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         return keys
  64
  65 def check_signature(path):
  66         data = file(path).read()
  67         xml_comment = data.rfind('\n<!-- Base64 Signature')
  68         if xml_comment >= 0:
  69                 data_stream, sigs = gpg.check_stream(file(path))
  70                 sign_fn = sign_xml
  71                 data = data[:xml_comment + 1]
  72                 data_stream.close()
  73         elif data.startswith('-----BEGIN'):
  74                 data_stream, sigs = gpg.check_stream(file(path))
  75                 sign_fn = sign_xml              # Don't support saving as plain
  76                 data = data_stream.read()
  77         else:
  78                 return data, sign_unsigned, None
  79         for sig in sigs:
  80                 if isinstance(sig, gpg.ValidSig):
  81                         return data, sign_fn, sig.fingerprint
  82         error = "ERROR: No valid signatures found!\n"
  83         for sig in sigs:
  84                 error += "\nGot: %s" % sig
  85         error += '\n\nTo edit it anyway, remove the signature using a text editor.'
  86         raise Exception(error)
  87
  88 def write_tmp(path, data):
  89         """Create a temporary file in the same directory as 'path' and write data to it."""
  90         fd, tmp = tempfile.mkstemp(prefix = 'tmp-', dir = os.path.dirname(path))
  91         stream = os.fdopen(fd, 'w')
  92         stream.write(data)
  93         stream.close()
  94         os.chmod(tmp, 0644 &~umask)
  95         return tmp
  96
  97 def run_gpg(default_key, *arguments):
  98         arguments = list(arguments)
  99         if default_key is not None:
 100                 arguments = ['--default-key', default_key] + arguments
 101         arguments.insert(0, 'gpg')
 102         if os.spawnvp(os.P_WAIT, 'gpg', arguments):
 103                 raise SafeException("Command '%s' failed" % arguments)
 104
 105 def sign_unsigned(path, data, key, callback):
 106         os.rename(write_tmp(path, data), path)
 107         if callback: callback()
 108
 109 def sign_xml(path, data, key, callback):
 110         import main
 111         wTree = g.glade.XML(main.gladefile, 'get_passphrase')
 112         box = wTree.get_widget('get_passphrase')
 113         box.set_default_response(g.RESPONSE_OK)
 114         entry = wTree.get_widget('passphrase')
 115
 116         buffer = LineBuffer()
 117
 118         killed = False
 119         error = False
 120         tmp = None
 121         r, w = os.pipe()
 122         try:
 123                 def setup_child():
 124                         os.close(r)
 125
 126                 tmp = write_tmp(path, data)
 127                 sigtmp = tmp + '.sig'
 128
 129                 child = subprocess.Popen(('gpg', '--default-key', key,
 130                                           '--detach-sign', '--status-fd', str(w),
 131                                           '--command-fd', '0',
 132                                           '--no-tty',
 133                                           '--output', sigtmp,
 134                                           '-q',
 135                                           tmp),
 136                                          preexec_fn = setup_child,
 137                                          stdin = subprocess.PIPE)
 138
 139                 os.close(w)
 140                 w = None
 141                 while True:
 142                         input = InputBlocker(r)
 143                         yield input
 144                         msg = os.read(r, 100)
 145                         if not msg: break
 146                         buffer.add(msg)
 147                         for command in buffer:
 148                                 if command.startswith('[GNUPG:] NEED_PASSPHRASE '):
 149                                         entry.set_text('')
 150                                         box.present()
 151                                         resp = box.run()
 152                                         box.hide()
 153                                         if resp == g.RESPONSE_OK:
 154                                                 child.stdin.write(entry.get_text() + '\n')
 155                                                 child.stdin.flush()
 156                                         else:
 157                                                 os.kill(child.pid, signal.SIGTERM)
 158                                                 killed = True
 159
 160                 status = child.wait()
 161                 if status:
 162                         raise Exception("GPG failed with exit code %d" % status)
 163         except:
 164                 # No generator finally blocks in Python 2.4...
 165                 error = True
 166
 167         if r is not None: os.close(r)
 168         if w is not None: os.close(w)
 169         if tmp is not None: os.unlink(tmp)
 170
 171         if killed: return
 172         if error: raise
 173
 174         encoded = base64.encodestring(file(sigtmp).read())
 175         os.unlink(sigtmp)
 176         sig = "<!-- Base64 Signature\n" + encoded + "\n-->\n"
 177         os.rename(write_tmp(path, data + sig), path)
 178
 179         if callback: callback()
 180
 181 def export_key(dir, fingerprint):
 182         assert fingerprint is not None
 183         # Convert fingerprint to key ID
 184         stream = os.popen('gpg --with-colons --list-keys %s' % fingerprint)
 185         try:
 186                 keyID = None
 187                 for line in stream:
 188                         parts = line.split(':')
 189                         if parts[0] == 'pub':
 190                                 if keyID:
 191                                         raise Exception('Two key IDs returned from GPG!')
 192                                 keyID = parts[4]
 193         finally:
 194                 stream.close()
 195         key_file = os.path.join(dir, keyID + '.gpg')
 196         if os.path.isfile(key_file):
 197                 return None
 198         key_stream = file(key_file, 'w')
 199         stream = os.popen("gpg -a --export '%s'" % fingerprint)
 200         shutil.copyfileobj(stream, key_stream)
 201         stream.close()
 202         key_stream.close()
 203         return key_file