signing.py

   1 from zeroinstall import SafeException
   2 from zeroinstall.injector import gpg
   3 import tempfile, os, base64, sys, shutil, signal
   4 import subprocess
   5 from rox import tasks, g
   6 import gobject
   7
   8 umask = os.umask(0)
   9 os.umask(umask)
  10
  11 class LineBuffer:
  12         def __init__(self):
  13                 self.data = ''
  14
  15         def add(self, new):
  16                 assert new
  17                 self.data += new
  18
  19         def __iter__(self):
  20                 while '\n' in self.data:
  21                         command, self.data = self.data.split('\n', 1)
  22                         yield command
  23
  24 def _io_callback(src, cond, blocker):
  25         blocker.trigger()
  26         return False
  27
  28 # (version in ROX-Lib < 2.0.4 is buggy; missing IO_HUP)
  29 class InputBlocker(tasks.Blocker):
  30         """Triggers when os.read(stream) would not block."""
  31         _tag = None
  32         _stream = None
  33         def __init__(self, stream):
  34                 tasks.Blocker.__init__(self)
  35                 self._stream = stream
  36
  37         def add_task(self, task):
  38                 tasks.Blocker.add_task(self, task)
  39                 if self._tag is None:
  40                         self._tag = gobject.io_add_watch(self._stream, gobject.IO_IN | gobject.IO_HUP,
  41                                 _io_callback, self)
  42
  43         def remove_task(self, task):
  44                 tasks.Blocker.remove_task(self, task)
  45                 if not self._rox_lib_tasks:
  46                         gobject.source_remove(self._tag)
  47                         self._tag = None
  48
  49 def get_secret_keys():
  50         child = subprocess.Popen(('gpg', '--list-secret-keys', '--with-colons', '--with-fingerprint'),
  51                                  stdout = subprocess.PIPE)
  52         stdout, _ = child.communicate()
  53         status = child.wait()
  54         if status:
  55                 raise Exception("GPG failed with exit code %d" % status)
  56         keys = []
  57         for line in stdout.split('\n'):
  58                 line = line.split(':')
  59                 if line[0] == 'sec':
  60                         keys.append([None, line[9]])
  61                 elif line[0] == 'fpr':
  62                         keys[-1][0] = line[9]
  63                 elif line[0] == 'uid':
  64                         keys.append([keys[-1][0], line[9]])
  65         return keys
  66
  67 def check_signature(path):
  68         data = file(path).read()
  69         xml_comment = data.rfind('\n<!-- Base64 Signature')
  70         if xml_comment >= 0:
  71                 data_stream, sigs = gpg.check_stream(file(path))
  72                 sign_fn = sign_xml
  73                 data = data[:xml_comment + 1]
  74                 data_stream.close()
  75         elif data.startswith('-----BEGIN'):
  76                 data_stream, sigs = gpg.check_stream(file(path))
  77                 sign_fn = sign_xml              # Don't support saving as plain
  78                 data = data_stream.read()
  79         else:
  80                 return data, sign_unsigned, None
  81         for sig in sigs:
  82                 if isinstance(sig, gpg.ValidSig):
  83                         return data, sign_fn, sig.fingerprint
  84         error = "ERROR: No valid signatures found!\n"
  85         for sig in sigs:
  86                 error += "\nGot: %s" % sig
  87         error += '\n\nTo edit it anyway, remove the signature using a text editor.'
  88         raise Exception(error)
  89
  90 def write_tmp(path, data):
  91         """Create a temporary file in the same directory as 'path' and write data to it."""
