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.
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class
Cookie.BaseCookie([input])¶ This class is a dictionary-like object whose keys are strings and whose values are
Morselinstances. Note that upon setting a key to a value, the value is first converted to aMorselcontaining the key and the value.If input is given, it is passed to the
load()method.
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class
Cookie.SimpleCookie([input])¶ This class derives from
BaseCookieand overridesvalue_decode()andvalue_encode()to be the identity andstr()respectively.
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class
Cookie.SerialCookie([input])¶ This class derives from
BaseCookieand 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
SerialCookieapplies 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
20.22.1. Cookie Objects¶
-
BaseCookie.value_decode(val)¶ Return a decoded value from a string representation. Return value can be any type. This method does nothing in
BaseCookie— it exists so it can be overridden.
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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
BaseCookie— it exists so it can be overridden.In general, it should be the case that
value_encode()andvalue_decode()are inverses on the range of value_decode.
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BaseCookie.output([attrs[, header[, sep]]])¶ Return a string representation suitable to be sent as HTTP headers. attrs and header are sent to each
Morsel’soutput()method. sep is used to join the headers together, and is by default the combination'\r\n'(CRLF).Changed in version 2.5: The default separator has been changed from
'\n'to match the cookie specification.
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
expirespathcommentdomainmax-agesecureversionhttponly
The attribute
httponlyspecifies 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
httponlyattribute was added.
-
Morsel.value¶ The value of the cookie.
-
Morsel.coded_value¶ The encoded value of the cookie — this is what should be sent.
-
Morsel.key¶ The name of the cookie.
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Morsel.set(key, value, coded_value)¶ Set the key, value and coded_value attributes.
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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:".
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