linkchecker/linkcheck/checker/nntpurl.py

# -*- coding: iso-8859-1 -*-
"""Handle nntp: and news: links"""
# Copyright (C) 2000-2004  Bastian Kleineidam
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

import re
import time
import sys
import nntplib
import socket
import urlparse
import random

import linkcheck
import urlbase
import linkcheck.log

random.seed()

class NoNetrcNNTP (nntplib.NNTP):
    """NNTP class ignoring possible entries in ~/.netrc"""

    def __init__ (self, host, port=nntplib.NNTP_PORT, user=None,
                  password=None, readermode=None):
        """Initialize an instance.  Arguments:
        - host: hostname to connect to
        - port: port to connect to (default the standard NNTP port)
        - user: username to authenticate with
        - password: password to use with username
        - readermode: if true, send 'mode reader' command after
                      connecting.

        readermode is sometimes necessary if you are connecting to an
        NNTP server on the local machine and intend to call
        reader-specific comamnds, such as `group'.  If you get
        unexpected NNTPPermanentErrors, you might need to set
        readermode.
        """
        self.host = host
        self.port = port
        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.sock.connect((self.host, self.port))
        self.file = self.sock.makefile('rb')
        self.debugging = 0
        self.welcome = self.getresp()

        # 'mode reader' is sometimes necessary to enable 'reader' mode.
        # However, the order in which 'mode reader' and 'authinfo' need to
        # arrive differs between some NNTP servers. Try to send
        # 'mode reader', and if it fails with an authorization failed
        # error, try again after sending authinfo.
        readermode_afterauth = 0
        if readermode:
            try:
                self.welcome = self.shortcmd('mode reader')
            except nntplib.NNTPPermanentError:
                # error 500, probably 'not implemented'
                pass
            except nntplib.NNTPTemporaryError, e:
                if user and e.response[:3] == '480':
                    # Need authorization before 'mode reader'
                    readermode_afterauth = 1
                else:
                    raise
        # Perform NNRP authentication if needed.
        if user:
            resp = self.shortcmd('authinfo user '+user)
            if resp[:3] == '381':
                if not password:
                    raise nntplib.NNTPReplyError(resp)
                else:
                    resp = self.shortcmd(
                            'authinfo pass '+password)
                    if resp[:3] != '281':
                        raise nntplib.NNTPPermanentError(resp)
            if readermode_afterauth:
                try:
                    self.welcome = self.shortcmd('mode reader')
                except nntplib.NNTPPermanentError:
                    # error 500, probably 'not implemented'
                    pass


class NntpUrl (urlbase.UrlBase):
    """Url link with NNTP scheme"""

    def check_connection (self):
        nntpserver = self.host or self.consumer.config["nntpserver"]
        if not nntpserver:
            self.add_warning(
                    _("No NNTP server was specified, skipping this URL."))
            return
        nntp = self._connectNntp(nntpserver)
        group = self.urlparts[2]
        while group[:1] == '/':
            group = group[1:]
        if '@' in group:
            # request article
            resp, number, mid = nntp.stat("<"+group+">")
            self.add_info(_('Articel number %s found.') % number)
        else:
            # split off trailing articel span
            group = group.split('/', 1)[0]
            if group:
                # request group info
                resp, count, first, last, name = nntp.group(group)
                self.add_info(_("Group %s has %s articles, range %s to %s.")%\
                             (name, count, first, last))
            else:
                # group name is the empty string
                self.add_warning(_("No newsgroup specified in NNTP URL."))

    def _connectNntp (self, nntpserver):
        """This is done only once per checking task. Also, the newly
        introduced error codes 504 and 505 (both inclining "Too busy, retry
        later", are caught."""
        tries = 0
        nntp = value = None
        while tries < 5:
            tries += 1
            try:
                nntp = NoNetrcNNTP(nntpserver)
            except nntplib.error_perm:
                value = sys.exc_info()[1]
                if re.compile("^50[45]").search(str(value)):
                    time.sleep(random.randrange(10, 30))
                else:
                    raise
        if nntp is None:
            raise linkcheck.LinkCheckerError(
               _("NTTP server too busy; tried more than %d times.") % tries)
        if value is not None:
            self.add_warning(_("NNTP busy: %s.") % str(value))
        return nntp

    def can_get_content (self):
        return False