--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libervia/backend/plugins/plugin_comp_file_sharing.py	Fri Jun 02 11:49:51 2023 +0200
@@ -0,0 +1,884 @@
+#!/usr/bin/env python3
+
+# Libervia File Sharing component
+# Copyright (C) 2009-2021 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/>.
+
+import os
+import os.path
+import mimetypes
+import tempfile
+from functools import partial
+import shortuuid
+import unicodedata
+from urllib.parse import urljoin, urlparse, quote, unquote
+from pathlib import Path
+from libervia.backend.core.i18n import _, D_
+from libervia.backend.core.constants import Const as C
+from libervia.backend.core import exceptions
+from libervia.backend.core.log import getLogger
+from libervia.backend.tools import stream
+from libervia.backend.tools import video
+from libervia.backend.tools.utils import ensure_deferred
+from libervia.backend.tools.common import regex
+from libervia.backend.tools.common import uri
+from libervia.backend.tools.common import files_utils
+from libervia.backend.tools.common import utils
+from libervia.backend.tools.common import tls
+from twisted.internet import defer, reactor
+from twisted.words.protocols.jabber import error
+from twisted.web import server, resource, static, http
+from wokkel import pubsub
+from wokkel import generic
+
+
+log = getLogger(__name__)
+
+
+PLUGIN_INFO = {
+    C.PI_NAME: "File sharing component",
+    C.PI_IMPORT_NAME: "file-sharing",
+    C.PI_MODES: [C.PLUG_MODE_COMPONENT],
+    C.PI_TYPE: C.PLUG_TYPE_ENTRY_POINT,
+    C.PI_PROTOCOLS: [],
+    C.PI_DEPENDENCIES: [
+        "FILE",
+        "FILE_SHARING_MANAGEMENT",
+        "XEP-0106",
+        "XEP-0234",
+        "XEP-0260",
+        "XEP-0261",
+        "XEP-0264",
+        "XEP-0329",
+        "XEP-0363",
+    ],
+    C.PI_RECOMMENDATIONS: [],
+    C.PI_MAIN: "FileSharing",
+    C.PI_HANDLER: C.BOOL_TRUE,
+    C.PI_DESCRIPTION: _("""Component hosting and sharing files"""),
+}
+
+HASH_ALGO = "sha-256"
+NS_COMMENTS = "org.salut-a-toi.comments"
+NS_FS_AFFILIATION = "org.salut-a-toi.file-sharing-affiliation"
+COMMENT_NODE_PREFIX = "org.salut-a-toi.file_comments/"
+# Directory used to buffer request body (i.e. file in case of PUT) we use more than one @
+# there, to be sure than it's not conflicting with a JID
+TMP_BUFFER_DIR = "@@tmp@@"
+OVER_QUOTA_TXT = D_(
+    "You are over quota, your maximum allowed size is {quota} and you are already using "
+    "{used_space}, you can't upload {file_size} more."
