cookie.py

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#!/usr/bin/env python
#

####
# Copyright 2000 by Timothy O'Malley <[e-mail]>
#
#                All Rights Reserved
#
# Permission to use, copy, modify, and distribute this software
# and its documentation for any purpose and without fee is hereby
# granted, provided that the above copyright notice appear in all
# copies and that both that copyright notice and this permission
# notice appear in supporting documentation, and that the name of
# Timothy O'Malley  not be used in advertising or publicity
# pertaining to distribution of the software without specific, written
# prior permission.
#
# Timothy O'Malley DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
# SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS, IN NO EVENT SHALL Timothy O'Malley BE LIABLE FOR
# ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.
#
####
#
# Id: Cookie.py,v 2.29 2000/08/23 05:28:49 timo Exp
#   by Timothy O'Malley <[e-mail]>
#
#  Cookie.py is a Python module for the handling of HTTP
#  cookies as a Python dictionary.  See RFC 2109 for more
#  information on cookies.
#
#  The original idea to treat Cookies as a dictionary came from
#  Dave Mitchell ([e-mail]) in 1995, when he released the
#  first version of nscookie.py.
#
####

r"""
Here's a sample session to show how to use this module.
At the moment, this is the only documentation.

The Basics
----------

Importing is easy..

   >>> import Cookie

Most of the time you start by creating a cookie.  Cookies come in
three flavors, each with slightly different encoding semanitcs, but
more on that later.

   >>> C = Cookie.SimpleCookie()
   >>> C = Cookie.SerialCookie()
   >>> C = Cookie.SmartCookie()

[Note: Long-time users of Cookie.py will remember using
Cookie.Cookie() to create an Cookie object.  Although deprecated, it
is still supported by the code.  See the Backward Compatibility notes
for more information.]

Once you've created your Cookie, you can add values just as if it were
a dictionary.

   >>> C = Cookie.SmartCookie()
   >>> C["fig"] = "newton"
   >>> C["sugar"] = "wafer"
   >>> print C
   Set-Cookie: fig=newton;
   Set-Cookie: sugar=wafer;

Notice that the printable representation of a Cookie is the
appropriate format for a Set-Cookie: header.  This is the
default behavior.  You can change the header and printed
attributes by using the the .output() function

   >>> C = Cookie.SmartCookie()
   >>> C["rocky"] = "road"
   >>> C["rocky"]["path"] = "/cookie"
   >>> print C.output(header="Cookie:")
   Cookie: rocky=road; Path=/cookie;
   >>> print C.output(attrs=[], header="Cookie:")
   Cookie: rocky=road;

The load() method of a Cookie extracts cookies from a string.  In a
CGI script, you would use this method to extract the cookies from the
HTTP_COOKIE environment variable.

   >>> C = Cookie.SmartCookie()
   >>> C.load("chips=ahoy; vienna=finger")
   >>> print C
   Set-Cookie: chips=ahoy;
   Set-Cookie: vienna=finger;

The load() method is darn-tootin smart about identifying cookies
within a string.  Escaped quotation marks, nested semicolons, and other
such trickeries do not confuse it.

   >>> C = Cookie.SmartCookie()
   >>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";')
   >>> print C
   Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;";

Each element of the Cookie also supports all of the RFC 2109
Cookie attributes.  Here's an example which sets the Path
attribute.

   >>> C = Cookie.SmartCookie()
   >>> C["oreo"] = "doublestuff"
   >>> C["oreo"]["path"] = "/"
   >>> print C
   Set-Cookie: oreo=doublestuff; Path=/;

Each dictionary element has a 'value' attribute, which gives you
back the value associated with the key.

   >>> C = Cookie.SmartCookie()
   >>> C["twix"] = "none for you"
   >>> C["twix"].value
   'none for you'


A Bit More Advanced
-------------------

As mentioned before, there are three different flavors of Cookie
objects, each with different encoding/decoding semantics.  This
section briefly discusses the differences.

SimpleCookie

The SimpleCookie expects that all values should be standard strings.
Just to be sure, SimpleCookie invokes the str() builtin to convert
the value to a string, when the values are set dictionary-style.

   >>> C = Cookie.SimpleCookie()
   >>> C["number"] = 7
   >>> C["string"] = "seven"
   >>> C["number"].value
   '7'
   >>> C["string"].value
   'seven'
   >>> print C
   Set-Cookie: number=7;
   Set-Cookie: string=seven;


SerialCookie

The SerialCookie expects that all values should be serialized using
cPickle (or pickle, if cPickle isn't available).  As a result of
serializing, SerialCookie can save almost any Python object to a
value, and recover the exact same object when the cookie has been
returned.  (SerialCookie can yield some strange-looking cookie
values, however.)

