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# $Id: tftp.py 23 2006-11-08 15:45:33Z dugsong $
# -*- coding: utf-8 -*-
"""Trivial File Transfer Protocol."""
import struct
import dpkt
# Opcodes
OP_RRQ = 1 # read request
OP_WRQ = 2 # write request
OP_DATA = 3 # data packet
OP_ACK = 4 # acknowledgment
OP_ERR = 5 # error code
# Error codes
EUNDEF = 0 # not defined
ENOTFOUND = 1 # file not found
EACCESS = 2 # access violation
ENOSPACE = 3 # disk full or allocation exceeded
EBADOP = 4 # illegal TFTP operation
EBADID = 5 # unknown transfer ID
EEXISTS = 6 # file already exists
ENOUSER = 7 # no such user
class TFTP(dpkt.Packet):
__hdr__ = (('opcode', 'H', 1), )
def unpack(self, buf):
dpkt.Packet.unpack(self, buf)
if self.opcode in (OP_RRQ, OP_WRQ):
l = self.data.split('\x00')
self.filename = l[0]
self.mode = l[1]
self.data = ''
elif self.opcode in (OP_DATA, OP_ACK):
self.block = struct.unpack('>H', self.data[:2])
self.data = self.data[2:]
elif self.opcode == OP_ERR:
self.errcode = struct.unpack('>H', self.data[:2])
self.errmsg = self.data[2:].split('\x00')[0]
self.data = ''
def __len__(self):
return len(str(self))
def __str__(self):
if self.opcode in (OP_RRQ, OP_WRQ):
s = '%s\x00%s\x00' % (self.filename, self.mode)
elif self.opcode in (OP_DATA, OP_ACK):
s = struct.pack('>H', self.block)
elif self.opcode == OP_ERR:
s = struct.pack('>H', self.errcode) + ('%s\x00' % self.errmsg)
else:
s = ''
return self.pack_hdr() + s + self.data
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