Change domain blocks to automatically support subdomains (#11138)

* Change domain blocks to automatically support subdomains

If a more authoritative domain is blocked (example.com), then the
same block will be applied to a subdomain (foo.example.com)

* Match subdomains of existing accounts when blocking/unblocking domains

* Improve code style

4 files changed, 33 insertions, 4 deletions

diff --git a/app/models/account.rb b/app/models/account.rb
index 9276aa927..c588451fc 100644
--- a/app/models/account.rb
+++ b/app/models/account.rb
@@ -98,6 +98,7 @@ class Account < ApplicationRecord
   scope :tagged_with, ->(tag) { joins(:accounts_tags).where(accounts_tags: { tag_id: tag }) }
   scope :by_recent_status, -> { order(Arel.sql('(case when account_stats.last_status_at is null then 1 else 0 end) asc, account_stats.last_status_at desc')) }
   scope :popular, -> { order('account_stats.followers_count desc') }
+  scope :by_domain_and_subdomains, ->(domain) { where(domain: domain).or(where(arel_table[:domain].matches('%.' + domain))) }
 
   delegate :email,
            :unconfirmed_email,
diff --git a/app/models/custom_emoji.rb b/app/models/custom_emoji.rb
index d3cc70504..e73cd9bd2 100644
--- a/app/models/custom_emoji.rb
+++ b/app/models/custom_emoji.rb
@@ -39,6 +39,7 @@ class CustomEmoji < ApplicationRecord
   scope :local,      -> { where(domain: nil) }
   scope :remote,     -> { where.not(domain: nil) }
   scope :alphabetic, -> { order(domain: :asc, shortcode: :asc) }
+  scope :by_domain_and_subdomains, ->(domain) { where(domain: domain).or(where(arel_table[:domain].matches('%.' + domain))) }
 
   remotable_attachment :image, LIMIT
 
diff --git a/app/models/domain_block.rb b/app/models/domain_block.rb
index 84c08c158..25d3b87ef 100644
--- a/app/models/domain_block.rb
+++ b/app/models/domain_block.rb
@@ -24,14 +24,41 @@ class DomainBlock < ApplicationRecord
 
   scope :matches_domain, ->(value) { where(arel_table[:domain].matches("%#{value}%")) }
 
-  def self.blocked?(domain)
-    where(domain: domain, severity: :suspend).exists?
+  class << self
+    def suspend?(domain)
+      !!rule_for(domain)&.suspend?
+    end
+
+    def silence?(domain)
+      !!rule_for(domain)&.silence?
+    end
+
+    def reject_media?(domain)
+      !!rule_for(domain)&.reject_media?
+    end
+
+    def reject_reports?(domain)
+      !!rule_for(domain)&.reject_reports?
+    end
+
+    alias blocked? suspend?
+
+    def rule_for(domain)
+      return if domain.blank?
+
+      uri      = Addressable::URI.new.tap { |u| u.host = domain.gsub(/[\/]/, '') }
+      segments = uri.normalized_host.split('.')
+      variants = segments.map.with_index { |_, i| segments[i..-1].join('.') }
+
+      where(domain: variants[0..-2]).order(Arel.sql('char_length(domain) desc')).first
+    end
   end
 
   def stricter_than?(other_block)
-    return true if suspend?
+    return true  if suspend?
     return false if other_block.suspend? && (silence? || noop?)
     return false if other_block.silence? && noop?
+
     (reject_media || !other_block.reject_media) && (reject_reports || !other_block.reject_reports)
   end
 
diff --git a/app/models/instance.rb b/app/models/instance.rb
index 7bf000d40..a01db1212 100644
--- a/app/models/instance.rb
+++ b/app/models/instance.rb
@@ -8,7 +8,7 @@ class Instance
   def initialize(resource)
     @domain         = resource.domain
     @accounts_count = resource.is_a?(DomainBlock) ? nil : resource.accounts_count
-    @domain_block   = resource.is_a?(DomainBlock) ? resource : DomainBlock.find_by(domain: domain)
+    @domain_block   = resource.is_a?(DomainBlock) ? resource : DomainBlock.rule_for(domain)
   end
 
   def cached_sample_accounts