screenshot-tools/middleware/cors.js

const { allowedOrigins } = require('../config/config');

/**
 * CORS and Security middleware
 * Only allows requests from whitelisted domains
 */
function corsMiddleware(req, res, next) {
  const origin = req.headers.origin;
  const referer = req.headers.referer;
  
  // Check if origin is allowed
  const isOriginAllowed = origin && allowedOrigins.indexOf(origin) > -1;
  
  // Check if referer matches allowed domains
  const isRefererAllowed = referer && allowedOrigins.some(allowed => {
    try {
      const refererHost = new URL(referer).origin;
      return refererHost === allowed || referer.startsWith(allowed);
    } catch (e) {
      return false;
    }
  });
  
  // Allow if origin OR referer is whitelisted
  // Also allow health check endpoint without restrictions
  if (req.path === '/health') {
    return next();
  }
  
  if (!isOriginAllowed && !isRefererAllowed) {
    console.warn(`Blocked request from Origin: ${origin || 'none'}, Referer: ${referer || 'none'}`);
    return res.status(403).json({ 
      error: 'Forbidden', 
      message: 'Access denied. This API is restricted to authorized domains only.' 
    });
  }
  
  // Set CORS headers for allowed origin
  if (isOriginAllowed) {
    res.setHeader('Access-Control-Allow-Origin', origin);
  }
  
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
  res.setHeader('Access-Control-Allow-Credentials', true);
  
  // Handle preflight requests
  if (req.method === 'OPTIONS') {
    return res.status(200).end();
  }
  
  next();
}

module.exports = corsMiddleware;