#! @PYTHON@
# -*-python-*-

### External dependencies

import catacomb as C
import os as OS
import sys as SYS
import sre as RX
import getopt as O
from cStringIO import StringIO
from errno import *
from stat import *

### Useful regular expressions

r_comment = RX.compile(r'^\s*(#|$)')
r_keyval = RX.compile(r'^\s*([-\w]+)(?:\s+(?!=)|\s*=\s*)(|\S|\S.*\S)\s*$')
r_dollarsubst = RX.compile(r'\$\{([-\w]+)\}')
r_atsubst = RX.compile(r'@([-\w]+)@')
r_nonalpha = RX.compile(r'\W')

### Utility functions

class SubprocessError (Exception): pass
class VerifyError (Exception): pass

quis = OS.path.basename(SYS.argv[0])
PACKAGE = "@PACKAGE@"
VERSION = "@VERSION@"

def moan(msg):
  SYS.stderr.write('%s: %s\n' % (quis, msg))

def die(msg, rc = 1):
  moan(msg)
  SYS.exit(rc)

def subst(s, rx, map):
  out = StringIO()
  i = 0
  for m in rx.finditer(s):
    out.write(s[i:m.start()] + map[m.group(1)])
    i = m.end()
  out.write(s[i:])
  return out.getvalue()

def rmtree(path):
  try:
    st = OS.stat(path)
  except OSError, err:
    if err.errno == ENOENT:
      return
    raise
  if not S_ISDIR(st.st_mode):
    OS.unlink(path)
  else:
    cwd = OS.getcwd()
    try:
      OS.chdir(path)
      for i in OS.listdir('.'):
        rmtree(i)
    finally:
      OS.chdir(cwd)
    OS.rmdir(path)

def zap(file):
  try:
    OS.unlink(file)
  except OSError, err:
    if err.errno == ENOENT: return
    raise

def run(args):
  args = map(conf_subst, args.split())
  nargs = []
  for a in args:
    if len(a) > 0 and a[0] != '!':
      nargs += [a]
    else:
      nargs += a[1:].split()
  args = nargs
  print '+ %s' % ' '.join(args)
  rc = OS.spawnvp(OS.P_WAIT, args[0], args)
  if rc != 0:
    raise SubprocessError, rc

def hexhyphens(bytes):
  out = StringIO()
  for i in xrange(0, len(bytes)):
    if i > 0 and i % 4 == 0: out.write('-')
    out.write('%02x' % ord(bytes[i]))
  return out.getvalue()

def fingerprint(kf, ktag):
  h = C.gchashes[conf['fingerprint-hash']]()
  k = C.KeyFile(kf)[ktag].fingerprint(h, '-secret')
  return h.done()

### Read configuration

class ConfigFileError (Exception): pass
conf = {}

def conf_subst(s): return subst(s, r_dollarsubst, conf)

## Read the file
def conf_read(f):
  lno = 0
  for line in file(f):
    lno += 1
    if r_comment.match(line): continue
    if line[-1] == '\n': line = line[:-1]
    match = r_keyval.match(line)
    if not match:
      raise ConfigFileError, "%s:%d: bad line `%s'" % (f, lno, line)
    k, v = match.groups()
    conf[k] = conf_subst(v)

## Sift the wreckage
def conf_defaults():
  for k, v in [('sig-url', '${base-url}tripe-keys.sig'),
               ('repos-url', '${base-url}tripe-keys.tar.gz'),
               ('sig-file', '${base-dir}tripe-keys.sig'),
               ('repos-file', '${base-dir}tripe-keys.tar.gz'),
               ('conf-file', '${base-dir}tripe-keys.conf'),
               ('kx', 'dh'),
               ('kx-param', lambda: {'dh': '-LS -b2048 -B256',
                                     'ec': '-Cnist-p256'}[conf['kx']]),
               ('kx-expire', 'now + 1 year'),
               ('cipher', 'blowfish-cbc'),
               ('hash', 'sha256'),
               ('mgf', '${hash}-mgf'),
               ('mac', lambda: '%s-hmac/%d' %
                         (conf['hash'],
                          C.gchashes[conf['hash']].hashsz * 4)),
               ('sig', lambda: {'dh': 'dsa', 'ec': 'ecdsa'}[conf['kx']]),
               ('sig-fresh', 'always'),
               ('sig-genalg', lambda: {'kcdsa': 'dh',
                                       'dsa': 'dsa',
                                       'rsapkcs1': 'rsa',
                                       'rsapss': 'rsa',
                                       'ecdsa': 'ec',
                                       'eckcdsa': 'ec'}[conf['sig']]),
               ('sig-param', lambda: {'dh': '-LS -b2048 -B256',
                                      'dsa': '-b2048 -B256',
                                      'ec': '-Cnist-p256',
                                      'rsa': '-b2048'}[conf['sig-genalg']]),
               ('sig-hash', '${hash}'),
               ('sig-expire', 'forever'),
               ('fingerprint-hash', '${hash}')]:
    try:
      if k in conf: continue
      if type(v) == str:
        conf[k] = conf_subst(v)
      else:
        conf[k] = v()
    except KeyError, exc:
      if len(exc.args) == 0: raise
      conf[k] = '<missing-var %s>' % exc.args[0]

### Commands

def version(fp = SYS.stdout):
  fp.write('%s, %s version %s\n' % (quis, PACKAGE, VERSION))

def usage(fp):
  fp.write('Usage: %s SUBCOMMAND [ARGS...]\n' % quis)

def cmd_help(args):
  if len(args) == 0:
    version(SYS.stdout)
    print
    usage(SYS.stdout)
    print """
Key management utility for TrIPE.

