1:mod:`Cookie` --- HTTP state management
2=======================================
3
4.. module:: Cookie
5   :synopsis: Support for HTTP state management (cookies).
6.. moduleauthor:: Timothy O'Malley <[email protected]>
7.. sectionauthor:: Moshe Zadka <[email protected]>
8
9.. note::
10   The :mod:`Cookie` module has been renamed to :mod:`http.cookies` in Python
11   3.  The :term:`2to3` tool will automatically adapt imports when converting
12   your sources to Python 3.
13
14**Source code:** :source:`Lib/Cookie.py`
15
16--------------
17
18The :mod:`Cookie` module defines classes for abstracting the concept of
19cookies, an HTTP state management mechanism. It supports both simple string-only
20cookies, and provides an abstraction for having any serializable data-type as
21cookie value.
22
23The module formerly strictly applied the parsing rules described in the
24:rfc:`2109` and :rfc:`2068` specifications.  It has since been discovered that
25MSIE 3.0x doesn't follow the character rules outlined in those specs and also
26many current day browsers and servers have relaxed parsing rules when comes to
27Cookie handling.  As a result, the parsing rules used are a bit less strict.
28
29The character set, :data:`string.ascii_letters`, :data:`string.digits` and
30``!#$%&'*+-.^_`|~`` denote the set of valid characters allowed by this module
31in Cookie name (as :attr:`~Morsel.key`).
32
33
34.. note::
35
36   On encountering an invalid cookie, :exc:`CookieError` is raised, so if your
37   cookie data comes from a browser you should always prepare for invalid data
38   and catch :exc:`CookieError` on parsing.
39
40
41.. exception:: CookieError
42
43   Exception failing because of :rfc:`2109` invalidity: incorrect attributes,
44   incorrect :mailheader:`Set-Cookie` header, etc.
45
46
47.. class:: BaseCookie([input])
48
49   This class is a dictionary-like object whose keys are strings and whose values
50   are :class:`Morsel` instances. Note that upon setting a key to a value, the
51   value is first converted to a :class:`Morsel` containing the key and the value.
52
53   If *input* is given, it is passed to the :meth:`load` method.
54
55
56.. class:: SimpleCookie([input])
57
58   This class derives from :class:`BaseCookie` and overrides :meth:`value_decode`
59   and :meth:`value_encode` to be the identity and :func:`str` respectively.
60
61
62.. class:: SerialCookie([input])
63
64   This class derives from :class:`BaseCookie` and overrides :meth:`value_decode`
65   and :meth:`value_encode` to be the :func:`pickle.loads` and
66   :func:`pickle.dumps`.
67
68   .. deprecated:: 2.3
69      Reading pickled values from untrusted cookie data is a huge security hole, as
70      pickle strings can be crafted to cause arbitrary code to execute on your server.
71      It is supported for backwards compatibility only, and may eventually go away.
72
73
74.. class:: SmartCookie([input])
75
76   This class derives from :class:`BaseCookie`. It overrides :meth:`value_decode`
77   to be :func:`pickle.loads` if it is a valid pickle, and otherwise the value
78   itself. It overrides :meth:`value_encode` to be :func:`pickle.dumps` unless it
79   is a string, in which case it returns the value itself.
80
81   .. deprecated:: 2.3
82      The same security warning from :class:`SerialCookie` applies here.
83
84A further security note is warranted.  For backwards compatibility, the
85:mod:`Cookie` module exports a class named :class:`~Cookie.Cookie` which is
86just an alias for :class:`SmartCookie`.  This is probably a mistake and will
87likely be removed in a future version.  You should not use the
88:class:`~Cookie.Cookie` class in your applications, for the same reason why
89you should not use the :class:`SerialCookie` class.
90
91
92.. seealso::
93
94   Module :mod:`cookielib`
95      HTTP cookie handling for web *clients*.  The :mod:`cookielib` and :mod:`Cookie`
96      modules do not depend on each other.
97
98   :rfc:`2109` - HTTP State Management Mechanism
99      This is the state management specification implemented by this module.
100
101
102.. _cookie-objects:
103
104Cookie Objects
105--------------
106
107
108.. method:: BaseCookie.value_decode(val)
109
110   Return a decoded value from a string representation. Return value can be any
111   type. This method does nothing in :class:`BaseCookie` --- it exists so it can be
112   overridden.
113
114
115.. method:: BaseCookie.value_encode(val)
116
117   Return an encoded value. *val* can be any type, but return value must be a
118   string. This method does nothing in :class:`BaseCookie` --- it exists so it can
119   be overridden.
120
121   In general, it should be the case that :meth:`value_encode` and
122   :meth:`value_decode` are inverses on the range of *value_decode*.
123
124
125.. method:: BaseCookie.output([attrs[, header[, sep]]])
126
127   Return a string representation suitable to be sent as HTTP headers. *attrs* and
128   *header* are sent to each :class:`Morsel`'s :meth:`output` method. *sep* is used
129   to join the headers together, and is by default the combination ``'\r\n'``
130   (CRLF).
131
132   .. versionchanged:: 2.5
133      The default separator has been changed from ``'\n'`` to match the cookie
134      specification.
135
136
137.. method:: BaseCookie.js_output([attrs])
138
139   Return an embeddable JavaScript snippet, which, if run on a browser which
140   supports JavaScript, will act the same as if the HTTP headers was sent.