  92         fd, tmp = tempfile.mkstemp(prefix = 'tmp-', dir = os.path.dirname(path))
  93         stream = os.fdopen(fd, 'w')
  94         stream.write(data)
  95         stream.close()
  96         os.chmod(tmp, 0644 &~umask)
  97         return tmp
  98
  99 def run_gpg(default_key, *arguments):
 100         arguments = list(arguments)
 101         if default_key is not None:
 102                 arguments = ['--default-key', default_key] + arguments
 103         arguments.insert(0, 'gpg')
 104         if os.spawnvp(os.P_WAIT, 'gpg', arguments):
 105                 raise SafeException("Command '%s' failed" % arguments)
 106
 107 def sign_unsigned(path, data, key, callback):
 108         os.rename(write_tmp(path, data), path)
 109         if callback: callback()
 110
 111 def sign_xml(path, data, key, callback):
 112         import main
 113         wTree = g.glade.XML(main.gladefile, 'get_passphrase')
 114         box = wTree.get_widget('get_passphrase')
 115         box.set_default_response(g.RESPONSE_OK)
 116         entry = wTree.get_widget('passphrase')
 117
 118         buffer = LineBuffer()
 119
 120         killed = False
 121         error = False
 122         tmp = None
 123         r, w = os.pipe()
 124         try:
 125                 def setup_child():
 126                         os.close(r)
 127
 128                 tmp = write_tmp(path, data)
 129                 sigtmp = tmp + '.sig'
 130
 131                 hasAgent = os.environ["GPG_AGENT_INFO"]
 132                 child = subprocess.Popen(('gpg', '--default-key', key,
 133                                           '--detach-sign', '--status-fd', str(w),
 134                                           '--command-fd', '0',
 135                                           '--no-tty',
 136                                           '--output', sigtmp,
 137                                           '--use-agent',
 138                                           '-q',
 139                                           tmp),
 140                                          preexec_fn = setup_child,
 141                                          stdin = subprocess.PIPE)
 142
 143                 os.close(w)
 144                 w = None
 145                 while True:
 146                         input = InputBlocker(r)
 147                         yield input
 148                         msg = os.read(r, 100)
 149                         if not msg: break
 150                         buffer.add(msg)
 151                         for command in buffer:
 152                                 if command.startswith('[GNUPG:] NEED_PASSPHRASE ') and not hasAgent:
 153                                         entry.set_text('')
 154                                         box.present()
 155                                         resp = box.run()
 156                                         box.hide()
 157                                         if resp == g.RESPONSE_OK:
 158                                                 child.stdin.write(entry.get_text() + '\n')
 159                                                 child.stdin.flush()
 160                                         else:
 161                                                 os.kill(child.pid, signal.SIGTERM)
 162                                                 killed = True
 163
 164                 status = child.wait()
 165                 if status:
 166                         raise Exception("GPG failed with exit code %d" % status)
 167         except:
 168                 # No generator finally blocks in Python 2.4...
 169                 error = True
 170
 171         if r is not None: os.close(r)
 172         if w is not None: os.close(w)
 173         if tmp is not None: os.unlink(tmp)
 174
 175         if killed: return
 176         if error: raise
 177
 178         encoded = base64.encodestring(file(sigtmp).read())
 179         os.unlink(sigtmp)
 180         sig = "<!-- Base64 Signature\n" + encoded + "\n-->\n"
 181         os.rename(write_tmp(path, data + sig), path)
 182
 183         if callback: callback()
 184
 185 def export_key(dir, fingerprint):
 186         assert fingerprint is not None
 187         # Convert fingerprint to key ID
 188         stream = os.popen('gpg --with-colons --list-keys %s' % fingerprint)
 189         try:
 190                 keyID = None
 191                 for line in stream:
 192                         parts = line.split(':')
 193                         if parts[0] == 'pub':
 194                                 if keyID:
 195                                         raise Exception('Two key IDs returned from GPG!')
 196                                 keyID = parts[4]
 197         finally:
 198                 stream.close()
 199         key_file = os.path.join(dir, keyID + '.gpg')
 200         if os.path.isfile(key_file):
 201                 return None
 202         key_stream = file(key_file, 'w')
 203         stream = os.popen("gpg -a --export '%s'" % fingerprint)
 204         shutil.copyfileobj(stream, key_stream)
 205         stream.close()
 206         key_stream.close()
 207         return key_file