Need iRule to allow cross-domain requests

Hello everyone. I am new to BigIP and iRules, and am looking for an iRule for something that seems relatively simple.

 

 

Per the blog post here https://devcentral.f5.com/weblogs/m...pting.aspx I would like to use access-control-allow-origin in an iRule to allow domain1.com, domain2.com, and domain3.com to access services on domain4.com sitting behind my BigIP v10.2.3 F5 appliance.