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#--
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# CyborgHood, a distributed system management software.
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# Copyright (c) 2009-2010 Marc Dequènes (Duck) <Duck@DuckCorp.org>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#++
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require 'delegate'
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require 'mail'
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require 'mail/gpg'
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require 'cyborghood/objects'
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require 'fileutils'
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require 'digest/md5'
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require 'active_support/core_ext/hash/keys'
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# This class handles RFC3156 signed/encrypted messages, validates them, and extract content properly.
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# It also implements a protection against replay attacks.
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module CyborgHood
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class MailReport
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attr_reader :error, :warn_sender, :user, :message
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def initialize(params = {})
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@error = params[:error]
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@warn_sender = params[:warn_sender]
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@user = params[:user]
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@message = params[:message]
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@warn_sender = false
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end
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def ok?
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!!(@error.nil? and @user and @message)
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end
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def warn_sender
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# send reply message if user is identified or in selected situations
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# (@warn_sender acts as an override)
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@warn_sender || @user
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end
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end
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class Mail < Delegator
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include I18nTranslation
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# class variable SUX
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class << self; attr_accessor :delivery_initialized; end
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attr_accessor :user, :signature_timestamp
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def initialize(msg = nil)
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@config = Config.instance
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# needs to be initialized before _any_ ::Mail object is created
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unless self.class.delivery_initialized
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params = @config.mail.smtp.nil? ? {} : @config.mail.smtp.to_h.symbolize_keys
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::Mail.defaults do
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delivery_method :smtp, params
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end
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self.class.delivery_initialized = true
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end
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if msg.nil?
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@mail = ::Mail.new
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set_custom_headers
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elsif msg.is_a? ::Mail::Message
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@mail = msg
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else
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@mail = ::Mail.new(msg)
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end
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end
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def self.read(path)
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self.new(::Mail.read(path))
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end
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def __getobj__
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@mail
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end
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def process
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if is_marked?
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if @config.debug.flags.include?('ignorereplay')
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logger.warn "Debug: ignoring replay"
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else
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return MailReport.new(:error => _("Replay detected."))
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end
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end
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return process_signed() if is_pgp_signed?
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return process_encrypted() if is_pgp_encrypted?
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MailReport.new(:error => _("Mail not RFC3156 compliant."))
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end
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def reply
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mail_reply = self.class.new(@mail.reply)
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mail_reply.from = @config.mail.from_address if @config.mail.from_address
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mail_reply.set_custom_headers
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mail_reply.user = @user
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mail_reply
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end
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def create_simple_reject_reply(msg)
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mail_reply = reply()
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mail_reply.content_type = 'text/plain; charset="UTF-8"'
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mail_reply.body = msg + self.default_body_signature
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mail_reply.sign
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mail_reply.crypt(mail_reply.user.keyFingerPrint) unless mail_reply.user.nil?
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mail_reply
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end
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def set_custom_headers
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@mail['Organization'] = @config.mail.organization
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end
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def default_body_signature
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s = "\n" +
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"-- \n" +
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"#{CyborgHood::PRODUCT} v#{CyborgHood::VERSION}\n"
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s += _("Contact eMail:").to_s + " \"#{@config.contact.name}\" <#{@config.contact.email}>\n" if @config.contact.email
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s += _("Contact URL:").to_s + " #{@config.contact.url}\n" if @config.contact.url
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s
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end
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def to_s
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@mail.to_s
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end
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def crypt(fingerprint = nil)
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@mail = @mail.create_encrypted(fingerprint || @user.keyFingerPrint)
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end
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def sign
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# we don't check the uid, as there is only one signer
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@mail = @mail.create_signed(@config.mail.key_id) do |uid_hint, passphrase_info, prev_was_bad|
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@config.mail.key_passphrase
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end
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end
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def sign_and_crypt(fingerprint = nil)
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# not using sign_and_crypt(), to avoid repeating code
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sign
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crypt(fingerprint || @user.keyFingerPrint)
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end
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private
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def process_signed
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sigs_check = verify_pgp_signature()
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return MailReport.new(:error => _("Mail not formatted correctly (signed part).")) if sigs_check.nil? or sigs_check.size != 1
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sig = sigs_check.first
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return MailReport.new(:error => _("Mail content tampered or badly signed: %{sig_err}", :sig_err => sig.to_s)) if sig.bad?
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logger.info "Mail content was properly signed by key #{sig.fingerprint}"
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begin
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user = Person.find_by_fingerprint(sig.key.fingerprint)
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rescue EOFError => error
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return MailReport.new(:error => _("Could not get public key for '%{fpr}'", :fpr => check.fingerprint))
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end
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return MailReport.new(:error => _("Mail is from an unknown person."), :warn_sender => true) if user.nil?
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logger.info "Mail is from user #{user.uid} (#{user.cn})"
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@user = user
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drift = Time.new.to_i - sig.timestamp.to_i
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logger.debug "Signature drift time: #{drift}"
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unless drift.abs < @config.mail.max_drift_time
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if drift > 0
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return MailReport.new(:error => _("The signature was made too long ago (check your system clock). Rejected message to avoid replay attacks."), :user => user)
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else
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# mark message to prevent later replay of the message
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mark_processed(sig.timestamp)
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return MailReport.new(:error => _("The signature was made in the future (check your system clock). Rejected message to avoid replay attacks."), :user => user)
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end
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end
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logger.debug "Mail OK"
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mark_processed(self.signature_timestamp)
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signed_content = pgp_signed_part()
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# create a fake mail and chain parsing operations
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plain_mail = self.class.new(signed_content.encoded)
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plain_mail.user = @user
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plain_mail.signature_timestamp = sig.timestamp
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# propagate message_id to be able to mark messages (replay protection)
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plain_mail.message_id = @mail.message_id
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MailReport.new(:user => user, :message => plain_mail)
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end
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def process_encrypted
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catch :notforme do
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begin
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# block is not passed to delegate (limitation ?)
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clear_message = @mail.pgp_decrypt do |uid_hint, passphrase_info, prev_was_bad|
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logger.info "Mail crypted for #{uid_hint}"
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# check if requesting passphrase for the expected key
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key_id = passphrase_info.split(" ")[1]
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throw :notforme if key_id != @config.mail.key_id[-(key_id.size)..-1]
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# sending key
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@config.mail.key_passphrase
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end
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# create a fake mail and chain parsing operations
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clear_mail = self.class.new(clear_message)
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clear_mail.user = @user
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# propagate message_id to be able to mark messages (replay protection)
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clear_mail.message_id = @mail.message_id
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decrypted_mail = clear_mail.process
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# reverse propagate user information (convenience)
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@user = decrypted_mail.user
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return decrypted_mail
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rescue GPGME::Error::DecryptFailed
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# encrypted with an unknown key
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rescue GPGME::Error, NotImplementedError => e
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raise CyberError.new(:unrecoverable, "protocol/mail", e.message)
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end
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end
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MailReport.new(:error => _("Mail not formatted correctly (encrypted part), or not encrypted with the correct key."))
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end
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def mark_dir
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File.join(Config::VAR_DIR, "marks")
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end
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def mark_filename
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File.join(mark_dir(), Digest::MD5.hexdigest(self.message_id))
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end
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def mark_processed(time)
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FileUtils.mkdir_p(mark_dir())
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File.open(mark_filename(), "w") do |fp|
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fp.write self.message_id
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end
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File.utime(Time.now.to_i, time.to_i, mark_filename())
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end
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def is_marked?
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File.exists?(mark_filename())
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end
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end
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end
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