http.cookiejar —— HTTP 客户端的 Cookie 处理

源代码：Lib/http/cookiejar.py

http.cookiejar 模块定义了用于自动处理 HTTP cookie 的类。这对访问需要小段数据 —— cookies 的网站很有用，这些数据由 Web 服务器的 HTTP 响应在客户端计算机上设置，然后在以后的 HTTP 请求中返回给服务器。

常规的 Netscape Cookie 协议和 RFC 2965 定义的协议都可以处理。RFC 2965 处理默认情况下处于关闭状态。 RFC 2109 cookie 被解析为 Netscape cookie，随后根据有效的 'policy' 被视为 Netscape 或 RFC 2965 cookie。 请注意，Internet 上的大多数 cookie 是 Netscape cookie。 http.cookiejar 尝试遵循事实上的 Netscape cookie 协议（与原始 Netscape 规范中所设定的协议大不相同），包括注意 max-age 和 port RFC 2965 引入的 cookie 属性。

注解

在 Set-Cookie 和 Set-Cookie2 头中找到的各种命名参数通常指 attributes。为了不与 Python 属性相混淆，模块文档使用 cookie-attribute 代替。

此模块定义了以下异常：

  • exception http.cookiejar.LoadError
  • FileCookieJar 实例在从文件加载 cookies 出错时抛出这个异常。 LoadError 是 OSError 的一个子类。

在 3.3 版更改: LoadError 成为 OSError 的子类而不是 IOError。

提供了以下类：

  • class http.cookiejar.CookieJar(policy=None)
  • policy 是实现了 CookiePolicy 接口的一个对象。

CookieJar 类储存 HTTP cookies。它从 HTTP 请求提取 cookies，并在 HTTP 响应中返回它们。 CookieJar 实例在必要时自动处理包含 cookie 的到期情况。子类还负责储存和从文件或数据库中查找 cookies。

  • class http.cookiejar.FileCookieJar(filename, delayload=None, policy=None)
  • policy 是实现了 CookiePolicy 接口的一个对象。对于其他参数，参考相应属性的文档。

一个可以从磁盘文件中加载或保存 cookie 的 CookieJar。 cookie 不会 从指定的文件中加载，直到调用 load() 或 revert() 方法。 该类的子类文档请参阅 FileCookieJar subclasses and co-operation with web browsers。

  • class http.cookiejar.CookiePolicy
  • 此类负责确定是否应从服务器接受每个 cookie 或将其返回给服务器。
  • 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)
  • 构造器的参数应当只作为关键字参数传入。 blocked_domains 是一个域名序列，程序将绝不接受其 cookie 也绝不向其返回 cookie。 allowed_domains 如果不为 None，则也应是一个域名序列，程序将只对其中的域名接受和返回 cookie。 对于所有其他参数，请参阅 CookiePolicy 和 DefaultCookiePolicy 对象的文档。

DefaultCookiePolicy implements the standard accept / reject rules forNetscape and RFC 2965 cookies. By default, RFC 2109 cookies (ie. cookiesreceived in a Set-Cookie header with a version cookie-attribute of1) are treated according to the RFC 2965 rules. However, if RFC 2965 handlingis turned off or rfc2109_as_netscape is True, RFC 2109 cookies are'downgraded' by the CookieJar instance to Netscape cookies, bysetting the version attribute of the Cookie instance to 0.DefaultCookiePolicy also provides some parameters to allow somefine-tuning of policy.

  • class http.cookiejar.Cookie
  • This class represents Netscape, RFC 2109 and RFC 2965 cookies. It is notexpected that users of http.cookiejar construct their own Cookieinstances. Instead, if necessary, call make_cookies() on aCookieJar instance.

参见

RFC 2964 - Use of HTTP State Management

CookieJar 和 FileCookieJar 对象

CookieJar objects support the iterator protocol for iterating overcontained Cookie objects.

CookieJar has the following methods:

  • CookieJar.addcookie_header(_request)
  • Add correct Cookie header to request.

If policy allows (ie. the rfc2965 and hidecookie2 attributes ofthe CookieJar's CookiePolicy instance are true and falserespectively), 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 byurllib.request.

在 3.3 版更改: request object needs origin_req_host attribute. Dependency on adeprecated method get_origin_req_host() has been removed.

  • CookieJar.extractcookies(_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 andSet-Cookie2 headers in the response argument, and store cookiesas appropriate (subject to the CookiePolicy.set_ok() method's approval).

The response object (usually the result of a call tourllib.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 documentedby urllib.request. The request is used to set default values forcookie-attributes as well as for checking that the cookie is allowed to beset.

在 3.3 版更改: request object needs origin_req_host attribute. Dependency on adeprecated method get_origin_req_host() has been removed.

  • CookieJar.setpolicy(_policy)
  • Set the CookiePolicy instance to be used.
  • CookieJar.makecookies(_response, request)
  • Return sequence of Cookie objects extracted from response object.

