Store service: Node.js native ingress

node --check stores/relay.mjs
node stores/relay.mjs

#!/usr/bin/env node
// Optional Node18+ native HTTP ingress for the complete PHP store service.
// This is NOT a pure Node payment worker: service.php authenticates and commits.
// Set KDP_STORE_SERVICE_URL (HTTPS /provider-event), KDP_STORE_RELAY_PORT (8118).
// Run: node relay.mjs. Expected: only verified durable upstream receipts return202.
import http from 'node:http';

const target = new URL(process.env.KDP_STORE_SERVICE_URL ?? '');
const loopback = process.env.KDP_STORE_ENVIRONMENT === 'sandbox' && process.env.KDP_STORE_ALLOW_LOOPBACK === '1' && target.hostname === '127.0.0.1' && target.protocol === 'http:';
if ((target.protocol !== 'https:' && !loopback) || target.username || target.password || target.search || target.hash || target.pathname !== '/provider-event') throw new Error('Private service URL required');
const allowed = new Set(['content-type', 'stripe-signature', 'paddle-signature', 'x-signature', 'x-wc-webhook-signature', 'x-wc-webhook-topic', 'x-shopify-hmac-sha256', 'x-shopify-topic', 'x-shopify-shop-domain', 'x-shopify-webhook-id', 'x-fs-signature', 'paypal-auth-algo', 'paypal-cert-url', 'paypal-transmission-id', 'paypal-transmission-sig', 'paypal-transmission-time']);
const reply = (response, status, body) => { response.writeHead(status, { 'Content-Type': 'application/json', 'Cache-Control': 'no-store', 'X-Content-Type-Options': 'nosniff', Connection: 'close' }); response.end(body); };
const server = http.createServer((request, response) => {
  if (request.method !== 'POST' || request.url !== '/provider-event') return reply(response, 404, '{"accepted":false}');
  if (!/^\d+$/.test(request.headers['content-length'] ?? '') || request.headers['transfer-encoding']) return reply(response, 400, '{"accepted":false}');
  if (Number(request.headers['content-length']) > 262144) return reply(response, 413, '{"accepted":false}');
  const headers = {}, seen = new Set();
  for (let i = 0; i < request.rawHeaders.length; i += 2) {
    const name = request.rawHeaders[i].toLowerCase();
    if (!allowed.has(name)) continue;
    if (seen.has(name)) return reply(response, 401, '{"accepted":false}');
    seen.add(name); headers[name] = request.rawHeaders[i + 1];
  }
  const chunks = []; let length = 0;
  request.on('data', chunk => { length += chunk.length; if (length <= 262144) chunks.push(chunk); });
  request.on('error', () => response.destroy());
  request.on('end', async () => {
    if (length !== Number(request.headers['content-length']) || length > 262144) return reply(response, 400, '{"accepted":false}');
    try {
      const upstream = await fetch(target, { method: 'POST', headers, body: Buffer.concat(chunks), redirect: 'manual', signal: AbortSignal.timeout(12000) });
      // Bound allocation while reading, not only after an arbitrarily large body.
      const reader = upstream.body?.getReader();
      if (!reader) throw new Error('Missing receipt');
      const parts = []; let received = 0;
      try {
        while (true) {
          const { done, value } = await reader.read();
          if (done) break;
          received += value.byteLength;
          if (received > 4096) { await reader.cancel(); throw new Error('Invalid receipt'); }
          parts.push(Buffer.from(value));
        }
      } finally { reader.releaseLock(); }
      const bytes = Buffer.concat(parts, received);
      const receipt = JSON.parse(bytes.toString('utf8'));
      if (upstream.status === 202 && receipt.accepted === true && typeof receipt.duplicate === 'boolean') return reply(response, 202, JSON.stringify({ accepted: true, duplicate: receipt.duplicate }));
      return reply(response, [400, 401, 409, 413, 415, 429].includes(upstream.status) ? upstream.status : 503, '{"accepted":false}');
    } catch { return reply(response, 503, '{"accepted":false}'); }
  });
});
server.requestTimeout = 5000; server.headersTimeout = 5000; server.keepAliveTimeout = 1000;
server.listen(Number(process.env.KDP_STORE_RELAY_PORT ?? 8118), '127.0.0.1', () => console.log('{"listening":true,"loopback_only":true}'));