Merge branch 'master' of http://git.fucktheforce.de/cgi-bin/git/httpupload

11 files changed, 981 insertions, 108 deletions

diff --git a/gajim-plugin/httpupload/__init__.py b/gajim-plugin/httpupload/__init__.py
new file mode 100644
index 0000000..23c0eff
--- /dev/null
+++ b/gajim-plugin/httpupload/__init__.py
@@ -0,0 +1,2 @@
+# simple redirect
+from httpupload import HttpuploadPlugin
diff --git a/gajim-plugin/httpupload/httpupload.png b/gajim-plugin/httpupload/httpupload.png
new file mode 100644
index 0000000..c3b3733
--- /dev/null
+++ b/gajim-plugin/httpupload/httpupload.png
diff --git a/gajim-plugin/httpupload/httpupload.py b/gajim-plugin/httpupload/httpupload.py
new file mode 100644
index 0000000..b2bb3fc
--- /dev/null
+++ b/gajim-plugin/httpupload/httpupload.py
@@ -0,0 +1,702 @@
+# -*- coding: utf-8 -*-
+##
+## This file is part of Gajim.
+##
+## Gajim is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published
+## by the Free Software Foundation; version 3 only.
+##
+## Gajim 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 General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Gajim.  If not, see <http://www.gnu.org/licenses/>.
+##
+
+from common import demandimport
+demandimport.enable()
+demandimport.ignore += ['builtins', '__builtin__', 'PIL', '_imp']
+
+import gtk
+import gobject
+import os
+import time
+import base64
+import tempfile
+import urllib2
+import mimetypes        # better use the magic packet, but that's not a standard lib
+import gtkgui_helpers
+from Queue import Queue
+try:
+    from PIL import Image
+    pil_available = True
+except:
+    pil_available = False
+from io import BytesIO
+
+import binascii
+from common import gajim
+from common import ged
+import chat_control
+from plugins import GajimPlugin
+from plugins.helpers import log_calls
+import logging
+from dialogs import FileChooserDialog, ImageChooserDialog, ErrorDialog
+import nbxmpp
+
+log = logging.getLogger('gajim.plugin_system.httpupload')
+
+try:
+    if os.name == 'nt':
+        from cryptography.hazmat.backends.openssl import backend
+    else:
+        from cryptography.hazmat.backends import default_backend
+    from cryptography.hazmat.primitives.ciphers import Cipher
+    from cryptography.hazmat.primitives.ciphers import algorithms
+    from cryptography.hazmat.primitives.ciphers.modes import GCM
+    encryption_available = True
+except Exception as e:
+    DEP_MSG = 'For encryption of files, ' \
+              'please install python-cryptography!'
+    log.debug('Cryptography Import Error: ' + str(e))
+    log.info('Decryption/Encryption disabled due to errors')
+    encryption_available = False
+
+NS_HINTS = 'urn:xmpp:hints'
+# XEP-0363 (http://xmpp.org/extensions/xep-0363.html)
+NS_HTTPUPLOAD = 'urn:xmpp:http:upload'
+TAGSIZE = 16
+
+jid_to_servers = {}
+iq_ids_to_callbacks = {}
+last_info_query = {}
+max_thumbnail_size = 2048
+max_thumbnail_dimension = 160
+httpuploadurls = {}
+
+
+class HttpuploadPlugin(GajimPlugin):
+
+    @log_calls('HttpuploadPlugin')
+    def init(self):
+        if not encryption_available:
+            self.available_text = DEP_MSG
+        self.config_dialog = None  # HttpuploadPluginConfigDialog(self)
+        self.controls = []
+        self.events_handlers = {}
+        self.events_handlers['agent-info-received'] = (ged.PRECORE,
+                self.handle_agent_info_received)
+        self.events_handlers['raw-iq-received'] = (ged.PRECORE,
+                self.handle_iq_received)
+        self.events_handlers['stanza-message-outgoing'] = (ged.PRECORE,
+                self.handle_message_stanza_out)
+        self.gui_extension_points = {
+            'chat_control_base': (self.connect_with_chat_control,
+                self.disconnect_from_chat_control),
+            'chat_control_base_update_toolbar': (self.update_button_state,
+                None)}
+        self.first_run = True
+
+    def handle_iq_received(self, event):
+        global iq_ids_to_callbacks
+        id_ = event.stanza.getAttr("id")
+        if str(id_) in iq_ids_to_callbacks:
+            try:
+                iq_ids_to_callbacks[str(id_)](event.stanza)
+            except:
+                raise
+            finally:
+                del iq_ids_to_callbacks[str(id_)]
+
+    def handle_agent_info_received(self, event):
+        global jid_to_servers
+        if NS_HTTPUPLOAD in event.features and gajim.jid_is_transport(event.jid):
+            own_jid = gajim.get_jid_without_resource(str(event.stanza.getTo()))
+            jid_to_servers[own_jid] = event.jid        # map own jid to upload component's jid
+            log.info(own_jid + " can do http uploads via component " + event.jid)
+            # update all buttons
+            for base in self.controls:
+                self.update_button_state(base.chat_control)
+
+    @log_calls('HttpuploadPlugin')
+    def handle_message_stanza_out(self, event):
+        try:
+            global httpuploadurls
+            if not event.msg_iq.getTag('body'):
+                return
+            url = event.msg_iq.getBody()
+            if url in httpuploadurls:
+                # httpupload Hint
+                event.msg_iq.addChild('httpupload', namespace=NS_HINTS)
+                del httpuploadurls[url]
+        except Exception as e:
+            log.error(e)
+
+    @log_calls('HttpuploadPlugin')
+    def connect_with_chat_control(self, control):
+        self.chat_control = control
+        base = Base(self, self.chat_control)
+        self.controls.append(base)
+        if self.first_run:
+            # ALT + U
+            gtk.binding_entry_add_signal(control.msg_textview,
+                gtk.keysyms.u, gtk.gdk.MOD1_MASK, 'mykeypress',
+                int, gtk.keysyms.u, gtk.gdk.ModifierType, gtk.gdk.MOD1_MASK)
+            self.first_run = False
+        self.update_button_state(self.chat_control)
+
+    @log_calls('HttpuploadPlugin')
+    def disconnect_from_chat_control(self, chat_control):
+        for control in self.controls:
+            control.disconnect_from_chat_control()
+        self.controls = []
+
+    @log_calls('HttpuploadPlugin')
+    def update_button_state(self, chat_control):
+        global jid_to_servers
+        global iq_ids_to_callbacks
+        global last_info_query
+
+        if gajim.connections[chat_control.account].connection == None and \
+            gajim.get_jid_from_account(chat_control.account) in jid_to_servers:
+            # maybe don't delete this and detect vanished upload components when actually trying to upload something
+            log.info("Deleting %s from jid_to_servers (disconnected)" % gajim.get_jid_from_account(chat_control.account))
+            del jid_to_servers[gajim.get_jid_from_account(chat_control.account)]
+            #pass
+
+        # query info at most every 60 seconds in case something goes wrong
+        if (not chat_control.account in last_info_query or \
+            last_info_query[chat_control.account] + 60 < time.time()) and \
+            not gajim.get_jid_from_account(chat_control.account) in jid_to_servers and \
+            gajim.account_is_connected(chat_control.account):
+            log.info("Account %s: Using dicovery to find jid of httpupload component" % chat_control.account)
+            id_ = gajim.get_an_id()
+            iq = nbxmpp.Iq(
+                typ='get',
+                to=gajim.get_server_from_jid(gajim.get_jid_from_account(chat_control.account)),
+                queryNS="http://jabber.org/protocol/disco#items"
+            )
+            iq.setID(id_)
+            def query_info(stanza):
+                global last_info_query
+                for item in stanza.getTag("query").getTags("item"):
+                    id_ = gajim.get_an_id()
+                    iq = nbxmpp.Iq(
+                        typ='get',
+                        to=item.getAttr("jid"),
+                        queryNS="http://jabber.org/protocol/disco#info"
+                    )
+                    iq.setID(id_)
