mirror of https://github.com/python/cpython
568 lines
21 KiB
ReStructuredText
568 lines
21 KiB
ReStructuredText
:mod:`nntplib` --- NNTP protocol client
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=======================================
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.. module:: nntplib
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:synopsis: NNTP protocol client (requires sockets).
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**Source code:** :source:`Lib/nntplib.py`
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.. index::
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pair: NNTP; protocol
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single: Network News Transfer Protocol
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--------------
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This module defines the class :class:`NNTP` which implements the client side of
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the Network News Transfer Protocol. It can be used to implement a news reader
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or poster, or automated news processors. It is compatible with :rfc:`3977`
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as well as the older :rfc:`977` and :rfc:`2980`.
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Here are two small examples of how it can be used. To list some statistics
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about a newsgroup and print the subjects of the last 10 articles::
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>>> s = nntplib.NNTP('news.gmane.org')
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>>> resp, count, first, last, name = s.group('gmane.comp.python.committers')
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>>> print('Group', name, 'has', count, 'articles, range', first, 'to', last)
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Group gmane.comp.python.committers has 1096 articles, range 1 to 1096
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>>> resp, overviews = s.over((last - 9, last))
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>>> for id, over in overviews:
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... print(id, nntplib.decode_header(over['subject']))
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...
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1087 Re: Commit privileges for Łukasz Langa
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1088 Re: 3.2 alpha 2 freeze
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1089 Re: 3.2 alpha 2 freeze
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1090 Re: Commit privileges for Łukasz Langa
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1091 Re: Commit privileges for Łukasz Langa
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1092 Updated ssh key
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1093 Re: Updated ssh key
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1094 Re: Updated ssh key
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1095 Hello fellow committers!
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1096 Re: Hello fellow committers!
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>>> s.quit()
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'205 Bye!'
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To post an article from a binary file (this assumes that the article has valid
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headers, and that you have right to post on the particular newsgroup)::
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>>> s = nntplib.NNTP('news.gmane.org')
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>>> f = open('article.txt', 'rb')
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>>> s.post(f)
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'240 Article posted successfully.'
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>>> s.quit()
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'205 Bye!'
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The module itself defines the following classes:
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.. class:: NNTP(host, port=119, user=None, password=None, readermode=None, usenetrc=False, [timeout])
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Return a new :class:`NNTP` object, representing a connection
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to the NNTP server running on host *host*, listening at port *port*.
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An optional *timeout* can be specified for the socket connection.
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If the optional *user* and *password* are provided, or if suitable
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credentials are present in :file:`/.netrc` and the optional flag *usenetrc*
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is true, the ``AUTHINFO USER`` and ``AUTHINFO PASS`` commands are used
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to identify and authenticate the user to the server. If the optional
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flag *readermode* is true, then a ``mode reader`` command is sent before
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authentication is performed. Reader mode is sometimes necessary if you are
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connecting to an NNTP server on the local machine and intend to call
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reader-specific commands, such as ``group``. If you get unexpected
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:exc:`NNTPPermanentError`\ s, you might need to set *readermode*.
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The :class:`NNTP` class supports the :keyword:`with` statement to
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unconditionally consume :exc:`OSError` exceptions and to close the NNTP
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connection when done, e.g.:
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>>> from nntplib import NNTP
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>>> with NNTP('news.gmane.org') as n:
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... n.group('gmane.comp.python.committers')
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... # doctest: +SKIP
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('211 1755 1 1755 gmane.comp.python.committers', 1755, 1, 1755, 'gmane.comp.python.committers')
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>>>
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.. versionchanged:: 3.2
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*usenetrc* is now ``False`` by default.
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.. versionchanged:: 3.3
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Support for the :keyword:`with` statement was added.
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.. class:: NNTP_SSL(host, port=563, user=None, password=None, ssl_context=None, readermode=None, usenetrc=False, [timeout])
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Return a new :class:`NNTP_SSL` object, representing an encrypted
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connection to the NNTP server running on host *host*, listening at
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port *port*. :class:`NNTP_SSL` objects have the same methods as
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:class:`NNTP` objects. If *port* is omitted, port 563 (NNTPS) is used.
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*ssl_context* is also optional, and is a :class:`~ssl.SSLContext` object.
