Option for including a IP Database?

Problem/Motivation

The original request was to restrict access by country using an IP database such as MaxMind, because entering every range for a country by hand is not practical.

Rather than integrating any particular database, this module should provide an extension point so other modules can supply or adjust IP ranges from whatever source they like: settings.php, an external list, or a country database.

Proposed resolution

Add hook_restrict_by_ip_ranges_alter(), plus type-specific variants, letting modules alter each allow list before it is applied:

• the global login ranges,
• each user's ranges,
• each role's ranges, including roles with no ranges configured.

The allow/deny decision itself stays in this module: after altering, an empty list means the context is unrestricted, and a non-empty list means the request IP must match one of the ranges.

Country-level restriction is possible by implementing the hook in a module that maintains country ranges from an IP database. A point-lookup integration (querying a geo service per request) is out of scope here and better suited to a dedicated module.

API changes

New hooks: hook_restrict_by_ip_ranges_alter(), hook_restrict_by_ip_login_global_ranges_alter(), hook_restrict_by_ip_login_user_ranges_alter(), hook_restrict_by_ip_role_ranges_alter(). Documented in restrict_by_ip.api.php.