20.11. "nntplib" — NNTP protocol client
***************************************

**Source code:** Lib/nntplib.py

======================================================================

This module defines the class "NNTP" which implements the client side
of the NNTP protocol.  It can be used to implement a news reader or
poster, or automated news processors.  For more information on NNTP
(Network News Transfer Protocol), see Internet **RFC 977**.

Here are two small examples of how it can be used.  To list some
statistics about a newsgroup and print the subjects of the last 10
articles:

   >>> s = NNTP('news.gmane.org')
   >>> resp, count, first, last, name = s.group('gmane.comp.python.committers')
   >>> print 'Group', name, 'has', count, 'articles, range', first, 'to', last
   Group gmane.comp.python.committers has 1071 articles, range 1 to 1071
   >>> resp, subs = s.xhdr('subject', first + '-' + last)
   >>> for id, sub in subs[-10:]: print id, sub
   ...
   1062 Re: Mercurial Status?
   1063 Re: [python-committers]  (Windows) buildbots on 3.x
   1064 Re: Mercurial Status?
   1065 Re: Mercurial Status?
   1066 Python 2.6.6 status
   1067 Commit Privileges for Ask Solem
   1068 Re: Commit Privileges for Ask Solem
   1069 Re: Commit Privileges for Ask Solem
   1070 Re: Commit Privileges for Ask Solem
   1071 2.6.6 rc 2
   >>> s.quit()
   '205 Bye!'

To post an article from a file (this assumes that the article has
valid headers, and that you have right to post on the particular
newsgroup):

   >>> s = NNTP('news.gmane.org')
   >>> f = open('articlefile')
   >>> s.post(f)
   '240 Article posted successfully.'
   >>> s.quit()
   '205 Bye!'

The module itself defines the following items:

class nntplib.NNTP(host[, port [, user[, password [, readermode] [, usenetrc]]]])

   Return a new instance of the "NNTP" class, representing a
   connection to the NNTP server running on host *host*, listening at
   port *port*.  The default *port* is 119.  If the optional *user*
   and *password* are provided, or if suitable credentials are present
   in "/.netrc" and the optional flag *usenetrc* is true (the
   default), the "AUTHINFO USER" and "AUTHINFO PASS" commands are used
   to identify and authenticate the user to the server. If the
   optional flag *readermode* is true, then a "mode reader" command is
   sent before authentication is performed.  Reader mode is sometimes
   necessary if you are connecting to an NNTP server on the local
   machine and intend to call reader-specific commands, such as
   "group".  If you get unexpected "NNTPPermanentError"s, you might
   need to set *readermode*. *readermode* defaults to "None".
   *usenetrc* defaults to "True".

   Changed in version 2.4: *usenetrc* argument added.

exception nntplib.NNTPError

   Derived from the standard exception "Exception", this is the base
   class for all exceptions raised by the "nntplib" module.

exception nntplib.NNTPReplyError

   Exception raised when an unexpected reply is received from the
   server.  For backwards compatibility, the exception "error_reply"
   is equivalent to this class.

exception nntplib.NNTPTemporaryError

   Exception raised when an error code in the range 400–499 is
   received.  For backwards compatibility, the exception "error_temp"
   is equivalent to this class.

exception nntplib.NNTPPermanentError

   Exception raised when an error code in the range 500–599 is
   received.  For backwards compatibility, the exception "error_perm"
   is equivalent to this class.

exception nntplib.NNTPProtocolError

   Exception raised when a reply is received from the server that does
   not begin with a digit in the range 1–5.  For backwards
   compatibility, the exception "error_proto" is equivalent to this
   class.

exception nntplib.NNTPDataError

   Exception raised when there is some error in the response data.
   For backwards compatibility, the exception "error_data" is
   equivalent to this class.


20.11.1. NNTP Objects
=====================

NNTP instances have the following methods.  The *response* that is
returned as the first item in the return tuple of almost all methods
is the server’s response: a string beginning with a three-digit code.
If the server’s response indicates an error, the method raises one of
the above exceptions.

NNTP.getwelcome()

   Return the welcome message sent by the server in reply to the
   initial connection.  (This message sometimes contains disclaimers
   or help information that may be relevant to the user.)