   >>> C = Cookie.SerialCookie()
   >>> C["number"] = 7
   >>> C["string"] = "seven"
   >>> C["number"].value
   7
   >>> C["string"].value
   'seven'
   >>> print C
   Set-Cookie: number="I7\012.";
   Set-Cookie: string="S'seven'\012p1\012.";

Be warned, however, if SerialCookie cannot de-serialize a value (because
it isn't a valid pickle'd object), IT WILL RAISE AN EXCEPTION.


SmartCookie

The SmartCookie combines aspects of each of the other two flavors.
When setting a value in a dictionary-fashion, the SmartCookie will
serialize (ala cPickle) the value *if and only if* it isn't a
Python string.  String objects are *not* serialized.  Similarly,
when the load() method parses out values, it attempts to de-serialize
the value.  If it fails, then it fallsback to treating the value
as a string.

   >>> C = Cookie.SmartCookie()
   >>> C["number"] = 7
   >>> C["string"] = "seven"
   >>> C["number"].value
   7
   >>> C["string"].value
   'seven'
   >>> print C
   Set-Cookie: number="I7\012.";
   Set-Cookie: string=seven;


Backwards Compatibility
-----------------------

In order to keep compatibilty with earlier versions of Cookie.py,
it is still possible to use Cookie.Cookie() to create a Cookie.  In
fact, this simply returns a SmartCookie.

   >>> C = Cookie.Cookie()
   >>> print C.__class__.__name__
   SmartCookie


Finis.
"""  #"
#     ^
#     |----helps out font-lock

#
# Import our required modules
#
import string
from UserDict import UserDict

try:
    from cPickle import dumps, loads
except ImportError:
    from pickle import dumps, loads

try:
    import re
except ImportError:
    raise ImportError, "Cookie.py requires 're' from Python 1.5 or later"

__all__ = ["CookieError","BaseCookie","SimpleCookie","SerialCookie",
           "SmartCookie","Cookie"]

#
# Define an exception visible to External modules
#
class CookieError(Exception):
    pass


# These quoting routines conform to the RFC2109 specification, which in
# turn references the character definitions from RFC2068.  They provide
# a two-way quoting algorithm.  Any non-text character is translated
# into a 4 character sequence: a forward-slash followed by the
# three-digit octal equivalent of the character.  Any '\' or '"' is
# quoted with a preceeding '\' slash.
#
# These are taken from RFC2068 and RFC2109.
#       _LegalChars       is the list of chars which don't require "'s
#       _Translator       hash-table for fast quoting
#
_LegalChars       = string.ascii_letters + string.digits + "!#$%&'*+-.^_`|~"
_Translator       = {
    '\000' : '\\000',  '\001' : '\\001',  '\002' : '\\002',
    '\003' : '\\003',  '\004' : '\\004',  '\005' : '\\005',
    '\006' : '\\006',  '\007' : '\\007',  '\010' : '\\010',
    '\011' : '\\011',  '\012' : '\\012',  '\013' : '\\013',
    '\014' : '\\014',  '\015' : '\\015',  '\016' : '\\016',
    '\017' : '\\017',  '\020' : '\\020',  '\021' : '\\021',
    '\022' : '\\022',  '\023' : '\\023',  '\024' : '\\024',
    '\025' : '\\025',  '\026' : '\\026',  '\027' : '\\027',
    '\030' : '\\030',  '\031' : '\\031',  '\032' : '\\032',
    '\033' : '\\033',  '\034' : '\\034',  '\035' : '\\035',
    '\036' : '\\036',  '\037' : '\\037',

