| Python 3.6.5 Documentation > "http.cookiejar" — Cookie handling for HTTP clients
"http.cookiejar" — Cookie handling for HTTP clients
***************************************************
**Source code:** Lib/http/cookiejar.py
======================================================================
The "http.cookiejar" module defines classes for automatic handling of
HTTP cookies. It is useful for accessing web sites that require small
pieces of data – *cookies* – to be set on the client machine by an
HTTP response from a web server, and then returned to the server in
later HTTP requests.
Both the regular Netscape cookie protocol and the protocol defined by
**RFC 2965** are handled. RFC 2965 handling is switched off by
default. **RFC 2109** cookies are parsed as Netscape cookies and
subsequently treated either as Netscape or RFC 2965 cookies according
to the ‘policy’ in effect. Note that the great majority of cookies on
the Internet are Netscape cookies. "http.cookiejar" attempts to follow
the de-facto Netscape cookie protocol (which differs substantially
from that set out in the original Netscape specification), including
taking note of the "max-age" and "port" cookie-attributes introduced
with RFC 2965.
Note: The various named parameters found in *Set-Cookie* and *Set-
Cookie2* headers (eg. "domain" and "expires") are conventionally
referred to as *attributes*. To distinguish them from Python
attributes, the documentation for this module uses the term *cookie-
attribute* instead.
The module defines the following exception:
exception http.cookiejar.LoadError
Instances of "FileCookieJar" raise this exception on failure to
load cookies from a file. "LoadError" is a subclass of "OSError".
Changed in version 3.3: LoadError was made a subclass of "OSError"
instead of "IOError".
The following classes are provided:
class http.cookiejar.CookieJar(policy=None)
*policy* is an object implementing the "CookiePolicy" interface.
The "CookieJar" class stores HTTP cookies. It extracts cookies
from HTTP requests, and returns them in HTTP responses. "CookieJar"
instances automatically expire contained cookies when necessary.
Subclasses are also responsible for storing and retrieving cookies
from a file or database.
class http.cookiejar.FileCookieJar(filename, delayload=None, policy=None)
*policy* is an object implementing the "CookiePolicy" interface.
For the other arguments, see the documentation for the
corresponding attributes.
A "CookieJar" which can load cookies from, and perhaps save cookies
to, a file on disk. Cookies are **NOT** loaded from the named file
until either the "load()" or "revert()" method is called.
Subclasses of this class are documented in section FileCookieJar
subclasses and co-operation with web browsers.
class http.cookiejar.CookiePolicy
This class is responsible for deciding whether each cookie should
be accepted from / returned to the server.
class http.cookiejar.DefaultCookiePolicy(blocked_domains=None, allowed_domains=None, netscape=True, rfc2965=False, rfc2109_as_netscape=None, hide_cookie2=False, strict_domain=False, strict_rfc2965_unverifiable=True, strict_ns_unverifiable=False, strict_ns_domain=DefaultCookiePolicy.DomainLiberal, strict_ns_set_initial_dollar=False, strict_ns_set_path=False)
Constructor arguments should be passed as keyword arguments only.
*blocked_domains* is a sequence of domain names that we never
accept cookies from, nor return cookies to. *allowed_domains* if
not "None", this is a sequence of the only domains for which we
accept and return cookies. For all other arguments, see the
documentation for "CookiePolicy" and "DefaultCookiePolicy" objects.
"DefaultCookiePolicy" implements the standard accept / reject rules
for Netscape and RFC 2965 cookies. By default, RFC 2109 cookies
(ie. cookies received in a *Set-Cookie* header with a version
cookie-attribute of 1) are treated according to the RFC 2965 rules.
However, if RFC 2965 handling is turned off or
"rfc2109_as_netscape" is "True", RFC 2109 cookies are ‘downgraded’
by the "CookieJar" instance to Netscape cookies, by setting the
"version" attribute of the "Cookie" instance to 0.
