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File Content: `packet.py`

"""M2Crypto PGP2.

This module implements PGP packets per RFC1991 and various source distributions.

Each packet type is represented by a class; packet classes derive from 
the abstract 'packet' class. 

The 'message digest' packet type, mentioned but not documented in RFC1991,
is not implemented.

Copyright (c) 1999-2003 Ng Pheng Siong. All rights reserved."""

# XXX Work-in-progress.

# Be liberal in what you accept.
# Be conservative in what you send. 
# Be lazy in what you eval.

import struct, time

try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO

from M2Crypto import EVP, RSA
from M2Crypto.util import octx_to_num

from constants import *

_OK_VERSION     = ('\002', '\003')
_OK_VALIDITY    = ('\000',)
_OK_PKC         = ('\001',)


class packet:
    def __init__(self, ctb, body=None):
        import warnings
        warnings.warn('Deprecated. No maintainer for PGP. If you use this, please inform M2Crypto maintainer.', DeprecationWarning)
        
        self.ctb = ctb
        if body is not None:
            self.body = StringIO(body)
        else:
            self.body = None

    def validate(self):
        return 1

    def pack(self):
        raise NotImplementedError, '%s.pack(): abstract method' % (self.__class__,)

    def version(self):
        if hasattr(self, '_version'):
            return ord(self._version)
        else:
            return None

    def timestamp(self):
        if hasattr(self, '_timestamp'):
            return struct.unpack('>L', self._timestamp)[0]
        else:
            return None

    def validity(self):
        if hasattr(self, '_validity'):
            return struct.unpack('>H', self._validity)[0]
        else:
            return None

    def pkc(self):
        if hasattr(self, '_pkc'):
            return self._pkc
        else:
            return None

    def _llf(self, lenf):
        if lenf < 256:  
            return (0, chr(lenf))
        elif lenf < 65536:
            return (1, struct.pack('>H', lenf))
        else: 
            assert lenf < 2L**32
            return (2, struct.pack('>L', lenf))

    def _ctb(self, llf):
        ctbv = _FACTORY[self.__class__]
        return chr((1 << 7) | (ctbv << 2) | llf)


class public_key_packet(packet):
    def __init__(self, ctb, body=None):
        packet.__init__(self, ctb, body)
        if self.body is not None:
            self._version = self.body.read(1)
            self._timestamp = self.body.read(4)
            self._validity = self.body.read(2)
            self._pkc = self.body.read(1)

            self._nlen = self.body.read(2)
            nlen = (struct.unpack('>H', self._nlen)[0] + 7) / 8
            self._n = self.body.read(nlen)
            
            self._elen = self.body.read(2)
            elen = (struct.unpack('>H', self._elen)[0] + 7) / 8
            self._e = self.body.read(elen)

    def pack(self):
        if self.body is None:
            self.body = StringIO()
            self.body.write(self._version)
            self.body.write(self._timestamp)
            self.body.write(self._validity)
            self.body.write(self._pkc)
            self.body.write(self._nlen)
            self.body.write(self._n)
            self.body.write(self._elen)
            self.body.write(self._e)
        self.body = self.body.getvalue()
        llf, lenf = self._llf(len(self.body))
        ctb = self._ctb(llf)
        return '%s%s%s' % (ctb, lenf, self.body)

    def pubkey(self):
        return self._pubkey.pub()


class trust_packet(packet):
    # This implementation neither interprets nor emits trust packets.
    def __init__(self, ctb, body=None):
        packet.__init__(self, ctb, body)
        if body is not None:
            self.trust = self.body.read(1)


class userid_packet(packet):
    def __init__(self, ctb, body=None):
        packet.__init__(self, ctb, body)
        if body is not None:
            self._userid = body

    def pack(self):
        if self.body is None:
            self.body = StringIO()
            self.body.write(chr(len(self._userid)))
            self.body.write(self._userid)
            self.body = self.body.getvalue()
        return self.ctb + self.body

    def userid(self):   
        return self._userid


class comment_packet(packet):
    def __init__(self, ctb, body=None):
        packet.__init__(self, ctb, body)
        if body is not None:
            self.comment = self.body.getvalue()

    def pack(self):
        if self.body is None:
            self.body = StringIO()
            self.body.write(chr(len(self.comment)))
            self.body.write(self.comment)
            self.body = self.body.getvalue()
        return self.ctb + self.body


class signature_packet(packet):
    def __init__(self, ctb, body=None):
        packet.__init__(self, ctb, body)
        if body is not None:
            self._version = self.body.read(1)
            self._len_md_stuff = self.body.read(1)
            self._classification = self.body.read(1)
            self._timestamp = self.body.read(4)
            self._keyid = self.body.read(8)
            self._pkc = self.body.read(1)
            self._md_algo = self.body.read(1)
            self._md_chksum = self.body.read(2)
            self._sig = self.body.read()

    def pack(self):
        if self.body is None:
            self.body = StringIO()
            self.body.write(self._version)
            self.body.write(self._len_md_stuff)
            self.body.write(self._classification)
            self.body.write(self._timestamp)
            self.body.write(self._keyid)
            self.body.write(self._pkc)
            self.body.write(self._md_algo)
            self.body.write(self._md_chksum)
            self.body.write(self._sig)
            self.body = self.body.getvalue()
        llf, lenf = self._llf(len(body))
        self.ctb = self.ctb | llf
        return '%s%s%s' % (self.ctb, lenf, self.body)


    def validate(self):
        if self._version not in _OK_VERSION:
            return None
        if self._len_md_stuff != '\005':
            return None


