node http client 使用自定义lookup

const http = require('http'); // 换成https同样适用
const dns = require('dns');
function customlookup(hostname, options, callback) {
  if (typeof options === 'function') {
    callback = options;
    options = null;
  }
  // todo: check `options` for options like `all` and `family`
  if (hostname.toLowerCase() === 'www.sample.com') { // 动态绑定IP:www.sample.com=>127.0.0.1
      const host = {
          address: '127.0.0.1', 
          family: 4 // or 6 (IPV6)
      }
      return callback(null, host.address, host.family);
  }
  return dns.lookup(hostname, options, callback);
}

http.get({
  hostname: 'www.sample.com', 
  lookup: customlookup
}, (res) => {
  console.log(`STATUS: ${res.statusCode}`);
  console.log(`HEADERS: ${JSON.stringify(res.headers)}`);
  res.setEncoding('utf8');
  res.on('data', (chunk) => {
    console.log(`BODY: ${chunk}`);
  });
  res.on('end', () => {

  });
});