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from TftpShared import *
from TftpPacketTypes import *
from TftpPacketFactory import *
import socket, time
###############################################################################
# Utility classes
###############################################################################
class TftpMetrics(object):
"""A class representing metrics of the transfer."""
def __init__(self):
# Bytes transferred
self.bytes = 0
# Duplicate packets received
self.dups = {}
self.dupcount = 0
# Times
self.start_time = 0
self.end_time = 0
self.duration = 0
# Rates
self.bps = 0
self.kbps = 0
def compute(self):
# Compute transfer time
self.duration = self.end_time - self.start_time
logger.debug("TftpMetrics.compute: duration is %s" % self.duration)
self.bps = (self.bytes * 8.0) / self.duration
self.kbps = self.bps / 1024.0
logger.debug("TftpMetrics.compute: kbps is %s" % self.kbps)
dupcount = 0
for key in self.dups:
dupcount += self.dups[key]
###############################################################################
# Context classes
###############################################################################
class TftpContext(object):
"""The base class of the contexts."""
def __init__(self, host, port):
"""Constructor for the base context, setting shared instance
variables."""
self.factory = TftpPacketFactory()
self.host = host
self.port = port
# The port associated with the TID
self.tidport = None
# Metrics
self.metrics = TftpMetrics()
def start(self):
return NotImplementedError, "Abstract method"
def end(self):
return NotImplementedError, "Abstract method"
def gethost(self):
"Simple getter method for use in a property."
return self.__host
def sethost(self, host):
"""Setter method that also sets the address property as a result
of the host that is set."""
self.__host = host
self.address = socket.gethostbyname(host)
host = property(gethost, sethost)
def sendAck(self, blocknumber):
"""This method sends an ack packet to the block number specified."""
logger.info("sending ack to block %d" % blocknumber)
ackpkt = TftpPacketACK()
ackpkt.blocknumber = blocknumber
self.sock.sendto(ackpkt.encode().buffer, (self.host, self.tidport))
def sendError(self, errorcode):
"""This method uses the socket passed, and uses the errorcode to
compose and send an error packet."""
logger.debug("In sendError, being asked to send error %d" % errorcode)
errpkt = TftpPacketERR()
errpkt.errorcode = errorcode
self.sock.sendto(errpkt.encode().buffer, (self.host, self.tidport))
class TftpContextClient(TftpContext):
"""This class represents shared functionality by both the download and
upload client contexts."""
def __init__(self, host, port, filename, options, packethook, timeout):
TftpContext.__init__(self, host, port)
self.file_to_transfer = filename
self.options = options
self.packethook = packethook
self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self.sock.settimeout(timeout)
self.state = None
self.next_block = 0
def setNextBlock(self, block):
if block > 2 ** 16:
logger.debug("block number rollover to 0 again")
block = 0
self.__eblock = block
def getNextBlock(self):
return self.__eblock
next_block = property(getNextBlock, setNextBlock)
def cycle(self):
"""Here we wait for a response from the server after sending it
something, and dispatch appropriate action to that response."""
for i in range(TIMEOUT_RETRIES):
logger.debug("in cycle, receive attempt %d" % i)
try:
(buffer, (raddress, rport)) = self.sock.recvfrom(MAX_BLKSIZE)
except socket.timeout, err:
logger.warn("Timeout waiting for traffic, retrying...")
continue
break
else:
raise TftpException, "Hit max timeouts, giving up."
# Ok, we've received a packet. Log it.
logger.debug("Received %d bytes from %s:%s"
% (len(buffer), raddress, rport))
# Decode it.
recvpkt = self.factory.parse(buffer)
# Check for known "connection".
if raddress != self.address:
logger.warn("Received traffic from %s, expected host %s. Discarding"
% (raddress, self.host))
if self.tidport and self.tidport != rport:
logger.warn("Received traffic from %s:%s but we're "
"connected to %s:%s. Discarding."
% (raddress, rport,
self.host, self.tidport))
# If there is a packethook defined, call it. We unconditionally
# pass all packets, it's up to the client to screen out different
# kinds of packets. This way, the client is privy to things like
# negotiated options.
if self.packethook:
self.packethook(recvpkt)
# And handle it, possibly changing state.
self.state = self.state.handle(recvpkt, raddress, rport)
class TftpContextClientUpload(TftpContextClient):
"""The upload context for the client during an upload."""
def __init__(self, host, port, filename, input, options, packethook, timeout):
TftpContextClient.__init__(self,
host,
port,
filename,
options,
packethook,
timeout)
self.fileobj = open(input, "wb")
logger.debug("TftpContextClientUpload.__init__()")
logger.debug("file_to_transfer = %s, options = %s" %
(self.file_to_transfer, self.options))
def start(self):
logger.info("sending tftp upload request to %s" % self.host)
logger.info(" filename -> %s" % self.file_to_transfer)
logger.info(" options -> %s" % self.options)
self.metrics.start_time = time.time()
logger.debug("set metrics.start_time to %s" % self.metrics.start_time)
# FIXME: put this in a sendWRQ method?
pkt = TftpPacketWRQ()
pkt.filename = self.file_to_transfer
pkt.mode = "octet" # FIXME - shouldn't hardcode this
pkt.options = self.options
self.sock.sendto(pkt.encode().buffer, (self.host, self.port))
self.next_block = 1
self.state = TftpStateSentWRQ(self)
try:
while self.state:
logger.debug("state is %s" % self.state)
self.cycle()
finally:
self.fileobj.close()
def end(self):
pass
class TftpContextClientDownload(TftpContextClient):
"""The download context for the client during a download."""