"DefaultCookiePolicy" also provides some parameters to allow some
fine-tuning of policy.
class http.cookiejar.Cookie
This class represents Netscape, RFC 2109 and RFC 2965 cookies. It
is not expected that users of "http.cookiejar" construct their own
"Cookie" instances. Instead, if necessary, call "make_cookies()"
on a "CookieJar" instance.
See also:
Module "urllib.request"
URL opening with automatic cookie handling.
Module "http.cookies"
HTTP cookie classes, principally useful for server-side code.
The "http.cookiejar" and "http.cookies" modules do not depend on
each other.
https://curl.haxx.se/rfc/cookie_spec.html
The specification of the original Netscape cookie protocol.
Though this is still the dominant protocol, the ‘Netscape cookie
protocol’ implemented by all the major browsers (and
"http.cookiejar") only bears a passing resemblance to the one
sketched out in "cookie_spec.html".
**RFC 2109** - HTTP State Management Mechanism
Obsoleted by RFC 2965. Uses *Set-Cookie* with version=1.
**RFC 2965** - HTTP State Management Mechanism
The Netscape protocol with the bugs fixed. Uses *Set-Cookie2* in
place of *Set-Cookie*. Not widely used.
http://kristol.org/cookie/errata.html
Unfinished errata to RFC 2965.
**RFC 2964** - Use of HTTP State Management
CookieJar and FileCookieJar Objects
===================================
"CookieJar" objects support the *iterator* protocol for iterating over
contained "Cookie" objects.
"CookieJar" has the following methods:
CookieJar.add_cookie_header(request)
Add correct *Cookie* header to *request*.
If policy allows (ie. the "rfc2965" and "hide_cookie2" attributes
of the "CookieJar"’s "CookiePolicy" instance are true and false
respectively), the *Cookie2* header is also added when appropriate.
The *request* object (usually a "urllib.request..Request" instance)
must support the methods "get_full_url()", "get_host()",
"get_type()", "unverifiable()", "has_header()", "get_header()",
"header_items()", "add_unredirected_header()" and "origin_req_host"
attribute as documented by "urllib.request".
Changed in version 3.3: *request* object needs "origin_req_host"
attribute. Dependency on a deprecated method
"get_origin_req_host()" has been removed.
CookieJar.extract_cookies(response, request)
Extract cookies from HTTP *response* and store them in the
"CookieJar", where allowed by policy.
The "CookieJar" will look for allowable *Set-Cookie* and *Set-
Cookie2* headers in the *response* argument, and store cookies as
appropriate (subject to the "CookiePolicy.set_ok()" method’s
approval).
The *response* object (usually the result of a call to
"urllib.request.urlopen()", or similar) should support an "info()"
method, which returns an "email.message.Message" instance.
The *request* object (usually a "urllib.request.Request" instance)
must support the methods "get_full_url()", "get_host()",
"unverifiable()", and "origin_req_host" attribute, as documented by
"urllib.request". The request is used to set default values for
cookie-attributes as well as for checking that the cookie is
allowed to be set.
Changed in version 3.3: *request* object needs "origin_req_host"
attribute. Dependency on a deprecated method
"get_origin_req_host()" has been removed.
CookieJar.set_policy(policy)
Set the "CookiePolicy" instance to be used.
CookieJar.make_cookies(response, request)
Return sequence of "Cookie" objects extracted from *response*
object.
See the documentation for "extract_cookies()" for the interfaces
required of the *response* and *request* arguments.
CookieJar.set_cookie_if_ok(cookie, request)
Set a "Cookie" if policy says it’s OK to do so.
CookieJar.set_cookie(cookie)
Set a "Cookie", without checking with policy to see whether or not
it should be set.
CookieJar.clear([domain[, path[, name]]])
Clear some cookies.
If invoked without arguments, clear all cookies. If given a single
argument, only cookies belonging to that *domain* will be removed.
