1 :mod:`Cookie` --- HTTP state management

     2 =======================================

     3 

     4 .. module:: Cookie

     5    :synopsis: Support for HTTP state management (cookies).

     6 .. moduleauthor:: Timothy O'Malley <timo@alum.mit.edu>

     7 .. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>

     8 

     9 .. note::

    10    The :mod:`Cookie` module has been renamed to :mod:`http.cookies` in Python

    11    3.0.  The :term:`2to3` tool will automatically adapt imports when converting

    12    your sources to 3.0.

    13 

    14 

    15 The :mod:`Cookie` module defines classes for abstracting the concept of

    16 cookies, an HTTP state management mechanism. It supports both simple string-only

    17 cookies, and provides an abstraction for having any serializable data-type as

    18 cookie value.

    19 

    20 The module formerly strictly applied the parsing rules described in the

    21 :rfc:`2109` and :rfc:`2068` specifications.  It has since been discovered that

    22 MSIE 3.0x doesn't follow the character rules outlined in those specs.  As a

    23 result, the parsing rules used are a bit less strict.

    24 

    25 .. note::

    26 

    27    On encountering an invalid cookie, :exc:`CookieError` is raised, so if your

    28    cookie data comes from a browser you should always prepare for invalid data

    29    and catch :exc:`CookieError` on parsing.

    30 

    31 

    32 .. exception:: CookieError

    33 

    34    Exception failing because of :rfc:`2109` invalidity: incorrect attributes,

    35    incorrect :mailheader:`Set-Cookie` header, etc.

    36 

    37 

    38 .. class:: BaseCookie([input])

    39 

    40    This class is a dictionary-like object whose keys are strings and whose values

    41    are :class:`Morsel` instances. Note that upon setting a key to a value, the

    42    value is first converted to a :class:`Morsel` containing the key and the value.

    43 

    44    If *input* is given, it is passed to the :meth:`load` method.

    45 

    46 

    47 .. class:: SimpleCookie([input])

    48 

    49    This class derives from :class:`BaseCookie` and overrides :meth:`value_decode`

    50    and :meth:`value_encode` to be the identity and :func:`str` respectively.

    51 

    52 

    53 .. class:: SerialCookie([input])

    54 

    55    This class derives from :class:`BaseCookie` and overrides :meth:`value_decode`

    56    and :meth:`value_encode` to be the :func:`pickle.loads` and

    57    :func:`pickle.dumps`.

    58 

    59    .. deprecated:: 2.3

    60       Reading pickled values from untrusted cookie data is a huge security hole, as

    61       pickle strings can be crafted to cause arbitrary code to execute on your server.

    62       It is supported for backwards compatibility only, and may eventually go away.

    63 

    64 

    65 .. class:: SmartCookie([input])

    66 

    67    This class derives from :class:`BaseCookie`. It overrides :meth:`value_decode`

    68    to be :func:`pickle.loads` if it is a valid pickle, and otherwise the value

    69    itself. It overrides :meth:`value_encode` to be :func:`pickle.dumps` unless it

    70    is a string, in which case it returns the value itself.

    71 

    72    .. deprecated:: 2.3

    73       The same security warning from :class:`SerialCookie` applies here.

    74 

    75 A further security note is warranted.  For backwards compatibility, the

    76 :mod:`Cookie` module exports a class named :class:`Cookie` which is just an

    77 alias for :class:`SmartCookie`.  This is probably a mistake and will likely be

    78 removed in a future version.  You should not use the :class:`Cookie` class in

    79 your applications, for the same reason why you should not use the

    80 :class:`SerialCookie` class.

    81 

    82 

    83 .. seealso::

    84 

    85    Module :mod:`cookielib`

    86       HTTP cookie handling for web *clients*.  The :mod:`cookielib` and :mod:`Cookie`

    87       modules do not depend on each other.

    88 

    89    :rfc:`2109` - HTTP State Management Mechanism

    90       This is the state management specification implemented by this module.

    91 

    92 

    93 .. _cookie-objects:

    94 

    95 Cookie Objects

    96 --------------

    97 

    98 

    99 .. method:: BaseCookie.value_decode(val)

   100 

   101    Return a decoded value from a string representation. Return value can be any

   102    type. This method does nothing in :class:`BaseCookie` --- it exists so it can be

   103    overridden.

   104 

   105 

   106 .. method:: BaseCookie.value_encode(val)

   107 

   108    Return an encoded value. *val* can be any type, but return value must be a

   109    string. This method does nothing in :class:`BaseCookie` --- it exists so it can

   110    be overridden

   111 

   112    In general, it should be the case that :meth:`value_encode` and

   113    :meth:`value_decode` are inverses on the range of *value_decode*.

   114 

   115 

   116 .. method:: BaseCookie.output([attrs[, header[, sep]]])

   117 

   118    Return a string representation suitable to be sent as HTTP headers. *attrs* and

   119    *header* are sent to each :class:`Morsel`'s :meth:`output` method. *sep* is used

   120    to join the headers together, and is by default the combination ``'\r\n'``

   121    (CRLF).

   122 

   123    .. versionchanged:: 2.5

   124       The default separator has been changed from ``'\n'`` to match the cookie

   125       specification.

   126 

   127 

   128 .. method:: BaseCookie.js_output([attrs])

   129 

   130    Return an embeddable JavaScript snippet, which, if run on a browser which

   131    supports JavaScript, will act the same as if the HTTP headers was sent.

