Initial commit

.gitignore

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+*.gem
+*.rbc
+.bundle
+.config
+.yardoc
+Gemfile.lock
+InstalledFiles
+_yardoc
+coverage
+doc/
+lib/bundler/man
+pkg
+rdoc
+spec/reports
+test/tmp
+test/version_tmp
+tmp

Gemfile

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+source 'https://rubygems.org'
+
+# Specify your gem's dependencies in verifier.gemspec
+gemspec

LICENSE.txt

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+Copyright (c) 2012 Kamil Ciemniewski
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# Email Verifier
+
+Helper validation utility for checking whether given email address is real or not.
+Many times as developers we've put in our models statements for checking email address
+*format*. This gem will complete your existing setups with validator that actually
+connects with given mail server and asks if given email address exists for real.
+
+## Installation
+
+Add this line to your application's Gemfile:
+
+    gem 'email_verifier'
+
+And then execute:
+
+    $ bundle
+
+Or install it yourself as:
+
+    $ gem install verifier
+
+## Usage
+
+Just put this in your model e. g:
+
+    validates_email_realness_of :email
+
+Or - if you'd like to use it outside of your models:
+
+    EmailValidator.check(youremail)
+
+This method will return true or false, or - will throw exception 
+with nicely detailed info about what's wrong.
+
+## Credits
+![End Point Corporation](http://www.endpoint.com/images/end_point.png)
+
+Email Verifier is maintained and funded by [End Point Corporation](http://www.endpoint.com/)
+
+Please send questions to [kamil@endpoint.com](mailto:kamil@endpoint.com)
+
+## Contributing
+
+1. Fork it
+2. Create your feature branch (`git checkout -b my-new-feature`)
+3. Commit your changes (`git commit -am 'Add some feature'`)
+4. Push to the branch (`git push origin my-new-feature`)
+5. Create new Pull Request

Rakefile

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+require "bundler/gem_tasks"

email_verifier.gemspec

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+# -*- encoding: utf-8 -*-
+lib = File.expand_path('../lib', __FILE__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+require 'email_verifier/version'
+
+Gem::Specification.new do |gem|
+  gem.name          = "email_verifier"
+  gem.version       = EmailVerifier::VERSION
+  gem.authors       = ["Kamil Ciemniewski"]
+  gem.email         = ["kamil@endpoint.com"]
+  gem.description   = %q{Helper utility checking if given email address exists or not}
+  gem.summary       = %q{Helper utility checking if given email address exists or not}
+  gem.homepage      = "http://endpoint.com"
+
+  gem.files         = `git ls-files`.split($/)
+  gem.executables   = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
+  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
+  gem.require_paths = ["lib"]
+end

lib/email_verifier.rb

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+require "email_verifier/version"
+
+module EmailVerifier
+  require 'email_verifier/checker'
+  require 'email_verifier/exceptions'
+  require 'email_verifier/config'
+  require "email_verifier/validates_email_realness"
+
+  def self.check(email)
+    v = EmailVerifier::Checker.new(email)
+    v.connect
+    v.verify
+  end
+
+  def self.config(&block)
+    if block_given?
+      block.call(EmailVerifier::Config)
+    else
+      EmailVerifier::Config
+    end
+  end
+end

