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20.22. Cookie — HTTP state management
Note
The Cookie
module has been renamed to http.cookies
in Python 3. The 2to3 tool will automatically adapt imports when converting your sources to Python 3.
Source code: Lib/Cookie.py
The 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, string.ascii_letters
, string.digits
and !#$%&'*+-.^_`|~
denote the set of valid characters allowed by this module in Cookie name (as key
).
Note
On encountering an invalid cookie, CookieError
is raised, so if your cookie data comes from a browser you should always prepare for invalid data and catch CookieError
on parsing.
- exception
Cookie.
CookieError
-
Exception failing because of RFC 2109 invalidity: incorrect attributes, incorrect Set-Cookie header, etc.
- class
Cookie.
BaseCookie
( [ input ] ) -
This class is a dictionary-like object whose keys are strings and whose values are
Morsel
instances. Note that upon setting a key to a value, the value is first converted to aMorsel
containing the key and the value.If input is given, it is passed to the
load()
method.
- class
Cookie.
SimpleCookie
( [ input ] ) -
This class derives from
BaseCookie
and overridesvalue_decode()
andvalue_encode()
to be the identity andstr()
respectively.
- class
Cookie.
SerialCookie
( [ input ] ) -
This class derives from
BaseCookie
and overridesvalue_decode()
andvalue_encode()
to be thepickle.loads()
andpickle.dumps()
.Deprecated since version 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
Cookie.
SmartCookie
( [ input ] ) -
This class derives from
BaseCookie
. It overridesvalue_decode()
to bepickle.loads()
if it is a valid pickle, and otherwise the value itself. It overridesvalue_encode()
to bepickle.dumps()
unless it is a string, in which case it returns the value itself.Deprecated since version 2.3: The same security warning from
SerialCookie
applies here.
A further security note is warranted. For backwards compatibility, the Cookie
module exports a class named Cookie
which is just an alias for SmartCookie
. This is probably a mistake and will likely be removed in a future version. You should not use the Cookie
class in your applications, for the same reason why you should not use the SerialCookie
class.
See also
20.22.2. Morsel Objects
- class
Cookie.
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
httponly
specifies that the cookie is only transferred 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.
New in version 2.6: The
httponly
attribute was added.
Morsel.
isReservedKey
( K )-
Whether K is a member of the set of keys of a
Morsel
.
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:"
.
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
output()
.
Morsel.
OutputString
( [ attrs ] )-
Return a string representing the Morsel, without any surrounding HTTP or JavaScript.
The meaning for attrs is the same as in
output()
.
20.22.3. Example
The following example demonstrates how to use the Cookie
module.
>>> 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