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Validate that e-mail resolves with MX and it's not blacklisted (#7631)

Original patch by @j-a4
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Gargron authored and ykzts committed May 27, 2018
1 parent 182bdbc commit 63c7b9157274f57c496399a1a5c728b32415034c
Showing with 26 additions and 0 deletions.
  1. +1 −0 app/models/user.rb
  2. +25 −0 app/validators/email_mx_validator.rb
@@ -65,6 +65,7 @@ class User < ApplicationRecord

validates :locale, inclusion: I18n.available_locales.map(&:to_s), if: :locale?
validates_with BlacklistedEmailValidator, if: :email_changed?
validates_with EmailMxValidator, if: :email_changed?

scope :recent, -> { order(id: :desc) }
scope :admins, -> { where(admin: true) }
@@ -0,0 +1,25 @@
# frozen_string_literal: true

require 'resolv'

class EmailMxValidator < ActiveModel::Validator
def validate(user)
return if Rails.env.test?
user.errors.add(:email, I18n.t('users.invalid_email')) if invalid_mx?(user.email)
end

private

def invalid_mx?(value)
_, domain = value.split('@', 2)

return true if domain.nil?

records = Resolv::DNS.new.getresources(domain, Resolv::DNS::Resource::IN::MX).to_a.map { |e| e.exchange.to_s }
records.empty? || on_blacklist?(records)
end

def on_blacklist?(values)
EmailDomainBlock.where(domain: values).any?
end
end

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