If given two arguments, cookies belonging to the specified *domain*
and URL *path* are removed. If given three arguments, then the
cookie with the specified *domain*, *path* and *name* is removed.
Raises "KeyError" if no matching cookie exists.
CookieJar.clear_session_cookies()
Discard all session cookies.
Discards all contained cookies that have a true "discard" attribute
(usually because they had either no "max-age" or "expires" cookie-
attribute, or an explicit "discard" cookie-attribute). For
interactive browsers, the end of a session usually corresponds to
closing the browser window.
Note that the "save()" method won’t save session cookies anyway,
unless you ask otherwise by passing a true *ignore_discard*
argument.
"FileCookieJar" implements the following additional methods:
FileCookieJar.save(filename=None, ignore_discard=False, ignore_expires=False)
Save cookies to a file.
This base class raises "NotImplementedError". Subclasses may leave
this method unimplemented.
*filename* is the name of file in which to save cookies. If
*filename* is not specified, "self.filename" is used (whose default
is the value passed to the constructor, if any); if "self.filename"
is "None", "ValueError" is raised.
*ignore_discard*: save even cookies set to be discarded.
*ignore_expires*: save even cookies that have expired
The file is overwritten if it already exists, thus wiping all the
cookies it contains. Saved cookies can be restored later using the
"load()" or "revert()" methods.
FileCookieJar.load(filename=None, ignore_discard=False, ignore_expires=False)
Load cookies from a file.
Old cookies are kept unless overwritten by newly loaded ones.
Arguments are as for "save()".
The named file must be in the format understood by the class, or
"LoadError" will be raised. Also, "OSError" may be raised, for
example if the file does not exist.
Changed in version 3.3: "IOError" used to be raised, it is now an
alias of "OSError".
FileCookieJar.revert(filename=None, ignore_discard=False, ignore_expires=False)
Clear all cookies and reload cookies from a saved file.
"revert()" can raise the same exceptions as "load()". If there is a
failure, the object’s state will not be altered.
"FileCookieJar" instances have the following public attributes:
FileCookieJar.filename
Filename of default file in which to keep cookies. This attribute
may be assigned to.
FileCookieJar.delayload
If true, load cookies lazily from disk. This attribute should not
be assigned to. This is only a hint, since this only affects
performance, not behaviour (unless the cookies on disk are
changing). A "CookieJar" object may ignore it. None of the
"FileCookieJar" classes included in the standard library lazily
loads cookies.
FileCookieJar subclasses and co-operation with web browsers
===========================================================
The following "CookieJar" subclasses are provided for reading and
writing.
class http.cookiejar.MozillaCookieJar(filename, delayload=None, policy=None)
A "FileCookieJar" that can load from and save cookies to disk in
the Mozilla "cookies.txt" file format (which is also used by the
Lynx and Netscape browsers).
Note: This loses information about RFC 2965 cookies, and also
about newer or non-standard cookie-attributes such as "port".
Warning: Back up your cookies before saving if you have cookies
whose loss / corruption would be inconvenient (there are some
subtleties which may lead to slight changes in the file over a
load / save round-trip).
Also note that cookies saved while Mozilla is running will get
clobbered by Mozilla.
class http.cookiejar.LWPCookieJar(filename, delayload=None, policy=None)
A "FileCookieJar" that can load from and save cookies to disk in
format compatible with the libwww-perl library’s "Set-Cookie3" file
format. This is convenient if you want to store cookies in a
human-readable file.
CookiePolicy Objects
====================
Objects implementing the "CookiePolicy" interface have the following
methods:
CookiePolicy.set_ok(cookie, request)
Return boolean value indicating whether cookie should be accepted
from server.
*cookie* is a "Cookie" instance. *request* is an object
implementing the interface defined by the documentation for
"CookieJar.extract_cookies()".