+                    last_info_query[chat_control.account] = time.time()
+                    gajim.connections[chat_control.account].connection.send(iq)
+            iq_ids_to_callbacks[str(id_)] = query_info
+            gajim.connections[chat_control.account].connection.send(iq)
+            #send disco query to main server jid
+            id_ = gajim.get_an_id()
+            iq = nbxmpp.Iq(
+                typ='get',
+                to=gajim.get_server_from_jid(gajim.get_jid_from_account(chat_control.account)),
+                queryNS="http://jabber.org/protocol/disco#info"
+            )
+            iq.setID(id_)
+            last_info_query[chat_control.account] = time.time()
+            gajim.connections[chat_control.account].connection.send(iq)
+
+        for base in self.controls:
+            if base.chat_control == chat_control:
+                is_supported = gajim.get_jid_from_account(chat_control.account) in jid_to_servers and \
+                    gajim.connections[chat_control.account].connection != None
+                log.info("Account %s: httpupload is_supported: %s" % (str(chat_control.account), str(is_supported)))
+                if not is_supported:
+                    text = _('Your server does not support http uploads')
+                    image_text = text
+                else:
+                    text = _('Send file via http upload')
+                    image_text = _('Send image via http upload')
+                base.button.set_sensitive(is_supported)
+                base.button.set_tooltip_text(text)
+                base.image_button.set_sensitive(is_supported)
+                base.image_button.set_tooltip_text(image_text)
+
+
+class Base(object):
+    def __init__(self, plugin, chat_control):
+        self.dlg = None
+        self.dialog_type = 'file'
+        self.keypress_id = chat_control.msg_textview.connect('mykeypress',
+            self.on_key_press)
+        self.plugin = plugin
+        self.encrypted_upload = False
+        self.chat_control = chat_control
+        actions_hbox = chat_control.xml.get_object('actions_hbox')
+        self.button = gtk.Button(label=None, stock=None, use_underline=True)
+        self.button.set_property('relief', gtk.RELIEF_NONE)
+        self.button.set_property('can-focus', False)
+        self.button.set_sensitive(False)
+        img = gtk.Image()
+        img.set_from_file(self.plugin.local_file_path('httpupload.png'))
+        self.button.set_image(img)
+        self.button.set_tooltip_text(_('Your server does not support http uploads'))
+        self.image_button = gtk.Button(label=None, stock=None, use_underline=True)
+        self.image_button.set_property('relief', gtk.RELIEF_NONE)
+        self.image_button.set_property('can-focus', False)
+        self.image_button.set_sensitive(False)
+        img = gtk.Image()
+        img.set_from_file(self.plugin.local_file_path('image.png'))
+        self.image_button.set_image(img)
+        self.image_button.set_tooltip_text(_('Your server does not support http uploads'))
+        send_button = chat_control.xml.get_object('send_button')
+        send_button_pos = actions_hbox.child_get_property(send_button,
+            'position')
+        actions_hbox.add_with_properties(self.button, 'position',
+            send_button_pos - 2, 'expand', False)
+
+        actions_hbox.add_with_properties(self.image_button, 'position',
+            send_button_pos - 1, 'expand', False)
+
+        file_id = self.button.connect('clicked', self.on_file_button_clicked)
+        image_id = self.image_button.connect('clicked', self.on_image_button_clicked)
+        chat_control.handlers[file_id] = self.button
+        chat_control.handlers[image_id] = self.image_button
+        chat_control.handlers[self.keypress_id] = chat_control.msg_textview
+        self.button.show()
+        self.image_button.show()
+
+    def on_key_press(self, widget, event_keyval, event_keymod):
+        # construct event instance from binding
+        event = gtk.gdk.Event(gtk.gdk.KEY_PRESS)  # it's always a key-press here
+        event.keyval = event_keyval
+        event.state = event_keymod
+        event.time = 0  # assign current time
+
+        if event.keyval != gtk.keysyms.u:
+            return
+        if event.state != gtk.gdk.MOD1_MASK:  # ALT+u
+            return
+        is_supported = gajim.get_jid_from_account(self.chat_control.account) in jid_to_servers and \
+                    gajim.connections[self.chat_control.account].connection != None
+        if not is_supported:
+            from dialogs import WarningDialog
+            WarningDialog('Warning', _('Your server does not support http uploads'),
+                transient_for=self.chat_control.parent_win.window)
+            return
+        self.on_file_button_clicked(widget)
+
+    def disconnect_from_chat_control(self):
+        actions_hbox = self.chat_control.xml.get_object('actions_hbox')
+        actions_hbox.remove(self.button)
+        actions_hbox.remove(self.image_button)
+        if self.keypress_id in self.chat_control.handlers and \
+            self.chat_control.handlers[self.keypress_id].handler_is_connected(self.keypress_id):
+            self.chat_control.handlers[self.keypress_id].disconnect(self.keypress_id)
+            del self.chat_control.handlers[self.keypress_id]
+
+    def encryption_activated(self):
+        if not encryption_available:
+            return False
+        jid = self.chat_control.contact.jid
+        account = self.chat_control.account
+        for plugin in gajim.plugin_manager.active_plugins:
+            if type(plugin).__name__ == 'OmemoPlugin':
+                omemo = plugin
+                break
+        if omemo:
+            state = omemo.get_omemo_state(account)
+            log.info('Encryption is: ' +
+                      str(state.encryption.is_active(jid)))
+            return state.encryption.is_active(jid)
+        log.info('Encryption is: False / OMEMO not found')
+        return False
+
+    def on_file_dialog_ok(self, widget, path_to_file=None):
+        global jid_to_servers
+
+        try:
+            self.encrypted_upload = self.encryption_activated()
+        except Exception as e:
+            log.debug(e)
+            self.encrypted_upload = False
+
+        if not path_to_file:
+            path_to_file = self.dlg.get_filename()
+            if not path_to_file:
+                self.dlg.destroy()
+                return
+            path_to_file = gtkgui_helpers.decode_filechooser_file_paths(
+                    (path_to_file,))[0]
+        self.dlg.destroy()
+        if not os.path.exists(path_to_file):
+            return
+        if self.encrypted_upload:
+            filesize = os.path.getsize(path_to_file) + TAGSIZE  # in bytes
+        else:
+            filesize = os.path.getsize(path_to_file)
+        invalid_file = False
+        msg = ''
+        if os.path.isfile(path_to_file):
+            stat = os.stat(path_to_file)
+            if stat[6] == 0:
+                invalid_file = True
+                msg = _('File is empty')
+        else:
+            invalid_file = True
+            msg = _('File does not exist')
+        if invalid_file:
+            ErrorDialog(_('Could not open file'), msg, transient_for=self.chat_control.parent_win.window)
+            return
+
+        mime_type = mimetypes.MimeTypes().guess_type(path_to_file)[0]
+        if not mime_type:
+            mime_type = 'application/octet-stream'  # fallback mime type
+        log.info("Detected MIME Type of file: " + str(mime_type))
+        progress_messages = Queue(8)
+        progress_window = ProgressWindow(_('HTTP Upload'), _('Requesting HTTP Upload Slot...'), progress_messages, self.plugin)
+        def upload_file(stanza):
+            slot = stanza.getTag("slot")
+            if not slot:
+                progress_window.close_dialog()
+                log.error("got unexpected stanza: "+str(stanza))
+                error = stanza.getTag("error")
+                if error and error.getTag("text"):