+)
+
+HTTP_VERSION = unicodedata.normalize(
+    'NFKD',
+    f"{C.APP_NAME} file sharing {C.APP_VERSION}"
+)
+
+
+class HTTPFileServer(resource.Resource):
+    isLeaf = True
+
+    def errorPage(self, request, code):
+        request.setResponseCode(code)
+        if code == http.BAD_REQUEST:
+            brief = 'Bad Request'
+            details = "Your request is invalid"
+        elif code == http.FORBIDDEN:
+            brief = 'Forbidden'
+            details = "You're not allowed to use this resource"
+        elif code == http.NOT_FOUND:
+            brief = 'Not Found'
+            details = "No resource found at this URL"
+        else:
+            brief = 'Error'
+            details = "This resource can't be used"
+            log.error(f"Unexpected return code used: {code}")
+        log.warning(
+            f'Error returned while trying to access url {request.uri.decode()}: '
+            f'"{brief}" ({code}): {details}'
+        )
+
+        return resource.ErrorPage(code, brief, details).render(request)
+
+    def get_disposition_type(self, media_type, media_subtype):
+        if media_type in ('image', 'video'):
+            return 'inline'
+        elif media_type == 'application' and media_subtype == 'pdf':
+            return 'inline'
+        else:
+            return 'attachment'
+
+    def render(self, request):
+        request.setHeader("server", HTTP_VERSION)
+        request.setHeader("Access-Control-Allow-Origin", "*")
+        request.setHeader("Access-Control-Allow-Methods", "OPTIONS, HEAD, GET, PUT")
+        request.setHeader(
+            "Access-Control-Allow-Headers",
+            "Content-Type, Range, Xmpp-File-Path, Xmpp-File-No-Http")
+        request.setHeader("Access-Control-Allow-Credentials", "true")
+        request.setHeader("Accept-Ranges", "bytes")
+
+        request.setHeader(
+            "Access-Control-Expose-Headers",
+            "Date, Content-Length, Content-Range")
+        return super().render(request)
+
+    def render_options(self, request):
+        request.setResponseCode(http.OK)
+        return b""
+
+    def render_GET(self, request):
+        try:
+            request.upload_data
+        except exceptions.DataError:
+            return self.errorPage(request, http.NOT_FOUND)
+
+        defer.ensureDeferred(self.render_get(request))
+        return server.NOT_DONE_YET
+
+    async def render_get(self, request):
+        try:
+            upload_id, filename = request.upload_data
+        except exceptions.DataError:
+            request.write(self.errorPage(request, http.FORBIDDEN))
+            request.finish()
+            return
+        found_files = await request.file_sharing.host.memory.get_files(
+            client=None, peer_jid=None, perms_to_check=None, public_id=upload_id)
+        if not found_files:
+            request.write(self.errorPage(request, http.NOT_FOUND))
+            request.finish()
+            return
+        if len(found_files) > 1:
+            log.error(f"more that one files found for public id {upload_id!r}")
+
+        found_file = found_files[0]
+        file_path = request.file_sharing.files_path/found_file['file_hash']
+        file_res = static.File(file_path)
+        file_res.type = f'{found_file["media_type"]}/{found_file["media_subtype"]}'
+        file_res.encoding = file_res.contentEncodings.get(Path(found_file['name']).suffix)
+        disp_type = self.get_disposition_type(
+            found_file['media_type'], found_file['media_subtype'])
+        # the URL is percent encoded, and not all browsers/tools unquote the file name,
+        # thus we add a content disposition header
+        request.setHeader(
+            'Content-Disposition',
+            f"{disp_type}; filename*=UTF-8''{quote(found_file['name'])}"
+        )
+        # cf. https://xmpp.org/extensions/xep-0363.html#server
+        request.setHeader(
+            'Content-Security-Policy',
+            "default-src 'none'; frame-ancestors 'none';"
+        )
+        ret = file_res.render(request)
+        if ret != server.NOT_DONE_YET:
+            # HEAD returns directly the result (while GET use a produced)
+            request.write(ret)
+            request.finish()
+
+    def render_PUT(self, request):
+        defer.ensureDeferred(self.render_put(request))
+        return server.NOT_DONE_YET
+
+    async def render_put(self, request):
+        try:
+            client, upload_request = request.upload_request_data
+            upload_id, filename = request.upload_data
+        except AttributeError:
+            request.write(self.errorPage(request, http.BAD_REQUEST))
