import os, logging, random, socket, time
from twisted.internet import reactor, defer
from twisted.internet.protocol import DatagramProtocol
from .base import NBNS
class NetBIOSTimeout(Exception):
"""Raised in NBNSProtocol via Deferred.errback method when queryName method has timeout waiting for reply"""
pass
class NBNSProtocol(DatagramProtocol, NBNS):
log = logging.getLogger('NMB.NBNSProtocol')
def __init__(self, broadcast = True, listen_port = 0):
"""
Instantiate a NBNSProtocol instance.
This automatically calls reactor.listenUDP method to start listening for incoming packets, so you **must not** call the listenUDP method again.
: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.pending_trns = { } # TRN ID -> ( expiry_time, name, Deferred instance )
self.transport = reactor.listenUDP(listen_port, self)
if self.broadcast:
self.transport.getHandle().setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
reactor.callLater(1, self.cleanupPendingTrns)
def datagramReceived(self, data, from_info):
host, port = from_info
trn_id, ret = self.decodePacket(data)
# pending transaction exists for trn_id - handle it and remove from queue
if trn_id in self.pending_trns:
_, ip, d = self.pending_trns.pop(trn_id)
if ip is NAME_QUERY:
# decode as query packet
trn_id, ret = self.decodeIPQueryPacket(data)
d.callback(ret)
def write(self, data, ip, port):
# We don't use the transport.write method directly as it keeps raising DeprecationWarning for ip='<broadcast>'
self.transport.getHandle().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 returned Deferred instance will be called with a NetBIOSTimeout exception.
:return: A *twisted.internet.defer.Deferred* instance. The callback function will be called with a list of IP addresses in dotted notation (aaa.bbb.ccc.ddd).
On timeout, the errback function will be called with a Failure instance wrapping around a NetBIOSTimeout exception
"""
trn_id = random.randint(1, 0xFFFF)
while True:
if trn_id not in self.pending_trns:
break
else:
trn_id = (trn_id + 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)
d = defer.Deferred()
self.pending_trns[trn_id] = ( time.time()+timeout, name, d )
return d
def queryIPForName(self, ip, port = 137, timeout = 30):
"""
Send a query to the machine with *ip* and hopes that the machine will reply back with its name.
The implementation of this function is contributed by Jason Anderson.
: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 *twisted.internet.defer.Deferred* instance. The callback function will be called with a list of names of the machine at *ip*.
On timeout, the errback function will be called with a Failure instance wrapping around a NetBIOSTimeout exception
"""
trn_id = random.randint(1, 0xFFFF)
while True:
if trn_id not in self.pending_trns:
break
else:
trn_id = (trn_id + 1) & 0xFFFF
data = self.prepareNetNameQuery(trn_id)
self.write(data, ip, port)
d = defer.Deferred()
d2 = defer.Deferred()
d2.addErrback(d.errback)
def stripCode(ret):
if ret is not None: # got valid response. Somehow the callback is also called when there is an error.
d.callback(map(lambda s: s[0], filter(lambda s: s[1] == TYPE_SERVER, ret)))
d2.addCallback(stripCode)
self.pending_trns[trn_id] = ( time.time()+timeout, NAME_QUERY, d2 )
return d
def stopProtocol(self):
DatagramProtocol.stopProtocol(self)
def cleanupPendingTrns(self):
now = time.time()
# reply should have been received in the past
# info is tuple of ( expiry_time, name, d )
expired = filter(lambda trn_id, info: info[0] < now, self.pending_trns.iteritems())
# remove expired items from dict + call errback
def expire_item(item):
trn_id, (expiry_time, name, d) = item
del self.pending_trns[trn_id]
try:
d.errback(NetBIOSTimeout(name))
except: pass
map(expire_item, expired)
if self.transport:
reactor.callLater(1, self.cleanupPendingTrns)