+                    ErrorDialog(_('Could not request upload slot'), 
+                                _('Got unexpected response from server: %s') % str(error.getTagData("text")),
+                                transient_for=self.chat_control.parent_win.window)
+                else:
+                    ErrorDialog(_('Could not request upload slot'), 
+                                _('Got unexpected response from server (protocol mismatch??)'),
+                                transient_for=self.chat_control.parent_win.window)
+                return
+
+            try:
+                if self.encrypted_upload:
+                    key = os.urandom(32)
+                    iv = os.urandom(16)
+                    data = StreamFileWithProgress(path_to_file,
+                                                  "rb",
+                                                  progress_window.update_progress,
+                                                  self.encrypted_upload, key, iv)
+                else:
+                    data = StreamFileWithProgress(path_to_file,
+                                                  "rb",
+                                                  progress_window.update_progress)
+            except:
+                progress_window.close_dialog()
+                ErrorDialog(_('Could not open file'), 
+                            _('Exception raised while opening file (see error log for more information)'),
+                            transient_for=self.chat_control.parent_win.window)
+                raise       # fill error log with useful information
+
+            put = slot.getTag("put")
+            get = slot.getTag("get")
+            if not put or not get:
+                progress_window.close_dialog()
+                log.error("got unexpected stanza: " + str(stanza))
+                ErrorDialog(_('Could not request upload slot'), 
+                            _('Got unexpected response from server (protocol mismatch??)'),
+                            transient_for=self.chat_control.parent_win.window)
+                return
+
+            def upload_complete(response_code):
+                if response_code == 0:
+                    return      # Upload was aborted
+                if response_code >= 200 and response_code < 300:
+                    log.info("Upload completed successfully")
+                    xhtml = None
+                    is_image = mime_type.split('/', 1)[0] == 'image'
+                    if (not isinstance(self.chat_control, chat_control.ChatControl) or not self.chat_control.gpg_is_active) and \
+                        self.dialog_type == 'image' and is_image and not self.encrypted_upload:
+
+                        progress_messages.put(_('Calculating (possible) image thumbnail...'))
+                        thumb = None
+                        quality_steps = (100, 80, 60, 50, 40, 35, 30, 25, 23, 20, 18, 15, 13, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
+                        with open(path_to_file, 'rb') as content_file:
+                            thumb = urllib2.quote(base64.standard_b64encode(content_file.read()), '')
+                        if thumb and len(thumb) < max_thumbnail_size:
+                            quality = 100
+                            log.info("Image small enough (%d bytes), not resampling" % len(thumb))
+                        elif pil_available:
+                            log.info("PIL available, using it for image downsampling")
+                            try:
+                                for quality in quality_steps:
+                                    thumb = Image.open(path_to_file)
+                                    thumb.thumbnail((max_thumbnail_dimension, max_thumbnail_dimension), Image.ANTIALIAS)
+                                    output = BytesIO()
+                                    thumb.save(output, format='JPEG', quality=quality, optimize=True)
+                                    thumb = output.getvalue()
+                                    output.close()
+                                    thumb = urllib2.quote(base64.standard_b64encode(thumb), '')
+                                    log.debug("pil thumbnail jpeg quality %d produces an image of size %d..." % (quality, len(thumb)))
+                                    if len(thumb) < max_thumbnail_size:
+                                        break
+                            except:
+                                thumb = None
+                        else:
+                            thumb = None
+                        if not thumb:
+                            log.info("PIL not available, using GTK for image downsampling")
+                            temp_file = None
+                            try:
+                                with open(path_to_file, 'rb') as content_file:
+                                    thumb = content_file.read()
+                                loader = gtk.gdk.PixbufLoader()
+                                loader.write(thumb)
+                                loader.close()
+                                pixbuf = loader.get_pixbuf()
+                                scaled_pb = self.get_pixbuf_of_size(pixbuf, max_thumbnail_dimension)
+                                handle, temp_file = tempfile.mkstemp(suffix='.jpeg', prefix='gajim_httpupload_scaled_tmp', dir=gajim.TMP)
+                                log.debug("Saving temporary jpeg image to '%s'..." % temp_file)
+                                os.close(handle)
+                                for quality in quality_steps:
+                                    scaled_pb.save(temp_file, "jpeg", {"quality": str(quality)})
+                                    with open(temp_file, 'rb') as content_file:
+                                        thumb = content_file.read()
+                                    thumb = urllib2.quote(base64.standard_b64encode(thumb), '')
+                                    log.debug("gtk thumbnail jpeg quality %d produces an image of size %d..." % (quality, len(thumb)))
+                                    if len(thumb) < max_thumbnail_size:
+                                        break
+                            except:
+                                thumb = None
+                            finally:
+                                if temp_file:
+                                    os.unlink(temp_file)
+                        if thumb:
+                            if len(thumb) > max_thumbnail_size:
+                                log.info("Couldn't compress image enough, not sending any thumbnail")
+                            else:
+                                log.info("Using thumbnail jpeg quality %d (image size: %d bytes)" % (quality, len(thumb)))
+                                xhtml = '<body><br/><a href="%s"> <img alt="%s" src="data:image/png;base64,%s"/> </a></body>' % \
+                                    (get.getData(), get.getData(), thumb)
+                    progress_window.close_dialog()
+                    id_ = gajim.get_an_id()
+                    def add_oob_tag():
+                        pass
+                    if self.encrypted_upload:
+                        keyAndIv = '#' + binascii.hexlify(iv) + binascii.hexlify(key)
+                        self.chat_control.send_message(message=get.getData() + keyAndIv, xhtml=None)
+                    else:
+                        global httpuploadurls
+                        url = get.getData()
+                        httpuploadurls[url] = True
+                        self.chat_control.send_message(message=url, xhtml=xhtml)
+                    self.chat_control.msg_textview.grab_focus()
+                else:
+                    progress_window.close_dialog()
+                    log.error("got unexpected http upload response code: " + str(response_code))
+                    ErrorDialog(_('Could not upload file'),
