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# Source code for nmb.NetBIOS

    import os, logging, random, socket, time, select
    from base import NBNS

    class NetBIOS(NBNS):

        log = logging.getLogger('NMB.NetBIOS')

        def __init__(self, broadcast = True, listen_port = 0):
            """
            Instantiate a NetBIOS instance, and creates a IPv4 UDP socket to listen/send NBNS packets.

            :param boolean broadcast: A boolean flag to indicate if we should setup the listening UDP port in broadcast mode
            :param integer listen_port: Specifies the UDP port number to bind to for listening. If zero, OS will automatically select a free port number.
            """
            self.broadcast = broadcast
            self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
            if self.broadcast:
                self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
            if listen_port:
                self.sock.bind(( '', listen_port ))

        def close(self):
            """
            Close the underlying and free resources.

            The NetBIOS instance should not be used to perform any operations after this method returns.

            :return: None
            """
            self.sock.close()
            self.sock = None

        def write(self, data, ip, port):
            assert self.sock, 'Socket is already closed'
            self.sock.sendto(data, ( ip, port ))

        def queryName(self, name, ip = '', port = 137, timeout = 30):
            """
            Send a query on the network and hopes that if machine matching the *name* will reply with its IP address.

            :param string ip: If the NBNSProtocol instance was instianted with broadcast=True, then this parameter can be an empty string. We will leave it to the OS to determine an appropriate broadcast address.
                              If the NBNSProtocol instance was instianted with broadcast=False, then you should provide a target IP to send the query.
            :param integer port: The NetBIOS-NS port (IANA standard defines this port to be 137). You should not touch this parameter unless you know what you are doing.
            :param integer/float timeout: Number of seconds to wait for a reply, after which the method will return None
            :return: A list of IP addresses in dotted notation (aaa.bbb.ccc.ddd). On timeout, returns None.
            """
            assert self.sock, 'Socket is already closed'

            trn_id = random.randint(1, 0xFFFF)
            data = self.prepareNameQuery(trn_id, name)
            if self.broadcast and not ip:
                ip = '<broadcast>'
            elif not ip:
                self.log.warning('queryName: ip parameter is empty. OS might not transmit this query to the network')

            self.write(data, ip, port)

            return self._pollForNetBIOSPacket(trn_id, timeout)

        #
        # Protected Methods
        #

        def _pollForNetBIOSPacket(self, wait_trn_id, timeout):
            end_time = time.time() - timeout
            while True:
                try:
                    _timeout = time.time()-end_time
                    if _timeout <= 0:
                        return None

                    ready, _, _ = select.select([ self.sock.fileno() ], [ ], [ ], _timeout)
                    if not ready:
                        return None

                    data, _ = self.sock.recvfrom(0xFFFF)
                    trn_id, ret = self.decodePacket(data)

                    if trn_id == wait_trn_id:
                        return ret
                except select.error, ex:
                    if type(ex) is types.TupleType:
                        if ex[0] != errno.EINTR and ex[0] != errno.EAGAIN:
                            raise ex
                    else:
                        raise ex

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