Webhook Implementation

import express from "express";
import crypto from "crypto";

const app = express();

// Raw body is required for signature verification
app.post(
  "/webhooks/nudj",
  express.raw({ type: "application/json" }),
  (req, res) => {
    const signature = (req.headers["x-nudj-signature"] || "").replace(
      "sha256=",
      ""
    );
    const expected = crypto
      .createHmac("sha256", process.env.NUDJ_WEBHOOK_SECRET)
      .update(req.body)
      .digest("hex");

    if (
      signature.length !== expected.length ||
      !crypto.timingSafeEqual(
        Buffer.from(signature, "hex"),
        Buffer.from(expected, "hex")
      )
    ) {
      return res.status(401).send("invalid signature");
    }

    const event = JSON.parse(req.body.toString("utf8"));
    // process event here, ideally async via a queue
    res.status(200).send("ok");
  }
);

from flask import Flask, request, abort
import hmac, hashlib, os

app = Flask(__name__)

@app.post("/webhooks/nudj")
def handle_nudj_webhook():
    raw = request.get_data()
    signature = request.headers.get("X-Nudj-Signature", "").removeprefix("sha256=")
    expected = hmac.new(
        os.environ["NUDJ_WEBHOOK_SECRET"].encode(),
        raw,
        hashlib.sha256,
    ).hexdigest()
    if not hmac.compare_digest(signature, expected):
        abort(401)
    # process JSON payload (request.get_json() is safe after signature passes)
    return ("ok", 200)