+                                _('Got unexpected http response code from server: ') + str(response_code),
+                                transient_for=self.chat_control.parent_win.window)
+            
+            def uploader():
+                progress_messages.put(_('Uploading file via HTTP...'))
+                try:
+                    headers = {'User-Agent': 'Gajim %s' % gajim.version,
+                               'Content-Type': mime_type}
+                    request = urllib2.Request(put.getData().encode("utf-8"), data=data, headers=headers)
+                    request.get_method = lambda: 'PUT'
+                    log.debug("opening urllib2 upload request...")
+                    transfer = urllib2.urlopen(request, timeout=30)
+                    log.debug("urllib2 upload request done, response code: " + str(transfer.getcode()))
+                    return transfer.getcode()
+                except UploadAbortedException:
+                    log.info("Upload aborted")
+                except:
+                    progress_window.close_dialog()
+                    ErrorDialog(_('Could not upload file'),
+                                _('Got unexpected exception while uploading file (see error log for more information)'),
+                                transient_for=self.chat_control.parent_win.window)
+                    raise       # fill error log with useful information
+                return 0
+
+            log.info("Uploading file to '%s'..." % str(put.getData()))
+            log.info("Please download from '%s' later..." % str(get.getData()))
+
+            gajim.thread_interface(uploader, [], upload_complete)
+
+        is_supported = gajim.get_jid_from_account(self.chat_control.account) in jid_to_servers and \
+                    gajim.connections[self.chat_control.account].connection != None
+        log.info("jid_to_servers of %s: %s ; connection: %s" % (gajim.get_jid_from_account(self.chat_control.account), str(jid_to_servers[gajim.get_jid_from_account(self.chat_control.account)]), str(gajim.connections[self.chat_control.account].connection)))
+        if not is_supported:
+            progress_window.close_dialog()
+            log.error("upload component vanished, account got disconnected??")
+            ErrorDialog(_('Your server does not support http uploads or you just got disconnected.\nPlease try to reconnect or reopen the chat window to fix this.'),
+                transient_for=self.chat_control.parent_win.window)
+            return
+
+        # create iq for slot request
+        id_ = gajim.get_an_id()
+        iq = nbxmpp.Iq(
+            typ='get',
+            to=jid_to_servers[gajim.get_jid_from_account(self.chat_control.account)],
+            queryNS=None
+        )
+        iq.setID(id_)
+        request = iq.addChild(
+            name="request",
+            namespace=NS_HTTPUPLOAD
+        )
+        filename = request.addChild(
+            name="filename",
+        )
+        filename.addData(os.path.basename(path_to_file))
+        size = request.addChild(
+            name="size",
+        )
+        size.addData(filesize)
+        content_type = request.addChild(
+            name="content-type",
+        )
+        content_type.addData(mime_type)
+
+        # send slot request and register callback
+        log.debug("sending httpupload slot request iq...")
+        iq_ids_to_callbacks[str(id_)] = upload_file
+        gajim.connections[self.chat_control.account].connection.send(iq)
+
+        self.chat_control.msg_textview.grab_focus()
+
+    def on_file_button_clicked(self, widget):
+        self.dialog_type = 'file'
+        self.dlg = FileChooserDialog(on_response_ok=self.on_file_dialog_ok, on_response_cancel=None,
+            title_text = _('Choose file to send'), action = gtk.FILE_CHOOSER_ACTION_OPEN,
+            buttons = (gtk.STOCK_CANCEL, gtk.RESPONSE_CANCEL, gtk.STOCK_OPEN, gtk.RESPONSE_OK),
+            default_response = gtk.RESPONSE_OK,)
+
+    def on_image_button_clicked(self, widget):
+        self.dialog_type = 'image'
+        self.dlg = ImageChooserDialog(on_response_ok=self.on_file_dialog_ok, on_response_cancel=None)
+
+    def get_pixbuf_of_size(self, pixbuf, size):
+        # Creates a pixbuf that fits in the specified square of sizexsize
+        # while preserving the aspect ratio
+        # Returns scaled_pixbuf
+        image_width = pixbuf.get_width()
+        image_height = pixbuf.get_height()
+
+        if image_width > image_height:
+            if image_width > size:
+                image_height = int(size / float(image_width) * image_height)
+                image_width = int(size)
+        else:
+            if image_height > size:
+                image_width = int(size / float(image_height) * image_width)
+                image_height = int(size)
+
+        crop_pixbuf = pixbuf.scale_simple(image_width, image_height,
+            gtk.gdk.INTERP_BILINEAR)
+        return crop_pixbuf
+
+
+class StreamFileWithProgress(file):
+    def __init__(self, path, mode, callback=None,
+                 encrypted_upload=False, key=None, iv=None, *args):
+        file.__init__(self, path, mode)
+        self.encrypted_upload = encrypted_upload
+        self.seek(0, os.SEEK_END)
+        if self.encrypted_upload:
+            if os.name == 'nt':
+                self.backend = backend
+            else:
+                self.backend = default_backend()
+            self.encryptor = Cipher(
+                algorithms.AES(key),
+                GCM(iv),
+                backend=self.backend).encryptor()
+            self._total = self.tell() + TAGSIZE
+        else:
+            self._total = self.tell()
+        self.seek(0)
+        self._callback = callback
+        self._args = args
+        self._seen = 0
+
+    def __len__(self):
+        return self._total
+
+    def read(self, size):
+        if self.encrypted_upload:
+            data = file.read(self, size)
+            if len(data) > 0:
+                data = self.encryptor.update(data)
+                self._seen += len(data)
+                if (self._seen + TAGSIZE) == self._total:
+                    self.encryptor.finalize()
+                    data += self.encryptor.tag
+                    self._seen += TAGSIZE
+                if self._callback:
+                    self._callback(self._seen, self._total, *self._args)
+            return data
+        else:
+            data = file.read(self, size)
+            self._seen += len(data)
+            if self._callback:
+                self._callback(self._seen, self._total, *self._args)
+            return data
+
+
+class ProgressWindow:
+    def __init__(self, title_text, during_text, messages_queue, plugin):
+        self.plugin = plugin
+        self.xml = gtkgui_helpers.get_gtk_builder(self.plugin.local_file_path('upload_progress_dialog.ui'))
+        self.messages_queue = messages_queue
+        self.dialog = self.xml.get_object('progress_dialog')
+        self.label = self.xml.get_object('label')
+        self.cancel_button = self.xml.get_object('close_button')
+        self.label.set_markup('<big>' + during_text + '</big>')
+        self.progressbar = self.xml.get_object('progressbar')
+        self.progressbar.set_text("")
+        self.dialog.set_title(title_text)
+        self.dialog.set_geometry_hints(min_width=400, min_height=96)
+        self.dialog.set_position(gtk.WIN_POS_CENTER_ON_PARENT)
+        self.dialog.show_all()
+        self.xml.connect_signals(self)
+
+        self.stopped = False
+        self.pulse_progressbar_timeout_id = gobject.timeout_add(100, self.pulse_progressbar)
+        self.process_messages_queue_timeout_id = gobject.timeout_add(100, self.process_messages_queue)
+
+
+    def pulse_progressbar(self):
+        if self.dialog:
+            self.progressbar.pulse()
+            return True # loop forever
+        return False
+
+    def process_messages_queue(self):
+        if not self.messages_queue.empty():
+            self.label.set_markup('<big>' + self.messages_queue.get() + '</big>')
