Use Domain Access: https://www.drupal.org/project/domain

Core Drupal + Domain Access can do this, you don't need any code or custom modules. Your Drupal can load different content on each configured domain name. 

 1. Point all domains in Apache/Nginx at the same Drupal install
    directory.
 2. Install Drupal using your primary domain.
 3. Create your Landing Page nodes using the default Page Content Type.
 4. Install Domain Access.
 5. Add a new Domain at: http://example.com/admin/structure/domain/create
 6. Edit the Domain settings at: http://example.com/admin/structure/domain/view/:id/config and specify the *Site frontpage*.
 7. Done.

If you want it in code, you can export the entire configuration with the Features module: https://www.drupal.org/project/features