##  $Id: nnrpd_auth.py 10276 2018-04-18 19:43:27Z iulius $
##
##  This is a sample authentication module for the Python nnrpd hook.
##
##  See the INN Python Filtering and Authentication Hooks documentation
##  for more information.
##  The python_auth: parameter in readers.conf is used to load this script.
##
##  An instance of AUTH class is passed to nnrpd via the set_auth_hook()
##  function imported from nnrpd.  The following methods of that class
##  are known to nnrpd:
##
##  __init__()                  - Use this method to initialize your
##                                general variables or open a common
##                                database connection.  May be omitted.
##  authen_init()               - Init function specific to
##                                authentication.  May be omitted.
##  authenticate(attributes)    - Called when a python_auth statement
##                                is reached in the processing of
##                                readers.conf.  Returns a response
##                                code, an error string and an
##                                optional string to appear in the
##                                logs as the username (make sure that
##                                such a message is properly encoded
##                                in UTF-8 so as to comply with the
##                                NNTP protocol).
##  authen_close()              - Called on nnrpd termination.  Save
##                                your state variables or close a database
##                                connection.  May be omitted.
##
##  If there is a problem with return codes from any of these methods,
##  then nnrpd will die and syslog the exact reason.
##
##  There are also a few Python functions defined in nnrpd:
##
##  set_auth_hook()             - Called by nnrpd as this module is loaded.
##                              It is used to pass a reference to an
##                              instance of authentication class to nnrpd.
##  syslog()                    - An equivalent replacement for regular syslog.
##                              One consideration for using it is to
##                              uniform nnrpd logging.

##  Sample authentication class.  It defines all auth methods known to nnrpd.
class AUTH:
    """Provide authentication callbacks to nnrpd."""

    def __init__(self):
        """This is a good place to initialize variables or open a
           database connection."""

        # Create a list of NNTP codes to respond on authentication.
        self.authcodes = {  'ALLOWED': 281,
                            'DENIED': 481,
                            'ERROR': 403
        }

        syslog('notice', 'nnrpd authentication class instance created')

    def authen_init(self):
        """Called when this script is initialized."""
        pass

    def authenticate(self, attributes):
        """Called when python_auth: is encountered in readers.conf."""

        # Just for debugging purposes (in Python 3.x syntax).
        # By default, do not log passwords (available in attributes['pass']).
        # syslog('notice', 'n_a authenticate() invoked: hostname %s, ipaddress %s, port %lu, interface %s, intipaddr %s, intport %lu, user %s' % ( \
        #        attributes['hostname'].tobytes(), \
        #        attributes['ipaddress'].tobytes(), \
        #        attributes['port'], \
        #        attributes['interface'].tobytes(), \
        #        attributes['intipaddr'].tobytes(), \
        #        attributes['intport'], \
        #        (attributes['user'].tobytes() if attributes['user'] else "-")))

        # Do username password authentication.
        # Python 2.x syntax:
        #  if attributes['user'] and attributes['pass'] \
        #    and 'foo' == str(attributes['user']) \
        #    and 'foo' == str(attributes['pass']):
        # Python 3.x syntax:
        #  if attributes['user'] and attributes['pass'] \
        #    and b'foo' == attributes['user'].tobytes() \
        #    and b'foo' == attributes['pass'].tobytes():
        #      syslog('notice', 'authentication by username succeeded')
        #      return (self.authcodes['ALLOWED'], 'No error', 'default_user')

        syslog('notice', 'authentication by username failed')
        return (self.authcodes['DENIED'], 'Access Denied!')

    def authen_close(self):
        """Called on nnrpd termination."""
        pass


##  The rest is used to hook up the auth module on nnrpd.  It is unlikely
##  you will ever need to modify this.

##  Import functions exposed by nnrpd.  This import must succeed, or nothing
##  will work!
from nnrpd import *

##  Create a class instance.
myauth = AUTH()

##  ...and try to hook up on nnrpd.  This would make auth object methods visible
##  to nnrpd.
import sys
try:
    set_auth_hook(myauth)
    syslog('notice', "authentication module successfully hooked into nnrpd")
except Exception: # Syntax valid in both Python 2.x and 3.x.
    e = sys.exc_info()[1]
    syslog('error', "Cannot obtain nnrpd hook for authentication method: %s" % e.args[0])