+        if self.dialog:
+            return True # loop forever
+        return False
+
+    def on_progress_dialog_delete_event(self, widget, event):
+        self.stopped = True
+        if self.pulse_progressbar_timeout_id:
+            gobject.source_remove(self.pulse_progressbar_timeout_id)
+        gobject.source_remove(self.process_messages_queue_timeout_id)
+
+    def on_cancel(self, widget):
+        self.stopped = True
+        if self.pulse_progressbar_timeout_id:
+            gobject.source_remove(self.pulse_progressbar_timeout_id)
+        gobject.source_remove(self.process_messages_queue_timeout_id)
+        self.dialog.destroy()
+
+    def update_progress(self, seen, total):
+        if self.stopped == True:
+            raise UploadAbortedException
+        if self.pulse_progressbar_timeout_id:
+            gobject.source_remove(self.pulse_progressbar_timeout_id)
+            self.pulse_progressbar_timeout_id = None
+        pct = (float(seen) / total) * 100.0
+        self.progressbar.set_fraction(float(seen) / total)
+        self.progressbar.set_text(str(int(pct)) + "%")
+        log.debug('upload progress: %.2f%% (%d of %d bytes)' % (pct, seen, total))
+
+    def close_dialog(self):
+        self.on_cancel(None)
+
+class UploadAbortedException(Exception):
+    def __str__(self):
+        return "Upload Aborted"
diff --git a/gajim-plugin/httpupload/image.png b/gajim-plugin/httpupload/image.png
new file mode 100644
index 0000000..32dda52
--- /dev/null
+++ b/gajim-plugin/httpupload/image.png
diff --git a/gajim-plugin/httpupload/manifest.ini b/gajim-plugin/httpupload/manifest.ini
new file mode 100644
index 0000000..fa21628
--- /dev/null
+++ b/gajim-plugin/httpupload/manifest.ini
@@ -0,0 +1,16 @@
+[info]
+name: HttpUpload
+short_name: httpupload
+version: 0.4.1-thedevstack
+description: This plugin is designed to send a file to a contact or muc by using httpupload.<br/>
+ Your server must support <a href="http://xmpp.org/extensions/xep-0363.html">XEP-0363: HTTP Upload</a>.<br/>
+ Conversations supported this.<br/>
+ If the receiving side supports <a href="http://xmpp.org/extensions/xep-0071.html">XEP-0071: XHTML-IM</a>
+ and maintains the scheme data: URI, a thumbnail image is send along the link to the full size image.
+ If the receiving side doesn't support this, only a text message containing the link to the image is send.
+ This plugin adds additionally to this a hint for processing: <httpupload xmlns="urn:xmpp:hints"/>
+authors: Thilo Molitor <thilo@eightysoft.de>
+ Philipp Hörist <philipp@hoerist.com>
+homepage: https://trac-plugins.gajim.org/wiki/HttpUploadPlugin
+min_gajim_version: 0.16.5
+max_gajim_version: 0.16.9
diff --git a/gajim-plugin/httpupload/upload_progress_dialog.ui b/gajim-plugin/httpupload/upload_progress_dialog.ui
new file mode 100644
index 0000000..b50c3c2
--- /dev/null
+++ b/gajim-plugin/httpupload/upload_progress_dialog.ui
@@ -0,0 +1,105 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- Generated with glade 3.18.3 -->
+<interface>
+  <requires lib="gtk+" version="2.16"/>
+  <object class="GtkDialog" id="progress_dialog">
+    <property name="can_focus">True</property>
+    <property name="resizable">False</property>
+    <property name="icon_name">upload-media</property>
+    <property name="type_hint">dialog</property>
+    <signal name="delete-event" handler="on_progress_dialog_delete_event" swapped="no"/>
+    <child internal-child="vbox">
+      <object class="GtkBox" id="dialog-vbox">
+        <property name="visible">True</property>
+        <property name="can_focus">False</property>
+        <property name="orientation">vertical</property>
+        <property name="spacing">6</property>
+        <child internal-child="action_area">
+          <object class="GtkButtonBox" id="dialog-action_area11">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <property name="layout_style">end</property>
+            <child>
+              <object class="GtkAlignment" id="alignment3">
+                <property name="visible">True</property>
+                <property name="can_focus">False</property>
+                <property name="top_padding">2</property>
+                <property name="bottom_padding">4</property>
+                <property name="left_padding">0</property>
+                <property name="right_padding">3</property>
+                <child>
+                  <object class="GtkButton" id="close_button">
+                    <property name="label">gtk-cancel</property>
+                    <property name="visible">True</property>
+                    <property name="can_focus">True</property>
+                    <property name="can_default">True</property>
+                    <property name="receives_default">False</property>
+                    <property name="use_stock">True</property>
+                    <signal name="clicked" handler="on_cancel" swapped="no"/>
+                  </object>
+                </child>
+              </object>
+              <packing>
+                <property name="expand">False</property>
+                <property name="fill">True</property>
+                <property name="position">2</property>
+              </packing>
+            </child>
+          </object>
+          <packing>
+            <property name="expand">False</property>
+            <property name="fill">False</property>
+            <property name="pack_type">end</property>
+            <property name="position">0</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GtkAlignment" id="alignment1">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <property name="top_padding">8</property>
+            <property name="bottom_padding">4</property>
+            <property name="left_padding">8</property>
+            <property name="right_padding">8</property>
+            <child>
+              <object class="GtkLabel" id="label">
+                <property name="visible">True</property>
+                <property name="can_focus">False</property>
+                <property name="xalign">0</property>
+                <property name="use_markup">True</property>
+              </object>
+            </child>
+          </object>
+          <packing>
+            <property name="expand">False</property>
+            <property name="fill">True</property>
+            <property name="position">1</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GtkAlignment" id="alignment2">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <property name="top_padding">4</property>
+            <property name="bottom_padding">4</property>
+            <property name="left_padding">8</property>
+            <property name="right_padding">8</property>
+            <child>
+              <object class="GtkProgressBar" id="progressbar">
+                <property name="visible">True</property>
+                <property name="can_focus">False</property>
+                <property name="pulse_step">0.10000000149</property>
+                <property name="show_text">True</property>
+              </object>
+            </child>
+          </object>
+          <packing>
+            <property name="expand">False</property>
+            <property name="fill">True</property>
+            <property name="position">2</property>
+          </packing>
+        </child>
+      </object>
+    </child>
+  </object>
+</interface>
diff --git a/prosody-module/mod_http_upload_external/mod_http_upload_external.lua b/prosody-module/mod_http_upload_external/mod_http_upload_external.lua
index 11175ee..a9b4551 100644
--- a/prosody-module/mod_http_upload_external/mod_http_upload_external.lua
+++ b/prosody-module/mod_http_upload_external/mod_http_upload_external.lua
@@ -12,11 +12,13 @@
 -- configuration
 local external_url = module:get_option("http_upload_external_url");
 local xmpp_server_key = module:get_option("http_upload_external_server_key");
+local filetransfer_manager_ui_url = module:get_option("filetransfer_manager_ui_url");
 