   132 

   133    The meaning for *attrs* is the same as in :meth:`output`.

   134 

   135 

   136 .. method:: BaseCookie.load(rawdata)

   137 

   138    If *rawdata* is a string, parse it as an ``HTTP_COOKIE`` and add the values

   139    found there as :class:`Morsel`\ s. If it is a dictionary, it is equivalent to::

   140 

   141       for k, v in rawdata.items():

   142           cookie[k] = v

   143 

   144 

   145 .. _morsel-objects:

   146 

   147 Morsel Objects

   148 --------------

   149 

   150 

   151 .. class:: Morsel

   152 

   153    Abstract a key/value pair, which has some :rfc:`2109` attributes.

   154 

   155    Morsels are dictionary-like objects, whose set of keys is constant --- the valid

   156    :rfc:`2109` attributes, which are

   157 

   158    * ``expires``

   159    * ``path``

   160    * ``comment``

   161    * ``domain``

   162    * ``max-age``

   163    * ``secure``

   164    * ``version``

   165    * ``httponly``

   166 

   167    The attribute :attr:`httponly` specifies that the cookie is only transfered

   168    in HTTP requests, and is not accessible through JavaScript. This is intended

   169    to mitigate some forms of cross-site scripting.

   170 

   171    The keys are case-insensitive.

   172 

   173    .. versionadded:: 2.6

   174       The :attr:`httponly` attribute was added.

   175 

   176 

   177 .. attribute:: Morsel.value

   178 

   179    The value of the cookie.

   180 

   181 

   182 .. attribute:: Morsel.coded_value

   183 

   184    The encoded value of the cookie --- this is what should be sent.

   185 

   186 

   187 .. attribute:: Morsel.key

   188 

   189    The name of the cookie.

   190 

   191 

   192 .. method:: Morsel.set(key, value, coded_value)

   193 

   194    Set the *key*, *value* and *coded_value* members.

   195 

   196 

   197 .. method:: Morsel.isReservedKey(K)

   198 

   199    Whether *K* is a member of the set of keys of a :class:`Morsel`.

   200 

   201 

   202 .. method:: Morsel.output([attrs[, header]])

   203 

   204    Return a string representation of the Morsel, suitable to be sent as an HTTP

   205    header. By default, all the attributes are included, unless *attrs* is given, in

   206    which case it should be a list of attributes to use. *header* is by default

   207    ``"Set-Cookie:"``.

   208 

   209 

   210 .. method:: Morsel.js_output([attrs])

   211 

   212    Return an embeddable JavaScript snippet, which, if run on a browser which

   213    supports JavaScript, will act the same as if the HTTP header was sent.

   214 

   215    The meaning for *attrs* is the same as in :meth:`output`.

   216 

   217 

   218 .. method:: Morsel.OutputString([attrs])

   219 

   220    Return a string representing the Morsel, without any surrounding HTTP or

   221    JavaScript.

   222 

   223    The meaning for *attrs* is the same as in :meth:`output`.

   224 

   225 

   226 .. _cookie-example:

   227 

   228 Example

   229 -------

   230 

   231 The following example demonstrates how to use the :mod:`Cookie` module.

   232 

   233 .. doctest::

   234    :options: +NORMALIZE_WHITESPACE

   235 

   236    >>> import Cookie

   237    >>> C = Cookie.SimpleCookie()

   238    >>> C = Cookie.SerialCookie()

   239    >>> C = Cookie.SmartCookie()

   240    >>> C["fig"] = "newton"

   241    >>> C["sugar"] = "wafer"

   242    >>> print C # generate HTTP headers

   243    Set-Cookie: fig=newton

   244    Set-Cookie: sugar=wafer

   245    >>> print C.output() # same thing

   246    Set-Cookie: fig=newton

   247    Set-Cookie: sugar=wafer

   248    >>> C = Cookie.SmartCookie()

   249    >>> C["rocky"] = "road"

   250    >>> C["rocky"]["path"] = "/cookie"

   251    >>> print C.output(header="Cookie:")

   252    Cookie: rocky=road; Path=/cookie

   253    >>> print C.output(attrs=[], header="Cookie:")

   254    Cookie: rocky=road

   255    >>> C = Cookie.SmartCookie()

   256    >>> C.load("chips=ahoy; vienna=finger") # load from a string (HTTP header)

   257    >>> print C

   258    Set-Cookie: chips=ahoy

   259    Set-Cookie: vienna=finger

   260    >>> C = Cookie.SmartCookie()

   261    >>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";')

   262    >>> print C

   263    Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;"

   264    >>> C = Cookie.SmartCookie()

   265    >>> C["oreo"] = "doublestuff"

   266    >>> C["oreo"]["path"] = "/"

   267    >>> print C

   268    Set-Cookie: oreo=doublestuff; Path=/

   269    >>> C = Cookie.SmartCookie()

   270    >>> C["twix"] = "none for you"

   271    >>> C["twix"].value

   272    'none for you'

   273    >>> C = Cookie.SimpleCookie()

   274    >>> C["number"] = 7 # equivalent to C["number"] = str(7)

   275    >>> C["string"] = "seven"

   276    >>> C["number"].value

   277    '7'

   278    >>> C["string"].value

   279    'seven'

   280    >>> print C

   281    Set-Cookie: number=7

   282    Set-Cookie: string=seven

   283    >>> C = Cookie.SerialCookie()

   284    >>> C["number"] = 7

   285    >>> C["string"] = "seven"

   286    >>> C["number"].value

   287    7

   288    >>> C["string"].value

   289    'seven'

   290    >>> print C

   291    Set-Cookie: number="I7\012."

   292    Set-Cookie: string="S'seven'\012p1\012."

   293    >>> C = Cookie.SmartCookie()

   294    >>> C["number"] = 7

   295    >>> C["string"] = "seven"

   296    >>> C["number"].value

   297    7

   298    >>> C["string"].value

   299    'seven'

   300    >>> print C

   301    Set-Cookie: number="I7\012."

   302    Set-Cookie: string=seven

   303