+            request.finish()
+            return
+
+        # at this point request is checked and file is buffered, we can store it
+        # we close the content here, before registering the file
+        request.content.close()
+        tmp_file_path = Path(request.content.name)
+        request.content = None
+
+        # the 2 following headers are not standard, but useful in the context of file
+        # sharing with HTTP Upload: first one allow uploader to specify the path
+        # and second one will disable public exposure of the file through HTTP
+        path = request.getHeader("Xmpp-File-Path")
+        if path:
+            path = unquote(path)
+        else:
+            path =  "/uploads"
+        if request.getHeader("Xmpp-File-No-Http") is not None:
+            public_id = None
+        else:
+            public_id = upload_id
+
+        file_data = {
+            "name": unquote(upload_request.filename),
+            "mime_type": upload_request.content_type,
+            "size": upload_request.size,
+            "path": path
+        }
+
+        await request.file_sharing.register_received_file(
+            client, upload_request.from_, file_data, tmp_file_path,
+            public_id=public_id,
+        )
+
+        request.setResponseCode(http.CREATED)
+        request.finish()
+
+
+class FileSharingRequest(server.Request):
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._upload_data = None
+
+    @property
+    def upload_data(self):
+        """A tuple with upload_id and filename retrieved from requested path"""
+        if self._upload_data is not None:
+            return self._upload_data
+
+        # self.path is not available if we are early in the request (e.g. when gotLength
+        # is called), in which case channel._path must be used. On the other hand, when
+        # render_[VERB] is called, only self.path is available
+        path = self.channel._path if self.path is None else self.path
+        # we normalise the path
+        path = urlparse(path.decode()).path
+        try:
+            __, upload_id, filename = path.split('/')
+        except ValueError:
+            raise exceptions.DataError("no enought path elements")
+        if len(upload_id) < 10:
+            raise exceptions.DataError(f"invalid upload ID received for a PUT: {upload_id!r}")
+
+        self._upload_data = (upload_id, filename)
+        return self._upload_data
+
+    @property
+    def file_sharing(self):
+        return self.channel.site.file_sharing
+
+    @property
+    def file_tmp_dir(self):
+        return self.channel.site.file_tmp_dir
+
+    def refuse_request(self):
+        if self.content is not None:
+            self.content.close()
+        self.content = open(os.devnull, 'w+b')
+        self.channel._respondToBadRequestAndDisconnect()
+
+    def gotLength(self, length):
+        if self.channel._command.decode().upper() == 'PUT':
+            # for PUT we check early if upload_id is fine, to avoid buffering a file we'll refuse
+            # we buffer the file in component's TMP_BUFFER_DIR, so we just have to rename it at the end
+            try:
+                upload_id, filename = self.upload_data
+            except exceptions.DataError as e:
+                log.warning(f"Invalid PUT request, we stop here: {e}")
+                return self.refuse_request()
+            try:
+                client, upload_request, timer = self.file_sharing.expected_uploads.pop(upload_id)
+            except KeyError:
+                log.warning(f"unknown (expired?) upload ID received for a PUT: {upload_id!r}")
+                return self.refuse_request()
+
+            if not timer.active:
+                log.warning(f"upload id {upload_id!r} used for a PUT, but it is expired")
+                return self.refuse_request()
+
+            timer.cancel()
+
+            if upload_request.filename != filename:
+                log.warning(
+                    f"invalid filename for PUT (upload id: {upload_id!r}, URL: {self.channel._path.decode()}). Original "
+                    f"{upload_request.filename!r} doesn't match {filename!r}"
+                )
+                return self.refuse_request()
+
+            self.upload_request_data = (client, upload_request)
+
+            file_tmp_path = files_utils.get_unique_name(
+                self.file_tmp_dir/upload_id)
+
+            self.content = open(file_tmp_path, 'w+b')
+        else:
+            return super().gotLength(length)
+
+
+class FileSharingSite(server.Site):
+    requestFactory = FileSharingRequest
+
+    def __init__(self, file_sharing):
