[omemo] Add file decryption

omemo/file_decryption.py

+# -*- coding: utf-8 -*-
+#
+# Copyright 2017 Philipp Hörist <philipp@hoerist.com>
+#
+# This file is part of Gajim-OMEMO plugin.
+#
+# The Gajim-OMEMO plugin 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, either version 3 of the License, or (at your option) any
+# later version.
+#
+# Gajim-OMEMO 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
+# the Gajim-OMEMO plugin.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import os
+import hashlib
+import logging
+import socket
+import threading
+import platform
+import subprocess
+import binascii
+from urllib.request import urlopen
+from urllib.error import URLError
+from urllib.parse import urlparse, urldefrag
+from io import BufferedWriter, FileIO, BytesIO
+
+from gi.repository import GLib
+import gtkgui_helpers
+from common import configpaths
+from dialogs import ErrorDialog, YesNoDialog
+if os.name == 'nt':
+    import certifi
+
+log = logging.getLogger('gajim.plugin_system.omemo.filedecryption')
+
+ERROR = False
+try:
+    from cryptography.hazmat.primitives.ciphers import Cipher
+    from cryptography.hazmat.primitives.ciphers import algorithms
+    from cryptography.hazmat.primitives.ciphers.modes import GCM
+    from cryptography.hazmat.backends import default_backend
+except ImportError:
+    log.exception('ImportError')
+    ERROR = True
+
+DIRECTORY = os.path.join(configpaths.gajimpaths['MY_DATA'], 'downloads')
+
+try:
+    if not os.path.exists(DIRECTORY):
+        os.makedirs(DIRECTORY)
+except Exception:
+    ERROR = True
+    log.exception('Error')
+
+
+class File:
+    def __init__(self, url):
+        self.url, self.fragment = urldefrag(url)
+        self.key = None
+        self.iv = None
+        self.filepath = None
+        self.filename = None
+
+
+class FileDecryption:
+    def __init__(self, plugin):
+        self.plugin = plugin
+        self.window = None
+
+    def hyperlink_handler(self, url, kind, instance, window):
+        if ERROR or kind != 'url':
+            return
+        self.window = window
+        urlparts = urlparse(url)
+        file = File(urlparts.geturl())
+
+        if urlparts.scheme not in ["https"] or not urlparts.netloc:
+            log.info("Not accepting URL for decryption: %s", url)
+            return
+
+        if not self.is_encrypted(file):
+            log.info('Url not encrypted: %s', url)
+            return
+
+        self.create_paths(file)
+
+        if os.path.exists(file.filepath):
+            instance.plugin_modified = True
+            self.finished(file)
+            return
+
+        event = threading.Event()
+        progressbar = ProgressWindow(self.plugin, self.window, event)
+        thread = threading.Thread(target=Download,
+                                  args=(file, progressbar, self.window,
+                                        event, self))
+        thread.daemon = True
+        thread.start()
+        instance.plugin_modified = True
+
+    def is_encrypted(self, file):
+        if file.fragment:
+            try:
+                fragment = binascii.unhexlify(file.fragment)
+                file.key = fragment[16:]
+                file.iv = fragment[:16]
+                if len(file.key) == 32 and len(file.iv) == 16:
+                    return True
+            except:
+                return False
+        return False
+
+    def create_paths(self, file):
+        file.filename = os.path.basename(file.url)
+        ext = os.path.splitext(file.filename)[1]
+        name = os.path.splitext(file.filename)[0]
+        urlhash = hashlib.sha1(file.url.encode('utf-8')).hexdigest()
+        newfilename = name + '_' + urlhash[:10] + ext
+        file.filepath = os.path.join(DIRECTORY, newfilename)
+
+    def finished(self, file):
+        question = 'Do you want to open %s' % file.filename
+        YesNoDialog('Open File', question,
+                    transient_for=self.window,
+                    on_response_yes=(self.open_file, file.filepath))
+        return False
+
+    def open_file(self, checked, path):
+        if platform.system() == "Windows":
+            os.startfile(path)
+        elif platform.system() == "Darwin":
+            subprocess.Popen(["open", path])
+        else:
+            subprocess.Popen(["xdg-open", path])
+
+
+class Download:
+    def __init__(self, file, progressbar, window, event, base):
+        self.file = file
+        self.progressbar = progressbar
+        self.window = window
+        self.event = event
+        self.base = base
+        self.download()
+
+    def download(self):
+        GLib.idle_add(self.progressbar.set_text, 'Downloading...')
+        data = self.load_url()
+        if isinstance(data, str):
+            GLib.idle_add(self.progressbar.close_dialog)
+            GLib.idle_add(self.error, data)
+            return
+
+        GLib.idle_add(self.progressbar.set_text, 'Decrypting...')
+        decrypted_data = self.aes_decrypt(data)
+
+        GLib.idle_add(
+            self.progressbar.set_text, 'Writing file to harddisk...')
+        self.write_file(decrypted_data)
+
+        GLib.idle_add(self.progressbar.close_dialog)
+
+        GLib.idle_add(self.base.finished, self.file)
+
+    def load_url(self):
+        try:
+            stream = BytesIO()
+            if os.name == 'nt':
+                get_request = urlopen(
+                    self.file.url, cafile=certifi.where(), timeout=30)
+            else:
+                get_request = urlopen(self.file.url, timeout=30)
+            size = get_request.info()['Content-Length']
+            if not size:
+                errormsg = 'Content-Length not found in header'
+                log.error(errormsg)
+                return errormsg
+            while True:
+                try:
+                    if self.event.isSet():
+                        raise UploadAbortedException
+                    temp = get_request.read(10000)
+                    GLib.idle_add(
+                        self.progressbar.update_progress, len(temp), size)
+                except socket.timeout:
+                    errormsg = 'Request timeout'
+                    log.error(errormsg)
+                    return errormsg
+                if temp:
+                    stream.write(temp)
+                else:
+                    return stream
+        except UploadAbortedException as error:
+            log.info('Upload Aborted')
+            errormsg = error
+        except URLError as error:
+            log.exception('URLError')
+            errormsg = error.reason
+        except Exception as error:
+            log.exception('Error')
+            errormsg = error
+        stream.close()
+        return str(errormsg)
+
+    def aes_decrypt(self, payload):
+        # Use AES128 GCM with the given key and iv to decrypt the payload.
+        payload = payload.getvalue()
+        data = payload[:-16]
+        tag = payload[-16:]
+        decryptor = Cipher(
+            algorithms.AES(self.file.key),
+            GCM(self.file.iv, tag=tag),
+            backend=default_backend()).decryptor()
+        return decryptor.update(data) + decryptor.finalize()
+
+    def write_file(self, data):
+        log.info('Writing data to %s', self.file.filepath)
+        try:
+            with BufferedWriter(FileIO(self.file.filepath, "wb")) as output:
+                output.write(data)
+                output.close()
+        except Exception:
+            log.exception('Failed to write file')
+
+    def error(self, error):
+        ErrorDialog(_('Error'), error, transient_for=self.window)
+        return False
+
+
+class ProgressWindow:
+    def __init__(self, plugin, window, event):
+        self.plugin = plugin
+        self.event = event
+        self.xml = gtkgui_helpers.get_gtk_builder(
+            self.plugin.local_file_path('upload_progress_dialog.ui'))
+        self.dialog = self.xml.get_object('progress_dialog')
+        self.dialog.set_transient_for(window)
+        self.label = self.xml.get_object('label')
+        self.progressbar = self.xml.get_object('progressbar')
+        self.progressbar.set_text("")
+        self.dialog.show_all()
+        self.xml.connect_signals(self)
+        self.seen = 0
+
+    def set_text(self, text):
+        self.label.set_markup('<big>%s</big>' % text)
+        return False
+
+    def update_progress(self, seen, total):
+        self.seen += seen
+        pct = (self.seen / float(total)) * 100.0
+        self.progressbar.set_fraction(self.seen / float(total))
+        self.progressbar.set_text(str(int(pct)) + "%")
+        return False
+
+    def close_dialog(self, *args):
+        self.dialog.destroy()
+        return False
+
+    def on_destroy(self, *args):
+        self.event.set()
+
+
+class UploadAbortedException(Exception):
+    def __str__(self):
+        return _('Upload Aborted')

