18.22 cookielib -- Cookie handling for HTTP clients

18.22 `cookielib` -- Cookie handling for HTTP clients

New in version 2.4.

The cookielib 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. cookielib 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 LoadError: Instances of FileCookieJar raise this exception on failure to load cookies from a file. Note: For backwards-compatibility with Python 2.4 (which raised an IOError), LoadError is a subclass of IOError.

The following classes are provided:

class 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 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 18.22.2.

class CookiePolicy( ): This class is responsible for deciding whether each cookie should be accepted from / returned to the server.

class 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 Cookie( ): This class represents Netscape, RFC 2109 and RFC 2965 cookies. It is not expected that users of cookielib construct their own Cookie instances. Instead, if necessary, call make_cookies() on a CookieJar instance.