I have a NodeJS express service running on Centos and listens to GET requests and I need to identify the IP of the user.

Currently, I'm using this script

ip = req.headers['x-forwarded-for'] ||
      req.connection.remoteAddress ||
      req.socket.remoteAddress ||
      req.connection.socket.remoteAddress

The problem is that sometimes the IP returned is IPv4 and sometimes it is IPv6. Is there a way to get only IPv4 IPs?