url_image_preview.py

# -*- 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/>.
##

import os
import hashlib
import binascii
import logging
from urllib.parse import urlparse
from io import BytesIO
import shutil
from functools import partial

from gi.repository import Gtk, Gdk, GLib, GdkPixbuf

from gajim.common import app
from gajim.common import helpers
from gajim.common import configpaths
from gajim import dialogs
from gajim.plugins import GajimPlugin
from gajim.plugins.helpers import log_calls
from url_image_preview.http_functions import get_http_head, get_http_file
from url_image_preview.config_dialog import UrlImagePreviewConfigDialog

log = logging.getLogger('gajim.plugin_system.preview')

PILLOW_AVAILABLE = True
try:
    from PIL import Image
except:
    log.debug('Pillow not available')
    PILLOW_AVAILABLE = False

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
    decryption_available = True
except Exception:
    DEP_MSG = 'For preview of encrypted images, ' \
              'please install python-cryptography!'
    log.exception('Error')
    log.info('Decryption/Encryption disabled due to errors')
    decryption_available = False

ACCEPTED_MIME_TYPES = ('image/png', 'image/jpeg', 'image/gif', 'image/raw',
                       'image/svg+xml', 'image/x-ms-bmp')


class UrlImagePreviewPlugin(GajimPlugin):
    @log_calls('UrlImagePreviewPlugin')
    def init(self):
        if not decryption_available:
            self.available_text = DEP_MSG
        self.config_dialog = partial(UrlImagePreviewConfigDialog, self)
        self.gui_extension_points = {
            'chat_control_base': (self.connect_with_chat_control,
                                  self.disconnect_from_chat_control),
            'history_window':
                (self.connect_with_history, self.disconnect_from_history),
            'print_real_text': (self.print_real_text, None), }
        self.config_default_values = {
            'PREVIEW_SIZE': (150, 'Preview size(10-512)'),
            'MAX_FILE_SIZE': (524288, 'Max file size for image preview'),
            'LEFTCLICK_ACTION': ('open_menuitem', 'Open'),
            'ANONYMOUS_MUC': False,}
        self.controls = {}
        self.history_window_control = None

    @log_calls('UrlImagePreviewPlugin')
    def connect_with_chat_control(self, chat_control):
        account = chat_control.contact.account.name
        jid = chat_control.contact.jid
        if account not in self.controls:
            self.controls[account] = {}
        self.controls[account][jid] = Base(self, chat_control.conv_textview)

    @log_calls('UrlImagePreviewPlugin')
    def disconnect_from_chat_control(self, chat_control):
        account = chat_control.contact.account.name
        jid = chat_control.contact.jid
        self.controls[account][jid].deinit_handlers()
        del self.controls[account][jid]

    @log_calls('UrlImagePreviewPlugin')
    def connect_with_history(self, history_window):
        if self.history_window_control:
            log.error("connect_with_history: deinit handlers")
            self.history_window_control.deinit_handlers()
        log.error("connect_with_history: create base")
        self.history_window_control = Base(
            self, history_window.history_textview)

    @log_calls('UrlImagePreviewPlugin')
    def disconnect_from_history(self, history_window):
        if self.history_window_control:
            self.history_window_control.deinit_handlers()
        self.history_window_control = None

    def print_real_text(self, tv, real_text, text_tags, graphics,
                        iter_, additional_data):
        if tv.used_in_history_window and self.history_window_control:
            self.history_window_control.print_real_text(
                real_text, text_tags, graphics, iter_, additional_data)

        account = tv.account
        for jid in self.controls[account]:
            if self.controls[account][jid].textview != tv:
                continue
            self.controls[account][jid].print_real_text(
                real_text, text_tags, graphics, iter_, additional_data)
            return


class Base(object):
    def __init__(self, plugin, textview):
        self.plugin = plugin
        self.textview = textview
        self.handlers = {}

        self.directory = os.path.join(configpaths.gajimpaths['MY_DATA'],
                                      'downloads')
        self.thumbpath = os.path.join(configpaths.gajimpaths['MY_CACHE'],
                                      'downloads.thumb')