Options supported:

-h, --help		Show this help message.
-v, --version		Show the version number.
-u, --usage		Show pointlessly short usage string.

Subcommands available:
"""
    args = commands.keys()
    args.sort()
  for c in args:
    func, min, max, help = commands[c]
    print '%s %s' % (c, help)

def cmd_setup(args):
  OS.mkdir('repos')

  ## Generate the master key
  run('''key -kmaster add
    -a${sig-genalg} !${sig-param}
    -e${sig-expire} -l -ttripe-keys-master ccsig
    sig=${sig} hash=${sig-hash}''')
  run('key -kmaster extract -f-secret repos/master.pub tripe-keys-master')

  ## Generate the parameters key
  run('''key -krepos/param add
    -a${kx}-param !${kx-param}
    -eforever -tparam tripe-${kx}-param
    cipher=${cipher} hash=${hash} mac=${mac} mgf=${mgf}''')

  ## Get fingerprints
  print 'Setup OK: master key = %s' % \
        hexhyphens(fingerprint('repos/master.pub', 'tripe-keys-master'))

def cmd_upload(args):

  ## Sanitize the repository directory
  umask = OS.umask(0); OS.umask(umask)
  mode = 0666 & ~umask
  for f in OS.listdir('repos'):
    ff = OS.path.join('repos', f)
    if f.endswith('.old'):
      OS.unlink(ff)
      continue
    OS.chmod(OS.path.join('repos', f), mode)

  ## Build the configuration file
  v = {'HK-MASTER': hexhyphens(fingerprint('repos/master.pub',
                                           'tripe-keys-master'))}
  fin = file('tripe-keys.master')
  fout = file(conf_subst('${conf-file}.new'), 'w')
  for line in fin:
    fout.write(subst(line, r_atsubst, v))
  fin.close(); fout.close()

  ## Make and sign the repository archive
  run('tar chozf ${repos-file}.new repos')
  run('''catsign -kmaster sign -abdC -ktripe-keys-master
    -o${sig-file}.new ${repos-file}.new''')

  ## Commit the changes
  for i in ['conf-file', 'repos-file', 'sig-file']:
    base = conf[i]
    new = '%s.new' % base
    OS.rename(new, base)

def cmd_update(args):
  cwd = OS.getcwd()
  rmtree('tmp')
  try:

    ## Fetch a new distribution
    OS.mkdir('tmp')
    OS.chdir('tmp')
    run('wget -q -O tripe-keys.tar.gz ${repos-url}')
    run('wget -q -O tripe-keys.sig ${sig-url}')
    run('tar xfz tripe-keys.tar.gz')

    ## Verify the signature
    want = C.bytes(r_nonalpha.sub('', conf['hk-master']))
    got = fingerprint('repos/master.pub', 'tripe-keys-master')
    if want != got: raise VerifyError
    run('''catsign -krepos/master.pub verify -avC -ktripe-keys-master
      -t${sig-fresh} tripe-keys.sig tripe-keys.tar.gz''')

    ## OK: update our copy
    OS.chdir(cwd)
    if OS.path.exists('repos'): OS.rename('repos', 'repos.old')
    OS.rename('tmp/repos', 'repos')
    rmtree('repos.old')

  finally:
    OS.chdir(cwd)
    rmtree('tmp')
  cmd_rebuild(args)

def cmd_rebuild(args):
  zap('keyring.pub')
  for i in OS.listdir('repos'):
    if i.startswith('peer-') and i.endswith('.pub'):
      run('key -kkeyring.pub merge %s' % OS.path.join('repos', i))

def cmd_generate(args):
  tag, = args
  keyring_pub = 'peer-%s.pub' % tag
  zap('keyring'); zap(keyring_pub)
  run('key -kkeyring merge repos/param')
  run('key -kkeyring add -a${kx} -pparam -e${kx-expire} -t%s tripe-${kx}' %
      (tag,))
  run('key -kkeyring extract -f-secret %s %s' % (keyring_pub, tag))
  print 'Generated %s key = %s' % \
        (tag,
         hexhyphens(fingerprint('repos/master.pub', 'tripe-keys-master')))
  

def cmd_clean(args):
  rmtree('repos')
  rmtree('tmp')
  for i in 'master', 'keyring.pub':
    zap(i)
    zap('%s.old' % i)

### Main driver

class UsageError (Exception): pass
  
commands = {'help': (cmd_help, 0, 1, ''),
            'setup': (cmd_setup, 0, 0, ''),
            'upload': (cmd_upload, 0, 0, ''),
            'update': (cmd_update, 0, 0, ''),
            'clean': (cmd_clean, 0, 0, ''),
            'generate': (cmd_generate, 1, 1, 'TAG'),
            'rebuild': (cmd_rebuild, 0, 0, '')}

def init():
  for f in ['tripe-keys.master', 'tripe-keys.conf']:
    if OS.path.exists(f):
      conf_read(f)
      break
  conf_defaults()
def main(argv):
  try:
    opts, args = O.getopt(argv[1:], 'hvu',
                          ['help', 'version', 'usage'])
  except O.GetoptError, exc:
    moan(exc)
    usage(SYS.stderr)
    SYS.exit(1)
  for o, v in opts:
    if o in ('-h', '--help'):
      cmd_help([])
      SYS.exit(0)
    elif o in ('-v', '--version'):
      version(SYS.stdout)
      SYS.exit(0)
    elif o in ('-u', '--usage'):
      usage(SYS.stdout)
      SYS.exit(0)
  if len(argv) < 2:
    cmd_help([])
  else:
    c = argv[1]
    func, min, max, help = commands[c]
    args = argv[2:]
    if len(args) < min or (max > 0 and len(args) > max):
      raise UsageError, (c, help)
    func(args)

init()
main(SYS.argv)