Fix Discord interactions endpoint with proper raw body handling

cgen-3347352060874ae89711ff38495e64ab

api/discord/interactions.ts

@@ -1,10 +1,31 @@
 import { VercelRequest, VercelResponse } from "@vercel/node";
 import { createVerify } from "crypto";
 
+export const config = {
+  api: {
+    bodyParser: {
+      raw: {
+        type: "application/json",
+      },
+    },
+  },
+};
+
 export default function handler(req: VercelRequest, res: VercelResponse) {
-  // Only accept POST requests
+  // Set CORS headers for Discord
+  res.setHeader("Access-Control-Allow-Origin", "*");
+  res.setHeader("Access-Control-Allow-Methods", "POST, OPTIONS");
+  res.setHeader(
+    "Access-Control-Allow-Headers",
+    "Content-Type, x-signature-ed25519, x-signature-timestamp"
+  );
+
+  if (req.method === "OPTIONS") {
+    return res.status(200).end();
+  }
+
   if (req.method !== "POST") {
-    res.setHeader("Allow", "POST");
+    res.setHeader("Allow", "POST, OPTIONS");
     return res.status(405).json({ error: "Method not allowed" });
   }
 
@@ -13,29 +34,33 @@ export default function handler(req: VercelRequest, res: VercelResponse) {
     const timestamp = req.headers["x-signature-timestamp"] as string;
     const publicKey = process.env.DISCORD_PUBLIC_KEY;
 
-    console.log("[Discord] Interaction received at", new Date().toISOString());
+    console.log("[Discord] Interaction received");
+    console.log("[Discord] Has signature:", !!signature);
+    console.log("[Discord] Has timestamp:", !!timestamp);
+    console.log("[Discord] Has public key:", !!publicKey);
 
     if (!publicKey) {
       console.error("[Discord] DISCORD_PUBLIC_KEY not set");
-      return res.status(401).json({ error: "Server not configured" });
+      return res.status(500).json({ error: "Server not configured" });
     }
 
     if (!signature || !timestamp) {
-      console.error(
-        "[Discord] Missing headers - signature:",
-        !!signature,
-        "timestamp:",
-        !!timestamp,
-      );
+      console.error("[Discord] Missing required headers");
       return res.status(401).json({ error: "Invalid request" });
     }
 
-    // Get raw body
+    // Get raw body - Vercel sends it as Buffer with raw: true config
     const rawBody =
-      typeof req.body === "string" ? req.body : JSON.stringify(req.body);
+      req.body instanceof Buffer
+        ? req.body.toString("utf8")
+        : typeof req.body === "string"
+          ? req.body
+          : JSON.stringify(req.body);
 
     // Verify signature
     const message = `${timestamp}${rawBody}`;
+    console.log("[Discord] Verifying signature for message length:", message.length);
+
     const signatureBuffer = Buffer.from(signature, "hex");
     const verifier = createVerify("ed25519");
     verifier.update(message);
@@ -46,23 +71,31 @@ export default function handler(req: VercelRequest, res: VercelResponse) {
       return res.status(401).json({ error: "Invalid signature" });
     }
 
-    const interaction =
-      typeof req.body === "string" ? JSON.parse(req.body) : req.body;
-    console.log("[Discord] Valid interaction type:", interaction.type);
+    console.log("[Discord] Signature verified successfully");
+
+    let interaction;
+    try {
+      interaction = typeof rawBody === "string" ? JSON.parse(rawBody) : rawBody;
+    } catch {
+      console.error("[Discord] Failed to parse JSON body");
+      return res.status(400).json({ error: "Invalid JSON" });
+    }
+
+    console.log("[Discord] Interaction type:", interaction?.type);
 
     // Discord sends a PING to verify the endpoint
-    if (interaction.type === 1) {
+    if (interaction?.type === 1) {
       console.log("[Discord] ✓ PING verified");
-      return res.json({ type: 1 });
+      return res.status(200).json({ type: 1 });
     }
 
     // For all other interactions, acknowledge them
-    return res.json({
+    return res.status(200).json({
       type: 4,
       data: { content: "Interaction received" },
     });
   } catch (err: any) {
-    console.error("[Discord] Error:", err?.message);
+    console.error("[Discord] Error:", err?.message, err?.stack);
     return res.status(500).json({ error: "Server error" });
   }
 }