Add Mandrill support

app/controllers/action_mailbox/ingresses/mandrill/inbound_emails_controller.rb

@@ -0,0 +1,59 @@
+class ActionMailbox::Ingresses::Mandrill::InboundEmailsController < ActionMailbox::BaseController
+  before_action :ensure_authenticated
+
+  def create
+    raw_emails.each { |raw_email| ActionMailbox::InboundEmail.create_and_extract_message_id! raw_email }
+    head :ok
+  rescue JSON::ParserError => error
+    log.error error.message
+    head :unprocessable_entity
+  end
+
+  private
+    def raw_emails
+      events.lazy.
+        select { |event| event["event"] == "inbound" }.
+        collect { |event| event.dig("msg", "raw_msg") }.
+        collect { |message| StringIO.new message }
+    end
+
+    def events
+      JSON.parse params.require(:mandrill_events)
+    end
+
+
+    def ensure_authenticated
+      head :unauthorized unless authenticated?
+    end
+
+    def authenticated?
+      Authenticator.new(request).authenticated?
+    end
+
+    class Authenticator
+      cattr_accessor :key
+
+      attr_reader :request
+
+      def initialize(request)
+        @request = request
+      end
+
+      def authenticated?
+        ActiveSupport::SecurityUtils.secure_compare given_signature, expected_signature
+      end
+
+      private
+        def given_signature
+          request.headers["X-Mandrill-Signature"]
+        end
+
+        def expected_signature
+          Base64.encode64(OpenSSL::HMAC.digest(OpenSSL::Digest::SHA1.new, key, message)).strip
+        end
+
+        def message
+          [ request.original_url, request.POST.sort ].flatten.join
+        end
+    end
+end

config/routes.rb

@@ -5,6 +5,7 @@ Rails.application.routes.draw do
     post "/amazon/inbound_emails"   => "action_mailbox/ingresses/amazon/inbound_emails#create",   as: :rails_amazon_inbound_emails
     post "/postfix/inbound_emails"  => "action_mailbox/ingresses/postfix/inbound_emails#create",  as: :rails_postfix_inbound_emails
     post "/sendgrid/inbound_emails" => "action_mailbox/ingresses/sendgrid/inbound_emails#create", as: :rails_sendgrid_inbound_emails
+    post "/mandrill/inbound_emails" => "action_mailbox/ingresses/mandrill/inbound_emails#create", as: :rails_mandrill_inbound_emails
 
     # Mailgun requires that the webhook's URL end in 'mime' for it to receive the raw contents of emails.
     post "/mailgun/inbound_emails/mime" => "action_mailbox/ingresses/mailgun/inbound_emails#create", as: :rails_mailgun_inbound_emails

test/controllers/ingresses/mandrill/inbound_emails_controller_test.rb

@@ -0,0 +1,31 @@
+require "test_helper"
+
+ActionMailbox::Ingresses::Mandrill::InboundEmailsController::Authenticator.key = "1l9Qf7lutEf7h73VXfBwhw"
+
+class ActionMailbox::Ingresses::Mandrill::InboundEmailsControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    @events = JSON.generate([{ event: "inbound", msg: { raw_msg: file_fixture("../files/welcome.eml").read } }])
+  end
+
+  test "receiving an inbound email from Mandrill" do
+    assert_difference -> { ActionMailbox::InboundEmail.count }, +1 do
+      post rails_mandrill_inbound_emails_url,
+        headers: { "X-Mandrill-Signature" => "gldscd2tAb/G+DmpiLcwukkLrC4=" }, params: { mandrill_events: @events }
+    end
+
+    assert_response :ok
+
+    inbound_email = ActionMailbox::InboundEmail.last
+    assert_equal file_fixture("../files/welcome.eml").read, inbound_email.raw_email.download
+    assert_equal "0CB459E0-0336-41DA-BC88-E6E28C697DDB@37signals.com", inbound_email.message_id
+  end
+
+  test "rejecting a forged inbound email from Mandrill" do
+    assert_no_difference -> { ActionMailbox::InboundEmail.count } do
+      post rails_mandrill_inbound_emails_url,
+        headers: { "X-Mandrill-Signature" => "forged" }, params: { mandrill_events: @events }
+    end
+
+    assert_response :unauthorized
+  end
+end