+        self.file_sharing = file_sharing
+        self.file_tmp_dir = file_sharing.host.get_local_path(
+            None, C.FILES_TMP_DIR, TMP_BUFFER_DIR, component=True
+        )
+        for old_file in self.file_tmp_dir.iterdir():
+            log.debug(f"purging old buffer file at {old_file}")
+            old_file.unlink()
+        super().__init__(HTTPFileServer())
+
+    def getContentFile(self, length):
+        file_tmp_path = self.file_tmp_dir/shortuuid.uuid()
+        return open(file_tmp_path, 'w+b')
+
+
+class FileSharing:
+
+    def __init__(self, host):
+        self.host = host
+        self.initialised = False
+
+    def init(self):
+        # we init once on first component connection,
+        # there is not need to init this plugin if not component use it
+        # TODO: this plugin should not be loaded at all if no component uses it
+        #   and should be loaded dynamically as soon as a suitable profile is created
+        if self.initialised:
+            return
+        self.initialised = True
+        log.info(_("File Sharing initialization"))
+        self._f = self.host.plugins["FILE"]
+        self._jf = self.host.plugins["XEP-0234"]
+        self._h = self.host.plugins["XEP-0300"]
+        self._t = self.host.plugins["XEP-0264"]
+        self._hu = self.host.plugins["XEP-0363"]
+        self._hu.register_handler(self._on_http_upload)
+        self.host.trigger.add("FILE_getDestDir", self._get_dest_dir_trigger)
+        self.host.trigger.add(
+            "XEP-0234_fileSendingRequest", self._file_sending_request_trigger, priority=1000
+        )
+        self.host.trigger.add("XEP-0234_buildFileElement", self._add_file_metadata_elts)
+        self.host.trigger.add("XEP-0234_parseFileElement", self._get_file_metadata_elts)
+        self.host.trigger.add("XEP-0329_compGetFilesFromNode", self._add_file_metadata)
+        self.host.trigger.add(
+            "XEP-0329_compGetFilesFromNode_build_directory",
+            self._add_directory_metadata_elts)
+        self.host.trigger.add(
+            "XEP-0329_parseResult_directory",
+            self._get_directory_metadata_elts)
+        self.files_path = self.host.get_local_path(None, C.FILES_DIR)
+        self.http_port = int(self.host.memory.config_get(
+            'component file-sharing', 'http_upload_port', 8888))
+        connection_type = self.host.memory.config_get(
+            'component file-sharing', 'http_upload_connection_type', 'https')
+        if connection_type not in ('http', 'https'):
+            raise exceptions.ConfigError(
+                'bad http_upload_connection_type, you must use one of "http" or "https"'
+            )
+        self.server = FileSharingSite(self)
+        self.expected_uploads = {}
+        if connection_type == 'http':
+            reactor.listenTCP(self.http_port, self.server)
+        else:
+            options = tls.get_options_from_config(
+                self.host.memory.config, "component file-sharing")
+            tls.tls_options_check(options)
+            context_factory = tls.get_tls_context_factory(options)
+            reactor.listenSSL(self.http_port, self.server, context_factory)
+
+    def get_handler(self, client):
+        return Comments_handler(self)
+
+    def profile_connecting(self, client):
+        # we activate HTTP upload
+        client.enabled_features.add("XEP-0363")
+
+        self.init()
+        public_base_url = self.host.memory.config_get(
+            'component file-sharing', 'http_upload_public_facing_url')
+        if public_base_url is None:
+            client._file_sharing_base_url = f"https://{client.host}:{self.http_port}"
+        else:
+            client._file_sharing_base_url = public_base_url
+        path = client.file_tmp_dir = os.path.join(
+            self.host.memory.config_get("", "local_dir"),
+            C.FILES_TMP_DIR,
+            regex.path_escape(client.profile),
+        )
+        if not os.path.exists(path):
+            os.makedirs(path)
+
+    def get_quota(self, client, entity):
+        """Return maximum size allowed for all files for entity"""
+        quotas = self.host.memory.config_get("component file-sharing", "quotas_json", {})
+        if self.host.memory.is_admin_jid(entity):
+            quota = quotas.get("admins")
+        else:
+            try:
+                quota = quotas["jids"][entity.userhost()]
+            except KeyError:
+                quota = quotas.get("users")
+        return None if quota is None else utils.parse_size(quota)
+
+    async def generate_thumbnails(self, extra: dict, image_path: Path):
