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Revision cb0d68fd

Added by Marc Dequènes about 15 years ago

  • ID cb0d68fd2c857faea5a05f374b2bb4464a1191fd

[evol] commands management rework #2: moved command parsing out of the Mail class and created new classes to handle it

View differences:

lib/cyborghood/mail.rb
require 'digest/md5'
# This class handles RFC3156 signed messages, validates them, and extract orders properly.
# Encrypted content are not implemented yet.
# This class handles RFC3156 signed/encrypted messages, validates them, and extract content properly.
# It also implements a protection against replay attacks.
module CyborgHood
class Command
attr_reader :cmdline, :cmdsplit
class MailReport
attr_reader :error, :warn_sender, :user, :message
def initialize(cmdline, cmdsplit)
@cmdline = cmdline
@cmdsplit = cmdsplit
end
end
class SharedParameter
attr_reader :type, :content
def initialize(params = {})
@error = params[:error]
@warn_sender = params[:warn_sender]
@user = params[:user]
@message = params[:message]
def initialize(content, type = nil)
@content = content
@type = type
@warn_sender = false
end
end
class ParameterReference
attr_reader :reference
def initialize(reference)
@reference = reference
end
end
class Order
attr_accessor :ok, :message, :system_message, :user, :commands, :shared_parameters
attr_writer = :warn_sender
def initialize(ok, message = nil, system_message = nil)
@ok = ok
@message = message
@system_message = system_message
def ok?
@error.nil? and @user and @message
end
def warn_sender
......
@mail
end
def parse
def process
if is_marked?
return Order.new(false, "Replay detected.")
return MailReport.new(:error => "Replay detected.")
end
return parse_signed() if is_pgp_signed?
return parse_encrypted() if is_pgp_encrypted?
# don't parse commands if user is not identified
return parse_plain if self.user
return process_signed() if is_pgp_signed?
return process_encrypted() if is_pgp_encrypted?
Order.new(false, "Mail not RFC3156 compliant.")
MailReport.new(:error => "Mail not RFC3156 compliant.")
end
def create_reply
......
private
def parse_plain
command_txt = nil
shared_params = nil
if multipart?
if parts[0].content_type == "text/plain"
command_txt = self.parts[0].body
shared_params = {}
i = 1
self.parts.each do |p|
shared_params[i] = SharedParameter.new(p.body, p.content_type)
filename = p.header['content-type'].params('filename')
shared_params[filename] = ParameterReference.new(i) if filename
i += 1
end
end
else
command_txt = self.body if self.content_type == "text/plain"
shared_params = {}
end
unless command_txt
order = Order.new(false, N_("Mail does not contain a proper text part for commands."))
order.user = self.user
return order
end
commands = []
command_txt.each_line do |line|
line.chomp!
sline = line.strip
# skip empty lines and comments
next if sline == "" or sline[0, 1] == "#"
# stop processing when detecting message signature
break if line == "-- "
used_refs = []
cmd_parts = sline.shellsplit.collect do |word|
if =~ /^@([a-zA-Z0-9._-]+)$/
ref = $1
d_ref, d_param = dereference_param(shared_params, param)
# TODO: should add error message for attachment not found in the Command
used_refs << d_ref
d_param
else
word
end
end
commands << Command.new(sline, cmd_parts)
end
shared_params.delete_if{|ref, param| not used_refs.include?(ref) }
logger.debug "Mail OK"
mark_processed(self.signature_timestamp)
order = Order.new(true)
order.user = self.user
order.commands = commands
order.references = shared_params
order
end
def dereference_param(shared_params, param)
if param.is_a? SharedParameter
[ref, ParameterReference(ref)]
elsif param.is_a? ParameterReference
d_ref = param.reference
d_param = shared_params[d_ref]
return dereference_param(shared_params, d_param)
else
nil
end
end
def parse_signed
def process_signed
sigs_check = verify_pgp_signature()
return Order.new(false, N_("Mail not formatted correctly (signed part).")) if sigs_check.nil? or sigs_check.size != 1
return MailReport.new(:error => "Mail not formatted correctly (signed part).") if sigs_check.nil? or sigs_check.size != 1
sig_check = sigs_check.first
return Order.new(false, N_("Mail content tampered or badly signed: ") + sig_check.to_s) unless sig_check.status == 0
return MailReport.new(:error => "Mail content tampered or badly signed: " + sig_check.to_s) unless sig_check.status == 0
logger.info "Mail content was properly signed by key #{sig_check.fingerprint}"
user = Person.find_by_fingerprint(sig_check.fingerprint)
if user.nil?
order = Order.new(false, N_("Mail is from an unknown person."))
order.warn_sender = true
return order
end
return MailReport.new(:error => "Mail is from an unknown person.", :warn_sender => true) if user.nil?
logger.info "Mail is from user #{user.uid} (#{user.cn})"
self.user = user
......
logger.debug "Signature drift time: #{drift}"
unless drift.abs < MAX_DRIFT_TIME
if drift > 0
order = Order.new(false, N_("The signature was made too long ago (check your system clock). Rejected message to avoid replay attacks."))
order.user = self.user
return MailReport.new(:error => N_("The signature was made too long ago (check your system clock). Rejected message to avoid replay attacks."), :user => user)
else
# mark message to prevent later replay of the message
mark_processed(sig_check.timestamp)
order = Order.new(false, N_("The signature was made in the future (check your system clock). Rejected message to avoid replay attacks."))
order.user = self.user
return MailReport.new(:error => N_("The signature was made in the future (check your system clock). Rejected message to avoid replay attacks."), :user => user)
end
return order
end
logger.debug "Mail OK"
mark_processed(self.signature_timestamp)
signed_content = pgp_signed_part()
# create a fake mail and chain parsing operations
......
plain_mail.signature_timestamp = sig_check.timestamp
# propagate message_id to be able to mark messages (replay protection)
plain_mail.message_id = @mail.message_id
return plain_mail.parse
MailReport.new(:user => user, :message => plain_mail)
end
def parse_encrypted
def process_encrypted
catch :notforme do
begin
# block is not passed to delegate (limitation ?)
......
clear_mail.user = self.user
# propagate message_id to be able to mark messages (replay protection)
clear_mail.message_id = @mail.message_id
return clear_mail.parse
return clear_mail.process
rescue GPGME::Error, NotImplementedError => e
raise CyberError.new(:unrecoverable, "protocol/mail", e.message)
end
end
Order.new(false, N_("Mail not formatted correctly (encrypted part)."))
MailReport.new(:error => "Mail not formatted correctly (encrypted part).")
end
def mark_dir

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