Ticket/17904

[petitphp]

This PR implement changes proposed in ticket 17904#comment:64

The goal is to align how single and multisite check the validity of a username.

Changes in PR :

• Update validate_username() to include all restrictions from multisite,
• Introduce new function is_username_reserved(), this function performs the wp_signups query for existing username that was previously done in wpmu_validate_user_signup(),
• Introduce new function wp_validate_user_login(), that acts as a wrapper calling validate_username(), username_exists() and is_username_reserved(),
• Update codebase to use the new wp_validate_user_login() where applicable and remove code that was merge in validate_username(),
• Update User REST endpoint following the refactoring of validate_username(),
• Update wpmu_validate_blog_signup() to allow dashes in blogname.

Changes not in PR :

• Change username_exists() to accept a second parameter $check_reserved = true, this seem like a tricky change to me. Currently the function will return either a user id matching the username or false. Returning a true when the username is reserved could break other code casting the return of username_exists() to int.

Trac ticket: https://core.trac.wordpress.org/ticket/17904

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[audrasjb]

Thanks for the PR, I added a commit to fix a WPCS issue. It replaces current_time() with time(), as per WordPress Coding Standards.

[petitphp]

@dream-encode Thanks for taking the time to look at the PR. I've applied all your suggestions.

[github-actions[bot]]

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Props petitphp, audrasjb, davidbaumwald, peterwilsoncc, rajinsharwar.

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[github-actions[bot]]

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