signing.py

   1 from zeroinstall import SafeException
   2 from zeroinstall.injector import gpg
   3 import tempfile, os, base64, shutil, signal
   4 import subprocess
   5 from rox import tasks, g
   6
   7 umask = os.umask(0)
   8 os.umask(umask)
   9
  10 class LineBuffer:
  11         def __init__(self):
  12                 self.data = ''
  13
  14         def add(self, new):
  15                 assert new
  16                 self.data += new
  17
  18         def __iter__(self):
  19                 while '\n' in self.data:
  20                         command, self.data = self.data.split('\n', 1)
  21                         yield command
  22
  23 def _io_callback(src, cond, blocker):
  24         blocker.trigger()
  25         return False
  26
  27 def get_secret_keys():
  28         child = subprocess.Popen(('gpg', '--list-secret-keys', '--with-colons', '--with-fingerprint'),
  29                                  stdout = subprocess.PIPE)
  30         stdout, _ = child.communicate()
  31         status = child.wait()
  32         if status:
  33                 raise Exception("GPG failed with exit code %d" % status)
  34         # First, collect fingerprints for available secret keys
  35         keys = []
  36         for line in stdout.split('\n'):
  37                 line = line.split(':')
  38                 if line[0] == 'fpr':
  39                         keys.append([line[9], None])
  40         # When listing secret keys, the identity show may not be the primary identity as selected by
  41         # the user or shown when verifying a signature. However, the primary identity can be obtained
  42         # by listing the accompanying public key.
  43         loaded_keys = gpg.load_keys([k[0] for k in keys])
  44         for key in keys:
  45                 key[1] = loaded_keys[key[0]].name
  46         return keys
  47
  48 def check_signature(path):
  49         data = file(path).read()
  50         xml_comment = data.rfind('\n<!-- Base64 Signature')
  51         if xml_comment >= 0:
  52                 data_stream, sigs = gpg.check_stream(file(path))
  53                 sign_fn = sign_xml
  54                 data = data[:xml_comment + 1]
  55                 data_stream.close()
  56         elif data.startswith('-----BEGIN'):
  57                 data_stream, sigs = gpg.check_stream(file(path))
  58                 sign_fn = sign_xml              # Don't support saving as plain
  59                 data = data_stream.read()
  60         else:
  61                 return data, sign_unsigned, None
  62         for sig in sigs:
  63                 if isinstance(sig, gpg.ValidSig):
  64                         return data, sign_fn, sig.fingerprint
  65         error = "ERROR: No valid signatures found!\n"
  66         for sig in sigs:
  67                 error += "\nGot: %s" % sig
  68         error += '\n\nTo edit it anyway, remove the signature using a text editor.'
  69         raise Exception(error)
  70
  71 def write_tmp(path, data):
  72         """Create a temporary file in the same directory as 'path' and write data to it."""
  73         fd, tmp = tempfile.mkstemp(prefix = 'tmp-', dir = os.path.dirname(path))
  74         stream = os.fdopen(fd, 'w')
  75         stream.write(data)
  76         stream.close()
  77         os.chmod(tmp, 0644 &~umask)
  78         return tmp
  79
  80 def run_gpg(default_key, *arguments):
  81         arguments = list(arguments)
  82         if default_key is not None:
  83                 arguments = ['--default-key', default_key] + arguments
  84         arguments.insert(0, 'gpg')
  85         if os.spawnvp(os.P_WAIT, 'gpg', arguments):
  86                 raise SafeException("Command '%s' failed" % arguments)
  87
  88 def sign_unsigned(path, data, key, callback):
  89         os.rename(write_tmp(path, data), path)
  90         if callback: callback()
  91
  92 def sign_xml(path, data, key, callback):
  93         import main
  94         wTree = g.glade.XML(main.gladefile, 'get_passphrase')
  95         box = wTree.get_widget('get_passphrase')
  96         box.set_default_response(g.RESPONSE_OK)
  97         entry = wTree.get_widget('passphrase')
  98
  99         buffer = LineBuffer()
 100
 101         killed = False
 102         error = False
 103         tmp = None
 104         r, w = os.pipe()
 105         try:
 106                 def setup_child():
 107                         os.close(r)
 108
 109                 tmp = write_tmp(path, data)
 110                 sigtmp = tmp + '.sig'
 111
 112                 agent_info = os.environ.get("GPG_AGENT_INFO", None)
 113                 child = subprocess.Popen(('gpg', '--default-key', key,
 114                                           '--detach-sign', '--status-fd', str(w),
 115                                           '--command-fd', '0',
 116                                           '--no-tty',
 117                                           '--output', sigtmp,
 118                                           '--use-agent',
 119                                           '-q',
 120                                           tmp),
 121                                          preexec_fn = setup_child,
 122                                          stdin = subprocess.PIPE)
 123
 124                 os.close(w)
 125                 w = None
 126                 while True:
 127                         input = tasks.InputBlocker(r)
 128                         yield input
 129                         msg = os.read(r, 100)
 130                         if not msg: break
 131                         buffer.add(msg)
 132                         for command in buffer:
 133                                 if command.startswith('[GNUPG:] NEED_PASSPHRASE ') and not agent_info:
 134                                         entry.set_text('')
 135                                         box.present()
 136                                         resp = box.run()
 137                                         box.hide()
 138                                         if resp == g.RESPONSE_OK:
 139                                                 child.stdin.write(entry.get_text() + '\n')
 140                                                 child.stdin.flush()
 141                                         else:
 142                                                 os.kill(child.pid, signal.SIGTERM)
 143                                                 killed = True
 144
 145                 status = child.wait()
 146                 if status:
 147                         raise Exception("GPG failed with exit code %d" % status)
 148         except:
 149                 # No generator finally blocks in Python 2.4...
 150                 error = True
 151
 152         if r is not None: os.close(r)
 153         if w is not None: os.close(w)
 154         if tmp is not None: os.unlink(tmp)
 155
 156         if killed: return
 157         if error: raise
 158
 159         encoded = base64.encodestring(file(sigtmp).read())
 160         os.unlink(sigtmp)
 161         sig = "<!-- Base64 Signature\n" + encoded + "\n-->\n"
 162         os.rename(write_tmp(path, data + sig), path)
 163
 164         if callback: callback()
 165
 166 def export_key(dir, fingerprint):
 167         assert fingerprint is not None
 168         # Convert fingerprint to key ID
 169         stream = os.popen('gpg --with-colons --list-keys %s' % fingerprint)
 170         try:
 171                 keyID = None
 172                 for line in stream:
 173                         parts = line.split(':')
 174                         if parts[0] == 'pub':
 175                                 if keyID:
 176                                         raise Exception('Two key IDs returned from GPG!')
 177                                 keyID = parts[4]
 178         finally:
 179                 stream.close()
 180         key_file = os.path.join(dir, keyID + '.gpg')
 181         if os.path.isfile(key_file):
 182                 return None
 183         key_stream = file(key_file, 'w')
 184         stream = os.popen("gpg -a --export '%s'" % fingerprint)
 185         shutil.copyfileobj(stream, key_stream)
 186         stream.close()
 187         key_stream.close()
 188         return key_file