 -- imports
 local st = require"util.stanza";
 local http = require"socket.http";
 local json = require"util.json";
+local dataform = require "util.dataforms".new;
 
 -- depends
 module:depends("disco");
@@ -26,6 +28,12 @@ local xmlns_http_upload = "urn:xmpp:filetransfer:http";
 
 module:add_feature(xmlns_http_upload);
 
+-- add additional disco info to advertise managing UI
+module:add_extension(dataform {
+        { name = "FORM_TYPE", type = "hidden", value = xmlns_http_upload },
+        { name = "filetransfer-manager-ui-url", type = "text-single" },
+}:form({ ["filetransfer-manager-ui-url"] = filetransfer_manager_ui_url }, "result"));
+
 -- hooks
 module:hook("iq/host/"..xmlns_http_upload..":request", function (event)
    local stanza, origin = event.stanza, event.origin;
@@ -43,7 +51,12 @@ module:hook("iq/host/"..xmlns_http_upload..":request", function (event)
       return true;
    end
    local slot_type = request.attr.type;
-   module:log("debug", "incoming request is of type " .. slot_type);
+   if slot_type then
+      module:log("debug", "incoming request is of type " .. slot_type);
+   else
+      module:log("debug", "incoming request has no type - using default type 'upload'");
+   end
+   
    if not slot_type or slot_type == "upload" then
      -- validate
      local filename = request:get_child_text("filename");
@@ -67,7 +80,10 @@ module:hook("iq/host/"..xmlns_http_upload..":request", function (event)
 
      -- the request
      local respbody, statuscode = http.request(external_url, reqbody);
-     respbody = string.gsub(respbody, "\\/", "/")
+     -- respbody is nil in case the server is not reachable
+     if respbody ~= nil then
+        respbody = string.gsub(respbody, "\\/", "/");
+     end
 
      local get_url = nil;
      local put_url = nil;
@@ -87,19 +103,19 @@ module:hook("iq/host/"..xmlns_http_upload..":request", function (event)
                  origin.send(st.error_reply(stanza, "modify", "not-acceptable", errobj.msg));
                  return true;
               elseif errobj.err_code == 2 then
-                 origin.send(st.error_reply(stanza, "modify", "not-acceptable", errobj.msg,
-                    st.stanza("file-too-large", {xmlns=xmlns_http_upload})
-                       :tag("max-size"):text(errobj.parameters.max_file_size)));
+                 origin.send(st.error_reply(stanza, "modify", "not-acceptable", errobj.msg)
+                       :tag("file-too-large", {xmlns=xmlns_http_upload})
+                       :tag("max-size"):text(errobj.parameters.max_file_size));
                  return true;
               elseif errobj.err_code == 3 then
-                 origin.send(st.error_reply(stanza, "modify", "not-acceptable", errobj.msg,
-                    st.stanza("invalid-character", {xmlns=xmlns_http_upload})
-                       :text(errobj.parameters.invalid_character)));
+                 origin.send(st.error_reply(stanza, "modify", "not-acceptable", errobj.msg)
+                       :tag("invalid-character", {xmlns=xmlns_http_upload})
+                       :text(errobj.parameters.invalid_character));
                  return true;
               elseif errobj.err_code == 4 then
-                 origin.send(st.error_reply(stanza, "cancel", "internal-server-error", errobj.msg,
-                    st.stanza("missing-parameter", {xmlns=xmlns_http_upload})
-                       :text(errobj.parameters.missing_parameter)));
+                 origin.send(st.error_reply(stanza, "cancel", "internal-server-error", errobj.msg)
+                       :tag("missing-parameter", {xmlns=xmlns_http_upload})
+                       :text(errobj.parameters.missing_parameter));
                  return true;
               else
                  origin.send(st.error_reply(stanza, "cancel", "undefined-condition", "unknown err_code"));
@@ -127,9 +143,12 @@ module:hook("iq/host/"..xmlns_http_upload..":request", function (event)
               return true;
            end
         end
-     else
+     elseif respbody ~= nil then
         origin.send(st.error_reply(stanza, "cancel", "undefined-condition", "status code: " .. statuscode .. " response: " ..respbody));
         return true;
+     else
+        -- http file service not reachable
+        origin.send(st.error_reply(stanza, "cancel", "undefined-condition", "status code: " .. statuscode));
      end
 