CookiePolicy.return_ok(cookie, request)
Return boolean value indicating whether cookie should be returned
to server.
*cookie* is a "Cookie" instance. *request* is an object
implementing the interface defined by the documentation for
"CookieJar.add_cookie_header()".
CookiePolicy.domain_return_ok(domain, request)
Return false if cookies should not be returned, given cookie
domain.
This method is an optimization. It removes the need for checking
every cookie with a particular domain (which might involve reading
many files). Returning true from "domain_return_ok()" and
"path_return_ok()" leaves all the work to "return_ok()".
If "domain_return_ok()" returns true for the cookie domain,
"path_return_ok()" is called for the cookie path. Otherwise,
"path_return_ok()" and "return_ok()" are never called for that
cookie domain. If "path_return_ok()" returns true, "return_ok()"
is called with the "Cookie" object itself for a full check.
Otherwise, "return_ok()" is never called for that cookie path.
Note that "domain_return_ok()" is called for every *cookie* domain,
not just for the *request* domain. For example, the function might
be called with both "".example.com"" and ""www.example.com"" if the
request domain is ""www.example.com"". The same goes for
"path_return_ok()".
The *request* argument is as documented for "return_ok()".
CookiePolicy.path_return_ok(path, request)
Return false if cookies should not be returned, given cookie path.
See the documentation for "domain_return_ok()".
In addition to implementing the methods above, implementations of the
"CookiePolicy" interface must also supply the following attributes,
indicating which protocols should be used, and how. All of these
attributes may be assigned to.
CookiePolicy.netscape
Implement Netscape protocol.
CookiePolicy.rfc2965
Implement RFC 2965 protocol.
CookiePolicy.hide_cookie2
Don’t add *Cookie2* header to requests (the presence of this header
indicates to the server that we understand RFC 2965 cookies).
The most useful way to define a "CookiePolicy" class is by subclassing
from "DefaultCookiePolicy" and overriding some or all of the methods
above. "CookiePolicy" itself may be used as a ‘null policy’ to allow
setting and receiving any and all cookies (this is unlikely to be
useful).
DefaultCookiePolicy Objects
===========================
Implements the standard rules for accepting and returning cookies.
Both RFC 2965 and Netscape cookies are covered. RFC 2965 handling is
switched off by default.
The easiest way to provide your own policy is to override this class
and call its methods in your overridden implementations before adding
your own additional checks:
import http.cookiejar
class MyCookiePolicy(http.cookiejar.DefaultCookiePolicy):
def set_ok(self, cookie, request):
if not http.cookiejar.DefaultCookiePolicy.set_ok(self, cookie, request):
return False
if i_dont_want_to_store_this_cookie(cookie):
return False
return True
In addition to the features required to implement the "CookiePolicy"
interface, this class allows you to block and allow domains from
setting and receiving cookies. There are also some strictness
switches that allow you to tighten up the rather loose Netscape
protocol rules a little bit (at the cost of blocking some benign
cookies).
A domain blacklist and whitelist is provided (both off by default).
Only domains not in the blacklist and present in the whitelist (if the
whitelist is active) participate in cookie setting and returning. Use
the *blocked_domains* constructor argument, and "blocked_domains()"
and "set_blocked_domains()" methods (and the corresponding argument
and methods for *allowed_domains*). If you set a whitelist, you can
turn it off again by setting it to "None".
Domains in block or allow lists that do not start with a dot must
equal the cookie domain to be matched. For example, ""example.com""
matches a blacklist entry of ""example.com"", but ""www.example.com""
does not. Domains that do start with a dot are matched by more
specific domains too. For example, both ""www.example.com"" and
""www.coyote.example.com"" match "".example.com"" (but ""example.com""
itself does not). IP addresses are an exception, and must match
exactly. For example, if blocked_domains contains ""192.168.1.2"" and
"".168.1.2"", 192.168.1.2 is blocked, but 193.168.1.2 is not.