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Please read :ref:`ssl-security` for best practices.
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All other parameters behave the same as for :class:`NNTP`.
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Note that SSL-on-563 is discouraged per :rfc:`4642`, in favor of
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STARTTLS as described below. However, some servers only support the
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former.
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.. versionadded:: 3.2
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.. versionchanged:: 3.4
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The class now supports hostname check with
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:attr:`ssl.SSLContext.check_hostname` and *Server Name Indication* (see
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:data:`ssl.HAS_SNI`).
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.. exception:: NNTPError
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Derived from the standard exception :exc:`Exception`, this is the base
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class for all exceptions raised by the :mod:`nntplib` module. Instances
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of this class have the following attribute:
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.. attribute:: response
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The response of the server if available, as a :class:`str` object.
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.. exception:: NNTPReplyError
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Exception raised when an unexpected reply is received from the server.
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.. exception:: NNTPTemporaryError
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Exception raised when a response code in the range 400--499 is received.
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.. exception:: NNTPPermanentError
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Exception raised when a response code in the range 500--599 is received.
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.. exception:: NNTPProtocolError
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Exception raised when a reply is received from the server that does not begin
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with a digit in the range 1--5.
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.. exception:: NNTPDataError
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Exception raised when there is some error in the response data.
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.. _nntp-objects:
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NNTP Objects
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------------
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When connected, :class:`NNTP` and :class:`NNTP_SSL` objects support the
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following methods and attributes.
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Attributes
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^^^^^^^^^^
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.. attribute:: NNTP.nntp_version
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An integer representing the version of the NNTP protocol supported by the
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server. In practice, this should be ``2`` for servers advertising
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:rfc:`3977` compliance and ``1`` for others.
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.. versionadded:: 3.2
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.. attribute:: NNTP.nntp_implementation
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A string describing the software name and version of the NNTP server,
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or :const:`None` if not advertised by the server.
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.. versionadded:: 3.2
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Methods
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^^^^^^^
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The *response* that is returned as the first item in the return tuple of almost
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all methods is the server's response: a string beginning with a three-digit
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code. If the server's response indicates an error, the method raises one of
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the above exceptions.
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Many of the following methods take an optional keyword-only argument *file*.
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When the *file* argument is supplied, it must be either a :term:`file object`
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opened for binary writing, or the name of an on-disk file to be written to.
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The method will then write any data returned by the server (except for the
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response line and the terminating dot) to the file; any list of lines,
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tuples or objects that the method normally returns will be empty.
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.. versionchanged:: 3.2
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Many of the following methods have been reworked and fixed, which makes
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them incompatible with their 3.1 counterparts.
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.. method:: NNTP.quit()
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Send a ``QUIT`` command and close the connection. Once this method has been
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called, no other methods of the NNTP object should be called.
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.. method:: NNTP.getwelcome()
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Return the welcome message sent by the server in reply to the initial
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connection. (This message sometimes contains disclaimers or help information
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that may be relevant to the user.)
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.. method:: NNTP.getcapabilities()
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Return the :rfc:`3977` capabilities advertised by the server, as a
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:class:`dict` instance mapping capability names to (possibly empty) lists
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of values. On legacy servers which don't understand the ``CAPABILITIES``
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command, an empty dictionary is returned instead.
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>>> s = NNTP('news.gmane.org')
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>>> 'POST' in s.getcapabilities()
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True
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.. versionadded:: 3.2
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.. method:: NNTP.login(user=None, password=None, usenetrc=True)
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Send ``AUTHINFO`` commands with the user name and password. If *user*
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and *password* are None and *usenetrc* is true, credentials from
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``~/.netrc`` will be used if possible.
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Unless intentionally delayed, login is normally performed during the
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:class:`NNTP` object initialization and separately calling this function
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is unnecessary. To force authentication to be delayed, you must not set
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*user* or *password* when creating the object, and must set *usenetrc* to
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False.
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.. versionadded:: 3.2
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.. method:: NNTP.starttls(ssl_context=None)
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Send a ``STARTTLS`` command. This will enable encryption on the NNTP
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connection. The *ssl_context* argument is optional and should be a
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:class:`ssl.SSLContext` object. Please read :ref:`ssl-security` for best
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practices.