        try:
            self._create_path(self.directory)
            self._create_path(self.thumbpath)
        except Exception:
            log.error("Error creating download and/or thumbnail folder!")
            raise

    def deinit_handlers(self):
        # remove all register handlers on wigets, created by self.xml
        # to prevent circular references among objects
        for i in list(self.handlers.keys()):
            if self.handlers[i].handler_is_connected(i):
                self.handlers[i].disconnect(i)
            del self.handlers[i]

    def print_real_text(self, real_text, text_tags, graphics, iter_,
                        additional_data):
        urlparts = urlparse(real_text)
        if (urlparts.scheme not in ["https", "aesgcm"] or
                not urlparts.netloc):
            log.info("Not accepting URL scheme '%s' for image preview: %s",
                     urlparts.scheme, real_text)
            return

        try:
            oob_url = additional_data["gajim"]["oob_url"]
        except (KeyError, AttributeError):
            oob_url = None

        # allow aesgcm uris without oob marker (aesgcm uris are always
        # httpupload filetransfers)
        if urlparts.scheme != "aesgcm" and real_text != oob_url:
            log.info("Not accepting URL for image preview "
                     "(wrong or no oob data): %s", real_text)
            log.debug("additional_data: %s", additional_data)
            return

        # Don't print the URL in the message window (in the calling function)
        self.textview.plugin_modified = True

        buffer_ = self.textview.tv.get_buffer()
        if not iter_:
            iter_ = buffer_.get_end_iter()

        # Show URL, until image is loaded (if ever)
        ttt = buffer_.get_tag_table()
        repl_start = buffer_.create_mark(None, iter_, True)
        buffer_.insert_with_tags(iter_, real_text,
            *[(ttt.lookup(t) if isinstance(t, str) else t) for t in ["url"]])
        repl_end = buffer_.create_mark(None, iter_, True)

        filename = os.path.basename(urlparts.path)
        ext = os.path.splitext(filename)[1]
        name = os.path.splitext(filename)[0]
        namehash = hashlib.sha1(real_text.encode('utf-8')).hexdigest()
        newfilename = name + '_' + namehash + ext
        thumbfilename = name + '_' + namehash + '_thumb_' \
            + str(self.plugin.config['PREVIEW_SIZE']) + ext

        filepath = os.path.join(self.directory, newfilename)
        thumbpath = os.path.join(self.thumbpath, thumbfilename)
        filepaths = [filepath, thumbpath]

        key = ''
        iv = ''
        encrypted = False
        if urlparts.fragment:
            fragment = binascii.unhexlify(urlparts.fragment)
            key = fragment[16:]
            iv = fragment[:16]
            if len(key) == 32 and len(iv) == 16:
                encrypted = True
            if not encrypted:
                key = fragment[12:]
                iv = fragment[:12]
                if len(key) == 32 and len(iv) == 12:
                    encrypted = True

        # file exists but thumbnail got deleted
        if os.path.exists(filepath) and not os.path.exists(thumbpath):
            with open(filepath, 'rb') as f:
                mem = f.read()
            app.thread_interface(
                self._save_thumbnail, [thumbpath, mem],
                self._update_img, [real_text, repl_start,
                                   repl_end, filepath, encrypted])

        # display thumbnail if already downloadeded
        # (but only if file also exists)
        elif os.path.exists(filepath) and os.path.exists(thumbpath):
            app.thread_interface(
                self._load_thumbnail, [thumbpath],
                self._update_img, [real_text, repl_start,
                                   repl_end, filepath, encrypted])

        # or download file, calculate thumbnail and finally display it
        else:
            if encrypted and not decryption_available:
                log.debug('Please install Crytography to decrypt pictures')
            else:
                # First get the http head request
                # which does not fetch data, just headers
                # then check the mime type and filesize
                if urlparts.scheme == 'aesgcm':
                    real_text = 'https://' + real_text[9:]
                app.thread_interface(
                    get_http_head, [self.textview.account, real_text],
                    self._check_mime_size, [real_text, repl_start, repl_end,
                                            filepaths, key, iv, encrypted])

    def _save_thumbnail(self, thumbpath, mem):
        size = self.plugin.config['PREVIEW_SIZE']

