--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/plugins/plugin_xep_0300.py	Mon Apr 02 19:44:50 2018 +0200
@@ -0,0 +1,212 @@
+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+# SAT plugin for Hash functions (XEP-0300)
+# Copyright (C) 2009-2018 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 implements
+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 = u"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((
+            (u'md5', hashlib.md5),
+            (u'sha-1', hashlib.sha1),
+            (u'sha-256', hashlib.sha256),
+            (u'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(u"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(callable): the method to call to initialise hash object
+        @return (str): the hex digest of the hash
+        """
+        hash_ = hasher()
+        while True:
+            buf = file_obj.read(BUFFER_SIZE)
+            if not buf:
+                break
+            hash_.update(buf)
+        return hash_.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.ALGOS[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[u'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:
+            hash_elt.addContent(base64.b64encode(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[unicode, str]): (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 = 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(u"Proposed {} algorithm is not managed".format(algo))
+                algo = None
+                continue
+
+            if best_algo is None or algos.index(best_algo) < idx:
+                best_algo = algo
+                best_value = base64.b64decode(unicode(hash_elt))
+
+        if not hash_elt:
+            raise exceptions.NotFound
+        if not best_algo or not best_value:
+            raise exceptions.DataError
+        return best_algo, best_value
+
+
+class XEP_0300_handler(XMPPHandler):
+    implements(iwokkel.IDisco)
+
+    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 []