don't 500 if a user banned/deleted before server move tries to log in

Also add a rake task documenting what jcs did before the server move.
(Though ModNote is new since then.)

app/controllers/login_controller.rb

@@ -1,6 +1,7 @@
 class LoginBannedError < StandardError; end
 class LoginDeletedError < StandardError; end
 class LoginTOTPFailedError < StandardError; end
+class LoginWipedError < StandardError; end
 class LoginFailedError < StandardError; end
 
 class LoginController < ApplicationController
@@ -35,6 +36,10 @@ class LoginController < ApplicationController
         raise LoginFailedError
       end
 
+      if user.is_wiped?
+        raise LoginWipedError
+      end
+
       if !user.authenticate(params[:password].to_s)
         raise LoginFailedError
       end
@@ -74,6 +79,9 @@ class LoginController < ApplicationController
       end
 
       return redirect_to "/"
+    rescue LoginWipedError
+      fail_reason = "Your account was banned or deleted before the site changed admins. " <<
+                    "Your email and password hash were wiped for privacy."
     rescue LoginBannedError
       fail_reason = "Your account has been banned."
     rescue LoginDeletedError

app/models/user.rb

@@ -419,6 +419,11 @@ class User < ApplicationRecord
     banned_at?
   end
 
+  # user was deleted/banned before a server move, see lib/tasks/privacy_wipe
+  def is_wiped?
+    password_digest == '*'
+  end
+
   def is_new?
     Time.current - self.created_at <= NEW_USER_DAYS.days
   end

lib/tasks/privacy_wipe.rake

@@ -0,0 +1,16 @@
+desc 'Wipe private data if site is changing hands'
+task privacy_wipe: :environment do
+  fail "Refusing to wipe. Read and edit this task if your site is really changing hands"
+
+  # It'll be really easy for this rarely-used code to slip out-of-sync,
+  # you MUST review how users are banned/deleted before you run this.
+  # At the least, check User#delete! and LoginController.
+  # User.where.not(deleted_at: nil)
+  #     .update_all("password_digest = '*', email = concat(username, '@lobsters.example')")
+
+  # wipe all moderator notes:
+  # ModNote.delete_all
+
+  # wipe all private messages:
+  # Message.delete_all
+end

spec/controllers/login_controller_spec.rb

@@ -4,45 +4,69 @@ describe LoginController do
   let(:user) { create(:user, password: 'asdf') }
   let(:banned) { create(:user, :banned, password: 'asdf') }
   let(:deleted) { create(:user, :deleted, password: 'asdf') }
-  let(:banned_gone) { create(:user, :banned, :gone, password: 'asdf') }
-  let(:deleted_gone) { create(:user, :deleted, :gone, password: 'asdf') }
+  let(:banned_wiped) { create(:user, :banned, :wiped, password: 'asdf') }
+  let(:deleted_wiped) { create(:user, :deleted, :wiped, password: 'asdf') }
 
-  it "logs in with email and correct password" do
-    post :login, params: { email: user.email, password: 'asdf' }
-    expect(flash[:error]).to be_nil
-    expect(response).to redirect_to('/')
-  end
+  describe "/login" do
+    describe "happy path" do
+      it "logs in with email and correct password" do
+        post :login, params: { email: user.email, password: 'asdf' }
+        expect(flash[:error]).to be_nil
+        expect(response).to redirect_to('/')
+      end
 
-  it "logs in with username and correct password" do
-    post :login, params: { email: user.username, password: 'asdf' }
-    expect(session[:u]).to eq(user.session_token)
-    expect(flash[:error]).to be_nil
-    expect(response).to redirect_to('/')
-  end
+      it "logs in with username and correct password" do
+        post :login, params: { email: user.username, password: 'asdf' }
+        expect(session[:u]).to eq(user.session_token)
+        expect(flash[:error]).to be_nil
+        expect(response).to redirect_to('/')
+      end
+    end
 
-  it "doesn't log in without correct password" do
-    post :login, params: { email: user.email, password: 'wrong' }
-    expect(session[:u]).to be_nil
-    expect(flash[:error]).to match(/Invalid/i)
+    describe "doesn't log in without correct password" do
+      it "doesn't log in with wrong password" do
+        post :login, params: { email: user.email, password: 'wrong' }
+        expect(session[:u]).to be_nil
+        expect(flash[:error]).to match(/Invalid/i)
+      end
 
-    post :login, params: { email: user.email, password: '' }
-    expect(session[:u]).to be_nil
-    expect(flash[:error]).to match(/Invalid/i)
+      it "doesn't log in with blank password" do
+        post :login, params: { email: user.email, password: '' }
+        expect(session[:u]).to be_nil
+        expect(flash[:error]).to match(/Invalid/i)
+      end
 
-    post :login, params: { email: user.email }
-    expect(session[:u]).to be_nil
-    expect(flash[:error]).to match(/Invalid/i)
-  end
+      it "doesn't log in without any password posted" do
+        post :login, params: { email: user.email }
+        expect(session[:u]).to be_nil
+        expect(flash[:error]).to match(/Invalid/i)
+      end
+    end
 
-  it "doesn't allow login by banned users" do
-    post :login, params: { email: banned.email, password: 'asdf' }
-    expect(session[:u]).to be_nil
-    expect(flash[:error]).to match(/banned/)
-  end
+    it "doesn't allow login by banned users" do
+      post :login, params: { email: banned.email, password: 'asdf' }
+      expect(session[:u]).to be_nil
+      expect(flash[:error]).to match(/banned/)
+    end
 
-  it "doesn't allow login by deleted users" do
-    post :login, params: { email: deleted.email, password: 'asdf' }
-    expect(session[:u]).to be_nil
-    expect(flash[:error]).to match(/deleted/)
+    it "doesn't allow login by deleted users" do
+      post :login, params: { email: deleted.email, password: 'asdf' }
+      expect(session[:u]).to be_nil
+      expect(flash[:error]).to match(/deleted/)
+    end
+
+    describe "wiped accounts" do
+      it "doesn't allow login by banned and wiped users" do
+        post :login, params: { email: banned_wiped.email, password: 'asdf' }
+        expect(session[:u]).to be_nil
+        expect(flash[:error]).to match(/wiped/)
+      end
+
+      it "doesn't allow login by deleted and wiped users" do
+        post :login, params: { email: deleted_wiped.email, password: 'asdf' }
+        expect(session[:u]).to be_nil
+        expect(flash[:error]).to match(/wiped/)
+      end
+    end
   end
 end

spec/factories/user.rb

@@ -27,6 +27,11 @@ FactoryBot.define do
     trait(:deleted) do
       deleted_at { Time.current }
     end
+    # users who were banned/deleted before a server move
+    # you must also add banned/deleted trait with this
+    trait(:wiped) do
+      password_digest { '*' }
+    end
     trait(:admin) do
       is_admin { true }
       is_moderator { true }