id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc
21142	Add a filter to domain_exists() function	jamescollins	ryan	"In Multisite, the domain_exists() function is used by WordPress to ""check whether the specified blogname is already taken"", however it doesn't provide any filter so that plugins can override the result.

'''Our Use Case:'''

On our multisite installs, we allow users to change their subdomain name (or domain name).

We keep a list of their previously used subdomains/domains, and if there is a HTTP request for one of their old domains, we automatically perform a 301 redirect to the new domain name.

However, we also want to make sure that other users cannot use any subdomain/domain name that has been used by another user.

Currently we have no way to override the return value of the domain_exists() function, which means we can't easily prevent other people from signing up for sites that use a domain/subdomain name 

'''Suggestion:'''

Add a simple filter to the end of the domain_exists() function. See attached patch."	enhancement	closed	normal	3.5	Multisite		normal	fixed	has-patch commit