view sat/plugins/plugin_xep_0071.py @ 3231:e756e0eb1be4

core (memory/encryption): automatic start encryption if peer send encrypted message: If peer sends encrypted message and we have no encryption activated, we automatically start encryption to avoid sending plain text message when answering. markAsEncrypted now needs the encryption algorithm namespace as mandatory argument.
author Goffi <goffi@goffi.org>
date Mon, 23 Mar 2020 17:52:18 +0100
parents dcebc585c29f
children be6d91572633
line wrap: on
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#!/usr/bin/env python3


# SAT plugin for Publish-Subscribe (xep-0071)
# 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 import exceptions
from sat.core.log import getLogger

log = getLogger(__name__)
from sat.tools.common import data_format

from twisted.internet import defer
from wokkel import disco, iwokkel
from zope.interface import implementer

# from lxml import etree
try:
    from lxml import html
except ImportError:
    raise exceptions.MissingModule(
        "Missing module lxml, please download/install it from http://lxml.de/"
    )
try:
    from twisted.words.protocols.xmlstream import XMPPHandler
except ImportError:
    from wokkel.subprotocols import XMPPHandler

NS_XHTML_IM = "http://jabber.org/protocol/xhtml-im"
NS_XHTML = "http://www.w3.org/1999/xhtml"

PLUGIN_INFO = {
    C.PI_NAME: "XHTML-IM Plugin",
    C.PI_IMPORT_NAME: "XEP-0071",
    C.PI_TYPE: "XEP",
    C.PI_PROTOCOLS: ["XEP-0071"],
    C.PI_DEPENDENCIES: ["TEXT_SYNTAXES"],
    C.PI_MAIN: "XEP_0071",
    C.PI_HANDLER: "yes",
    C.PI_DESCRIPTION: _("""Implementation of XHTML-IM"""),
}

allowed = {
    "a": set(["href", "style", "type"]),
    "blockquote": set(["style"]),
    "body": set(["style"]),
    "br": set([]),
    "cite": set(["style"]),
    "em": set([]),
    "img": set(["alt", "height", "src", "style", "width"]),
    "li": set(["style"]),
    "ol": set(["style"]),
    "p": set(["style"]),
    "span": set(["style"]),
    "strong": set([]),
    "ul": set(["style"]),
}

styles_allowed = [
    "background-color",
    "color",
    "font-family",
    "font-size",
    "font-style",
    "font-weight",
    "margin-left",
    "margin-right",
    "text-align",
    "text-decoration",
]

blacklist = ["script"]  # tag that we have to kill (we don't keep content)


class XEP_0071(object):
    SYNTAX_XHTML_IM = "XHTML-IM"

    def __init__(self, host):
        log.info(_("XHTML-IM plugin initialization"))
        self.host = host
        self._s = self.host.plugins["TEXT_SYNTAXES"]
        self._s.addSyntax(
            self.SYNTAX_XHTML_IM,
            lambda xhtml: xhtml,
            self.XHTML2XHTML_IM,
            [self._s.OPT_HIDDEN],
        )
        host.trigger.add("messageReceived", self.messageReceivedTrigger)
        host.trigger.add("sendMessage", self.sendMessageTrigger)

    def getHandler(self, client):
        return XEP_0071_handler(self)

    def _messagePostTreat(self, data, message_elt, body_elts, client):
        """Callback which manage the post treatment of the message in case of XHTML-IM found

        @param data: data send by messageReceived trigger through post_treat deferred
        @param message_elt: whole <message> stanza
        @param body_elts: XHTML-IM body elements found
        @return: the data with the extra parameter updated
        """
        # TODO: check if text only body is empty, then try to convert XHTML-IM to pure text and show a warning message
        def converted(xhtml, lang):
            if lang:
                data["extra"]["xhtml_{}".format(lang)] = xhtml
            else:
                data["extra"]["xhtml"] = xhtml

        defers = []
        for body_elt in body_elts:
            lang = body_elt.getAttribute((C.NS_XML, "lang"), "")
            treat_d = defer.succeed(None)  #  deferred used for treatments
            if self.host.trigger.point(
                "xhtml_post_treat", client, message_elt, body_elt, lang, treat_d
            ):
                continue
            treat_d.addCallback(
                lambda __: self._s.convert(
                    body_elt.toXml(), self.SYNTAX_XHTML_IM, safe=True
                )
            )
            treat_d.addCallback(converted, lang)
            defers.append(treat_d)

        d_list = defer.DeferredList(defers)
        d_list.addCallback(lambda __: data)
        return d_list

    def _fill_body_text(self, text, data, lang):
        data["message"][lang or ""] = text
        message_elt = data["xml"]
        body_elt = message_elt.addElement("body", content=text)
        if lang:
            body_elt[(C.NS_XML, "lang")] = lang

    def _check_body_text(self, data, lang, markup, syntax, defers):
        """check if simple text message exists, and fill if needed"""
        if not (lang or "") in data["message"]:
            d = self._s.convert(markup, syntax, self._s.SYNTAX_TEXT)
            d.addCallback(self._fill_body_text, data, lang)
            defers.append(d)

    def _sendMessageAddRich(self, data, client):
        """ Construct XHTML-IM node and add it XML element