class private_key_packet(packet):
    def __init__(self, ctb, body=None):
        packet.__init__(self, ctb, body)
        if body is not None:
            self._version = self.body.read(1)
            self._timestamp = self.body.read(4)
            self._validity = self.body.read(2)
            self._pkc = self.body.read(1)

            self._nlen = self.body.read(2)
            nlen = (struct.unpack('>H', self._nlen)[0] + 7) / 8
            self._n = self.body.read(nlen)
            
            self._elen = self.body.read(2)
            elen = (struct.unpack('>H', self._elen)[0] + 7) / 8
            self._e = self.body.read(elen)

            self._cipher = self.body.read(1)
            if self._cipher == '\001':
                self._iv = self.body.read(8)
            else:
                self._iv = None
    
            for param in ['d', 'p', 'q', 'u']:
                _plen = self.body.read(2)
                setattr(self, '_'+param+'len', _plen)
                plen = (struct.unpack('>H', _plen)[0] + 7) / 8
                setattr(self, '_'+param, self.body.read(plen))
    
            self._cksum = self.body.read(2)

    def is_encrypted(self):
        return ord(self._cipher)


class cke_packet(packet):
    def __init__(self, ctb, body=None):
        packet.__init__(self, ctb, body)
        if body is not None:
            self._iv = self.body.read(8)
            self._cksum = self.body.read(2)
            self._ctxt = self.body.read()


class pke_packet(packet):
    def __init__(self, ctb, body=None):
        packet.__init__(self, ctb, body)
        if body is not None:
            self._version = self.body.read(1)
            self._keyid = self.body.read(8)
            self._pkc = ord(self.body.read(1))
    
            deklen = (struct.unpack('>H', self.body.read(2))[0] + 7 ) / 8
            self._dek = octx_to_num(self.body.read(deklen))


class literal_packet(packet):
    def __init__(self, ctb, body=None):
        packet.__init__(self, ctb, body)
        if body is not None:
            self.fmode = self.body.read(1)
            fnlen = self.body.read(1)
            self.fname = self.body.read(fnlen)
            self.ftime = self.body.read(4)
            #self.data = self.body.read()


class compressed_packet(packet):
    def __init__(self, ctb, stream):
        packet.__init__(self, ctb, '')
        if body is not None:
            self.algo = stream.read(1)
            # This reads the entire stream into memory.
            self.data = stream.read()

    def validate(self):
        return (self.algo == '\001')

    def uncompress(self):
        import zlib
        decomp = zlib.decompressobj(-13)    # RFC 2440, pg 61.
        # This doubles the memory usage.
        stream = StringIO(decomp.decompress(self.data))
        return stream


_FACTORY = { 
    1 : pke_packet,
    2 : signature_packet,
    #3 : message_digest_packet,     # XXX not implemented
    5 : private_key_packet,
    6 : public_key_packet,
    #8 : compressed_packet,         # special case
    9 : cke_packet,
    11 : literal_packet,
    12 : trust_packet,
    13 : userid_packet,
    14 : comment_packet,
    pke_packet : 1,
    signature_packet : 2,
    #3 : message_digest_packet,     
    private_key_packet : 5,
    public_key_packet : 6,
    #8 : compressed_packet,
    cke_packet : 9,
    literal_packet : 11,
    trust_packet : 12,
    userid_packet : 13,
    comment_packet : 14
}


class packet_stream:
    def __init__(self, input):
        self.stream = input
        self.under_current = None
        self._count = 0

    def close(self):
        self.stream.close()
        if self.under_current is not None:
            self.under_current.close()

    def read(self, keep_trying=0):
        while 1:
            ctb0 = self.stream.read(1)
            if not ctb0:
                return None
            ctb = ord(ctb0)
            if is_ctb(ctb):
                break
            elif keep_trying:
                continue
            else:
                raise XXXError
        ctbt = (ctb & 0x3c) >> 2

        if ctbt == CTB_COMPRESSED_DATA:
            self.under_current = self.stream
            cp = compressed_packet(ctb0, self.stream)
            self.stream = cp.uncompress()
            return self.read()

        # Decode the length of following data. See RFC for details.
        llf = ctb & 3
        if llf == 0:
            lenf = ord(self.stream.read(1))
        elif llf == 1:
            lenf = struct.unpack('>H', self.stream.read(2))[0]
        elif llf == 2:
            lenf = struct.unpack('>L', self.stream.read(4))[0]
        else: # llf == 3
            raise XXXError, 'impossible case'

        body = self.stream.read(lenf)
        if not body or (len(body) != lenf):
            raise XXXError, 'corrupted packet'

        self._count = self.stream.tell()
        try: 
            return _FACTORY[ctbt](ctb0, body) 
        except KeyError:
            return packet(ctb0, body)

    def count(self):
        return self._count

def is_ctb(ctb):
    return ctb & 0xc0

def make_ctb(value, llf):
    return chr((1 << 7) | (value << 2) | llf)
Name	Size	Permission
PublicKey.py	1646 bytes	0644
PublicKey.pyc	3277 bytes	0644
PublicKey.pyo	3117 bytes	0644
PublicKeyRing.py	2171 bytes	0644
PublicKeyRing.pyc	3174 bytes	0644
PublicKeyRing.pyo	3174 bytes	0644
RSA.py	849 bytes	0644
RSA.pyc	1567 bytes	0644
RSA.pyo	1567 bytes	0644
__init__.py	349 bytes	0644
__init__.pyc	668 bytes	0644
__init__.pyo	668 bytes	0644
constants.py	381 bytes	0644
constants.pyc	608 bytes	0644
constants.pyo	608 bytes	0644
packet.py	11229 bytes	0644
packet.pyc	15189 bytes	0644
packet.pyo	15127 bytes	0644
File Content: packet.py

File Content: `packet.py`
