gitlab-org--gitlab-foss/lib/constraints/project_url_constrainer.rb

class ProjectUrlConstrainer
  def matches?(request)
    namespace_path = request.params[:namespace_id]
    project_path = request.params[:project_id] || request.params[:id]
    full_path = [namespace_path, project_path].join('/')

    return false unless DynamicPathValidator.valid_project_path?(full_path)

    Project.find_by_full_path(full_path, follow_redirects: request.get?).present?
  end
end