        try:
            loader = GdkPixbuf.PixbufLoader()
            loader.write(mem)
            loader.close()
            pixbuf = loader.get_pixbuf()
        except GLib.GError as error:
            log.info('Failed to load image using Gdk.Pixbuf')
            log.debug(error)

            if not PILLOW_AVAILABLE:
                log.info('Pillow not available')
                return
            # Try Pillow
            image = Image.open(BytesIO(mem)).convert("RGBA")
            array = GLib.Bytes.new(image.tobytes())
            width, height = image.size
            pixbuf = GdkPixbuf.Pixbuf.new_from_bytes(
                array, GdkPixbuf.Colorspace.RGB, True,
                8, width, height, width * 4)

        thumbnail = pixbuf.scale_simple(
            size, size, GdkPixbuf.InterpType.BILINEAR)

        try:
            self._create_path(os.path.dirname(thumbpath))
            thumbnail.savev(thumbpath, 'png', [], [])
        except Exception as error:
            dialogs.ErrorDialog(
                _('Could not save file'),
                _('Exception raised while saving thumbnail '
                  'for image file (see error log for more '
                  'information)'),
                transient_for=app.app.get_active_window())
            log.error(error)
            return
        return thumbnail

    def _load_thumbnail(self, thumbpath):
        return GdkPixbuf.Pixbuf.new_from_file(thumbpath)

    def _write_file(self, path, data):
        log.info("Writing '%s' of size %d...", path, len(data))
        try:
            with open(path, "wb") as output_file:
                output_file.write(data)
                output_file.closed
        except Exception as e:
            log.error("Failed to write file '%s'!", path)
            raise

    def _update_img(self, pixbuf, url, repl_start, repl_end,
                    filepath, encrypted):
        if pixbuf is None:
            # If image could not be downloaded, URL is already displayed
            log.error('Could not download image for URL: %s', url)
            return

        urlparts = urlparse(url)
        filename = os.path.basename(urlparts.path)
        event_box = Gtk.EventBox()
        event_box.connect('button-press-event', self.on_button_press_event,
                          filepath, filename, url, encrypted)
        event_box.connect('enter-notify-event', self.on_enter_event)
        event_box.connect('leave-notify-event', self.on_leave_event)

        def add_to_textview():
            try:
                at_end = self.textview.at_the_end()

                buffer_ = repl_start.get_buffer()
                iter_ = buffer_.get_iter_at_mark(repl_start)

                anchor = buffer_.create_child_anchor(iter_)

                image = Gtk.Image.new_from_pixbuf(pixbuf)
                event_box.add(image)
                event_box.show_all()
                self.textview.tv.add_child_at_anchor(event_box, anchor)
                buffer_.delete(iter_,
                               buffer_.get_iter_at_mark(repl_end))

                if at_end:
                    GLib.idle_add(self.textview.scroll_to_end_iter)
            except Exception as ex:
                log.exception("Exception while loading %s: %s", url, ex)
            return False
        # add to mainloop --> make call threadsafe
        GLib.idle_add(add_to_textview)

    def _check_mime_size(self, tuple_arg,
                         url, repl_start, repl_end, filepaths,
                         key, iv, encrypted):
        file_mime, file_size = tuple_arg
        # Check if mime type is acceptable
        if file_mime == '' and file_size == 0:
            log.info("Failed to load HEAD Request for URL: '%s'"
                     "(see debug log for more info)", url)
            # URL is already displayed
            return
        if file_mime.lower() not in ACCEPTED_MIME_TYPES:
            log.info("Not accepted mime type '%s' for URL: '%s'",
                     file_mime.lower(), url)
            # URL is already displayed
            return
        # Check if file size is acceptable
        max_size = int(self.plugin.config['MAX_FILE_SIZE'])
        if file_size > max_size or file_size == 0:
            log.info("File size (%s) too big or unknown (zero) for URL: '%s'",
                     file_size, url)
            # URL is already displayed
            return

        attributes = {'src': url,
                      'max_size': max_size,
                      'filepaths': filepaths,
                      'key': key,
                      'iv': iv}

        app.thread_interface(
            self._download_image, [self.textview.account,
                                   attributes, encrypted],
            self._update_img, [url, repl_start, repl_end,
                               filepaths[0], encrypted])

    def _download_image(self, account, attributes, encrypted):
        filepath = attributes['filepaths'][0]
        thumbpath = attributes['filepaths'][1]
        key = attributes['key']
        iv = attributes['iv']
        mem, alt = get_http_file(account, attributes)

