#!/usr/bin/env python

####################
__doc__="""\
This script expects a mandatory plain passwd, 
and an optional MD5-encoded passwd

If both are provided, we check that they match
Otherwise we return an encrypted passwd 
"""

__author__="Thierry Parmentelat, INRIA Sophia Antipolis"

####################
import getopt
import sys
import re

from crypt import crypt
import random
import string
    
#################### md5 passwds syntax
magic='$1$'
re_magic='\$1\$'  # $ needs \ in regular expression

####################
def usage():
   print "Usage: %s plain [encrypted]"%sys.argv[0]
   print __doc__

####################
####################
def getsalt(chars = string.letters + string.digits):
    # generate a random 8-character 'salt'
    return (random.choice(chars)
            + random.choice(chars)
            + random.choice(chars)
            + random.choice(chars)
            + random.choice(chars)
            + random.choice(chars)
            + random.choice(chars)
            + random.choice(chars))

##########
# returns a string
def compute_encrypted (plain):
   return crypt(plain,magic+getsalt()+'$')

####################
####################
# returns a boolean
def check_encrypted (plain,passwd):
   
   no_dollar="[^\$]+"
   re_passwd=(re_magic
              +"(%s)"%no_dollar
              +'\$'
              + "(%s)"%no_dollar)
#   print "in="+passwd
#   print "re="+re_passwd
   m_passwd=re.compile(re_passwd)
   r=m_passwd.match(passwd)

   if not r:
      print 'passwd wrong syntax %s'%passwd
      ok= False
   else:
      salt=r.group(1)
      checked=crypt(plain,magic+salt+'$')
      ok = (checked==passwd)
   return ok

####################
def main ():

   (opts, argv) = getopt.getopt(sys.argv[1:], "h")
   for (opt, optval) in opts:
      if opt == '-h':
         usage()
	 return 1

   args=len(argv)
   if args==1:
      [plain]=argv
      try:
         encrypted=compute_encrypted(plain)
         print encrypted
         return 0
      except:
         return 1
   elif args==2:
      [plain,passwd]=argv
      try:
         ok = check_encrypted (plain,passwd)
         if ok:
            return 0
         else:
            return 1
      except:
          return 1
   else:
       usage()
       return 1
   print "END should not occur"
         
####################
if __name__ == '__main__':
   sys.exit(main())