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Note that this may not be done after authentication information has
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been transmitted, and authentication occurs by default if possible during a
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:class:`NNTP` object initialization. See :meth:`NNTP.login` for information
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on suppressing this behavior.
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.. versionadded:: 3.2
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.. versionchanged:: 3.4
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The method now supports hostname check with
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:attr:`ssl.SSLContext.check_hostname` and *Server Name Indication* (see
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:data:`ssl.HAS_SNI`).
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.. method:: NNTP.newgroups(date, *, file=None)
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Send a ``NEWGROUPS`` command. The *date* argument should be a
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:class:`datetime.date` or :class:`datetime.datetime` object.
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Return a pair ``(response, groups)`` where *groups* is a list representing
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the groups that are new since the given *date*. If *file* is supplied,
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though, then *groups* will be empty.
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>>> from datetime import date, timedelta
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>>> resp, groups = s.newgroups(date.today() - timedelta(days=3))
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>>> len(groups) # doctest: +SKIP
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85
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>>> groups[0] # doctest: +SKIP
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GroupInfo(group='gmane.network.tor.devel', last='4', first='1', flag='m')
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.. method:: NNTP.newnews(group, date, *, file=None)
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Send a ``NEWNEWS`` command. Here, *group* is a group name or ``'*'``, and
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*date* has the same meaning as for :meth:`newgroups`. Return a pair
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``(response, articles)`` where *articles* is a list of message ids.
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This command is frequently disabled by NNTP server administrators.
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.. method:: NNTP.list(group_pattern=None, *, file=None)
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Send a ``LIST`` or ``LIST ACTIVE`` command. Return a pair
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``(response, list)`` where *list* is a list of tuples representing all
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the groups available from this NNTP server, optionally matching the
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pattern string *group_pattern*. Each tuple has the form
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``(group, last, first, flag)``, where *group* is a group name, *last*
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and *first* are the last and first article numbers, and *flag* usually
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takes one of these values:
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* ``y``: Local postings and articles from peers are allowed.
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* ``m``: The group is moderated and all postings must be approved.
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* ``n``: No local postings are allowed, only articles from peers.
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* ``j``: Articles from peers are filed in the junk group instead.
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* ``x``: No local postings, and articles from peers are ignored.
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* ``=foo.bar``: Articles are filed in the ``foo.bar`` group instead.
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If *flag* has another value, then the status of the newsgroup should be
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considered unknown.
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This command can return very large results, especially if *group_pattern*
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is not specified. It is best to cache the results offline unless you
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really need to refresh them.
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.. versionchanged:: 3.2
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*group_pattern* was added.
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.. method:: NNTP.descriptions(grouppattern)
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Send a ``LIST NEWSGROUPS`` command, where *grouppattern* is a wildmat string as
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specified in :rfc:`3977` (it's essentially the same as DOS or UNIX shell wildcard
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strings). Return a pair ``(response, descriptions)``, where *descriptions*
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is a dictionary mapping group names to textual descriptions.
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>>> resp, descs = s.descriptions('gmane.comp.python.*')
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>>> len(descs) # doctest: +SKIP
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295
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>>> descs.popitem() # doctest: +SKIP
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('gmane.comp.python.bio.general', 'BioPython discussion list (Moderated)')
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.. method:: NNTP.description(group)
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Get a description for a single group *group*. If more than one group matches
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(if 'group' is a real wildmat string), return the first match. If no group
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matches, return an empty string.
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This elides the response code from the server. If the response code is needed,
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use :meth:`descriptions`.
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.. method:: NNTP.group(name)
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Send a ``GROUP`` command, where *name* is the group name. The group is
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selected as the current group, if it exists. Return a tuple
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``(response, count, first, last, name)`` where *count* is the (estimated)
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number of articles in the group, *first* is the first article number in
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the group, *last* is the last article number in the group, and *name*
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is the group name.
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.. method:: NNTP.over(message_spec, *, file=None)
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Send an ``OVER`` command, or an ``XOVER`` command on legacy servers.
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*message_spec* can be either a string representing a message id, or
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a ``(first, last)`` tuple of numbers indicating a range of articles in
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the current group, or a ``(first, None)`` tuple indicating a range of
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articles starting from *first* to the last article in the current group,
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or :const:`None` to select the current article in the current group.
