fix: Harden docs security endpoints

apps/docs/app/actions/feedback/index.ts

@@ -3,38 +3,139 @@
 import { headers } from "next/headers";
 import type { Feedback } from "@/components/geistdocs/feedback";
 import { siteId } from "@/geistdocs";
+import { checkRateLimit } from "@/lib/rate-limit";
+import { getClientIp } from "@/lib/request-ip";
 import { emotions } from "./emotions";
 
 const protocol = process.env.NODE_ENV === "production" ? "https" : "http";
-const baseUrl = `${protocol}://${process.env.NEXT_PUBLIC_VERCEL_PROJECT_PRODUCTION_URL}`;
+const MAX_FEEDBACK_MESSAGE_LENGTH = 2000;
+const MAX_FEEDBACK_URL_LENGTH = 2048;
+const FEEDBACK_RATE_LIMIT = {
+  limit: 5,
+  windowSeconds: 60
+} as const;
+
+type HeaderList = Awaited<ReturnType<typeof headers>>;
+
+function getBaseUrl(headersList: HeaderList): URL | null {
+  const productionUrl = process.env.NEXT_PUBLIC_VERCEL_PROJECT_PRODUCTION_URL;
+
+  if (productionUrl) {
+    try {
+      return new URL(
+        productionUrl.startsWith("http")
+          ? productionUrl
+          : `${protocol}://${productionUrl}`
+      );
+    } catch {
+      return null;
+    }
+  }
+
+  if (process.env.VERCEL_ENV === "production") {
+    return null;
+  }
+
+  const host = headersList.get("host");
+  if (!host) {
+    return null;
+  }
+
+  const forwardedProto = headersList
+    .get("x-forwarded-proto")
+    ?.split(",")
+    .at(0)
+    ?.trim();
+  const requestProtocol =
+    forwardedProto === "http" || forwardedProto === "https"
+      ? forwardedProto
+      : protocol;
+
+  return new URL(`${requestProtocol}://${host}`);
+}
+
+function getValidatedFeedbackUrl(url: string, baseUrl: URL): string | null {
+  if (url.length > MAX_FEEDBACK_URL_LENGTH) {
+    return null;
+  }
+
+  try {
+    const feedbackUrl = new URL(url, baseUrl);
+
+    if (feedbackUrl.origin !== baseUrl.origin) {
+      return null;
+    }
+
+    return feedbackUrl.toString();
+  } catch {
+    return null;
+  }
+}
 
 export const sendFeedback = async (
   url: string,
   feedback: Feedback
 ): Promise<{ success: boolean }> => {
-  const emoji = emotions.find((e) => e.name === feedback.emotion)?.emoji;
-  const endpoint = new URL("/feedback", "https://geistdocs.com/feedback");
   const headersList = await headers();
+  const baseUrl = getBaseUrl(headersList);
+  const feedbackUrl =
+    baseUrl && typeof url === "string"
+      ? getValidatedFeedbackUrl(url, baseUrl)
+      : null;
+  const candidateFeedback = feedback as Partial<Feedback> | null | undefined;
 
-  const response = await fetch(endpoint, {
-    method: "POST",
-    headers: {
-      "Content-Type": "application/json"
-    },
-    body: JSON.stringify({
-      note: feedback.message,
-      url: new URL(url, baseUrl).toString(),
-      emotion: emoji,
-      ua: headersList.get("user-agent") ?? undefined,
-      ip: headersList.get("x-real-ip") || headersList.get("x-forwarded-for"),
-      label: siteId
-    })
+  if (
+    !candidateFeedback ||
+    typeof candidateFeedback.message !== "string" ||
+    typeof candidateFeedback.emotion !== "string"
+  ) {
+    return { success: false };
+  }
+
+  const emoji = emotions.find((e) => e.name === candidateFeedback.emotion)
+    ?.emoji;
+  const message = candidateFeedback.message.trim();
+
+  if (
+    !feedbackUrl ||
+    !emoji ||
+    message.length === 0 ||
+    message.length > MAX_FEEDBACK_MESSAGE_LENGTH
+  ) {
+    return { success: false };
+  }
+
+  const rateLimit = await checkRateLimit({
+    namespace: "feedback",
+    key: getClientIp(headersList),
+    ...FEEDBACK_RATE_LIMIT
   });
 
-  if (!response.ok) {
-    const error = await response.json();
+  if (!rateLimit.success) {
+    return { success: false };
+  }
+
+  try {
+    const response = await fetch("https://geistdocs.com/feedback", {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json"
+      },
+      body: JSON.stringify({
+        note: message,
+        url: feedbackUrl,
+        emotion: emoji,
+        label: siteId
+      })
+    });
+
+    if (!response.ok) {
+      console.error("Feedback request failed:", response.status);
 
-    console.error(error);
+      return { success: false };
+    }
+  } catch (error) {
+    console.error("Feedback request failed:", error);
 
     return { success: false };
   }