHOST.:34204") expect(req.headers.host).toBe("localhost:34204");
+    } else {
+      expect(writeHead).toHaveBeenCalledWith(status, { "Content-Type": "text/plain" });
+      expect(end).toHaveBeenCalledOnce();
+      expect(next).not.toHaveBeenCalled(); // In particular, cannot reach CORS/static serving.
+    }
+  });
+});
+
+describe("dev upgrades remain protected", () => {
+  it.each(cases)("%s", (_label, local, host, origin, status) => {
+    const { http, upgrade } = install("dev");
+    const end = vi.fn();
+    http.emit("upgrade", request(local, host, origin), { end }, Buffer.alloc(0));
+    if (status === 200) {
+      expect(upgrade).toHaveBeenCalledOnce();
+      expect(end).not.toHaveBeenCalled();
+    } else {
+      expect(upgrade).not.toHaveBeenCalled();
+      expect(end).toHaveBeenCalledWith(expect.stringContaining(`HTTP/1.1 ${status}`));
+    }
+  });
+});
+
+it("sets explicit allowlists and guarded CORS for preview as well as dev", () => {
+  const config = applyViteNetworkPolicy(
+    {
+      server: { host: true, port: 34204 },
+      preview: { host: true, port: 34204, cors: true, allowedHosts: true },
+    },
+    policy,
+  );
+  for (const serving of [config.server, config.preview]) {
+    expect(serving?.allowedHosts).toEqual([...policy.allowedHosts]);
+    expect(serving?.cors).toEqual({ origin: true });
+    expect(serving?.host).toBe(true);
+    expect(serving?.port).toBe(34204);
+  }
+  const plugin = config.plugins?.[0] as Plugin;
+  expect(plugin.configureServer).toBeTypeOf("function");
+  expect(plugin.configurePreviewServer).toBeTypeOf("function");
+});