Code Examples

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const express = require("express");
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const crypto = require("crypto");
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const app = express();
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const SIGNING_SECRET = process.env.VOICEBIP_SIGNING_SECRET;
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// Parse raw body for HMAC verification
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app.use(express.json({
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  verify: (req, _res, buf) => { req.rawBody = buf; }
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}));
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function verifySignature(req) {
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  const signature = req.headers["x-voicebip-signature"];
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  const timestamp = req.headers["x-voicebip-timestamp"];
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  if (!signature || !timestamp) return false;
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  // Reject replays older than 5 minutes
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  if (Math.abs(Date.now() / 1000 - parseInt(timestamp, 10)) > 300) return false;
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  // Signed payload is "{timestamp}.{body}"
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  const signedPayload = Buffer.concat([
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    Buffer.from(timestamp + "."),
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    req.rawBody,
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  ]);
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  const expected = "sha256=" + crypto
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    .createHmac("sha256", SIGNING_SECRET)
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    .update(signedPayload)
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    .digest("hex");
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  return crypto.timingSafeEqual(
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    Buffer.from(expected),
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    Buffer.from(signature)
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  );
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}
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app.post("/webhook", (req, res) => {
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  if (!verifySignature(req)) {
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    return res.status(401).json({ error: "Invalid signature" });
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  }
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  const { event_id, event_type, payload } = req.body;
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  // Deduplicate using event_id (idempotency)
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  // In production, check event_id against a cache or database
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  if (event_type === "call.transcription") {
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    const transcript = payload.text;
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    console.log(`[${event_id}] Caller said: ${transcript}`);
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    return res.json({
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      text: `You said: ${transcript}. How can I help you today?`,
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      end_call: false,
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    });
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  }
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  res.json({ status: "ok" });
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});
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app.listen(3000, () => console.log("Webhook handler listening on port 3000"));

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const express = require("express");
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const crypto = require("crypto");
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const OpenAI = require("openai");
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const app = express();
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const SIGNING_SECRET = process.env.VOICEBIP_SIGNING_SECRET;
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const openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });
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app.use(express.json({
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  verify: (req, _res, buf) => { req.rawBody = buf; }
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}));
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function verifySignature(req) {
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  const signature = req.headers["x-voicebip-signature"];
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  const timestamp = req.headers["x-voicebip-timestamp"];
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  if (!signature || !timestamp) return false;
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  // Reject replays older than 5 minutes
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  if (Math.abs(Date.now() / 1000 - parseInt(timestamp, 10)) > 300) return false;
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  // Signed payload is "{timestamp}.{body}"
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  const signedPayload = Buffer.concat([
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    Buffer.from(timestamp + "."),
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    req.rawBody,
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  ]);
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  const expected = "sha256=" + crypto
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    .createHmac("sha256", SIGNING_SECRET)
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    .update(signedPayload)
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    .digest("hex");
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  return crypto.timingSafeEqual(
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    Buffer.from(expected),
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    Buffer.from(signature)
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  );
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}
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app.post("/webhook", async (req, res) => {
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  if (!verifySignature(req)) {
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    return res.status(401).json({ error: "Invalid signature" });
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  }
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  const { event_type, payload } = req.body;
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  if (event_type === "call.transcription") {
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    // Build messages from conversation_history (last 20 turns included by Voicebip)
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    const messages = [
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      {
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        role: "system",
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        content:
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          "You are a helpful Nigerian customer support agent for Voicebip. " +
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          "Be concise — the caller is on a voice call. Keep responses under 2 sentences.",
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      },
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    ];
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    if (payload.conversation_history) {
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      for (const turn of payload.conversation_history) {
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        messages.push({
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          role: turn.role === "caller" ? "user" : "assistant",
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          content: turn.text,
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        });
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      }
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    }
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    // Add the current transcription
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    messages.push({ role: "user", content: payload.text });
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    const completion = await openai.chat.completions.create({
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      model: "gpt-4o",
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      messages,
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      max_tokens: 150,
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      temperature: 0.7,
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    });
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    const reply = completion.choices[0].message.content;
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    return res.json({
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      text: reply,
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      end_call: false,
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    });
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  }
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  res.json({ status: "ok" });
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});
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app.listen(3000, () => console.log("OpenAI webhook handler on port 3000"));