See the documentation for extract_cookies() for the interfaces required ofthe response and request arguments.

  • CookieJar.setcookie_if_ok(_cookie, request)
  • Set a Cookie if policy says it's OK to do so.
  • CookieJar.setcookie(_cookie)
  • Set a Cookie, without checking with policy to see whether or not itshould 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. Ifgiven three arguments, then the cookie with the specified domain, path andname 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 endof a session usually corresponds to closing the browser window.

Note that the save() method won't save session cookies anyway, unless youask 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 thismethod unimplemented.

filename is the name of file in which to save cookies. If filename is notspecified, self.filename is used (whose default is the value passed tothe constructor, if any); if self.filename is None,ValueError is raised.

ignore_discard: save even cookies set to be discarded. ignore_expires: saveeven cookies that have expired

The file is overwritten if it already exists, thus wiping all the cookies itcontains. Saved cookies can be restored later using the load() orrevert() 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, orLoadError will be raised. Also, OSError may be raised, forexample if the file does not exist.

在 3.3 版更改: 过去触发的 IOError，现在是 OSError 的别名。

  • 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 afailure, 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 beassigned to.
  • FileCookieJar.delayload
  • If true, load cookies lazily from disk. This attribute should not be assignedto. This is only a hint, since this only affects performance, not behaviour(unless the cookies on disk are changing). A CookieJar object mayignore it. None of the FileCookieJar classes included in the standardlibrary lazily loads cookies.

FileCookieJar subclasses and co-operation with web browsers

The following CookieJar subclasses are provided for reading andwriting.

  • class http.cookiejar.MozillaCookieJar(filename, delayload=None, policy=None)
  • A FileCookieJar that can load from and save cookies to disk in theMozilla cookies.txt file format (which is also used by the Lynx and Netscapebrowsers).

注解

This loses information about RFC 2965 cookies, and also about newer ornon-standard cookie-attributes such as port.

警告

Back up your cookies before saving if you have cookies whose loss / corruptionwould be inconvenient (there are some subtleties which may lead to slightchanges in the file over a load / save round-trip).

Also note that cookies saved while Mozilla is running will get clobbered byMozilla.

  • class http.cookiejar.LWPCookieJar(filename, delayload=None, policy=None)
  • A FileCookieJar that can load from and save cookies to disk in formatcompatible with the libwww-perl library's Set-Cookie3 file format. This isconvenient if you want to store cookies in a human-readable file.

CookiePolicy 对象

Objects implementing the CookiePolicy interface have the followingmethods:

  • CookiePolicy.setok(_cookie, request)
  • Return boolean value indicating whether cookie should be accepted from server.

cookie is a Cookie instance. request is an objectimplementing the interface defined by the documentation forCookieJar.extract_cookies().

  • CookiePolicy.returnok(_cookie, request)
  • Return boolean value indicating whether cookie should be returned to server.

cookie is a Cookie instance. request is an objectimplementing the interface defined by the documentation forCookieJar.add_cookie_header().

  • CookiePolicy.domainreturn_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 cookiewith a particular domain (which might involve reading many files). Returningtrue from domain_return_ok() and path_return_ok() leaves all thework 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 cookiedomain. If path_return_ok() returns true, return_ok() is calledwith 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 justfor 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.pathreturn_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 theCookiePolicy interface must also supply the following attributes,indicating which protocols should be used, and how. All of these attributes maybe 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 headerindicates to the server that we understand RFC 2965 cookies).

The most useful way to define a CookiePolicy class is by subclassingfrom DefaultCookiePolicy and overriding some or all of the methodsabove. CookiePolicy itself may be used as a 'null policy' to allowsetting and receiving any and all cookies (this is unlikely to be useful).

DefaultCookiePolicy 对象

Implements the standard rules for accepting and returning cookies.

Both RFC 2965 and Netscape cookies are covered. RFC 2965 handling is switchedoff by default.

The easiest way to provide your own policy is to override this class and callits methods in your overridden implementations before adding your own additionalchecks:

  1. import http.cookiejar
  2. class MyCookiePolicy(http.cookiejar.DefaultCookiePolicy):
  3.     def set_ok(self, cookie, request):
  4.         if not http.cookiejar.DefaultCookiePolicy.set_ok(self, cookie, request):
  5.             return False
  6.         if i_dont_want_to_store_this_cookie(cookie):
  7.             return False
  8.         return True

In addition to the features required to implement the CookiePolicyinterface, this class allows you to block and allow domains from setting andreceiving cookies. There are also some strictness switches that allow you totighten up the rather loose Netscape protocol rules a little bit (at the cost ofblocking some benign cookies).

A domain blacklist and whitelist is provided (both off by default). Only domainsnot 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() andset_blocked_domains() methods (and the corresponding argument and methodsfor _allowed_domains). If you set a whitelist, you can turn it off again bysetting it to None.

