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

=======================================

.. module:: Cookie

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

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

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

.. note::

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

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

   your sources to 3.0.

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

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

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

cookie value.

The module formerly strictly applied the parsing rules described in the

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

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

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

.. note::

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

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

   and catch :exc:`CookieError` on parsing.

.. exception:: CookieError

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

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

.. class:: BaseCookie([input])

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

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

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

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

.. class:: SimpleCookie([input])

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

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

.. class:: SerialCookie([input])

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

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

   :func:`pickle.dumps`.

   .. deprecated:: 2.3

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

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

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

.. class:: SmartCookie([input])

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

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

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

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

   .. deprecated:: 2.3

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

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

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

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

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

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

:class:`SerialCookie` class.

.. seealso::

   Module :mod:`cookielib`

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

      modules do not depend on each other.

   :rfc:`2109` - HTTP State Management Mechanism

      This is the state management specification implemented by this module.

.. _cookie-objects:

Cookie Objects

--------------

.. method:: BaseCookie.value_decode(val)

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

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

   overridden.

.. method:: BaseCookie.value_encode(val)

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

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

   be overridden

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

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

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

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

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

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

   (CRLF).

   .. versionchanged:: 2.5

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

      specification.

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

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

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

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

.. method:: BaseCookie.load(rawdata)

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

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

      for k, v in rawdata.items():

          cookie[k] = v

.. _morsel-objects:

Morsel Objects

--------------

.. class:: Morsel

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

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

   :rfc:`2109` attributes, which are

   * ``expires``

   * ``path``

   * ``comment``

   * ``domain``

   * ``max-age``

   * ``secure``

   * ``version``

   * ``httponly``

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

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

   to mitigate some forms of cross-site scripting.

   The keys are case-insensitive.

   .. versionadded:: 2.6

      The :attr:`httponly` attribute was added.

.. attribute:: Morsel.value

   The value of the cookie.

.. attribute:: Morsel.coded_value

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

.. attribute:: Morsel.key

   The name of the cookie.

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

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

.. method:: Morsel.isReservedKey(K)

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

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

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

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

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

   ``"Set-Cookie:"``.

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

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

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

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

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

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

   JavaScript.

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

.. _cookie-example:

Example

-------

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

.. doctest::

   :options: +NORMALIZE_WHITESPACE

   >>> import Cookie

   >>> C = Cookie.SimpleCookie()

   >>> C = Cookie.SerialCookie()

   >>> C = Cookie.SmartCookie()

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

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

   >>> print C # generate HTTP headers

   Set-Cookie: fig=newton

   Set-Cookie: sugar=wafer

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

   Set-Cookie: fig=newton

   Set-Cookie: sugar=wafer

   >>> 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

   >>> C = Cookie.SmartCookie()

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

   >>> print C

   Set-Cookie: chips=ahoy

   Set-Cookie: vienna=finger

   >>> C = Cookie.SmartCookie()

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

   >>> print C

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

   >>> C = Cookie.SmartCookie()

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

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

   >>> print C

   Set-Cookie: oreo=doublestuff; Path=/

   >>> C = Cookie.SmartCookie()

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

   >>> C["twix"].value

   'none for you'

   >>> C = Cookie.SimpleCookie()

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

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

   >>> C["number"].value

   '7'

   >>> C["string"].value

   'seven'

   >>> print C

   Set-Cookie: number=7

   Set-Cookie: string=seven

   >>> 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."

   >>> 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