Add new IP address search page.

Add a new IP address search page at /ip_addresses. Replaces the old
search page at /moderator/ip_addrs.

On user profile pages, show the user's last known IP to mods. Also add
search links for finding other IPs or accounts associated with the user.

IP address search uses a big UNION ALL statement to merge IP addresses
across various tables into a single view. This makes searching easier,
but is known to timeout in certain cases.

Fixes #4207 (the new IP search page supports searching by subnet).

app/models/application_record.rb

@@ -50,6 +50,11 @@ class ApplicationRecord < ActiveRecord::Base
         where.not("#{qualified_column_for(attr)} ~ ?", "(?e)" + value)
       end
 
+      def where_inet_matches(attr, value)
+        ip = IPAddress.parse(value)
+        where("#{qualified_column_for(attr)} <<= ?", ip.to_string)
+      end
+
       def where_array_includes_any(attr, values)
         where("#{qualified_column_for(attr)} && ARRAY[?]", values)
       end
@@ -79,6 +84,14 @@ class ApplicationRecord < ActiveRecord::Base
         end
       end
 
+      def search_inet_attribute(attr, params)
+        if params[attr].present?
+          where_inet_matches(attr, params[attr])
+        else
+          all
+        end
+      end
+
       # range: "5", ">5", "<5", ">=5", "<=5", "5..10", "5,6,7"
       def numeric_attribute_matches(attribute, range)
         return all unless range.present?
@@ -130,6 +143,8 @@ class ApplicationRecord < ActiveRecord::Base
           search_boolean_attribute(name, params)
         when :integer, :datetime
           numeric_attribute_matches(name, params[name])
+        when :inet
+          search_inet_attribute(name, params)
         else
           raise NotImplementedError, "unhandled attribute type"
         end

app/models/ip_address.rb

@@ -0,0 +1,28 @@
+class IpAddress < ApplicationRecord
+  belongs_to :model, polymorphic: true
+  belongs_to :user
+  attribute :ip_addr, IpAddressType.new
+
+  def self.model_types
+    %w[Post User Comment Dmail ArtistVersion ArtistCommentaryVersion NoteVersion WikiPageVersion]
+  end
+
+  def self.search(params)
+    q = super
+    q = q.where.not(model_type: "Dmail") unless CurrentUser.is_admin?
+    q = q.search_attributes(params, :user, :model_type, :model_id, :ip_addr)
+    q.order(created_at: :desc)
+  end
+
+  def self.group_by_ip_addr
+    group(:ip_addr).select("ip_addr, COUNT(*) AS count_all").reorder("count_all DESC, ip_addr")
+  end
+
+  def self.group_by_user
+    group(:user_id).select("user_id, COUNT(*) AS count_all").reorder("count_all DESC, user_id")
+  end
+
+  def readonly?
+    true
+  end
+end