"DefaultCookiePolicy" implements the following additional methods:
DefaultCookiePolicy.blocked_domains()
Return the sequence of blocked domains (as a tuple).
DefaultCookiePolicy.set_blocked_domains(blocked_domains)
Set the sequence of blocked domains.
DefaultCookiePolicy.is_blocked(domain)
Return whether *domain* is on the blacklist for setting or
receiving cookies.
DefaultCookiePolicy.allowed_domains()
Return "None", or the sequence of allowed domains (as a tuple).
DefaultCookiePolicy.set_allowed_domains(allowed_domains)
Set the sequence of allowed domains, or "None".
DefaultCookiePolicy.is_not_allowed(domain)
Return whether *domain* is not on the whitelist for setting or
receiving cookies.
"DefaultCookiePolicy" instances have the following attributes, which
are all initialised from the constructor arguments of the same name,
and which may all be assigned to.
DefaultCookiePolicy.rfc2109_as_netscape
If true, request that the "CookieJar" instance downgrade RFC 2109
cookies (ie. cookies received in a *Set-Cookie* header with a
version cookie-attribute of 1) to Netscape cookies by setting the
version attribute of the "Cookie" instance to 0. The default value
is "None", in which case RFC 2109 cookies are downgraded if and
only if RFC 2965 handling is turned off. Therefore, RFC 2109
cookies are downgraded by default.
General strictness switches:
DefaultCookiePolicy.strict_domain
Don’t allow sites to set two-component domains with country-code
top-level domains like ".co.uk", ".gov.uk", ".co.nz".etc. This is
far from perfect and isn’t guaranteed to work!
RFC 2965 protocol strictness switches:
DefaultCookiePolicy.strict_rfc2965_unverifiable
Follow RFC 2965 rules on unverifiable transactions (usually, an
unverifiable transaction is one resulting from a redirect or a
request for an image hosted on another site). If this is false,
cookies are *never* blocked on the basis of verifiability
Netscape protocol strictness switches:
DefaultCookiePolicy.strict_ns_unverifiable
Apply RFC 2965 rules on unverifiable transactions even to Netscape
cookies.
DefaultCookiePolicy.strict_ns_domain
Flags indicating how strict to be with domain-matching rules for
Netscape cookies. See below for acceptable values.
DefaultCookiePolicy.strict_ns_set_initial_dollar
Ignore cookies in Set-Cookie: headers that have names starting with
"'$'".
DefaultCookiePolicy.strict_ns_set_path
Don’t allow setting cookies whose path doesn’t path-match request
URI.
"strict_ns_domain" is a collection of flags. Its value is constructed
by or-ing together (for example,
"DomainStrictNoDots|DomainStrictNonDomain" means both flags are set).
DefaultCookiePolicy.DomainStrictNoDots
When setting cookies, the ‘host prefix’ must not contain a dot (eg.
"www.foo.bar.com" can’t set a cookie for ".bar.com", because
"www.foo" contains a dot).
DefaultCookiePolicy.DomainStrictNonDomain
Cookies that did not explicitly specify a "domain" cookie-attribute
can only be returned to a domain equal to the domain that set the
cookie (eg. "spam.example.com" won’t be returned cookies from
"example.com" that had no "domain" cookie-attribute).
DefaultCookiePolicy.DomainRFC2965Match
When setting cookies, require a full RFC 2965 domain-match.
The following attributes are provided for convenience, and are the
most useful combinations of the above flags:
DefaultCookiePolicy.DomainLiberal
Equivalent to 0 (ie. all of the above Netscape domain strictness
flags switched off).
DefaultCookiePolicy.DomainStrict
Equivalent to "DomainStrictNoDots|DomainStrictNonDomain".
Cookie Objects
==============
"Cookie" instances have Python attributes roughly corresponding to the
standard cookie-attributes specified in the various cookie standards.
