/usr/lib/python3/dist-packages/tftp/protocol.py is in python3-txtftp 0.1~bzr47-0ubuntu2.
This file is owned by root:root, with mode 0o644.
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@author: shylent
'''
from tftp.bootstrap import RemoteOriginWriteSession, RemoteOriginReadSession
from tftp.datagram import (TFTPDatagramFactory, split_opcode, OP_WRQ,
ERRORDatagram, ERR_NOT_DEFINED, ERR_ACCESS_VIOLATION, ERR_FILE_EXISTS,
ERR_ILLEGAL_OP, OP_RRQ, ERR_FILE_NOT_FOUND)
from tftp.errors import (FileExists, Unsupported, AccessViolation, BackendError,
FileNotFound)
from tftp.netascii import NetasciiReceiverProxy, NetasciiSenderProxy
from twisted.internet import reactor
from twisted.internet.defer import inlineCallbacks, returnValue
from twisted.internet.protocol import DatagramProtocol
from twisted.python import log
from twisted.python.context import call
class TFTP(DatagramProtocol):
"""TFTP dispatch protocol. Handles read requests (RRQ) and write requests (WRQ)
and starts the corresponding sessions.
@ivar backend: an L{IBackend} provider, that will handle interaction with
local resources
@type backend: L{IBackend} provider
"""
def __init__(self, backend, _clock=None):
self.backend = backend
if _clock is None:
self._clock = reactor
else:
self._clock = _clock
def startProtocol(self):
addr = self.transport.getHost()
log.msg("TFTP Listener started at %s:%s" % (addr.host, addr.port))
def datagramReceived(self, datagram, addr):
datagram = TFTPDatagramFactory(*split_opcode(datagram))
log.msg("Datagram received from %s: %s" % (addr, datagram))
if datagram.opcode not in (OP_WRQ, OP_RRQ):
log.msg(
"Datagram with unexpected opcode %s was received without establishing "
"the session. Ignoring." % datagram.opcode)
return
mode = datagram.mode.lower()
if mode not in (b'netascii', b'octet'):
errmsg = (
u"Unknown transfer mode '%s', - expected 'netascii' or 'octet'"
u"(case-insensitive)" % mode.decode("ascii"))
return self.transport.write(ERRORDatagram.from_code(
ERR_ILLEGAL_OP, errmsg.encode("ascii", "replace")).to_wire(), addr)
self._clock.callLater(0, self._startSession, datagram, addr, mode)
@inlineCallbacks
def _startSession(self, datagram, addr, mode):
# Set up a call context so that we can pass extra arbitrary
# information to interested backends without adding extra call
# arguments, or switching to using a request object, for example.
context = {}
if self.transport is not None:
# Add the local and remote addresses to the call context.
local = self.transport.getHost()
context["local"] = local.host, local.port
context["remote"] = addr
try:
if datagram.opcode == OP_WRQ:
fs_interface = yield call(
context, self.backend.get_writer, datagram.filename)
elif datagram.opcode == OP_RRQ:
fs_interface = yield call(
context, self.backend.get_reader, datagram.filename)
except Unsupported as e:
self.transport.write(ERRORDatagram.from_code(ERR_ILLEGAL_OP,
u"{}".format(e).encode("ascii", "replace")).to_wire(), addr)
except AccessViolation:
self.transport.write(ERRORDatagram.from_code(ERR_ACCESS_VIOLATION).to_wire(), addr)
except FileExists:
self.transport.write(ERRORDatagram.from_code(ERR_FILE_EXISTS).to_wire(), addr)
except FileNotFound:
self.transport.write(ERRORDatagram.from_code(ERR_FILE_NOT_FOUND).to_wire(), addr)
except BackendError as e:
self.transport.write(ERRORDatagram.from_code(ERR_NOT_DEFINED,
u"{}".format(e).encode("ascii", "replace")).to_wire(), addr)
else:
if datagram.opcode == OP_WRQ:
if mode == b'netascii':
fs_interface = NetasciiReceiverProxy(fs_interface)
session = RemoteOriginWriteSession(addr, fs_interface,
datagram.options, _clock=self._clock)
reactor.listenUDP(0, session)
returnValue(session)
elif datagram.opcode == OP_RRQ:
if mode == b'netascii':
fs_interface = NetasciiSenderProxy(fs_interface)
session = RemoteOriginReadSession(addr, fs_interface,
datagram.options, _clock=self._clock)
reactor.listenUDP(0, session)
returnValue(session)
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