Implement the email_blacklist_regexp ssite setting

app/models/user.rb

@@ -28,6 +28,7 @@ class User < ActiveRecord::Base
   validates_presence_of :email
   validates_uniqueness_of :email
   validate :username_validator
+  validate :email_validator
   validate :password_validator
 
   before_save :cook
@@ -481,6 +482,15 @@ class User < ActiveRecord::Base
       end
     end
 
+    def email_validator
+      if (setting = SiteSetting.email_blacklist_regexp.try(:strip)).present?
+        regexp = Regexp.new(setting, true)
+        if self.email =~ regexp
+          return errors.add(:email, I18n.t(:'user.email.not_allowed'))
+        end
+      end
+    end
+
     def password_validator
       if (@raw_password and @raw_password.length < 6) or (@password_required and !@raw_password)
         return errors.add(:password, "must be 6 letters or longer")

config/locales/en.yml

@@ -1052,6 +1052,8 @@ en:
       unique: "must be unique"
       blank: "must be present"
       must_begin_with_alphanumeric: "must begin with a letter or number"
+    email:
+      not_allowed: "is not allowed from that email provider. Please use another email address."
 
   invite_mailer:
     subject_template: "[%{site_name}] %{invitee_name} invited you to join a discussion on %{site_name}"

spec/models/user_spec.rb

@@ -445,6 +445,31 @@ describe User do
     end
   end
 
+  describe 'email_validator' do
+    it 'should allow good emails' do
+      user = Fabricate.build(:user, email: 'good@gmail.com')
+      user.should be_valid
+    end
+
+    it 'should reject some emails based on the email_blacklist_regexp site setting' do
+      SiteSetting.stubs(:email_blacklist_regexp).returns('@mailinator')
+      Fabricate.build(:user, email: 'notgood@mailinator.com').should_not be_valid
+      Fabricate.build(:user, email: 'mailinator@gmail.com').should be_valid
+    end
+
+    it 'should reject some emails based on the email_blacklist_regexp site setting' do
+      SiteSetting.stubs(:email_blacklist_regexp).returns('@(mailinator|aol)\.com')
+      Fabricate.build(:user, email: 'notgood@mailinator.com').should_not be_valid
+      Fabricate.build(:user, email: 'notgood@aol.com').should_not be_valid
+      Fabricate.build(:user, email: 'aol+mailinator@gmail.com').should be_valid
+    end
+
+    it 'should reject some emails based on the email_blacklist_regexp site setting ignoring case' do
+      SiteSetting.stubs(:email_blacklist_regexp).returns('@mailinator')
+      Fabricate.build(:user, email: 'notgood@MAILINATOR.COM').should_not be_valid
+    end
+  end
+
   describe 'passwords' do
     before do
       @user = Fabricate.build(:user)