ctypescrypto/oid.py

   1 """
   2  Interface to OpenSSL object identifier database.
   3
   4  It is primarily intended to deal with OIDs which are compiled into the
   5  database or defined in the openssl configuration files.
   6
   7  But see create() function
   8
   9 """
  10 from ctypescrypto import libcrypto
  11 from ctypes import c_char_p, c_void_p, c_int, create_string_buffer
  12
  13 __all__ = ['Oid','create','cleanup']
  14
  15 class Oid(object):
  16         """
  17                 Represents an OID. It can be consturucted by textual
  18                 representation like Oid("commonName") or Oid("CN"),
  19                 dotted-decimal Oid("1.2.3.4") or using OpenSSL numeric
  20                 identifer (NID), which is typically returned or required by
  21                 OpenSSL API functions. If object is consturcted from textual
  22                 representation which is not present in the database, it fails
  23                 with ValueError
  24
  25                 attribute nid - contains object nid.
  26
  27
  28         """
  29
  30         def __init__(self,value):
  31                 " Object constuctor. Accepts string or integer"
  32                 if isinstance(value,unicode):
  33                         value=value.encode('ascii')
  34                 if isinstance(value,str):
  35                         self.nid=libcrypto.OBJ_txt2nid(value)
  36                         if self.nid==0:
  37                                 raise ValueError("Cannot find object %s in the database"%(value))
  38                 elif isinstance(value,(int,long)):
  39                         cn=libcrypto.OBJ_nid2sn(value)
  40                         if cn is None:
  41                                 raise ValueError("No such nid %d in the database"%(value))
  42                         self.nid=value
  43                 else:
  44                         raise TypeError("Cannot convert this type to object identifier")
  45         def __hash__(self):
  46                 " Returns NID "
  47                 return self.nid
  48         def __cmp__(self,other):
  49                 " Compares NIDs of two objects "
  50                 return self.nid-other.nid
  51         def __str__(self):
  52                 " Default string representation of Oid is dotted-decimal"
  53                 return self.dotted()
  54         def __repr__(self):
  55                 return "Oid('%s')"%(self.dotted())
  56         def shortname(self):
  57                 " Returns short name if any "
  58                 return libcrypto.OBJ_nid2sn(self.nid)
  59         def longname(self):
  60                 " Returns logn name if any "
  61                 return  libcrypto.OBJ_nid2ln(self.nid)
  62         def dotted(self):
  63                 " Returns dotted-decimal reperesentation "
  64                 obj=libcrypto.OBJ_nid2obj(self.nid)
  65                 buf=create_string_buffer(256)
  66                 libcrypto.OBJ_obj2txt(buf,256,obj,1)
  67                 return buf.value
  68         @staticmethod
  69         def fromobj(obj):
  70                 """
  71                 Creates an OID object from the pointer to ASN1_OBJECT c structure.
  72                 Strictly for internal use
  73                 """
  74                 nid=libcrypto.OBJ_obj2nid(obj)
  75                 if nid==0:
  76                         buf=create_string_buffer(80)
  77                         l=libcrypto.OBJ_obj2txt(buf,80,obj,1)
  78                         oid=create(buf[0:l],buf[0:l],buf[0:l])
  79                 else:
  80                         oid=Oid(nid)
  81                 return oid
  82
  83 def create(dotted,shortname,longname):
  84         """
  85                 Creates new OID in the database
  86
  87                 @param dotted - dotted-decimal representation of new OID
  88                 @param shortname - short name for new OID
  89                 @param longname - long name for new OID
  90
  91                 @returns Oid object corresponding to new OID
  92
  93                 This function should be used with exreme care. Whenever
  94                 possible, it is better to add new OIDs via OpenSSL configuration
  95                 file
  96
  97                 Results of calling this function twice for same OIDor for
  98                 Oid alredy in database are undefined
  99         """
 100         nid=libcrypto.OBJ_create(dotted,shortname,longname)
 101         if nid == 0:
 102                 raise LibCryptoError("Problem adding new OID to the  database")
 103         return Oid(nid)
 104
 105 def cleanup():
 106         """
 107                 Removes all the objects, dynamically added by current
 108                 application from database.
 109         """
 110         libcrypto.OBJ_cleanup()
 111
 112 libcrypto.OBJ_nid2sn.restype=c_char_p
 113 libcrypto.OBJ_nid2ln.restype=c_char_p
 114 libcrypto.OBJ_nid2obj.restype=c_void_p
 115 libcrypto.OBJ_obj2txt.argtypes=(c_char_p,c_int,c_void_p,c_int)
 116 libcrypto.OBJ_txt2nid.argtupes=(c_char_p,)
 117 libcrypto.OBJ_create.argtypes=(c_char_p,c_char_p,c_char_p)