mysociety/alaveteli

#!/usr/bin/env ruby

# Handle email responses sent to us.
#
# This script is invoked as a pipe command, i.e. with the raw email message on stdin.
# - If a message is identified as a permanent bounce, the user is marked as having a
#   bounced address, and will not be sent any more messages.
# - If a message is identified as an out-of-office autoreply, it is discarded.
# - Any other messages are forwarded to config.get("FORWARD_NONBOUNCE_RESPONSES_TO")
#   or config.get("FORWARD_PRO_NONBOUNCE_RESPONSES_TO") depending on whether
#   they were sent from the normal contact address or the pro one initially.

# We want to avoid loading rails unless we need it, so we start by just loading the
# config file ourselves.
require 'active_support/all'

$alaveteli_dir = File.expand_path(File.join(File.dirname(__FILE__), '..'))

$LOAD_PATH.push(File.join($alaveteli_dir, 'commonlib', 'rblib'))
load 'validate.rb'
load 'config.rb'
MySociety::Config.set_file(File.join($alaveteli_dir, 'config', 'general'), true)
MySociety::Config.load_default

$LOAD_PATH.push(File.join($alaveteli_dir, 'lib'))
load 'configuration.rb'

$LOAD_PATH.push(File.join($alaveteli_dir, 'app', 'helpers'))
require 'config_helper'

$LOAD_PATH.push(File.join($alaveteli_dir, 'lib', 'mail_handler'))
require 'mail_handler'
require 'mail_handler/reply_handler'

# the default encoding for IO is utf-8, and we use utf-8 internally
Encoding.default_external = Encoding.default_internal = Encoding::UTF_8

def content_type(message)
  MailHandler.get_content_type(message)
end

def temporary_failure?(message)
  content_type(message) == 'multipart/report'
end

def delivery_delay?(message)
  subject = MailHandler.get_header_string('Subject', message)

  content_type(message) == 'multipart/mixed' &&
    subject == 'Delivery Status Notification (Delay)'
end

def record_permanently_failed(message, raw_message, in_test_mode)
  permanently_failed_addresses =
    MailHandler::ReplyHandler.permanently_failed_addresses(message)

  permanently_failed_addresses.each do |pfa|
    if in_test_mode
      puts pfa
    else
      MailHandler::ReplyHandler.record_bounce(pfa, raw_message)
    end
  end

  true unless permanently_failed_addresses.empty?
end

def main(in_test_mode)
  Dir.chdir($alaveteli_dir) do
    raw_message = $stdin.read

    begin
      message = MailHandler.mail_from_raw_email(raw_message)
    rescue
      # Error parsing message. Just pass it on, to be on the safe side.
      MailHandler::ReplyHandler.forward_on(raw_message) unless in_test_mode
      return 0
    end

    return 1 if record_permanently_failed(message, raw_message, in_test_mode)

    # If we are still here, there are no permanent failures,
    # so if the message is a multipart/report then it must be
    # reporting a temporary failure. In this case we discard it
    return 1 if temporary_failure?(message)

    # Another style of temporary failure message
    return 1 if delivery_delay?(message)

    # Discard out-of-office messages
    # Use a different return code, to distinguish OOFs from bounces
    return 2 if MailHandler::ReplyHandler.is_oof?(message)

    # Otherwise forward the message on
    unless in_test_mode
      MailHandler::ReplyHandler.forward_on(raw_message, message)
    end
    return 0
  end
end

in_test_mode = (ARGV[0] == "--test")
status = main(in_test_mode)
exit(status) if in_test_mode