NNTP.set_debuglevel(level)

   Set the instance’s debugging level.  This controls the amount of
   debugging output printed.  The default, "0", produces no debugging
   output.  A value of "1" produces a moderate amount of debugging
   output, generally a single line per request or response.  A value
   of "2" or higher produces the maximum amount of debugging output,
   logging each line sent and received on the connection (including
   message text).

NNTP.newgroups(date, time[, file])

   Send a "NEWGROUPS" command.  The *date* argument should be a string
   of the form "'yymmdd'" indicating the date, and *time* should be a
   string of the form "'hhmmss'" indicating the time.  Return a pair
   "(response, groups)" where *groups* is a list of group names that
   are new since the given date and time. If the *file* parameter is
   supplied, then the output of the  "NEWGROUPS" command is stored in
   a file.  If *file* is a string,  then the method will open a file
   object with that name, write to it  then close it.  If *file* is a
   file object, then it will start calling "write()" on it to store
   the lines of the command output. If *file* is supplied, then the
   returned *list* is an empty list.

NNTP.newnews(group, date, time[, file])

   Send a "NEWNEWS" command.  Here, *group* is a group name or "'*'",
   and *date* and *time* have the same meaning as for "newgroups()".
   Return a pair "(response, articles)" where *articles* is a list of
   message ids. If the *file* parameter is supplied, then the output
   of the  "NEWNEWS" command is stored in a file.  If *file* is a
   string,  then the method will open a file object with that name,
   write to it  then close it.  If *file* is a file object, then it
   will start calling "write()" on it to store the lines of the
   command output. If *file* is supplied, then the returned *list* is
   an empty list.

NNTP.list([file])

   Send a "LIST" command.  Return a pair "(response, list)" where
   *list* is a list of tuples.  Each tuple has the form "(group, last,
   first, flag)", where *group* is a group name, *last* and *first*
   are the last and first article numbers (as strings), and *flag* is
   "'y'" if posting is allowed, "'n'" if not, and "'m'" if the
   newsgroup is moderated.  (Note the ordering: *last*, *first*.) If
   the *file* parameter is supplied, then the output of the  "LIST"
   command is stored in a file.  If *file* is a string,  then the
   method will open a file object with that name, write to it  then
   close it.  If *file* is a file object, then it will start calling
   "write()" on it to store the lines of the command output. If *file*
   is supplied, then the returned *list* is an empty list.

NNTP.descriptions(grouppattern)

   Send a "LIST NEWSGROUPS" command, where *grouppattern* is a wildmat
   string as specified in RFC2980 (it’s essentially the same as DOS or
   UNIX shell wildcard strings).  Return a pair "(response, list)",
   where *list* is a list of tuples containing "(name, title)".

   New in version 2.4.

NNTP.description(group)

   Get a description for a single group *group*.  If more than one
   group matches (if ‘group’ is a real wildmat string), return the
   first match.   If no group matches, return an empty string.

   This elides the response code from the server.  If the response
   code is needed, use "descriptions()".

   New in version 2.4.

NNTP.group(name)

   Send a "GROUP" command, where *name* is the group name. Return a
   tuple "(response, count, first, last, name)" where *count* is the
   (estimated) number of articles in the group, *first* is the first
   article number in the group, *last* is the last article number in
   the group, and *name* is the group name. The numbers are returned
   as strings.

NNTP.help([file])

   Send a "HELP" command.  Return a pair "(response, list)" where
   *list* is a list of help strings. If the *file* parameter is
   supplied, then the output of the  "HELP" command is stored in a
   file.  If *file* is a string,  then the method will open a file
   object with that name, write to it  then close it.  If *file* is a
   file object, then it will start calling "write()" on it to store
   the lines of the command output. If *file* is supplied, then the
   returned *list* is an empty list.

NNTP.stat(id)

   Send a "STAT" command, where *id* is the message id (enclosed in
   "'<'" and "'>'") or an article number (as a string). Return a
   triple "(response, number, id)" where *number* is the article
   number (as a string) and *id* is the message id  (enclosed in "'<'"
   and "'>'").

