bridgedb/qrcodes.py

   1 # -*- coding: utf-8 ; test-case-name: bridgedb.test.test_qrcodes ; -*-
   2 #_____________________________________________________________________________
   3 #
   4 # This file is part of BridgeDB, a Tor bridge distribution system.
   5 #
   6 # :authors: Isis Lovecruft 0xA3ADB67A2CDB8B35 <isis@torproject.org>
   7 #           please also see AUTHORS file
   8 # :copyright: (c) 2007-2017, The Tor Project, Inc.
   9 #             (c) 2014-2017, Isis Lovecruft
  10 # :license: see LICENSE for licensing information
  11 #_____________________________________________________________________________
  12
  13 """Utilities for working with QRCodes."""
  14
  15
  16 import io
  17 import logging
  18
  19 try:
  20     import qrcode
  21 except ImportError:  # pragma: no cover
  22     qrcode = False
  23     logging.warn("Could not import Python qrcode module.")
  24     logging.debug(("You'll need the qrcode Python module for this to "
  25                    "work. On Debian-based systems, this should be in the "
  26                    "python-qrcode package."))
  27
  28
  29 def generateQR(bridgelines, imageFormat='JPEG', bridgeSchema=False):
  30     """Generate a QRCode for the client's bridge lines.
  31
  32     :param str bridgelines: The Bridge Lines which we are distributing to the
  33         client.
  34     :param bool bridgeSchema: If ``True``, prepend ``'bridge://'`` to the
  35         beginning of each bridge line before QR encoding.
  36     :rtype: str or ``None``
  37     :returns: The generated QRCode, as a string.
  38     """
  39     logging.debug("Attempting to encode bridge lines into a QRCode...")
  40
  41     if not bridgelines:
  42         return
  43
  44     if not qrcode:
  45         logging.info("Not creating QRCode for bridgelines; no qrcode module.")
  46         return
  47
  48     try:
  49         if bridgeSchema:
  50             # See https://bugs.torproject.org/12639 for why bridge:// is used.
  51             # (Hopefully, Orbot will pick up the ACTION_VIEW intent.)
  52             schema = 'bridge://'
  53             prefixed = []
  54             for line in bridgelines.strip().split('\n'):
  55                 prefixed.append(schema + line)
  56             bridgelines = '\n'.join(prefixed)
  57
  58         logging.debug("QR encoding bridge lines: %s" % bridgelines)
  59
  60         qr = qrcode.QRCode()
  61         qr.add_data(bridgelines)
  62
  63         buf = io.BytesIO()
  64         img = qr.make_image().resize([350, 350])
  65         img.save(buf, imageFormat)
  66         buf.seek(0)
  67
  68         imgstr = buf.read()
  69         return imgstr
  70
  71     except KeyError as error:
  72         logging.error(str(error))
  73         logging.debug(("It seems python-imaging doesn't understand how to "
  74                        "save in the %s format.") % imageFormat)
  75     except Exception as error:  # pragma: no cover
  76         logging.error(("There was an error while attempting to generate the "
  77                        "QRCode: %s") % str(error))