+        thumbnails = extra.setdefault(C.KEY_THUMBNAILS, [])
+        for max_thumb_size in self._t.SIZES:
+            try:
+                thumb_size, thumb_id = await self._t.generate_thumbnail(
+                    image_path,
+                    max_thumb_size,
+                    #  we keep thumbnails for 6 months
+                    60 * 60 * 24 * 31 * 6,
+                )
+            except Exception as e:
+                log.warning(_("Can't create thumbnail: {reason}").format(reason=e))
+                break
+            thumbnails.append({"id": thumb_id, "size": thumb_size})
+
+    async def register_received_file(
+            self, client, peer_jid, file_data, file_path, public_id=None, extra=None):
+        """Post file reception tasks
+
+        once file is received, this method create hash/thumbnails if necessary
+        move the file to the right location, and create metadata entry in database
+        """
+        name = file_data["name"]
+        if extra is None:
+            extra = {}
+
+        mime_type = file_data.get("mime_type")
+        if not mime_type or mime_type == "application/octet-stream":
+            mime_type = mimetypes.guess_type(name)[0]
+
+        is_image = mime_type is not None and mime_type.startswith("image")
+        is_video = mime_type is not None and mime_type.startswith("video")
+
+        if file_data.get("hash_algo") == HASH_ALGO:
+            log.debug(_("Reusing already generated hash"))
+            file_hash = file_data["hash_hasher"].hexdigest()
+        else:
+            hasher = self._h.get_hasher(HASH_ALGO)
+            with file_path.open('rb') as f:
+                file_hash = await self._h.calculate_hash(f, hasher)
+        final_path = self.files_path/file_hash
+
+        if final_path.is_file():
+            log.debug(
+                "file [{file_hash}] already exists, we can remove temporary one".format(
+                    file_hash=file_hash
+                )
+            )
+            file_path.unlink()
+        else:
+            file_path.rename(final_path)
+            log.debug(
+                "file [{file_hash}] moved to {files_path}".format(
+                    file_hash=file_hash, files_path=self.files_path
+                )
+            )
+
+        if is_image:
+            await self.generate_thumbnails(extra, final_path)
+        elif is_video:
+            with tempfile.TemporaryDirectory() as tmp_dir:
+                thumb_path = Path(tmp_dir) / "thumbnail.jpg"
+                try:
+                    await video.get_thumbnail(final_path, thumb_path)
+                except Exception as e:
+                    log.warning(_("Can't get thumbnail for {final_path}: {e}").format(
+                        final_path=final_path, e=e))
+                else:
+                    await self.generate_thumbnails(extra, thumb_path)
+
+        await self.host.memory.set_file(
+            client,
+            name=name,
+            version="",
+            file_hash=file_hash,
+            hash_algo=HASH_ALGO,
+            size=file_data["size"],
+            path=file_data.get("path"),
+            namespace=file_data.get("namespace"),
+            mime_type=mime_type,
+            public_id=public_id,
+            owner=peer_jid,
+            extra=extra,
+        )
+
+    async def _get_dest_dir_trigger(
+        self, client, peer_jid, transfer_data, file_data, stream_object
+    ):
+        """This trigger accept file sending request, and store file locally"""
+        if not client.is_component:
+            return True, None
+        # client._file_sharing_allowed_hosts is set in plugin XEP-0329
+        if peer_jid.host not in client._file_sharing_allowed_hosts:
+            raise error.StanzaError("forbidden")
+        assert stream_object
+        assert "stream_object" not in transfer_data
+        assert C.KEY_PROGRESS_ID in file_data
+        filename = file_data["name"]
+        assert filename and not "/" in filename
+        quota = self.get_quota(client, peer_jid)
+        if quota is not None:
+            used_space = await self.host.memory.file_get_used_space(client, peer_jid)
+
+            if (used_space + file_data["size"]) > quota:
+                raise error.StanzaError(
+                    "not-acceptable",
+                    text=OVER_QUOTA_TXT.format(
+                        quota=utils.get_human_size(quota),
+                        used_space=utils.get_human_size(used_space),
+                        file_size=utils.get_human_size(file_data['size'])
+                    )
+                )