lib/email_verifier/checker.rb

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+require 'net/smtp'
+
+class EmailVerifier::Checker
+
+  ##
+  # Returns server object for given email address or throws exception
+  # Object returned isn't yet connected. It has internally a list of 
+  # real mail servers got from MX dns lookup
+  def initialize(address)
+    @email   = address
+    @domain  = address.split("@").last
+    @servers = list_mxs @domain
+    raise EmailVerifier::NoMailServerException.new("No mail server for #{address}") if @servers.empty?
+    @smtp    = nil
+
+    # this is because some mail servers won't give any info unless 
+    # a real user asks for it:
+    @user_email = EmailVerifier.config.verifier_email
+  end
+
+  def list_mxs(domain)
+    `host -t MX #{domain}`.scan(/(?<=by ).+/).map do |mx| 
+      res = mx.split(" ")
+      next if res.last[0..-2].strip.empty?
+      { priority: res.first.to_i, address: res.last[0..-2] }
+    end.reject(&:nil?).sort_by { |mx| mx[:priority] }
+  end
+
+  def is_connected
+    !@smtp.nil?
+  end
+
+  def connect
+    begin
+      server = next_server
+      raise EmailVerifier::OutOfMailServersException.new("Unable to connect to any one of mail servers for #{@email}") if server.nil?
+      @smtp = Net::SMTP.start(server[:address], 25)
+      return true
+    rescue EmailVerifier::OutOfMailServersException => e
+      return false
+    rescue => e
+      retry
+    end
+  end
+
+  def next_server
+    @servers.shift
+  end
+
+  def verify
+    self.helo @user_email
+    self.mailfrom @user_email
+    self.rcptto(@email)
+  end
+
+  def helo(address)
+    ensure_connected
+
+    ensure_250 @smtp.helo(@domain)
+  end
+
+  def mailfrom(address)
+    ensure_connected
+
+    ensure_250 @smtp.mailfrom(address)
+  end
+
+  def rcptto(address)
+    ensure_connected
+
+    begin
+      ensure_250 @smtp.rcptto(address)
+    rescue => e
+      if e.message[/^550/]
+        return false
+      else
+        raise EmailVerifier::FailureException.new(e.message)
+      end
+    end
+  end
+
+  def ensure_connected
+    raise EmailVerifier::NotConnectedException.new("You have to connect first") if @smtp.nil?
+  end
+
+  def ensure_250(smtp_return)
+    if smtp_return.status.to_i == 250
+      return true
+    else
+      raise EmailVerifier::FailureException.new "Mail server responded with #{smtp_return.status} when we were expecting 250"
+    end
+  end
+
+end

lib/email_verifier/config.rb

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+module EmailVerifier
+  module Config
+    class << self
+      attr_accessor :verifier_email
+
+      def reset
+        @verifier_email = "nobody@nonexistant.com"
+      end
+    end
+    self.reset
+  end
+end

lib/email_verifier/exceptions.rb

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+
+module EmailVerifier
+
+  class NoMailServerException < StandardError; end
+  class OutOfMailServersException < StandardError; end
+  class NotConnectedException < StandardError; end
+  class FailureException < StandardError; end
+
+end

lib/email_verifier/validates_email_realness.rb

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+require "active_record"
+
+module EmailVerifier
+  module ValidatesEmailRealness
+
+    module Validator
+      class EmailRealnessValidator < ActiveModel::EachValidator
+        def validate_each(record, attribute, value)
+          begin
+            record.errors.add attribute, 'must point to a real mail account' unless EmailVerifier.check(value)
+          rescue EmailVerifier::OutOfMailServersException
+            record.errors.add attribute, 'appears to point to dead mail server'
+          rescue EmailVerifier::NoMailServerException
+            record.errors.add attribute, "appears to point to domain which doesn't handle e-mail"
+          rescue EmailVerifier::FailureException
+            record.errors.add attribute, "could not be checked if is real"
+          end
+        end
+      end
+    end
+
+    module ClassMethods
+      def validates_email_realness_of(*attr_names)
+        validates_with ActiveRecord::Base::EmailRealnessValidator, _merge_attributes(attr_names)
+      end
+    end
+
+  end
+end
+
+ActiveRecord::Base.send(:include, EmailVerifier::ValidatesEmailRealness::Validator)
+ActiveRecord::Base.send(:extend,  EmailVerifier::ValidatesEmailRealness::ClassMethods)

lib/email_verifier/version.rb

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+module EmailVerifier
+  VERSION = "0.0.1"
+end

rails/init.rb

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+require 'email_verifier'