Mercurial > libervia-backend
view sat/plugins/plugin_xep_0300.py @ 3319:3a15e76a694e
core (memory): `setFileAccessModel` implementation:
this method let change read permission using access model similar to what is used with
Pubsub.
author | Goffi <goffi@goffi.org> |
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date | Sat, 01 Aug 2020 16:07:39 +0200 |
parents | ddf3ded93b78 |
children | be6d91572633 |
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#!/usr/bin/env python3 # SAT plugin for Hash functions (XEP-0300) # Copyright (C) 2009-2020 Jérôme Poisson (goffi@goffi.org) # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU Affero 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 Affero General Public License for more details. # You should have received a copy of the GNU Affero General Public License # along with this program. If not, see <http://www.gnu.org/licenses/>. from sat.core.i18n import _ from sat.core.constants import Const as C from sat.core.log import getLogger log = getLogger(__name__) from sat.core import exceptions from twisted.words.xish import domish from twisted.words.protocols.jabber.xmlstream import XMPPHandler from twisted.internet import threads from twisted.internet import defer from zope.interface import implementer from wokkel import disco, iwokkel from collections import OrderedDict import hashlib import base64 PLUGIN_INFO = { C.PI_NAME: "Cryptographic Hash Functions", C.PI_IMPORT_NAME: "XEP-0300", C.PI_TYPE: "XEP", C.PI_MODES: C.PLUG_MODE_BOTH, C.PI_PROTOCOLS: ["XEP-0300"], C.PI_MAIN: "XEP_0300", C.PI_HANDLER: "yes", C.PI_DESCRIPTION: _("""Management of cryptographic hashes"""), } NS_HASHES = "urn:xmpp:hashes:2" NS_HASHES_FUNCTIONS = "urn:xmpp:hash-function-text-names:{}" BUFFER_SIZE = 2 ** 12 ALGO_DEFAULT = "sha-256" class XEP_0300(object): # TODO: add blake after moving to Python 3 ALGOS = OrderedDict( ( ("md5", hashlib.md5), ("sha-1", hashlib.sha1), ("sha-256", hashlib.sha256), ("sha-512", hashlib.sha512), ) ) def __init__(self, host): log.info(_("plugin Hashes initialization")) host.registerNamespace("hashes", NS_HASHES) def getHandler(self, client): return XEP_0300_handler() def getHasher(self, algo=ALGO_DEFAULT): """Return hasher instance @param algo(unicode): one of the XEP_300.ALGOS keys @return (hash object): same object s in hashlib. update method need to be called for each chunh diget or hexdigest can be used at the end """ return self.ALGOS[algo]() def getDefaultAlgo(self): return ALGO_DEFAULT @defer.inlineCallbacks def getBestPeerAlgo(self, to_jid, profile): """Return the best available hashing algorith of other peer @param to_jid(jid.JID): peer jid @parm profile: %(doc_profile)s @return (D(unicode, None)): best available algorithm, or None if hashing is not possible """ client = self.host.getClient(profile) for algo in reversed(XEP_0300.ALGOS): has_feature = yield self.host.hasFeature( client, NS_HASHES_FUNCTIONS.format(algo), to_jid ) if has_feature: log.debug( "Best hashing algorithm found for {jid}: {algo}".format( jid=to_jid.full(), algo=algo ) ) defer.returnValue(algo) def _calculateHashBlocking(self, file_obj, hasher): """Calculate hash in a blocking way /!\\ blocking method, please use calculateHash instead @param file_obj(file): a file-like object @param hasher(hash object): the method to call to initialise hash object @return (str): the hex digest of the hash """ while True: buf = file_obj.read(BUFFER_SIZE) if not buf: break hasher.update(buf) return hasher.hexdigest() def calculateHash(self, file_obj, hasher): return threads.deferToThread(self._calculateHashBlocking, file_obj, hasher) def calculateHashElt(self, file_obj=None, algo=ALGO_DEFAULT): """Compute hash and build hash element @param file_obj(file, None): file-like object to use to calculate the hash @param algo(unicode): algorithme to use, must be a key of XEP_0300.ALGOS @return (D(domish.Element)): hash element """ def hashCalculated(hash_): return self.buildHashElt(hash_, algo) hasher = self.getHasher(algo) hash_d = self.calculateHash(file_obj, hasher) hash_d.addCallback(hashCalculated) return hash_d def buildHashUsedElt(self, algo=ALGO_DEFAULT): hash_used_elt = domish.Element((NS_HASHES, "hash-used")) hash_used_elt["algo"] = algo return hash_used_elt def parseHashUsedElt(self, parent): """Find and parse a hash-used element @param (domish.Element): parent of <hash/> element @return (unicode): hash algorithm used @raise exceptions.NotFound: the element is not present @raise exceptions.DataError: the element is invalid """ try: hash_used_elt = next(parent.elements(NS_HASHES, "hash-used")) except StopIteration: raise exceptions.NotFound algo = hash_used_elt["algo"] if not algo: raise exceptions.DataError return algo def buildHashElt(self, hash_, algo=ALGO_DEFAULT): """Compute hash and build hash element @param hash_(str): hash to use @param algo(unicode): algorithme to use, must be a key of XEP_0300.ALGOS @return (domish.Element): computed hash """ assert hash_ assert algo hash_elt = domish.Element((NS_HASHES, "hash")) if hash_ is not None: b64_hash = base64.b64encode(hash_.encode('utf-8')).decode('utf-8') hash_elt.addContent(b64_hash) hash_elt["algo"] = algo return hash_elt def parseHashElt(self, parent): """Find and parse a hash element if multiple elements are found, the strongest managed one is returned @param (domish.Element): parent of <hash/> element @return (tuple[str, bytes]): (algo, hash) tuple both values can be None if <hash/> is empty @raise exceptions.NotFound: the element is not present @raise exceptions.DataError: the element is invalid """ algos = list(XEP_0300.ALGOS.keys()) hash_elt = None best_algo = None best_value = None for hash_elt in parent.elements(NS_HASHES, "hash"): algo = hash_elt.getAttribute("algo") try: idx = algos.index(algo) except ValueError: log.warning(f"Proposed {algo} algorithm is not managed") algo = None continue if best_algo is None or algos.index(best_algo) < idx: best_algo = algo best_value = base64.b64decode(str(hash_elt)).decode('utf-8') if not hash_elt: raise exceptions.NotFound if not best_algo or not best_value: raise exceptions.DataError return best_algo, best_value @implementer(iwokkel.IDisco) class XEP_0300_handler(XMPPHandler): def getDiscoInfo(self, requestor, target, nodeIdentifier=""): hash_functions_names = [ disco.DiscoFeature(NS_HASHES_FUNCTIONS.format(algo)) for algo in XEP_0300.ALGOS ] return [disco.DiscoFeature(NS_HASHES)] + hash_functions_names def getDiscoItems(self, requestor, target, nodeIdentifier=""): return []