+        file_tmp_dir = self.host.get_local_path(
+            None, C.FILES_TMP_DIR, peer_jid.userhost(), component=True
+        )
+        file_tmp_path = file_data['file_path'] = files_utils.get_unique_name(
+            file_tmp_dir/filename)
+
+        transfer_data["finished_d"].addCallback(
+            lambda __: defer.ensureDeferred(
+                self.register_received_file(client, peer_jid, file_data, file_tmp_path)
+            )
+        )
+
+        self._f.open_file_write(
+            client, file_tmp_path, transfer_data, file_data, stream_object
+        )
+        return False, True
+
+    async def _retrieve_files(
+        self, client, session, content_data, content_name, file_data, file_elt
+    ):
+        """This method retrieve a file on request, and send if after checking permissions"""
+        peer_jid = session["peer_jid"]
+        if session['local_jid'].user:
+            owner = client.get_owner_from_jid(session['local_jid'])
+        else:
+            owner = peer_jid
+        try:
+            found_files = await self.host.memory.get_files(
+                client,
+                peer_jid=peer_jid,
+                name=file_data.get("name"),
+                file_hash=file_data.get("file_hash"),
+                hash_algo=file_data.get("hash_algo"),
+                path=file_data.get("path"),
+                namespace=file_data.get("namespace"),
+                owner=owner,
+            )
+        except exceptions.NotFound:
+            found_files = None
+        except exceptions.PermissionError:
+            log.warning(
+                _("{peer_jid} is trying to access an unauthorized file: {name}").format(
+                    peer_jid=peer_jid, name=file_data.get("name")
+                )
+            )
+            return False
+
+        if not found_files:
+            log.warning(
+                _("no matching file found ({file_data})").format(file_data=file_data)
+            )
+            return False
+
+        # we only use the first found file
+        found_file = found_files[0]
+        if found_file['type'] != C.FILE_TYPE_FILE:
+            raise TypeError("a file was expected, type is {type_}".format(
+                type_=found_file['type']))
+        file_hash = found_file["file_hash"]
+        file_path = self.files_path / file_hash
+        file_data["hash_hasher"] = hasher = self._h.get_hasher(found_file["hash_algo"])
+        size = file_data["size"] = found_file["size"]
+        file_data["file_hash"] = file_hash
+        file_data["hash_algo"] = found_file["hash_algo"]
+
+        # we complete file_elt so peer can have some details on the file
+        if "name" not in file_data:
+            file_elt.addElement("name", content=found_file["name"])
+        file_elt.addElement("size", content=str(size))
+        content_data["stream_object"] = stream.FileStreamObject(
+            self.host,
+            client,
+            file_path,
+            uid=self._jf.get_progress_id(session, content_name),
+            size=size,
+            data_cb=lambda data: hasher.update(data),
+        )
+        return True
+
+    def _file_sending_request_trigger(
+        self, client, session, content_data, content_name, file_data, file_elt
+    ):
+        if not client.is_component:
+            return True, None
+        else:
+            return (
+                False,
+                defer.ensureDeferred(self._retrieve_files(
+                    client, session, content_data, content_name, file_data, file_elt
+                )),
+            )
+
+    ## HTTP Upload ##
+
+    def _purge_slot(self, upload_id):
+        try:
+            del self.expected_uploads[upload_id]
+        except KeyError:
+            log.error(f"trying to purge an inexisting upload slot ({upload_id})")
+
+    async def _on_http_upload(self, client, request):
+        # filename should be already cleaned, but it's better to double check
+        assert '/' not in request.filename
+        # client._file_sharing_allowed_hosts is set in plugin XEP-0329
+        if request.from_.host not in client._file_sharing_allowed_hosts:
+            raise error.StanzaError("forbidden")
+
+        quota = self.get_quota(client, request.from_)
+        if quota is not None:
+            used_space = await self.host.memory.file_get_used_space(client, request.from_)
+
+            if (used_space + request.size) > quota:
+                raise error.StanzaError(
+                    "not-acceptable",
+                    text=OVER_QUOTA_TXT.format(
+                        quota=utils.get_human_size(quota),