The correspondence is not one-to-one, because there are complicated
rules for assigning default values, because the "max-age" and
"expires" cookie-attributes contain equivalent information, and
because RFC 2109 cookies may be ‘downgraded’ by "http.cookiejar" from
version 1 to version 0 (Netscape) cookies.
Assignment to these attributes should not be necessary other than in
rare circumstances in a "CookiePolicy" method. The class does not
enforce internal consistency, so you should know what you’re doing if
you do that.
Cookie.version
Integer or "None". Netscape cookies have "version" 0. RFC 2965 and
RFC 2109 cookies have a "version" cookie-attribute of 1. However,
note that "http.cookiejar" may ‘downgrade’ RFC 2109 cookies to
Netscape cookies, in which case "version" is 0.
Cookie.name
Cookie name (a string).
Cookie.value
Cookie value (a string), or "None".
Cookie.port
String representing a port or a set of ports (eg. ‘80’, or
‘80,8080’), or "None".
Cookie.path
Cookie path (a string, eg. "'/acme/rocket_launchers'").
Cookie.secure
"True" if cookie should only be returned over a secure connection.
Cookie.expires
Integer expiry date in seconds since epoch, or "None". See also
the "is_expired()" method.
Cookie.discard
"True" if this is a session cookie.
Cookie.comment
String comment from the server explaining the function of this
cookie, or "None".
Cookie.comment_url
URL linking to a comment from the server explaining the function of
this cookie, or "None".
Cookie.rfc2109
"True" if this cookie was received as an RFC 2109 cookie (ie. the
cookie arrived in a *Set-Cookie* header, and the value of the
Version cookie-attribute in that header was 1). This attribute is
provided because "http.cookiejar" may ‘downgrade’ RFC 2109 cookies
to Netscape cookies, in which case "version" is 0.
Cookie.port_specified
"True" if a port or set of ports was explicitly specified by the
server (in the *Set-Cookie* / *Set-Cookie2* header).
Cookie.domain_specified
"True" if a domain was explicitly specified by the server.
Cookie.domain_initial_dot
"True" if the domain explicitly specified by the server began with
a dot ("'.'").
Cookies may have additional non-standard cookie-attributes. These may
be accessed using the following methods:
Cookie.has_nonstandard_attr(name)
Return true if cookie has the named cookie-attribute.
Cookie.get_nonstandard_attr(name, default=None)
If cookie has the named cookie-attribute, return its value.
Otherwise, return *default*.
Cookie.set_nonstandard_attr(name, value)
Set the value of the named cookie-attribute.
The "Cookie" class also defines the following method:
Cookie.is_expired(now=None)
"True" if cookie has passed the time at which the server requested
it should expire. If *now* is given (in seconds since the epoch),
return whether the cookie has expired at the specified time.
Examples
========
The first example shows the most common usage of "http.cookiejar":
import http.cookiejar, urllib.request
cj = http.cookiejar.CookieJar()
opener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))
r = opener.open("http://example.com/")
This example illustrates how to open a URL using your Netscape,
Mozilla, or Lynx cookies (assumes Unix/Netscape convention for
location of the cookies file):
import os, http.cookiejar, urllib.request
cj = http.cookiejar.MozillaCookieJar()
cj.load(os.path.join(os.path.expanduser("~"), ".netscape", "cookies.txt"))
opener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))
r = opener.open("http://example.com/")
The next example illustrates the use of "DefaultCookiePolicy". Turn on
RFC 2965 cookies, be more strict about domains when setting and
returning Netscape cookies, and block some domains from setting
cookies or having them returned:
import urllib.request
from http.cookiejar import CookieJar, DefaultCookiePolicy
policy = DefaultCookiePolicy(
rfc2965=True, strict_ns_domain=Policy.DomainStrict,
blocked_domains=["ads.net", ".ads.net"])
cj = CookieJar(policy)
opener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))
r = opener.open("http://example.com/")
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