def __init__(self, host, port, filename, output, options, packethook, timeout):
TftpContextClient.__init__(self,
host,
port,
filename,
options,
packethook,
timeout)
# FIXME - need to support alternate return formats than files?
# File-like objects would be ideal, ala duck-typing.
self.fileobj = open(output, "wb")
logger.debug("TftpContextClientDownload.__init__()")
logger.debug("file_to_transfer = %s, options = %s" %
(self.file_to_transfer, self.options))
def start(self):
"""Initiate the download."""
logger.info("sending tftp download request to %s" % self.host)
logger.info(" filename -> %s" % self.file_to_transfer)
logger.info(" options -> %s" % self.options)
self.metrics.start_time = time.time()
logger.debug("set metrics.start_time to %s" % self.metrics.start_time)
# FIXME: put this in a sendRRQ method?
pkt = TftpPacketRRQ()
pkt.filename = self.file_to_transfer
pkt.mode = "octet" # FIXME - shouldn't hardcode this
pkt.options = self.options
self.sock.sendto(pkt.encode().buffer, (self.host, self.port))
self.next_block = 1
self.state = TftpStateSentRRQ(self)
try:
while self.state:
logger.debug("state is %s" % self.state)
self.cycle()
finally:
self.fileobj.close()
def end(self):
"""Finish up the context."""
self.metrics.end_time = time.time()
logger.debug("set metrics.end_time to %s" % self.metrics.end_time)
self.metrics.compute()
###############################################################################
# State classes
###############################################################################
class TftpState(object):
"""The base class for the states."""
def __init__(self, context):
"""Constructor for setting up common instance variables. The involved
file object is required, since in tftp there's always a file
involved."""
self.context = context
def handle(self, pkt, raddress, rport):
"""An abstract method for handling a packet. It is expected to return
a TftpState object, either itself or a new state."""
raise NotImplementedError, "Abstract method"
def handleOACK(self, pkt):
"""This method handles an OACK from the server, syncing any accepted
options."""
if pkt.options.keys() > 0:
if pkt.match_options(self.context.options):
logger.info("Successful negotiation of options")
# Set options to OACK options
self.context.options = pkt.options
for key in self.context.options:
logger.info(" %s = %s" % (key, self.context.options[key]))
else:
logger.error("failed to negotiate options")
raise TftpException, "Failed to negotiate options"
else:
raise TftpException, "No options found in OACK"
class TftpStateUpload(TftpState):
"""A class holding common code for upload states."""
def sendDat(self, resend=False):
finished = False
blocknumber = self.context.next_block
if not resend:
blksize = int(self.context.options['blksize'])
buffer = self.context.fileobj.read(blksize)
logger.debug("Read %d bytes into buffer" % len(buffer))
if len(buffer) < blksize:
logger.info("Reached EOF on file %s" % self.context.input)
finished = True
self.context.next_block += 1
self.bytes += len(buffer)
else:
logger.warn("Resending block number %d" % blocknumber)
dat = TftpPacketDAT()
dat.data = buffer
dat.blocknumber = blocknumber
logger.debug("Sending DAT packet %d" % blocknumber)
self.context.sock.sendto(dat.encode().buffer,
(self.context.host, self.context.port))
if self.context.packethook:
self.context.packethook(dat)
return finished
class TftpStateDownload(TftpState):
"""A class holding common code for download states."""
def handleDat(self, pkt):
"""This method handles a DAT packet during a download."""
logger.info("handling DAT packet - block %d" % pkt.blocknumber)
logger.debug("expecting block %s" % self.context.next_block)
if pkt.blocknumber == self.context.next_block:
logger.debug("good, received block %d in sequence"
% pkt.blocknumber)
self.context.sendAck(pkt.blocknumber)
self.context.next_block += 1
logger.debug("writing %d bytes to output file"
% len(pkt.data))
self.context.fileobj.write(pkt.data)
self.context.metrics.bytes += len(pkt.data)
# Check for end-of-file, any less than full data packet.
if len(pkt.data) < int(self.context.options['blksize']):
logger.info("end of file detected")
return None
elif pkt.blocknumber < self.context.next_block:
logger.warn("dropping duplicate block %d" % pkt.blocknumber)
if self.context.metrics.dups.has_key(pkt.blocknumber):
self.context.metrics.dups[pkt.blocknumber] += 1
else:
self.context.metrics.dups[pkt.blocknumber] = 1
tftpassert(self.context.metrics.dups[pkt.blocknumber] < MAX_DUPS,
"Max duplicates for block %d reached" % pkt.blocknumber)
# FIXME: double-check sorceror's apprentice problem!
logger.debug("ACKing block %d again, just in case" % pkt.blocknumber)
self.context.sendAck(pkt.blocknumber)
else:
# FIXME: should we be more tolerant and just discard instead?
msg = "Whoa! Received future block %d but expected %d" \
% (pkt.blocknumber, self.context.next_block)
logger.error(msg)
raise TftpException, msg
# Default is to ack
return TftpStateSentACK(self.context)
class TftpStateSentWRQ(TftpStateUpload):
"""Just sent an WRQ packet for an upload."""