+                        used_space=utils.get_human_size(used_space),
+                        file_size=utils.get_human_size(request.size)
+                    ),
+                    appCondition = self._hu.get_file_too_large_elt(max(quota - used_space, 0))
+                )
+
+        upload_id = shortuuid.ShortUUID().random(length=30)
+        assert '/' not in upload_id
+        timer = reactor.callLater(30, self._purge_slot, upload_id)
+        self.expected_uploads[upload_id] = (client, request, timer)
+        url = urljoin(client._file_sharing_base_url, f"{upload_id}/{request.filename}")
+        slot = self._hu.Slot(
+            put=url,
+            get=url,
+            headers=[],
+        )
+        return slot
+
+    ## metadata triggers ##
+
+    def _add_file_metadata_elts(self, client, file_elt, extra_args):
+        # affiliation
+        affiliation = extra_args.get('affiliation')
+        if affiliation is not None:
+            file_elt.addElement((NS_FS_AFFILIATION, "affiliation"), content=affiliation)
+
+        # comments
+        try:
+            comments_url = extra_args.pop("comments_url")
+        except KeyError:
+            return
+
+        comment_elt = file_elt.addElement((NS_COMMENTS, "comments"), content=comments_url)
+
+        try:
+            count = len(extra_args["extra"]["comments"])
+        except KeyError:
+            count = 0
+
+        comment_elt["count"] = str(count)
+        return True
+
+    def _get_file_metadata_elts(self, client, file_elt, file_data):
+        # affiliation
+        try:
+            affiliation_elt = next(file_elt.elements(NS_FS_AFFILIATION, "affiliation"))
+        except StopIteration:
+            pass
+        else:
+            file_data["affiliation"] = str(affiliation_elt)
+
+        # comments
+        try:
+            comments_elt = next(file_elt.elements(NS_COMMENTS, "comments"))
+        except StopIteration:
+            pass
+        else:
+            file_data["comments_url"] = str(comments_elt)
+            file_data["comments_count"] = comments_elt["count"]
+        return True
+
+    def _add_file_metadata(
+            self, client, iq_elt, iq_result_elt, owner, node_path, files_data):
+        for file_data in files_data:
+            file_data["comments_url"] = uri.build_xmpp_uri(
+                "pubsub",
+                path=client.jid.full(),
+                node=COMMENT_NODE_PREFIX + file_data["id"],
+            )
+        return True
+
+    def _add_directory_metadata_elts(
+            self, client, file_data, directory_elt, owner, node_path):
+        affiliation = file_data.get('affiliation')
+        if affiliation is not None:
+            directory_elt.addElement(
+                (NS_FS_AFFILIATION, "affiliation"),
+                content=affiliation
+            )
+
+    def _get_directory_metadata_elts(
+            self, client, elt, file_data):
+        try:
+            affiliation_elt = next(elt.elements(NS_FS_AFFILIATION, "affiliation"))
+        except StopIteration:
+            pass
+        else:
+            file_data['affiliation'] = str(affiliation_elt)
+
+
+class Comments_handler(pubsub.PubSubService):
+    """This class is a minimal Pubsub service handling virtual nodes for comments"""
+
+    def __init__(self, plugin_parent):
+        super(Comments_handler, self).__init__()
+        self.host = plugin_parent.host
+        self.plugin_parent = plugin_parent
+        self.discoIdentity = {
+            "category": "pubsub",
+            "type": "virtual",  # FIXME: non standard, here to avoid this service being considered as main pubsub one
+            "name": "files commenting service",
+        }
+
+    def _get_file_id(self, nodeIdentifier):
+        if not nodeIdentifier.startswith(COMMENT_NODE_PREFIX):
+            raise error.StanzaError("item-not-found")
+        file_id = nodeIdentifier[len(COMMENT_NODE_PREFIX) :]
+        if not file_id:
+            raise error.StanzaError("item-not-found")
+        return file_id
+
+    async def get_file_data(self, requestor, nodeIdentifier):
+        file_id = self._get_file_id(nodeIdentifier)
+        try:
+            files = await self.host.memory.get_files(self.parent, requestor, file_id)
+        except (exceptions.NotFound, exceptions.PermissionError):
+            # we don't differenciate between NotFound and PermissionError
+            # to avoid leaking information on existing files
+            raise error.StanzaError("item-not-found")
+        if not files:
+            raise error.StanzaError("item-not-found")
+        if len(files) > 1:
+            raise error.InternalError("there should be only one file")
+        return files[0]
+
+    def comments_update(self, extra, new_comments, peer_jid):
+        """update comments (replace or insert new_comments)
+
+        @param extra(dict): extra data to update
+        @param new_comments(list[tuple(unicode, unicode, unicode)]): comments to update or insert
+        @param peer_jid(unicode, None): bare jid of the requestor, or None if request is done by owner
+        """
+        current_comments = extra.setdefault("comments", [])
+        new_comments_by_id = {c[0]: c for c in new_comments}
+        updated = []
+        # we now check every current comment, to see if one id in new ones
+        # exist, in which case we must update
+        for idx, comment in enumerate(current_comments):
+            comment_id = comment[0]
+            if comment_id in new_comments_by_id:
+                # a new comment has an existing id, update is requested
+                if peer_jid and comment[1] != peer_jid:
+                    # requestor has not the right to modify the comment
+                    raise exceptions.PermissionError
+                # we replace old_comment with updated one
+                new_comment = new_comments_by_id[comment_id]
+                current_comments[idx] = new_comment
+                updated.append(new_comment)
+
+        # we now remove every updated comments, to only keep
+        # the ones to insert
+        for comment in updated:
+            new_comments.remove(comment)
+
+        current_comments.extend(new_comments)
+
+    def comments_delete(self, extra, comments):
+        try:
+            comments_dict = extra["comments"]
+        except KeyError:
+            return
+        for comment in comments:
+            try:
+                comments_dict.remove(comment)
+            except ValueError:
+                continue
+
+    def _get_from(self, item_elt):
+        """retrieve publisher of an item
+
+        @param item_elt(domish.element): <item> element
+        @return (unicode): full jid as string
+        """
+        iq_elt = item_elt
+        while iq_elt.parent != None:
+            iq_elt = iq_elt.parent
+        return iq_elt["from"]
+
+    @ensure_deferred
+    async def publish(self, requestor, service, nodeIdentifier, items):
+        #  we retrieve file a first time to check authorisations
+        file_data = await self.get_file_data(requestor, nodeIdentifier)
+        file_id = file_data["id"]
+        comments = [(item["id"], self._get_from(item), item.toXml()) for item in items]
+        if requestor.userhostJID() == file_data["owner"]:
+            peer_jid = None
+        else:
+            peer_jid = requestor.userhost()
+        update_cb = partial(self.comments_update, new_comments=comments, peer_jid=peer_jid)
+        try:
+            await self.host.memory.file_update(file_id, "extra", update_cb)
+        except exceptions.PermissionError:
+            raise error.StanzaError("not-authorized")
+
+    @ensure_deferred
+    async def items(self, requestor, service, nodeIdentifier, maxItems, itemIdentifiers):
+        file_data = await self.get_file_data(requestor, nodeIdentifier)
+        comments = file_data["extra"].get("comments", [])
+        if itemIdentifiers:
+            return [generic.parseXml(c[2]) for c in comments if c[0] in itemIdentifiers]
+        else:
+            return [generic.parseXml(c[2]) for c in comments]
+
+    @ensure_deferred
+    async def retract(self, requestor, service, nodeIdentifier, itemIdentifiers):
+        file_data = await self.get_file_data(requestor, nodeIdentifier)
+        file_id = file_data["id"]
+        try:
+            comments = file_data["extra"]["comments"]
+        except KeyError:
+            raise error.StanzaError("item-not-found")
+
+        to_remove = []
+        for comment in comments:
+            comment_id = comment[0]
+            if comment_id in itemIdentifiers:
+                to_remove.append(comment)
+                itemIdentifiers.remove(comment_id)
+                if not itemIdentifiers:
+                    break
+
+        if itemIdentifiers:
+            # not all items have been to_remove, we can't continue
+            raise error.StanzaError("item-not-found")
+
+        if requestor.userhostJID() != file_data["owner"]:
+            if not all([c[1] == requestor.userhost() for c in to_remove]):
+                raise error.StanzaError("not-authorized")
+
+        remove_cb = partial(self.comments_delete, comments=to_remove)
+        await self.host.memory.file_update(file_id, "extra", remove_cb)