      local reply = st.reply(stanza);
@@ -148,7 +167,10 @@ module:hook("iq/host/"..xmlns_http_upload..":request", function (event)
      local reqbody = "xmpp_server_key=" .. xmpp_server_key .. "&slot_type=delete&file_url=" .. fileurl .. "&user_jid=" .. orig_from;
      -- the request
      local respbody, statuscode = http.request(external_url, reqbody);
-     respbody = string.gsub(respbody, "\\/", "/")
+     -- respbody is nil in case the server is not reachable
+     if respbody ~= nil then
+        respbody = string.gsub(respbody, "\\/", "/");
+     end
      
      local delete_token = nil;
      -- check the response
@@ -163,9 +185,9 @@ module:hook("iq/host/"..xmlns_http_upload..":request", function (event)
         else
            if errobj["err_code"] ~= nil and errobj["msg"] ~= nil then
               if errobj.err_code == 4 then
-                 origin.send(st.error_reply(stanza, "cancel", "internal-server-error", errobj.msg,
-                    st.stanza("missing-parameter", {xmlns=xmlns_http_upload})
-                       :text(errobj.parameters.missing_parameter)));
+                 origin.send(st.error_reply(stanza, "cancel", "internal-server-error", errobj.msg)
+                       :tag("missing-parameter", {xmlns=xmlns_http_upload})
+                       :text(errobj.parameters.missing_parameter));
                  return true;
               else
                  origin.send(st.error_reply(stanza, "cancel", "undefined-condition", "unknown err_code"));
@@ -192,9 +214,12 @@ module:hook("iq/host/"..xmlns_http_upload..":request", function (event)
               return true;
            end
         end
-     else
+     elseif respbody ~= nil then
         origin.send(st.error_reply(stanza, "cancel", "undefined-condition", "status code: " .. statuscode .. " response: " ..respbody));
         return true;
+     else
+        -- http file service not reachable
+        origin.send(st.error_reply(stanza, "cancel", "undefined-condition", "status code: " .. statuscode));
      end
 
      local reply = st.reply(stanza);
diff --git a/storage-backend/index.php b/storage-backend/index.php
index a7c79d3..d153e63 100644
--- a/storage-backend/index.php
+++ b/storage-backend/index.php
@@ -11,6 +11,7 @@
  *   size
  *   content_type
  *   user_jid
+ *   receipient_jid
  * 403: In case the XMPP Server Key is not valid
  * 406:
  *   File is empty (error code: 1)
@@ -46,7 +47,9 @@
  *   The slot's delete token does not match the header field "X-FILETRANSFER-HTTP-DELETE-TOKEN"
  *   The slot's delete token is not valid any more
  */
- 
+include_once(__DIR__.'/lib/functions.common.inc.php');
+include_once(__DIR__.'/lib/functions.http.inc.php');
+include_once(__DIR__.'/lib/functions.filetransfer.inc.php');
 $method = $_SERVER['REQUEST_METHOD'];
 
 // Load configuration
@@ -101,6 +104,7 @@ switch ($method) {
         $filename = rawurlencode(getMandatoryPostParameter('filename'));
         $filesize = getMandatoryPostParameter('size');
         $mimeType = getOptionalPostParameter('content_type');
+        $receipientJid = getMandatoryPostParameter('receipient_jid');
         
         // check file name - return 406 (not acceptable) if file contains invalid characters
         foreach ($config['invalid_characters_in_filename'] as $invalidCharacter) {
@@ -118,7 +122,7 @@ switch ($method) {
         }
         // generate slot uuid, register slot uuid and expected file size and expected mime type
         $slotUUID = generate_uuid();
-        registerSlot($slotUUID, $filename, $filesize, $mimeType, $userJid, $config);
+        registerSlot($slotUUID, $filename, $filesize, $mimeType, $userJid, $receipientJid, $config);
         if (!mkdir(getUploadFilePath($slotUUID, $config))) {
           sendHttpReturnCodeAndJson(500, "Could not create directory for upload.");
         }
@@ -217,13 +221,6 @@ function checkFilenameParameter($filename, $slotParameters) {
   return $slotParameters['filename'] == $filename;
 }
 
-function loadSlotParameters($slotUUID, $config) {
-  $slotParameters = require(getSlotFilePath($slotUUID, $config));
-  $slotParameters['filename'] = $slotParameters['filename'];
-  
-  return $slotParameters;
-}
-
 function getMandatoryPostParameter($parameterName) {
   $parameter = $_POST[$parameterName];
   if (!isset($parameter) || is_null($parameter) || empty($parameter)) {
@@ -232,26 +229,6 @@ function getMandatoryPostParameter($parameterName) {
   return $parameter;
 }
 
-function getOptionalPostParameter($parameterName, $default = NULL) {
-  $parameter = $_POST[$parameterName];
-  if (!isset($parameter) || is_null($parameter) || empty($parameter)) {
-    $parameter = $default;
-  }
-  return $parameter;
-}
-
-function sendHttpReturnCodeAndJson($code, $data) {
-  if (!is_array($data)) {
-    $data = ['msg' => $data];
-  }
-  sendHttpReturnCodeAndMessage($code, json_encode($data));
-}
-
-function sendHttpReturnCodeAndMessage($code, $text = '') {
-  http_response_code($code);
-  exit($text);
-}
-
 function getUUIDFromUri($uri) {
   $pattern = "/[a-f0-9]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/";
   preg_match($pattern, $uri, $matches);
@@ -263,10 +240,11 @@ function getFilenameFromUri($uri) {
   return substr($uri, $lastSlash);
 }
 