        # Decrypt file if necessary
        if encrypted:
            mem = self._aes_decrypt_fast(key, iv, mem)

        try:
            # Write file to harddisk
            self._write_file(filepath, mem)
        except Exception as e:
            dialogs.ErrorDialog(
                _('Could not save file'),
                _('Exception raised while saving image file'
                  ' (see error log for more information)'),
                transient_for=app.app.get_active_window())
            log.error(str(e))

        # Create thumbnail, write it to harddisk and return it
        return self._save_thumbnail(thumbpath, mem)

    def _create_path(self, folder):
        if os.path.exists(folder):
            return
        log.debug("creating folder '%s'" % folder)
        os.mkdir(folder, 0o700)

    def _aes_decrypt_fast(self, key, iv, payload):
        # Use AES128 GCM with the given key and iv to decrypt the payload.
        if os.name == 'nt':
            be = backend
        else:
            be = default_backend()
        data = payload[:-16]
        tag = payload[-16:]
        decryptor = Cipher(
            algorithms.AES(key),
            GCM(iv, tag=tag),
            backend=be).decryptor()
        return decryptor.update(data) + decryptor.finalize()

    def make_rightclick_menu(self, event, data):
        xml = Gtk.Builder()
        xml.set_translation_domain('gajim_plugins')
        xml.add_from_file(self.plugin.local_file_path('context_menu.ui'))
        menu = xml.get_object('context_menu')

        open_menuitem = xml.get_object('open_menuitem')
        save_as_menuitem = xml.get_object('save_as_menuitem')
        copy_link_location_menuitem = \
            xml.get_object('copy_link_location_menuitem')
        open_link_in_browser_menuitem = \
            xml.get_object('open_link_in_browser_menuitem')
        open_file_in_browser_menuitem = \
            xml.get_object('open_file_in_browser_menuitem')
        extras_separator = \
            xml.get_object('extras_separator')

        if data["encrypted"]:
            open_link_in_browser_menuitem.hide()
        if app.config.get('autodetect_browser_mailer') \
                or app.config.get('custombrowser') == '':
            extras_separator.hide()
            open_file_in_browser_menuitem.hide()

        id_ = open_menuitem.connect(
            'activate', self.on_open_menuitem_activate, data)
        self.handlers[id_] = open_menuitem
        id_ = save_as_menuitem.connect(
            'activate', self.on_save_as_menuitem_activate, data)
        self.handlers[id_] = save_as_menuitem
        id_ = copy_link_location_menuitem.connect(
            'activate', self.on_copy_link_location_menuitem_activate, data)
        self.handlers[id_] = copy_link_location_menuitem
        id_ = open_link_in_browser_menuitem.connect(
            'activate', self.on_open_link_in_browser_menuitem_activate, data)
        self.handlers[id_] = open_link_in_browser_menuitem
        id_ = open_file_in_browser_menuitem.connect(
            'activate', self.on_open_file_in_browser_menuitem_activate, data)
        self.handlers[id_] = open_file_in_browser_menuitem

        return menu

    def on_open_menuitem_activate(self, menu, data):
        filepath = data["filepath"]
        helpers.launch_file_manager(filepath)

    def on_save_as_menuitem_activate(self, menu, data):
        filepath = data["filepath"]
        original_filename = data["original_filename"]

        def on_continue(response, target_path):
            if response < 0:
                return
            shutil.copy(filepath, target_path)
            dialog.destroy()