NNTP.next()

   Send a "NEXT" command.  Return as for "stat()".

NNTP.last()

   Send a "LAST" command.  Return as for "stat()".

NNTP.head(id)

   Send a "HEAD" command, where *id* has the same meaning as for
   "stat()". Return a tuple "(response, number, id, list)" where the
   first three are the same as for "stat()", and *list* is a list of
   the article’s headers (an uninterpreted list of lines, without
   trailing newlines).

NNTP.body(id[, file])

   Send a "BODY" command, where *id* has the same meaning as for
   "stat()". If the *file* parameter is supplied, then the body is
   stored in a file.  If *file* is a string, then the method will open
   a file object with that name, write to it then close it. If *file*
   is a file object, then it will start calling "write()" on it to
   store the lines of the body. Return as for "head()".  If *file* is
   supplied, then the returned *list* is an empty list.

NNTP.article(id)

   Send an "ARTICLE" command, where *id* has the same meaning as for
   "stat()".  Return as for "head()".

NNTP.slave()

   Send a "SLAVE" command.  Return the server’s *response*.

NNTP.xhdr(header, string[, file])

   Send an "XHDR" command.  This command is not defined in the RFC but
   is a common extension.  The *header* argument is a header keyword,
   e.g. "'subject'".  The *string* argument should have the form
   "'first-last'" where *first* and *last* are the first and last
   article numbers to search. Return a pair "(response, list)", where
   *list* is a list of pairs "(id, text)", where *id* is an article
   number (as a string) and *text* is the text of the requested header
   for that article. If the *file* parameter is supplied, then the
   output of the  "XHDR" command is stored in a file.  If *file* is a
   string, then the method will open a file object with that name,
   write to it  then close it.  If *file* is a file object, then it
   will start calling "write()" on it to store the lines of the
   command output. If *file* is supplied, then the returned *list* is
   an empty list.

NNTP.post(file)

   Post an article using the "POST" command.  The *file* argument is
   an open file object which is read until EOF using its "readline()"
   method.  It should be a well-formed news article, including the
   required headers.  The "post()" method automatically escapes lines
   beginning with ".".

NNTP.ihave(id, file)

   Send an "IHAVE" command. *id* is a message id (enclosed in  "'<'"
   and "'>'"). If the response is not an error, treat *file* exactly
   as for the "post()" method.

NNTP.date()

   Return a triple "(response, date, time)", containing the current
   date and time in a form suitable for the "newnews()" and
   "newgroups()" methods. This is an optional NNTP extension, and may
   not be supported by all servers.

NNTP.xgtitle(name[, file])

   Process an "XGTITLE" command, returning a pair "(response, list)",
   where *list* is a list of tuples containing "(name, title)". If the
   *file* parameter is supplied, then the output of the  "XGTITLE"
   command is stored in a file. If *file* is a string,  then the
   method will open a file object with that name, write to it  then
   close it.  If *file* is a file object, then it will start calling
   "write()" on it to store the lines of the command output. If *file*
   is supplied, then the returned *list* is an empty list. This is an
   optional NNTP extension, and may not be supported by all servers.

   RFC2980 says “It is suggested that this extension be deprecated”.
   Use "descriptions()" or "description()" instead.

NNTP.xover(start, end[, file])

   Return a pair "(resp, list)".  *list* is a list of tuples, one for
   each article in the range delimited by the *start* and *end*
   article numbers.  Each tuple is of the form "(article number,
   subject, poster, date, id, references, size, lines)". If the *file*
   parameter is supplied, then the output of the "XOVER" command is
   stored in a file.  If *file* is a string,  then the method will
   open a file object with that name, write to it  then close it.  If
   *file* is a file object, then it will start calling "write()" on it
   to store the lines of the command output. If *file* is supplied,
   then the returned *list* is an empty list. This is an optional NNTP
   extension, and may not be supported by all servers.

NNTP.xpath(id)

   Return a pair "(resp, path)", where *path* is the directory path to
   the article with message ID *id*.  This is an optional NNTP
   extension, and may not be supported by all servers.

NNTP.quit()

   Send a "QUIT" command and close the connection.  Once this method
   has been called, no other methods of the NNTP object should be
   called.
