cpython/Doc/library/cookie.rst

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: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.
**Source code:** :source:`Lib/Cookie.py`
--------------
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 and also
many current day browsers and servers have relaxed parsing rules when comes to
Cookie handling. As a result, the parsing rules used are a bit less strict.
The character set, :data:`string.ascii_letters`, :data:`string.digits` and
``!#$%&'*+-.^_`|~`` denote the set of valid characters allowed by this module
in Cookie name (as :attr:`~Morsel.key`).
.. 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* attributes.
.. 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["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.SimpleCookie()
>>> 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.SimpleCookie()
>>> C.load("chips=ahoy; vienna=finger") # load from a string (HTTP header)
>>> print C
Set-Cookie: chips=ahoy
Set-Cookie: vienna=finger
>>> C = Cookie.SimpleCookie()
>>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";')
>>> print C
Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;"
>>> C = Cookie.SimpleCookie()
>>> C["oreo"] = "doublestuff"
>>> C["oreo"]["path"] = "/"
>>> print C
Set-Cookie: oreo=doublestuff; Path=/
>>> 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
>>> # SerialCookie and SmartCookie are deprecated
>>> # using it can cause security loopholes in your code.
>>> 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