    '"' : '\\"',       '\\' : '\\\\',

    '\177' : '\\177',  '\200' : '\\200',  '\201' : '\\201',
    '\202' : '\\202',  '\203' : '\\203',  '\204' : '\\204',
    '\205' : '\\205',  '\206' : '\\206',  '\207' : '\\207',
    '\210' : '\\210',  '\211' : '\\211',  '\212' : '\\212',
    '\213' : '\\213',  '\214' : '\\214',  '\215' : '\\215',
    '\216' : '\\216',  '\217' : '\\217',  '\220' : '\\220',
    '\221' : '\\221',  '\222' : '\\222',  '\223' : '\\223',
    '\224' : '\\224',  '\225' : '\\225',  '\226' : '\\226',
    '\227' : '\\227',  '\230' : '\\230',  '\231' : '\\231',
    '\232' : '\\232',  '\233' : '\\233',  '\234' : '\\234',
    '\235' : '\\235',  '\236' : '\\236',  '\237' : '\\237',
    '\240' : '\\240',  '\241' : '\\241',  '\242' : '\\242',
    '\243' : '\\243',  '\244' : '\\244',  '\245' : '\\245',
    '\246' : '\\246',  '\247' : '\\247',  '\250' : '\\250',
    '\251' : '\\251',  '\252' : '\\252',  '\253' : '\\253',
    '\254' : '\\254',  '\255' : '\\255',  '\256' : '\\256',
    '\257' : '\\257',  '\260' : '\\260',  '\261' : '\\261',
    '\262' : '\\262',  '\263' : '\\263',  '\264' : '\\264',
    '\265' : '\\265',  '\266' : '\\266',  '\267' : '\\267',
    '\270' : '\\270',  '\271' : '\\271',  '\272' : '\\272',
    '\273' : '\\273',  '\274' : '\\274',  '\275' : '\\275',
    '\276' : '\\276',  '\277' : '\\277',  '\300' : '\\300',
    '\301' : '\\301',  '\302' : '\\302',  '\303' : '\\303',
    '\304' : '\\304',  '\305' : '\\305',  '\306' : '\\306',
    '\307' : '\\307',  '\310' : '\\310',  '\311' : '\\311',
    '\312' : '\\312',  '\313' : '\\313',  '\314' : '\\314',
    '\315' : '\\315',  '\316' : '\\316',  '\317' : '\\317',
    '\320' : '\\320',  '\321' : '\\321',  '\322' : '\\322',
    '\323' : '\\323',  '\324' : '\\324',  '\325' : '\\325',
    '\326' : '\\326',  '\327' : '\\327',  '\330' : '\\330',
    '\331' : '\\331',  '\332' : '\\332',  '\333' : '\\333',
    '\334' : '\\334',  '\335' : '\\335',  '\336' : '\\336',
    '\337' : '\\337',  '\340' : '\\340',  '\341' : '\\341',
    '\342' : '\\342',  '\343' : '\\343',  '\344' : '\\344',
    '\345' : '\\345',  '\346' : '\\346',  '\347' : '\\347',
    '\350' : '\\350',  '\351' : '\\351',  '\352' : '\\352',
    '\353' : '\\353',  '\354' : '\\354',  '\355' : '\\355',
    '\356' : '\\356',  '\357' : '\\357',  '\360' : '\\360',
    '\361' : '\\361',  '\362' : '\\362',  '\363' : '\\363',
    '\364' : '\\364',  '\365' : '\\365',  '\366' : '\\366',
    '\367' : '\\367',  '\370' : '\\370',  '\371' : '\\371',
    '\372' : '\\372',  '\373' : '\\373',  '\374' : '\\374',
    '\375' : '\\375',  '\376' : '\\376',  '\377' : '\\377'
    }

def _quote(str, LegalChars=_LegalChars,
    join=string.join, idmap=string._idmap, translate=string.translate):
    #
    # If the string does not need to be double-quoted,
    # then just return the string.  Otherwise, surround
    # the string in doublequotes and precede quote (with a \)
    # special characters.
    #
    if "" == translate(str, idmap, LegalChars):
        return str
    else:
        return '"' + join( map(_Translator.get, str, str), "" ) + '"'
# end _quote


_OctalPatt = re.compile(r"\\[0-3][0-7][0-7]")
_QuotePatt = re.compile(r"[\\].")

def _unquote(str, join=string.join, atoi=string.atoi):
    # If there aren't any doublequotes,
    # then there can't be any special characters.  See RFC 2109.
    if  len(str) < 2:
        return str
    if str[0] != '"' or str[-1] != '"':
        return str

    # We have to assume that we must decode this string.
    # Down to work.

    # Remove the "s
    str = str[1:-1]

    # Check for special sequences.  Examples:
    #    \012 --> \n
    #    \"   --> "
    #
    i = 0
    n = len(str)
    res = []
    while 0 <= i < n:
        Omatch = _OctalPatt.search(str, i)
        Qmatch = _QuotePatt.search(str, i)
        if not Omatch and not Qmatch:              # Neither matched
            res.append(str[i:])
            break
        # else:
        j = k = -1
        if Omatch: j = Omatch.start(0)
        if Qmatch: k = Qmatch.start(0)
        if Qmatch and ( not Omatch or k < j ):     # QuotePatt matched
            res.append(str[i:k])
            res.append(str[k+1])
            i = k+2
        else:                                      # OctalPatt matched
            res.append(str[i:j])
            res.append( chr( atoi(str[j+1:j+4], 8) ) )
            i = j+4
    return join(res, "")
# end _unquote