Domains in block or allow lists that do not start with a dot must equal thecookie domain to be matched. For example, "example.com" matches a blacklistentry of "example.com", but "www.example.com" does not. Domains that dostart 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, andmust 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.setblocked_domains(_blocked_domains)
  • Set the sequence of blocked domains.
  • DefaultCookiePolicy.isblocked(_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.setallowed_domains(_allowed_domains)
  • Set the sequence of allowed domains, or None.
  • DefaultCookiePolicy.isnot_allowed(_domain)
  • Return whether domain is not on the whitelist for setting or receivingcookies.

DefaultCookiePolicy instances have the following attributes, which areall initialised from the constructor arguments of the same name, and which mayall 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 versioncookie-attribute of 1) to Netscape cookies by setting the version attribute ofthe Cookie instance to 0. The default value is None, in whichcase RFC 2109 cookies are downgraded if and only if RFC 2965 handling is turnedoff. 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-leveldomains like .co.uk, .gov.uk, .co.nz.etc. This is far from perfectand isn't guaranteed to work!

RFC 2965 protocol strictness switches:

  • DefaultCookiePolicy.strict_rfc2965_unverifiable
  • Follow RFC 2965 rules on unverifiable transactions (usually, an unverifiabletransaction is one resulting from a redirect or a request for an image hosted onanother site). If this is false, cookies are never blocked on the basis ofverifiability

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 Netscapecookies. 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 byor-ing together (for example, DomainStrictNoDots|DomainStrictNonDomain meansboth 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.foocontains a dot).
  • DefaultCookiePolicy.DomainStrictNonDomain
  • Cookies that did not explicitly specify a domain cookie-attribute can onlybe 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 nodomain 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 usefulcombinations of the above flags:

  • DefaultCookiePolicy.DomainLiberal
  • Equivalent to 0 (ie. all of the above Netscape domain strictness flags switchedoff).
  • DefaultCookiePolicy.DomainStrict
  • Equivalent to DomainStrictNoDots|DomainStrictNonDomain.

Cookie 对象

Cookie instances have Python attributes roughly corresponding to thestandard cookie-attributes specified in the various cookie standards. Thecorrespondence is not one-to-one, because there are complicated rules forassigning default values, because the max-age and expirescookie-attributes contain equivalent information, and because RFC 2109 cookiesmay be 'downgraded' by http.cookiejar from version 1 to version 0 (Netscape)cookies.

Assignment to these attributes should not be necessary other than in rarecircumstances in a CookiePolicy method. The class does not enforceinternal 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 andRFC 2109 cookies have a version cookie-attribute of 1. However, note thathttp.cookiejar may 'downgrade' RFC 2109 cookies to Netscape cookies, in whichcase 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'), orNone.
  • 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 theis_expired() method.
  • Cookie.discard
  • True if this is a session cookie.
  • Cookie.comment
  • String comment from the server explaining the function of this cookie, orNone.
  • 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 cookiearrived in a Set-Cookie header, and the value of the Versioncookie-attribute in that header was 1). This attribute is provided becausehttp.cookiejar may 'downgrade' RFC 2109 cookies to Netscape cookies, inwhich case version is 0.
  • Cookie.port_specified
  • True if a port or set of ports was explicitly specified by the server (in theSet-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 beaccessed using the following methods:

  • Cookie.hasnonstandard_attr(_name)
  • Return True if cookie has the named cookie-attribute.
  • Cookie.getnonstandard_attr(_name, default=None)
  • If cookie has the named cookie-attribute, return its value. Otherwise, returndefault.
  • Cookie.setnonstandard_attr(_name, value)
  • Set the value of the named cookie-attribute.

The Cookie class also defines the following method:

  • Cookie.isexpired(_now=None)
  • True if cookie has passed the time at which the server requested it shouldexpire. If now is given (in seconds since the epoch), return whether thecookie has expired at the specified time.

例子

The first example shows the most common usage of http.cookiejar:

  1. import http.cookiejar, urllib.request
  2. cj = http.cookiejar.CookieJar()
  3. opener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))
  4. r = opener.open("http://example.com/")

This example illustrates how to open a URL using your Netscape, Mozilla, or Lynxcookies (assumes Unix/Netscape convention for location of the cookies file):

  1. import os, http.cookiejar, urllib.request
  2. cj = http.cookiejar.MozillaCookieJar()
  3. cj.load(os.path.join(os.path.expanduser("~"), ".netscape", "cookies.txt"))
  4. opener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))
  5. r = opener.open("http://example.com/")

The next example illustrates the use of DefaultCookiePolicy. Turn onRFC 2965 cookies, be more strict about domains when setting and returningNetscape cookies, and block some domains from setting cookies or having themreturned:

  1. import urllib.request
  2. from http.cookiejar import CookieJar, DefaultCookiePolicy
  3. policy = DefaultCookiePolicy(
  4.     rfc2965=True, strict_ns_domain=Policy.DomainStrict,
  5.     blocked_domains=["ads.net", ".ads.net"])
  6. cj = CookieJar(policy)
  7. opener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))
  8. r = opener.open("http://example.com/")