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

1 files changed, 74 insertions, 0 deletions

diff --git a/scripts/vite-network-guard.ts b/scripts/vite-network-guard.ts
new file mode 100644
index 0000000..7fe9eca
--- /dev/null
+++ b/scripts/vite-network-guard.ts
@@ -0,0 +1,74 @@
+import type { IncomingMessage } from "node:http";
+import type { Plugin, UserConfig } from "vite";
+import { checkDevRequest, type DevNetworkPolicy, normalizeHostHeader } from "./network-policy";
+
+/** Explicitly protect BOTH serving modes; preview must not inherit permissive CORS alone. */
+export function applyViteNetworkPolicy(config: UserConfig, network: DevNetworkPolicy): UserConfig {
+  return {
+    ...config,
+    plugins: [devNetworkGuard(network), ...(config.plugins ?? [])],
+    server: {
+      ...config.server,
+      allowedHosts: [...network.allowedHosts],
+      // Safe reflection only after our pre-middleware validates the Origin.
+      cors: { origin: true },
+    },
+    preview: {
+      ...config.preview,
+      allowedHosts: [...network.allowedHosts],
+      cors: { origin: true },
+    },
+  };
+}
+
+export function devNetworkGuard(policy: DevNetworkPolicy): Plugin {
+  const check = (req: IncomingMessage) =>
+    checkDevRequest(
+      {
+        localAddress: req.socket.localAddress,
+        host: req.headers.host,
+        origin: req.headers.origin,
+      },
+      policy,
+    );
+  // Installed before Vite's CORS, host check and static-file middleware in
+  // either mode. No post-hook: even preflights and error responses are guarded.
+  const middleware: import("vite").Connect.NextHandleFunction = (req, res, next) => {
+    const decision = check(req);
+    if (decision !== "ok") {
+      res.writeHead(decision.status, { "Content-Type": "text/plain" });
+      res.end(decision.reason);
+      return;
+    }
+    req.headers.host = normalizeHostHeader(req.headers.host ?? "");
+    next();
+  };
+  return {
+    name: "dispatch-dev-network-guard",
+    enforce: "pre",
+    configurePreviewServer(server) {
+      server.middlewares.use(middleware);
+    },
+    configureServer(server) {
+      server.middlewares.use(middleware);
+      // Vite registers HMR before configureServer. Wrap (rather than prepend to)
+      // its listeners: EventEmitter otherwise continues into HMR after a denial.
+      const http = server.httpServer;
+      if (http) {
+        const upgrades = http.listeners("upgrade");
+        http.removeAllListeners("upgrade");
+        http.on("upgrade", (req, socket, head) => {
+          const decision = check(req);
+          if (decision !== "ok") {
+            socket.end(
+              `HTTP/1.1 ${decision.status} ${decision.status === 421 ? "Misdirected Request" : "Forbidden"}\r\nConnection: close\r\nContent-Length: 0\r\n\r\n`,
+            );
+            return;
+          }
+          req.headers.host = normalizeHostHeader(req.headers.host ?? "");
+          for (const upgrade of upgrades) upgrade.call(http, req, socket, head);
+        });
+      }
+    },
+  };
+}