-function registerSlot($slotUUID, $filename, $filesize, $contentType, $userJid, $config) {
+function registerSlot($slotUUID, $filename, $filesize, $contentType, $userJid, $receipientJid, $config) {
   $contents = "<?php\n/*\n * This is an autogenerated file - do not edit\n */\n\n";
   $contents .= 'return [\'filename\' => \''.$filename.'\', \'filesize\' => \''.$filesize.'\', ';
-  $contents .= '\'content_type\' => \''.$contentType.'\', \'user_jid\' => \''.$userJid.'\'];\n?>';
+  $contents .= '\'content_type\' => \''.$contentType.'\', \'user_jid\' => \''.$userJid.'\', \'receipient_jid\' => \''.$receipientJid.'\'];';
+  $contents .= "\n?>";
   if (!file_put_contents(getSlotFilePath($slotUUID, $config), $contents)) {
     sendHttpReturnCodeAndMessage(500, "Could not create slot registry entry.");
   }
@@ -285,64 +263,4 @@ function registerDeleteToken($slotUUID, $filename, $deleteToken, $config) {
 function slotExists($slotUUID, $config) {
   return file_exists(getSlotFilePath($slotUUID, $config));
 }
-
-function getSlotFilePath($slotUUID, $config) {
-  return $config['slot_registry_dir'].$slotUUID;
-}
-
-function getUploadFilePath($slotUUID, $config, $filename = NULL) {
-  $path = $config['storage_base_path'].$slotUUID;
-  if (!is_null($filename)) {
-    $path .= '/'.$filename;
-  }
-  return $path;
-}
-
-/**
- * Inspired by https://github.com/owncloud/core/blob/master/lib/private/appframework/http/request.php#L523
- */
-function getServerProtocol() {
-  if (isset($_SERVER['HTTP_X_FORWARDED_PROTO'])) {
-      if (strpos($_SERVER['HTTP_X_FORWARDED_PROTO'], ',') !== false) {
-          $parts = explode(',', $_SERVER['HTTP_X_FORWARDED_PROTO']);
-          $proto = strtolower(trim($parts[0]));
-      } else {
-          $proto = strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']);
-      }
-      // Verify that the protocol is always HTTP or HTTPS
-      // default to http if an invalid value is provided
-      return $proto === 'https' ? 'https' : 'http';
-  }
-  if (isset($_SERVER['HTTPS'])
-      && $_SERVER['HTTPS'] !== null
-      && $_SERVER['HTTPS'] !== 'off'
-      && $_SERVER['HTTPS'] !== '') {
-      return 'https';
-  }
-  return 'http';
-}
-
-function getRequestHostname() {
-  if (isset($_SERVER['HTTP_X_FORWARDED_HOST'])) {
-    return strtolower($_SERVER['HTTP_X_FORWARDED_HOST']);
-  }
-  return strtolower($_SERVER['HTTP_HOST']);
-}
-
-function getRequestUriWithoutFilename() {
-  return strtolower(substr($_SERVER['REQUEST_URI'], 0, strrpos($_SERVER['REQUEST_URI'], '/') + 1));
-}
-
-/**
- * Copied from http://rogerstringer.com/2013/11/15/generate-uuids-php/
- */ 
-function generate_uuid() {
-  return sprintf( '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
-    mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ),
-    mt_rand( 0, 0xffff ),
-    mt_rand( 0, 0x0fff ) | 0x4000,
-    mt_rand( 0, 0x3fff ) | 0x8000,
-    mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff )
-  );
-}
 ?>
diff --git a/storage-backend/lib/functions.common.inc.php b/storage-backend/lib/functions.common.inc.php
new file mode 100644
index 0000000..b47268e
--- /dev/null
+++ b/storage-backend/lib/functions.common.inc.php
@@ -0,0 +1,18 @@
+<?php
+/*
+ * This file contains functions commonly used.
+ */
+
+/**
+ * Copied from http://rogerstringer.com/2013/11/15/generate-uuids-php/
+ */ 
+function generate_uuid() {
+  return sprintf( '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
+    mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ),
+    mt_rand( 0, 0xffff ),
+    mt_rand( 0, 0x0fff ) | 0x4000,
+    mt_rand( 0, 0x3fff ) | 0x8000,
+    mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff )
+  );
+}
+?>
\ No newline at end of file
diff --git a/storage-backend/lib/functions.filetransfer.inc.php b/storage-backend/lib/functions.filetransfer.inc.php
new file mode 100644
index 0000000..679cef1
--- /dev/null
+++ b/storage-backend/lib/functions.filetransfer.inc.php
@@ -0,0 +1,23 @@
+<?php
+/*
+ * This file contains the functions for the storage-backend.
+ */
+
+function getSlotFilePath($slotUUID, $config) {
+  return $config['slot_registry_dir'].$slotUUID;
+}
+
+function getUploadFilePath($slotUUID, $config, $filename = NULL) {
+  $path = $config['storage_base_path'].$slotUUID;
+  if (!is_null($filename)) {
+    $path .= '/'.$filename;
+  }
+  return $path;
+}
+
+function loadSlotParameters($slotUUID, $config) {
+  $slotParameters = require(getSlotFilePath($slotUUID, $config));
+  $slotParameters['filename'] = $slotParameters['filename'];
+  
+  return $slotParameters;
+}
\ No newline at end of file
diff --git a/storage-backend/lib/functions.http.inc.php b/storage-backend/lib/functions.http.inc.php
new file mode 100644
index 0000000..c508b20
--- /dev/null
+++ b/storage-backend/lib/functions.http.inc.php
@@ -0,0 +1,64 @@
+<?php
+/*
+ *
+ * This file contains functions to be used to
+ * extract information based on http request information.
+ *
+ */
+ 
+/**
+ * Inspired by https://github.com/owncloud/core/blob/master/lib/private/appframework/http/request.php#L523
+ */
+function getServerProtocol() {
+  if (isset($_SERVER['HTTP_X_FORWARDED_PROTO'])) {
+      if (strpos($_SERVER['HTTP_X_FORWARDED_PROTO'], ',') !== false) {
+          $parts = explode(',', $_SERVER['HTTP_X_FORWARDED_PROTO']);
+          $proto = strtolower(trim($parts[0]));
+      } else {
+          $proto = strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']);
+      }
+      // Verify that the protocol is always HTTP or HTTPS
+      // default to http if an invalid value is provided
+      return $proto === 'https' ? 'https' : 'http';
+  }
+  if (isset($_SERVER['HTTPS'])
+      && $_SERVER['HTTPS'] !== null
+      && $_SERVER['HTTPS'] !== 'off'
+      && $_SERVER['HTTPS'] !== '') {
+      return 'https';
+  }
+  return 'http';
+}
+
+function getRequestHostname() {
+  if (isset($_SERVER['HTTP_X_FORWARDED_HOST'])) {
+    return strtolower($_SERVER['HTTP_X_FORWARDED_HOST']);
+  }
+  return strtolower($_SERVER['HTTP_HOST']);
+}
+
+function getRequestUriWithoutFilename() {
+  return strtolower(substr($_SERVER['REQUEST_URI'], 0, strrpos($_SERVER['REQUEST_URI'], '/') + 1));
+}
+
+function sendHttpReturnCodeAndJson($code, $data) {
+  if (!is_array($data)) {
+    $data = ['msg' => $data];
+  }
+  header('Content-Type: application/json');
+  sendHttpReturnCodeAndMessage($code, json_encode($data));
+}
+
+function sendHttpReturnCodeAndMessage($code, $text = '') {
+  http_response_code($code);
+  exit($text);
+}
+
+function getOptionalPostParameter($parameterName, $default = NULL) {
+  $parameter = $_POST[$parameterName];
+  if (!isset($parameter) || is_null($parameter) || empty($parameter)) {
+    $parameter = $default;
+  }
+  return $parameter;
+}
+?>
\ No newline at end of file