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