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Return a pair ``(response, overviews)``. *overviews* is a list of
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``(article_number, overview)`` tuples, one for each article selected
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by *message_spec*. Each *overview* is a dictionary with the same number
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of items, but this number depends on the server. These items are either
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message headers (the key is then the lower-cased header name) or metadata
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items (the key is then the metadata name prepended with ``":"``). The
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following items are guaranteed to be present by the NNTP specification:
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* the ``subject``, ``from``, ``date``, ``message-id`` and ``references``
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headers
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* the ``:bytes`` metadata: the number of bytes in the entire raw article
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(including headers and body)
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* the ``:lines`` metadata: the number of lines in the article body
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The value of each item is either a string, or :const:`None` if not present.
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It is advisable to use the :func:`decode_header` function on header
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values when they may contain non-ASCII characters::
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>>> _, _, first, last, _ = s.group('gmane.comp.python.devel')
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>>> resp, overviews = s.over((last, last))
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>>> art_num, over = overviews[0]
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>>> art_num
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117216
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>>> list(over.keys())
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['xref', 'from', ':lines', ':bytes', 'references', 'date', 'message-id', 'subject']
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>>> over['from']
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'=?UTF-8?B?Ik1hcnRpbiB2LiBMw7Z3aXMi?= <martin@v.loewis.de>'
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>>> nntplib.decode_header(over['from'])
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'"Martin v. Löwis" <martin@v.loewis.de>'
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.. versionadded:: 3.2
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.. method:: NNTP.help(*, file=None)
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Send a ``HELP`` command. Return a pair ``(response, list)`` where *list* is a
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list of help strings.
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.. method:: NNTP.stat(message_spec=None)
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Send a ``STAT`` command, where *message_spec* is either a message id
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(enclosed in ``'<'`` and ``'>'``) or an article number in the current group.
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If *message_spec* is omitted or :const:`None`, the current article in the
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current group is considered. Return a triple ``(response, number, id)``
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where *number* is the article number and *id* is the message id.
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>>> _, _, first, last, _ = s.group('gmane.comp.python.devel')
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>>> resp, number, message_id = s.stat(first)
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>>> number, message_id
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(9099, '<20030112190404.GE29873@epoch.metaslash.com>')
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.. method:: NNTP.next()
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Send a ``NEXT`` command. Return as for :meth:`.stat`.
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.. method:: NNTP.last()
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Send a ``LAST`` command. Return as for :meth:`.stat`.
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.. method:: NNTP.article(message_spec=None, *, file=None)
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Send an ``ARTICLE`` command, where *message_spec* has the same meaning as
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for :meth:`.stat`. Return a tuple ``(response, info)`` where *info*
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is a :class:`~collections.namedtuple` with three attributes *number*,
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*message_id* and *lines* (in that order). *number* is the article number
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in the group (or 0 if the information is not available), *message_id* the
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message id as a string, and *lines* a list of lines (without terminating
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newlines) comprising the raw message including headers and body.
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>>> resp, info = s.article('<20030112190404.GE29873@epoch.metaslash.com>')
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>>> info.number
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0
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>>> info.message_id
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'<20030112190404.GE29873@epoch.metaslash.com>'
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>>> len(info.lines)
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65
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>>> info.lines[0]
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b'Path: main.gmane.org!not-for-mail'
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>>> info.lines[1]
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b'From: Neal Norwitz <neal@metaslash.com>'
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>>> info.lines[-3:]
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[b'There is a patch for 2.3 as well as 2.2.', b'', b'Neal']
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.. method:: NNTP.head(message_spec=None, *, file=None)
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Same as :meth:`article()`, but sends a ``HEAD`` command. The *lines*
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returned (or written to *file*) will only contain the message headers, not
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the body.
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.. method:: NNTP.body(message_spec=None, *, file=None)
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Same as :meth:`article()`, but sends a ``BODY`` command. The *lines*
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returned (or written to *file*) will only contain the message body, not the
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headers.