omemo/omemoplugin.py

@@ -30,6 +30,7 @@ from plugins import GajimPlugin
 from plugins.helpers import log_calls
 from nbxmpp.simplexml import Node
 from nbxmpp import NS_CORRECT, NS_ADDRESS
+from .file_decryption import FileDecryption
 
 from .xmpp import (
     NS_NOTIFY, NS_OMEMO, NS_EME, BundleInformationAnnouncement,
@@ -115,7 +116,9 @@ class OmemoPlugin(GajimPlugin):
         self.gui_extension_points = {'chat_control': (self.connect_ui,
                                                       self.disconnect_ui),
                                      'groupchat_control': (self.connect_ui,
-                                                           self.disconnect_ui)}
+                                                           self.disconnect_ui),
+                                     'hyperlink_handler': (self.file_decryption,
+                                                           None)}
         SUPPORTED_PERSONAL_USER_EVENTS.append(DevicelistPEP)
         self.plugin = self
         self.announced = []
@@ -179,6 +182,9 @@ class OmemoPlugin(GajimPlugin):
                              'enable_esessions', False)
         log.info(str(account) + " => Gajim E2E encryption disabled")
 
+    def file_decryption(self, url, kind, instance, window):
+        FileDecryption(self).hyperlink_handler(url, kind, instance, window)
+
     @log_calls('OmemoPlugin')
     def signed_in(self, event):
         """ Method called on SignIn

omemo/upload_progress_dialog.ui

+<?xml version="1.0" encoding="UTF-8"?>
+<!-- Generated with glade 3.20.0 -->
+<interface>
+  <requires lib="gtk+" version="3.0"/>
+  <object class="GtkDialog" id="progress_dialog">
+    <property name="can_focus">True</property>
+    <property name="title" translatable="yes">Download</property>
+    <property name="resizable">False</property>
+    <property name="window_position">center-on-parent</property>
+    <property name="destroy_with_parent">True</property>
+    <property name="icon_name">go-down</property>
+    <property name="type_hint">dialog</property>
+    <child internal-child="vbox">
+      <object class="GtkBox" id="dialog-vbox">
+        <property name="width_request">250</property>
+        <property name="visible">True</property>
+        <property name="can_focus">False</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="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="close_dialog" swapped="no"/>
+                    <signal name="destroy" handler="on_destroy" 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="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>