        @param data: message data as sended by sendMessage callback
        """
        # at this point, either ['extra']['rich'] or ['extra']['xhtml'] exists
        # but both can't exist at the same time
        message_elt = data["xml"]
        html_elt = message_elt.addElement((NS_XHTML_IM, "html"))

        def syntax_converted(xhtml_im, lang):
            body_elt = html_elt.addElement((NS_XHTML, "body"))
            if lang:
                body_elt[(C.NS_XML, "lang")] = lang
                data["extra"]["xhtml_{}".format(lang)] = xhtml_im
            else:
                data["extra"]["xhtml"] = xhtml_im
            body_elt.addRawXml(xhtml_im)

        syntax = self._s.getCurrentSyntax(client.profile)
        defers = []
        if "xhtml" in data["extra"]:
            # we have directly XHTML
            for lang, xhtml in data_format.getSubDict("xhtml", data["extra"]):
                self._check_body_text(data, lang, xhtml, self._s.SYNTAX_XHTML, defers)
                d = self._s.convert(xhtml, self._s.SYNTAX_XHTML, self.SYNTAX_XHTML_IM)
                d.addCallback(syntax_converted, lang)
                defers.append(d)
        elif "rich" in data["extra"]:
            # we have rich syntax to convert
            for lang, rich_data in data_format.getSubDict("rich", data["extra"]):
                self._check_body_text(data, lang, rich_data, syntax, defers)
                d = self._s.convert(rich_data, syntax, self.SYNTAX_XHTML_IM)
                d.addCallback(syntax_converted, lang)
                defers.append(d)
        else:
            exceptions.InternalError("xhtml or rich should be present at this point")
        d_list = defer.DeferredList(defers)
        d_list.addCallback(lambda __: data)
        return d_list

    def messageReceivedTrigger(self, client, message, post_treat):
        """ Check presence of XHTML-IM in message
        """
        try:
            html_elt = next(message.elements(NS_XHTML_IM, "html"))
        except StopIteration:
            # No XHTML-IM
            pass
        else:
            body_elts = html_elt.elements(NS_XHTML, "body")
            post_treat.addCallback(self._messagePostTreat, message, body_elts, client)
        return True

    def sendMessageTrigger(self, client, data, pre_xml_treatments, post_xml_treatments):
        """ Check presence of rich text in extra """
        rich = {}
        xhtml = {}
        for key, value in data["extra"].items():
            if key.startswith("rich"):
                rich[key[5:]] = value
            elif key.startswith("xhtml"):
                xhtml[key[6:]] = value
        if rich and xhtml:
            raise exceptions.DataError(
                _("Can't have XHTML and rich content at the same time")
            )
        if rich or xhtml:
            if rich:
                data["rich"] = rich
            else:
                data["xhtml"] = xhtml
            post_xml_treatments.addCallback(self._sendMessageAddRich, client)
        return True

    def _purgeStyle(self, styles_raw):
        """ Remove unauthorised styles according to the XEP-0071
        @param styles_raw: raw styles (value of the style attribute)
        """
        purged = []

        styles = [style.strip().split(":") for style in styles_raw.split(";")]

        for style_tuple in styles:
            if len(style_tuple) != 2:
                continue
            name, value = style_tuple
            name = name.strip()
            if name not in styles_allowed:
                continue
            purged.append((name, value.strip()))

        return "; ".join(["%s: %s" % data for data in purged])

    def XHTML2XHTML_IM(self, xhtml):
        """ Convert XHTML document to XHTML_IM subset
        @param xhtml: raw xhtml to convert
        """
        # TODO: more clever tag replacement (replace forbidden tags with equivalents when possible)

        parser = html.HTMLParser(remove_comments=True, encoding="utf-8")
        root = html.fromstring(xhtml, parser=parser)
        body_elt = root.find("body")
        if body_elt is None:
            # we use the whole XML as body if no body element is found
            body_elt = html.Element("body")
            body_elt.append(root)
        else:
            body_elt.attrib.clear()

        allowed_tags = list(allowed.keys())
        to_strip = []
        for elem in body_elt.iter():
            if elem.tag not in allowed_tags:
                to_strip.append(elem)
            else:
                # we remove unallowed attributes
                attrib = elem.attrib
                att_to_remove = set(attrib).difference(allowed[elem.tag])
                for att in att_to_remove:
                    del (attrib[att])
                if "style" in attrib:
                    attrib["style"] = self._purgeStyle(attrib["style"])

        for elem in to_strip:
            if elem.tag in blacklist:
                # we need to remove the element and all descendants
                log.debug("removing black listed tag: %s" % (elem.tag))
                elem.drop_tree()
            else:
                elem.drop_tag()
        if len(body_elt) != 1:
            root_elt = body_elt
            body_elt.tag = "p"
        else:
            root_elt = body_elt[0]

        return html.tostring(root_elt, encoding="unicode", method="xml")


@implementer(iwokkel.IDisco)
class XEP_0071_handler(XMPPHandler):

    def __init__(self, plugin_parent):
        self.plugin_parent = plugin_parent
        self.host = plugin_parent.host

    def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
        return [disco.DiscoFeature(NS_XHTML_IM)]

    def getDiscoItems(self, requestor, target, nodeIdentifier=""):
        return []