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.. method:: NNTP.post(data)
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Post an article using the ``POST`` command. The *data* argument is either
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a :term:`file object` opened for binary reading, or any iterable of bytes
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objects (representing raw lines of the article to be posted). It should
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represent a well-formed news article, including the required headers. The
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:meth:`post` method automatically escapes lines beginning with ``.`` and
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appends the termination line.
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If the method succeeds, the server's response is returned. If the server
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refuses posting, a :class:`NNTPReplyError` is raised.
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.. method:: NNTP.ihave(message_id, data)
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Send an ``IHAVE`` command. *message_id* is the id of the message to send
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to the server (enclosed in ``'<'`` and ``'>'``). The *data* parameter
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and the return value are the same as for :meth:`post()`.
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.. method:: NNTP.date()
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Return a pair ``(response, date)``. *date* is a :class:`~datetime.datetime`
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object containing the current date and time of the server.
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.. method:: NNTP.slave()
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Send a ``SLAVE`` command. Return the server's *response*.
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.. method:: NNTP.set_debuglevel(level)
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Set the instance's debugging level. This controls the amount of debugging
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output printed. The default, ``0``, produces no debugging output. A value of
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``1`` produces a moderate amount of debugging output, generally a single line
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per request or response. A value of ``2`` or higher produces the maximum amount
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of debugging output, logging each line sent and received on the connection
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(including message text).
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The following are optional NNTP extensions defined in :rfc:`2980`. Some of
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them have been superseded by newer commands in :rfc:`3977`.
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.. method:: NNTP.xhdr(hdr, str, *, file=None)
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Send an ``XHDR`` command. The *hdr* argument is a header keyword, e.g.
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``'subject'``. The *str* argument should have the form ``'first-last'``
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where *first* and *last* are the first and last article numbers to search.
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Return a pair ``(response, list)``, where *list* is a list of pairs ``(id,
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text)``, where *id* is an article number (as a string) and *text* is the text of
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the requested header for that article. If the *file* parameter is supplied, then
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the output of the ``XHDR`` command is stored in a file. If *file* is a string,
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then the method will open a file with that name, write to it then close it.
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If *file* is a :term:`file object`, then it will start calling :meth:`write` on
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it to store the lines of the command output. If *file* is supplied, then the
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returned *list* is an empty list.
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.. method:: NNTP.xover(start, end, *, file=None)
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Send an ``XOVER`` command. *start* and *end* are article numbers
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delimiting the range of articles to select. The return value is the
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same of for :meth:`over()`. It is recommended to use :meth:`over()`
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instead, since it will automatically use the newer ``OVER`` command
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if available.
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.. method:: NNTP.xpath(id)
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Return a pair ``(resp, path)``, where *path* is the directory path to the
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article with message ID *id*. Most of the time, this extension is not
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enabled by NNTP server administrators.
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.. deprecated:: 3.3
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The XPATH extension is not actively used.
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.. XXX deprecated:
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.. method:: NNTP.xgtitle(name, *, file=None)
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Process an ``XGTITLE`` command, returning a pair ``(response, list)``, where
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*list* is a list of tuples containing ``(name, title)``. If the *file* parameter
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is supplied, then the output of the ``XGTITLE`` command is stored in a file.
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If *file* is a string, then the method will open a file with that name, write
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to it then close it. If *file* is a :term:`file object`, then it will start
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calling :meth:`write` on it to store the lines of the command output. If *file*
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is supplied, then the returned *list* is an empty list. This is an optional NNTP
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extension, and may not be supported by all servers.
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RFC2980 says "It is suggested that this extension be deprecated". Use
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:meth:`descriptions` or :meth:`description` instead.
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Utility functions
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-----------------
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The module also defines the following utility function:
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.. function:: decode_header(header_str)
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Decode a header value, un-escaping any escaped non-ASCII characters.
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*header_str* must be a :class:`str` object. The unescaped value is
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returned. Using this function is recommended to display some headers
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in a human readable form::
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>>> decode_header("Some subject")
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'Some subject'
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>>> decode_header("=?ISO-8859-15?Q?D=E9buter_en_Python?=")
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'Débuter en Python'
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>>> decode_header("Re: =?UTF-8?B?cHJvYmzDqG1lIGRlIG1hdHJpY2U=?=")
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'Re: problème de matrice'
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