141
142   The meaning for *attrs* is the same as in :meth:`output`.
143
144
145.. method:: BaseCookie.load(rawdata)
146
147   If *rawdata* is a string, parse it as an ``HTTP_COOKIE`` and add the values
148   found there as :class:`Morsel`\ s. If it is a dictionary, it is equivalent to::
149
150      for k, v in rawdata.items():
151          cookie[k] = v
152
153
154.. _morsel-objects:
155
156Morsel Objects
157--------------
158
159
160.. class:: Morsel
161
162   Abstract a key/value pair, which has some :rfc:`2109` attributes.
163
164   Morsels are dictionary-like objects, whose set of keys is constant --- the valid
165   :rfc:`2109` attributes, which are
166
167   * ``expires``
168   * ``path``
169   * ``comment``
170   * ``domain``
171   * ``max-age``
172   * ``secure``
173   * ``version``
174   * ``httponly``
175
176   The attribute :attr:`httponly` specifies that the cookie is only transferred
177   in HTTP requests, and is not accessible through JavaScript. This is intended
178   to mitigate some forms of cross-site scripting.
179
180   The keys are case-insensitive.
181
182   .. versionadded:: 2.6
183      The :attr:`httponly` attribute was added.
184
185
186.. attribute:: Morsel.value
187
188   The value of the cookie.
189
190
191.. attribute:: Morsel.coded_value
192
193   The encoded value of the cookie --- this is what should be sent.
194
195
196.. attribute:: Morsel.key
197
198   The name of the cookie.
199
200
201.. method:: Morsel.set(key, value, coded_value)
202
203   Set the *key*, *value* and *coded_value* attributes.
204
205
206.. method:: Morsel.isReservedKey(K)
207
208   Whether *K* is a member of the set of keys of a :class:`Morsel`.
209
210
211.. method:: Morsel.output([attrs[, header]])
212
213   Return a string representation of the Morsel, suitable to be sent as an HTTP
214   header. By default, all the attributes are included, unless *attrs* is given, in
215   which case it should be a list of attributes to use. *header* is by default
216   ``"Set-Cookie:"``.
217
218
219.. method:: Morsel.js_output([attrs])
220
221   Return an embeddable JavaScript snippet, which, if run on a browser which
222   supports JavaScript, will act the same as if the HTTP header was sent.
223
224   The meaning for *attrs* is the same as in :meth:`output`.
225
226
227.. method:: Morsel.OutputString([attrs])
228
229   Return a string representing the Morsel, without any surrounding HTTP or
230   JavaScript.
231
232   The meaning for *attrs* is the same as in :meth:`output`.
233
234
235.. _cookie-example:
236
237Example
238-------
239
240The following example demonstrates how to use the :mod:`Cookie` module.
241
242.. doctest::
243   :options: +NORMALIZE_WHITESPACE
244
245   >>> import Cookie
246   >>> C = Cookie.SimpleCookie()
247   >>> C["fig"] = "newton"
248   >>> C["sugar"] = "wafer"
249   >>> print C # generate HTTP headers
250   Set-Cookie: fig=newton
251   Set-Cookie: sugar=wafer
252   >>> print C.output() # same thing
253   Set-Cookie: fig=newton
254   Set-Cookie: sugar=wafer
255   >>> C = Cookie.SimpleCookie()
256   >>> C["rocky"] = "road"
257   >>> C["rocky"]["path"] = "/cookie"
258   >>> print C.output(header="Cookie:")
259   Cookie: rocky=road; Path=/cookie
260   >>> print C.output(attrs=[], header="Cookie:")
261   Cookie: rocky=road
262   >>> C = Cookie.SimpleCookie()
263   >>> C.load("chips=ahoy; vienna=finger") # load from a string (HTTP header)
264   >>> print C
265   Set-Cookie: chips=ahoy
266   Set-Cookie: vienna=finger
267   >>> C = Cookie.SimpleCookie()
268   >>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";')
269   >>> print C
270   Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;"
271   >>> C = Cookie.SimpleCookie()
272   >>> C["oreo"] = "doublestuff"
273   >>> C["oreo"]["path"] = "/"
274   >>> print C
275   Set-Cookie: oreo=doublestuff; Path=/
276   >>> C["twix"] = "none for you"
277   >>> C["twix"].value
278   'none for you'
279   >>> C = Cookie.SimpleCookie()
280   >>> C["number"] = 7 # equivalent to C["number"] = str(7)
281   >>> C["string"] = "seven"
282   >>> C["number"].value
283   '7'
284   >>> C["string"].value
285   'seven'
286   >>> print C
287   Set-Cookie: number=7
288   Set-Cookie: string=seven
289   >>> # SerialCookie and SmartCookie are deprecated
290   >>> # using it can cause security loopholes in your code.
291   >>> C = Cookie.SerialCookie()
292   >>> C["number"] = 7
293   >>> C["string"] = "seven"
294   >>> C["number"].value
295   7
296   >>> C["string"].value
297   'seven'
298   >>> print C
299   Set-Cookie: number="I7\012."
300   Set-Cookie: string="S'seven'\012p1\012."
301   >>> C = Cookie.SmartCookie()
302   >>> C["number"] = 7
303   >>> C["string"] = "seven"
304   >>> C["number"].value
305   7
306   >>> C["string"].value
307   'seven'
308   >>> print C
309   Set-Cookie: number="I7\012."
310   Set-Cookie: string=seven
311
312