Node.jsでの接続元IPアドレス取得

getIP.js

var getIP = function (req) {
  if (req.headers['x-forwarded-for']) {
    return req.headers['x-forwarded-for'];
  }
  if (req.connection && req.connection.remoteAddress) {
    return req.connection.remoteAddress;
  }
  if (req.connection.socket && req.connection.socket.remoteAddress) {
    return req.connection.socket.remoteAddress;
  }
  if (req.socket && req.socket.remoteAddress) {
    return req.socket.remoteAddress;
  }
  return '0.0.0.0';
};