        def on_ok(widget):
            target_path = dialog.get_filename()
            if os.path.exists(target_path):
                # check if we have write permissions
                if not os.access(target_path, os.W_OK):
                    file_name = os.path.basename(target_path)
                    dialogs.ErrorDialog(
                        _('Cannot overwrite existing file "%s"') % file_name,
                        _('A file with this name already exists and you do '
                          'not have permission to overwrite it.'))
                    return
                dialog2 = dialogs.FTOverwriteConfirmationDialog(
                    _('This file already exists'),
                    _('What do you want to do?'),
                    propose_resume=False,
                    on_response=(on_continue, target_path),
                    transient_for=dialog)
                dialog2.set_destroy_with_parent(True)
            else:
                dirname = os.path.dirname(target_path)
                if not os.access(dirname, os.W_OK):
                    dialogs.ErrorDialog(
                        _('Directory "%s" is not writable') % dirname,
                        _('You do not have permission to '
                          'create files in this directory.'))
                    return
                on_continue(0, target_path)

        def on_cancel(widget):
            dialog.destroy()

        dialog = dialogs.FileChooserDialog(
            title_text=_('Save Image as...'),
            action=Gtk.FileChooserAction.SAVE,
            buttons=(Gtk.STOCK_CANCEL, Gtk.ResponseType.CANCEL,
                     Gtk.STOCK_SAVE, Gtk.ResponseType.OK),
            default_response=Gtk.ResponseType.OK,
            current_folder=app.config.get('last_save_dir'),
            on_response_ok=on_ok,
            on_response_cancel=on_cancel)

        dialog.set_current_name(original_filename)
        dialog.connect('delete-event', lambda widget, event:
                       on_cancel(widget))

    def on_copy_link_location_menuitem_activate(self, menu, data):
        url = data["url"]
        clipboard = Gtk.Clipboard.get(Gdk.SELECTION_CLIPBOARD)
        clipboard.set_text(url, -1)
        clipboard.store()

    def on_open_link_in_browser_menuitem_activate(self, menu, data):
        url = data["url"]
        if data["encrypted"]:
            dialogs.ErrorDialog(
                _('Encrypted file'),
                _('You cannot open encrypted files in your '
                  'browser directly. Try "Open Downloaded File '
                  'in Browser" instead.'),
                transient_for=app.app.get_active_window())
        else:
            helpers.launch_browser_mailer('url', url)

    def on_open_file_in_browser_menuitem_activate(self, menu, data):
        if os.name == "nt":
            filepath = "file://" + os.path.abspath(data["filepath"])
        else:
            filepath = "file://" + data["filepath"]
        if app.config.get('autodetect_browser_mailer') \
                or app.config.get('custombrowser') == '':
            dialogs.ErrorDialog(
                _('Cannot open downloaded file in browser'),
                _('You have to set a custom browser executable '
                  'in your gajim settings for this to work.'),
                transient_for=app.app.get_active_window())
            return
        command = app.config.get('custombrowser')
        command = helpers.build_command(command, filepath)
        try:
            helpers.exec_command(command)
        except Exception:
            pass

    # Change mouse pointer to HAND2 when
    # mouse enter the eventbox with the image
    def on_enter_event(self, eb, event):
        self.textview.tv.get_window(
            Gtk.TextWindowType.TEXT).set_cursor(Gdk.Cursor(Gdk.CursorType.HAND2))

    # Change mouse pointer to default when mouse leaves the eventbox
    def on_leave_event(self, eb, event):
        self.textview.tv.get_window(
            Gtk.TextWindowType.TEXT).set_cursor(Gdk.Cursor(Gdk.CursorType.XTERM))

    def on_button_press_event(self, eb, event, filepath,
                              original_filename, url, encrypted):
        data = {"filepath": filepath,
                "original_filename": original_filename,
                "url": url,
                "encrypted": encrypted}
        # left click
        if event.type == Gdk.EventType.BUTTON_PRESS and event.button == 1:
            method = getattr(self, "on_"
                             + self.plugin.config['LEFTCLICK_ACTION']
                             + "_activate")
            method(event, data)
        # right klick
        elif event.type == Gdk.EventType.BUTTON_PRESS and event.button == 3:
            menu = self.make_rightclick_menu(event, data)
            # menu.attach_to_widget(self.tv, None)
            # menu.popup(None, None, None, event.button, event.time)
            menu.popup_at_pointer(event)

    def disconnect_from_chat_control(self):
        pass