def handle(self, pkt, raddress, rport):
"""Handle a packet we just received."""
if not self.context.tidport:
self.context.tidport = rport
logger.debug("Set remote port for session to %s" % rport)
# If we're going to successfully transfer the file, then we should see
# either an OACK for accepted options, or an ACK to ignore options.
if isinstance(pkt, TftpPacketOACK):
logger.info("received OACK from server")
try:
self.handleOACK(pkt)
except TftpException, err:
logger.error("failed to negotiate options")
self.context.sendError(TftpErrors.FailedNegotiation)
raise
else:
logger.debug("sending first DAT packet")
fin = self.context.sendDat()
if fin:
logger.info("Add done")
return None
else:
logger.debug("Changing state to TftpStateSentDAT")
return TftpStateSentDAT(self.context)
elif isinstance(pkt, TftpPacketACK):
logger.info("received ACK from server")
logger.debug("apparently the server ignored our options")
# The block number should be zero.
if pkt.blocknumber == 0:
logger.debug("ack blocknumber is zero as expected")
logger.debug("sending first DAT packet")
fin = self.context.sendDat()
if fin:
logger.info("Add done")
return None
else:
logger.debug("Changing state to TftpStateSentDAT")
return TftpStateSentDAT(self.context)
else:
logger.warn("discarding ACK to block %s" % pkt.blocknumber)
logger.debug("still waiting for valid response from server")
return self
elif isinstance(pkt, TftpPacketERR):
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received ERR from server: " + str(pkt)
elif isinstance(pkt, TftpPacketRRQ):
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received RRQ from server while in upload"
elif isinstance(pkt, TftpPacketDAT):
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received DAT from server while in upload"
else:
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received unknown packet type from server: " + str(pkt)
# By default, no state change.
return self
class TftpStateSentDAT(TftpStateUpload):
"""This class represents the state of the transfer when a DAT was just
sent, and we are waiting for an ACK from the server. This class is the
same one used by the client during the upload, and the server during the
download."""
class TftpStateSentRRQ(TftpStateDownload):
"""Just sent an RRQ packet."""
def handle(self, pkt, raddress, rport):
"""Handle the packet in response to an RRQ to the server."""
if not self.context.tidport:
self.context.tidport = rport
logger.debug("Set remote port for session to %s" % rport)
# Now check the packet type and dispatch it properly.
if isinstance(pkt, TftpPacketOACK):
logger.info("received OACK from server")
try:
self.handleOACK(pkt)
except TftpException, err:
logger.error("failed to negotiate options: %s" % str(err))
self.context.sendError(TftpErrors.FailedNegotiation)
raise
else:
logger.debug("sending ACK to OACK")
self.context.sendAck(blocknumber=0)
logger.debug("Changing state to TftpStateSentACK")
return TftpStateSentACK(self.context)
elif isinstance(pkt, TftpPacketDAT):
# If there are any options set, then the server didn't honour any
# of them.
logger.info("received DAT from server")
if self.context.options:
logger.info("server ignored options, falling back to defaults")
self.context.options = { 'blksize': DEF_BLKSIZE }
return self.handleDat(pkt)
# Every other packet type is a problem.
elif isinstance(recvpkt, TftpPacketACK):
# Umm, we ACK, the server doesn't.
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received ACK from server while in download"
elif isinstance(recvpkt, TftpPacketWRQ):
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received WRQ from server while in download"
elif isinstance(recvpkt, TftpPacketERR):
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received ERR from server: " + str(recvpkt)
else:
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received unknown packet type from server: " + str(recvpkt)
# By default, no state change.
return self
class TftpStateSentACK(TftpStateDownload):
"""Just sent an ACK packet. Waiting for DAT."""
def handle(self, pkt, raddress, rport):
"""Handle the packet in response to an ACK, which should be a DAT."""
if isinstance(pkt, TftpPacketDAT):
return self.handleDat(pkt)
# Every other packet type is a problem.
elif isinstance(recvpkt, TftpPacketACK):
# Umm, we ACK, the server doesn't.
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received ACK from server while in download"
elif isinstance(recvpkt, TftpPacketWRQ):
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received WRQ from server while in download"
elif isinstance(recvpkt, TftpPacketERR):
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received ERR from server: " + str(recvpkt)
else:
self.context.sendError(TftpErrors.IllegalTftpOp)
raise TftpException, "Received unknown packet type from server: " + str(recvpkt)
|