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Diffstat (limited to 'src/leap/mail/incoming/service.py')
| -rw-r--r-- | src/leap/mail/incoming/service.py | 760 |
1 files changed, 760 insertions, 0 deletions
diff --git a/src/leap/mail/incoming/service.py b/src/leap/mail/incoming/service.py new file mode 100644 index 0000000..e52c727 --- /dev/null +++ b/src/leap/mail/incoming/service.py @@ -0,0 +1,760 @@ +# -*- coding: utf-8 -*- +# service.py +# Copyright (C) 2015 LEAP +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. +""" +Incoming mail fetcher. +""" +import copy +import logging +import shlex +import threading +import time +import traceback +import warnings + +from email.parser import Parser +from email.generator import Generator +from email.utils import parseaddr +from StringIO import StringIO +from urlparse import urlparse + +from twisted.application.service import Service +from twisted.python import log +from twisted.internet import defer, reactor +from twisted.internet.task import LoopingCall +from twisted.internet.task import deferLater +from u1db import errors as u1db_errors + +from leap.common import events as leap_events +from leap.common.check import leap_assert, leap_assert_type +from leap.common.events.events_pb2 import IMAP_FETCHED_INCOMING +from leap.common.events.events_pb2 import IMAP_MSG_PROCESSING +from leap.common.events.events_pb2 import IMAP_MSG_DECRYPTED +from leap.common.events.events_pb2 import IMAP_MSG_SAVED_LOCALLY +from leap.common.events.events_pb2 import IMAP_MSG_DELETED_INCOMING +from leap.common.events.events_pb2 import IMAP_UNREAD_MAIL +from leap.common.events.events_pb2 import SOLEDAD_INVALID_AUTH_TOKEN +from leap.common.mail import get_email_charset +from leap.keymanager import errors as keymanager_errors +from leap.keymanager.openpgp import OpenPGPKey +from leap.mail.adaptors import soledad_indexes as fields +from leap.mail.decorators import deferred_to_thread +from leap.mail.utils import json_loads, empty, first +from leap.soledad.client import Soledad +from leap.soledad.common.crypto import ENC_SCHEME_KEY, ENC_JSON_KEY +from leap.soledad.common.errors import InvalidAuthTokenError + + +logger = logging.getLogger(__name__) + +MULTIPART_ENCRYPTED = "multipart/encrypted" +MULTIPART_SIGNED = "multipart/signed" +PGP_BEGIN = "-----BEGIN PGP MESSAGE-----" +PGP_END = "-----END PGP MESSAGE-----" + +# The period between succesive checks of the incoming mail +# queue (in seconds) +INCOMING_CHECK_PERIOD = 60 + + +class MalformedMessage(Exception): + """ + Raised when a given message is not well formed. + """ + pass + + +class IncomingMail(Service): + """ + Fetches and process mail from the incoming pool. + + This object implements IService interface, has public methods + startService and stopService that will actually initiate a + LoopingCall with check_period recurrency. + The LoopingCall itself will invoke the fetch method each time + that the check_period expires. + + This loop will sync the soledad db with the remote server and + process all the documents found tagged as incoming mail. + """ + + name = "IncomingMail" + + RECENT_FLAG = "\\Recent" + CONTENT_KEY = "content" + + LEAP_SIGNATURE_HEADER = 'X-Leap-Signature' + """ + Header added to messages when they are decrypted by the IMAP fetcher, + which states the validity of an eventual signature that might be included + in the encrypted blob. + """ + LEAP_SIGNATURE_VALID = 'valid' + LEAP_SIGNATURE_INVALID = 'invalid' + LEAP_SIGNATURE_COULD_NOT_VERIFY = 'could not verify' + + fetching_lock = threading.Lock() + + def __init__(self, keymanager, soledad, inbox, userid, + check_period=INCOMING_CHECK_PERIOD): + + """ + Initialize IncomingMail.. + + :param keymanager: a keymanager instance + :type keymanager: keymanager.KeyManager + + :param soledad: a soledad instance + :type soledad: Soledad + + :param inbox: the inbox where the new emails will be stored + :type inbox: IMAPMailbox + + :param check_period: the period to fetch new mail, in seconds. + :type check_period: int + """ + + leap_assert(keymanager, "need a keymanager to initialize") + leap_assert_type(soledad, Soledad) + leap_assert(check_period, "need a period to check incoming mail") + leap_assert_type(check_period, int) + leap_assert(userid, "need a userid to initialize") + + self._keymanager = keymanager + self._soledad = soledad + self._inbox = inbox + self._userid = userid + + self._loop = None + self._check_period = check_period + + # initialize a mail parser only once + self._parser = Parser() + + # + # Public API: fetch, start_loop, stop. + # + + def fetch(self): + """ + Fetch incoming mail, to be called periodically. + + Calls a deferred that will execute the fetch callback + in a separate thread + """ + def mail_compat(failure): + if failure.check(u1db_errors.InvalidGlobbing): + # It looks like we are a dealing with an outdated + # mx. Fallback to the version of the index + warnings.warn("JUST_MAIL_COMPAT_IDX will be deprecated!", + DeprecationWarning) + return self._soledad.get_from_index( + fields.JUST_MAIL_COMPAT_IDX, "*") + return failure + + def syncSoledadCallback(_): + d = self._soledad.get_from_index( + fields.JUST_MAIL_IDX, "*", "0") + d.addErrback(mail_compat) + d.addCallback(self._process_doclist) + return d + + logger.debug("fetching mail for: %s %s" % ( + self._soledad.uuid, self._userid)) + if not self.fetching_lock.locked(): + d1 = self._sync_soledad() + d = defer.gatherResults([d1], consumeErrors=True) + d.addCallbacks(syncSoledadCallback, self._errback) + d.addCallbacks(self._signal_fetch_to_ui, self._errback) + return d + else: + logger.debug("Already fetching mail.") + + def startService(self): + """ + Starts a loop to fetch mail. + """ + Service.startService(self) + if self._loop is None: + self._loop = LoopingCall(self.fetch) + self._loop.start(self._check_period) + else: + logger.warning("Tried to start an already running fetching loop.") + + def stopService(self): + """ + Stops the loop that fetches mail. + """ + if self._loop and self._loop.running is True: + self._loop.stop() + self._loop = None + Service.stopService(self) + + # + # Private methods. + # + + # synchronize incoming mail + + def _errback(self, failure): + logger.exception(failure.value) + traceback.print_exc() + + @deferred_to_thread + def _sync_soledad(self): + """ + Synchronize with remote soledad. + + :returns: a list of LeapDocuments, or None. + :rtype: iterable or None + """ + with self.fetching_lock: + try: + log.msg('FETCH: syncing soledad...') + self._soledad.sync() + log.msg('FETCH soledad SYNCED.') + except InvalidAuthTokenError: + # if the token is invalid, send an event so the GUI can + # disable mail and show an error message. + leap_events.signal(SOLEDAD_INVALID_AUTH_TOKEN) + + def _signal_fetch_to_ui(self, doclist): + """ + Send leap events to ui. + + :param doclist: iterable with msg documents. + :type doclist: iterable. + :returns: doclist + :rtype: iterable + """ + doclist = first(doclist) # gatherResults pass us a list + if doclist: + fetched_ts = time.mktime(time.gmtime()) + num_mails = len(doclist) if doclist is not None else 0 + if num_mails != 0: + log.msg("there are %s mails" % (num_mails,)) + leap_events.signal( + IMAP_FETCHED_INCOMING, str(num_mails), str(fetched_ts)) + return doclist + + def _signal_unread_to_ui(self, *args): + """ + Sends unread event to ui. + """ + leap_events.signal( + IMAP_UNREAD_MAIL, str(self._inbox.getUnseenCount())) + + # process incoming mail. + + def _process_doclist(self, doclist): + """ + Iterates through the doclist, checks if each doc + looks like a message, and yields a deferred that will decrypt and + process the message. + + :param doclist: iterable with msg documents. + :type doclist: iterable. + :returns: a list of deferreds for individual messages. + """ + log.msg('processing doclist') + if not doclist: + logger.debug("no docs found") + return + num_mails = len(doclist) + + deferreds = [] + for index, doc in enumerate(doclist): + logger.debug("processing doc %d of %d" % (index + 1, num_mails)) + leap_events.signal( + IMAP_MSG_PROCESSING, str(index), str(num_mails)) + + keys = doc.content.keys() + + # TODO Compatibility check with the index in pre-0.6 mx + # that does not write the ERROR_DECRYPTING_KEY + # This should be removed in 0.7 + + has_errors = doc.content.get(fields.ERROR_DECRYPTING_KEY, None) + if has_errors is None: + warnings.warn("JUST_MAIL_COMPAT_IDX will be deprecated!", + DeprecationWarning) + + if has_errors: + logger.debug("skipping msg with decrypting errors...") + elif self._is_msg(keys): + d = self._decrypt_doc(doc) + d.addCallback(self._extract_keys) + d.addCallbacks(self._add_message_locally, self._errback) + deferreds.append(d) + return defer.gatherResults(deferreds, consumeErrors=True) + + # + # operations on individual messages + # + + #FIXME: @deferred_to_thread + def _decrypt_doc(self, doc): + """ + Decrypt the contents of a document. + + :param doc: A document containing an encrypted message. + :type doc: SoledadDocument + + :return: A Deferred that will be fired with the document and the + decrypted message. + :rtype: SoledadDocument, str + """ + log.msg('decrypting msg') + + def process_decrypted(res): + if isinstance(res, tuple): + decrdata, _ = res + success = True + else: + decrdata = "" + success = False + + leap_events.signal(IMAP_MSG_DECRYPTED, "1" if success else "0") + return self._process_decrypted_doc(doc, decrdata) + + d = self._keymanager.decrypt( + doc.content[ENC_JSON_KEY], + self._userid, OpenPGPKey) + d.addErrback(self._errback) + d.addCallback(process_decrypted) + d.addCallback(lambda data: (doc, data)) + return d + + def _process_decrypted_doc(self, doc, data): + """ + Process a document containing a succesfully decrypted message. + + :param doc: the incoming message + :type doc: SoledadDocument + :param data: the json-encoded, decrypted content of the incoming + message + :type data: str + + :return: a Deferred that will be fired with an str of the proccessed + data. + :rtype: Deferred + """ + log.msg('processing decrypted doc') + + # XXX turn this into an errBack for each one of + # the deferreds that would process an individual document + try: + msg = json_loads(data) + except UnicodeError as exc: + logger.error("Error while decrypting %s" % (doc.doc_id,)) + logger.exception(exc) + + # we flag the message as "with decrypting errors", + # to avoid further decryption attempts during sync + # cycles until we're prepared to deal with that. + # What is the same, when Ivan deals with it... + # A new decrypting attempt event could be triggered by a + # future a library upgrade, or a cli flag to the client, + # we just `defer` that for now... :) + doc.content[fields.ERROR_DECRYPTING_KEY] = True + deferLater(reactor, 0, self._update_incoming_message, doc) + + # FIXME this is just a dirty hack to delay the proper + # deferred organization here... + # and remember, boys, do not do this at home. + return [] + + if not isinstance(msg, dict): + defer.returnValue(False) + if not msg.get(fields.INCOMING_KEY, False): + defer.returnValue(False) + + # ok, this is an incoming message + rawmsg = msg.get(self.CONTENT_KEY, None) + if not rawmsg: + return "" + return self._maybe_decrypt_msg(rawmsg) + + @deferred_to_thread + def _update_incoming_message(self, doc): + """ + Do a put for a soledad document. This probably has been called only + in the case that we've needed to update the ERROR_DECRYPTING_KEY + flag in an incoming message, to get it out of the decrypting queue. + + :param doc: the SoledadDocument to update + :type doc: SoledadDocument + """ + log.msg("Updating SoledadDoc %s" % (doc.doc_id)) + self._soledad.put_doc(doc) + + @deferred_to_thread + def _delete_incoming_message(self, doc): + """ + Delete document. + + :param doc: the SoledadDocument to delete + :type doc: SoledadDocument + """ + log.msg("Deleting Incoming message: %s" % (doc.doc_id,)) + self._soledad.delete_doc(doc) + + def _maybe_decrypt_msg(self, data): + """ + Tries to decrypt a gpg message if data looks like one. + + :param data: the text to be decrypted. + :type data: str + + :return: a Deferred that will be fired with an str of data, possibly + decrypted. + :rtype: Deferred + """ + leap_assert_type(data, str) + log.msg('maybe decrypting doc') + + # parse the original message + encoding = get_email_charset(data) + msg = self._parser.parsestr(data) + + fromHeader = msg.get('from', None) + senderAddress = None + if (fromHeader is not None + and (msg.get_content_type() == MULTIPART_ENCRYPTED + or msg.get_content_type() == MULTIPART_SIGNED)): + senderAddress = parseaddr(fromHeader) + + def add_leap_header(ret): + decrmsg, signkey = ret + if (senderAddress is None or + isinstance(signkey, keymanager_errors.KeyNotFound)): + decrmsg.add_header( + self.LEAP_SIGNATURE_HEADER, + self.LEAP_SIGNATURE_COULD_NOT_VERIFY) + elif isinstance(signkey, keymanager_errors.InvalidSignature): + decrmsg.add_header( + self.LEAP_SIGNATURE_HEADER, + self.LEAP_SIGNATURE_INVALID) + else: + decrmsg.add_header( + self.LEAP_SIGNATURE_HEADER, + self.LEAP_SIGNATURE_VALID, + pubkey=signkey.key_id) + return decrmsg.as_string() + + if msg.get_content_type() == MULTIPART_ENCRYPTED: + d = self._decrypt_multipart_encrypted_msg( + msg, encoding, senderAddress) + else: + d = self._maybe_decrypt_inline_encrypted_msg( + msg, encoding, senderAddress) + d.addCallback(add_leap_header) + return d + + def _decrypt_multipart_encrypted_msg(self, msg, encoding, senderAddress): + """ + Decrypt a message with content-type 'multipart/encrypted'. + + :param msg: The original encrypted message. + :type msg: Message + :param encoding: The encoding of the email message. + :type encoding: str + :param senderAddress: The email address of the sender of the message. + :type senderAddress: str + + :return: A Deferred that will be fired with a tuple containing a + decrypted Message and the signing OpenPGPKey if the signature + is valid or InvalidSignature or KeyNotFound. + :rtype: Deferred + """ + log.msg('decrypting multipart encrypted msg') + msg = copy.deepcopy(msg) + self._msg_multipart_sanity_check(msg) + + # parse message and get encrypted content + pgpencmsg = msg.get_payload()[1] + encdata = pgpencmsg.get_payload() + + # decrypt or fail gracefully + def build_msg(res): + decrdata, signkey = res + + decrmsg = self._parser.parsestr(decrdata) + # remove original message's multipart/encrypted content-type + del(msg['content-type']) + + # replace headers back in original message + for hkey, hval in decrmsg.items(): + try: + # this will raise KeyError if header is not present + msg.replace_header(hkey, hval) + except KeyError: + msg[hkey] = hval + + # all ok, replace payload by unencrypted payload + msg.set_payload(decrmsg.get_payload()) + return (msg, signkey) + + d = self._keymanager.decrypt( + encdata, self._userid, OpenPGPKey, + verify=senderAddress) + d.addCallbacks(build_msg, self._decryption_error, errbackArgs=(msg,)) + return d + + def _maybe_decrypt_inline_encrypted_msg(self, origmsg, encoding, + senderAddress): + """ + Possibly decrypt an inline OpenPGP encrypted message. + + :param origmsg: The original, possibly encrypted message. + :type origmsg: Message + :param encoding: The encoding of the email message. + :type encoding: str + :param senderAddress: The email address of the sender of the message. + :type senderAddress: str + + :return: A Deferred that will be fired with a tuple containing a + decrypted Message and the signing OpenPGPKey if the signature + is valid or InvalidSignature or KeyNotFound. + :rtype: Deferred + """ + log.msg('maybe decrypting inline encrypted msg') + # serialize the original message + buf = StringIO() + g = Generator(buf) + g.flatten(origmsg) + data = buf.getvalue() + + def decrypted_data(res): + decrdata, signkey = res + return data.replace(pgp_message, decrdata), signkey + + def encode_and_return(res): + data, signkey = res + if isinstance(data, unicode): + data = data.encode(encoding, 'replace') + return (self._parser.parsestr(data), signkey) + + # handle exactly one inline PGP message + if PGP_BEGIN in data: + begin = data.find(PGP_BEGIN) + end = data.find(PGP_END) + pgp_message = data[begin:end + len(PGP_END)] + d = self._keymanager.decrypt( + pgp_message, self._userid, OpenPGPKey, + verify=senderAddress) + d.addCallbacks(decrypted_data, self._decryption_error, + errbackArgs=(data,)) + else: + d = defer.succeed((data, None)) + d.addCallback(encode_and_return) + return d + + def _decryption_error(self, failure, msg): + """ + Check for known decryption errors + """ + if failure.check(keymanager_errors.DecryptError): + logger.warning('Failed to decrypt encrypted message (%s). ' + 'Storing message without modifications.' + % str(failure.value)) + return (msg, None) + elif failure.check(keymanager_errors.KeyNotFound): + logger.error('Failed to find private key for decryption (%s). ' + 'Storing message without modifications.' + % str(failure.value)) + return (msg, None) + else: + return failure + + def _extract_keys(self, msgtuple): + """ + Retrieve attached keys to the mesage and parse message headers for an + *OpenPGP* header as described on the `IETF draft + <http://tools.ietf.org/html/draft-josefsson-openpgp-mailnews-header-06>` + only urls with https and the same hostname than the email are supported + for security reasons. + + :param msgtuple: a tuple consisting of a SoledadDocument + instance containing the incoming message + and data, the json-encoded, decrypted content of the + incoming message + :type msgtuple: (SoledadDocument, str) + + :return: A Deferred that will be fired with msgtuple when key + extraction finishes + :rtype: Deferred + """ + OpenPGP_HEADER = 'OpenPGP' + doc, data = msgtuple + + # XXX the parsing of the message is done in mailbox.addMessage, maybe + # we should do it in this module so we don't need to parse it again + # here + msg = self._parser.parsestr(data) + _, fromAddress = parseaddr(msg['from']) + + header = msg.get(OpenPGP_HEADER, None) + dh = defer.succeed(None) + if header is not None: + dh = self._extract_openpgp_header(header, fromAddress) + + da = defer.succeed(None) + if msg.is_multipart(): + da = self._extract_attached_key(msg.get_payload(), fromAddress) + + d = defer.gatherResults([dh, da]) + d.addCallback(lambda _: msgtuple) + return d + + def _extract_openpgp_header(self, header, address): + """ + Import keys from the OpenPGP header + + :param header: OpenPGP header string + :type header: str + :param address: email address in the from header + :type address: str + + :return: A Deferred that will be fired when header extraction is done + :rtype: Deferred + """ + d = defer.succeed(None) + fields = dict([f.strip(' ').split('=') for f in header.split(';')]) + if 'url' in fields: + url = shlex.split(fields['url'])[0] # remove quotations + urlparts = urlparse(url) + addressHostname = address.split('@')[1] + if (urlparts.scheme == 'https' + and urlparts.hostname == addressHostname): + def fetch_error(failure): + if failure.check(keymanager_errors.KeyNotFound): + logger.warning("Url from OpenPGP header %s failed" + % (url,)) + elif failure.check(keymanager_errors.KeyAttributesDiffer): + logger.warning("Key from OpenPGP header url %s didn't " + "match the from address %s" + % (url, address)) + else: + return failure + + d = self._keymanager.fetch_key(address, url, OpenPGPKey) + d.addCallback( + lambda _: + logger.info("Imported key from header %s" % (url,))) + d.addErrback(fetch_error) + else: + logger.debug("No valid url on OpenPGP header %s" % (url,)) + else: + logger.debug("There is no url on the OpenPGP header: %s" + % (header,)) + return d + + def _extract_attached_key(self, attachments, address): + """ + Import keys from the attachments + + :param attachments: email attachment list + :type attachments: list(email.Message) + :param address: email address in the from header + :type address: str + + :return: A Deferred that will be fired when all the keys are stored + :rtype: Deferred + """ + MIME_KEY = "application/pgp-keys" + + deferreds = [] + for attachment in attachments: + if MIME_KEY == attachment.get_content_type(): + logger.debug("Add key from attachment") + d = self._keymanager.put_raw_key( + attachment.get_payload(), + OpenPGPKey, + address=address) + deferreds.append(d) + return defer.gatherResults(deferreds) + + def _add_message_locally(self, msgtuple): + """ + Adds a message to local inbox and delete it from the incoming db + in soledad. + + :param msgtuple: a tuple consisting of a SoledadDocument + instance containing the incoming message + and data, the json-encoded, decrypted content of the + incoming message + :type msgtuple: (SoledadDocument, str) + + :return: A Deferred that will be fired when the messages is stored + :rtype: Defferred + """ + doc, data = msgtuple + log.msg('adding message %s to local db' % (doc.doc_id,)) + + if isinstance(data, list): + if empty(data): + return False + data = data[0] + + def msgSavedCallback(result): + if not empty(result): + leap_events.signal(IMAP_MSG_SAVED_LOCALLY) + deferLater(reactor, 0, self._delete_incoming_message, doc) + leap_events.signal(IMAP_MSG_DELETED_INCOMING) + + d = self._inbox.addMessage(data, (self.RECENT_FLAG,)) + d.addCallbacks(msgSavedCallback, self._errback) + return d + + # + # helpers + # + + def _msg_multipart_sanity_check(self, msg): + """ + Performs a sanity check against a multipart encrypted msg + + :param msg: The original encrypted message. + :type msg: Message + """ + # sanity check + payload = msg.get_payload() + if len(payload) != 2: + raise MalformedMessage( + 'Multipart/encrypted messages should have exactly 2 body ' + 'parts (instead of %d).' % len(payload)) + if payload[0].get_content_type() != 'application/pgp-encrypted': + raise MalformedMessage( + "Multipart/encrypted messages' first body part should " + "have content type equal to 'application/pgp-encrypted' " + "(instead of %s)." % payload[0].get_content_type()) + if payload[1].get_content_type() != 'application/octet-stream': + raise MalformedMessage( + "Multipart/encrypted messages' second body part should " + "have content type equal to 'octet-stream' (instead of " + "%s)." % payload[1].get_content_type()) + + def _is_msg(self, keys): + """ + Checks if the keys of a dictionary match the signature + of the document type we use for messages. + + :param keys: iterable containing the strings to match. + :type keys: iterable of strings. + :rtype: bool + """ + return ENC_SCHEME_KEY in keys and ENC_JSON_KEY in keys |