libervia-backend/libervia/backend/plugins/plugin_xep_0477.py

#!/usr/bin/env python3

# Libervia plugin for Pubsub Targeted Encryption
# Copyright (C) 2009-2026 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 typing import Any, Dict, List, Optional

from twisted.internet import defer
from twisted.words.protocols.jabber import jid, xmlstream
from twisted.words.xish import domish
from tx_xmpp import disco, itx_xmpp
from tx_xmpp import rsm
from zope.interface import implementer

from libervia.backend.core import exceptions
from libervia.backend.core.constants import Const as C
from libervia.backend.core.core_types import SatXMPPEntity
from libervia.backend.core.i18n import _
from libervia.backend.core.log import getLogger

log = getLogger(__name__)

IMPORT_NAME = "XEP-0477"

PLUGIN_INFO = {
    C.PI_NAME: "Pubsub Targeted Encryption",
    C.PI_IMPORT_NAME: IMPORT_NAME,
    C.PI_TYPE: C.PLUG_TYPE_XEP,
    C.PI_MODES: C.PLUG_MODE_BOTH,
    C.PI_PROTOCOLS: [],
    C.PI_DEPENDENCIES: ["XEP-0060", "XEP-0384"],
    C.PI_MAIN: "XEP_0477",
    C.PI_HANDLER: "yes",
    C.PI_DESCRIPTION: _("""Encrypt some items to specific entities"""),
}
NS_PTE = "urn:xmpp:pte:0"


class XEP_0477:
    namespace = NS_PTE

    def __init__(self, host):
        log.info(_("Pubsub Targeted Encryption plugin initialization"))
        host.register_namespace("pte", NS_PTE)
        self.host = host
        self._o = host.plugins["XEP-0384"]
        host.trigger.add("XEP-0060_publish", self._publish_trigger)
        host.trigger.add("XEP-0060_items", self._items_trigger)

    def get_handler(self, client):
        return XEP_0477_Handler()

    async def _publish_trigger(
        self,
        client: SatXMPPEntity,
        service: jid.JID,
        node: str,
        items: Optional[List[domish.Element]],
        options: Optional[dict],
        sender: jid.JID,
        extra: Dict[str, Any],
    ) -> bool:
        if not items or extra.get("encrypted_for") is None:
            return True
        encrypt_data = extra["encrypted_for"]
        try:
            targets = {jid.JID(t) for t in encrypt_data["targets"]}
        except (KeyError, RuntimeError):
            raise exceptions.DataError(f"Invalid encryption data: {encrypt_data}")
        for item in items:
            log.debug(
                f"encrypting item {item.getAttribute('id', '')} for "
                f"{', '.join(t.full() for t in targets)}"
            )
            encryption_type = encrypt_data.get("type", self._o.NS_TWOMEMO)
            if encryption_type != self._o.NS_TWOMEMO:
                raise NotImplementedError("only TWOMEMO is supported for now")
            await self._o.encrypt(
                client,
                self._o.NS_TWOMEMO,
                item,
                targets,
                is_muc_message=False,
                stanza_id=None,
            )
            item_elts = list(item.elements())
            if len(item_elts) != 1:
                raise ValueError(
                    f"there should be exactly one item payload: {item.toXml()}"
                )
            encrypted_payload = item_elts[0]
            item.children.clear()
            encrypted_elt = item.addElement((NS_PTE, "encrypted"))
            encrypted_elt["by"] = sender.userhost()
            encrypted_elt["type"] = encryption_type
            encrypted_elt.addChild(encrypted_payload)

        return True

    async def _items_trigger(
        self,
        client: SatXMPPEntity,
        service: Optional[jid.JID],
        node: str,
        items: List[domish.Element],
        rsm_response: rsm.RSMResponse,
        extra: Dict[str, Any],
    ) -> bool:
        if not extra.get(C.KEY_DECRYPT, True):
            return True
        if service is None:
            service = client.jid.userhostJID()
        for item in items:
            payload = item.firstChildElement()
            if (
                payload is not None
                and payload.name == "encrypted"
                and payload.uri == NS_PTE
            ):
                encrypted_elt = payload
                item.children.clear()
                try:
                    encryption_type = encrypted_elt.getAttribute("type")
                    encrypted_by = jid.JID(encrypted_elt["by"])
                except (KeyError, RuntimeError):
                    raise exceptions.DataError(
                        f"invalid <encrypted> element: {encrypted_elt.toXml()}"
                    )
                if encryption_type != self._o.NS_TWOMEMO:
                    raise NotImplementedError("only TWOMEMO is supported for now")
                log.debug(f"decrypting item {item.getAttribute('id', '')}")

                # FIXME: we do use _message_received_trigger now to decrypt the stanza, a
                #   cleaner separated decrypt method should be used
                encrypted_elt["from"] = encrypted_by.full()
                if (
                    not await self._o._message_received_trigger(
                        client, encrypted_elt, defer.Deferred()
                    )
                    or not encrypted_elt.children
                ):
                    raise exceptions.EncryptionError("can't decrypt the message")

                item.addChild(encrypted_elt.firstChildElement())

                extra.setdefault("encrypted", {})[item["id"]] = {
                    "type": NS_PTE,
                    "algorithm": encryption_type,
                }
        return True


@implementer(itx_xmpp.IDisco)
class XEP_0477_Handler(xmlstream.XMPPHandler):

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

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