def fragment(self):
pac = self.packet
self.src_ip = Converter.get_decoded_ip(pac[:4])
self.req_type = ord(pac[4])
if self.req_type <= 0 or self.req_type > 5:
self.isvalid = 0
return
if self.req_type < 4:
#they bore a format shown above
#get the data length
if len(pac) < 6:
self.isvalid = 0
return
len_dat = ord(pac[5]) * 256 + ord(pac[6])
#check if length is within the bounds
if len_dat + 7 >= len(pac):
self.isvalid = 0
return
self.dat = pac[7:7 + len_dat]
#get the key length
key_len = ord(pac[7 + len_dat]) * 256 + ord(pac[7 + len_dat + 1])
#check the format of the packet
if len(self.packet) != 4 + 1 + 2 + 2 + len_dat + key_len:
self.isvalid = 0
return
self.key = pac[7 + len_dat + 2:7 + len_dat + 2 + key_len]
else:
#this will have simple format
self.dat = pac[5:]
def fragment(self): pac = self.packet self.src_ip = Converter.get_decoded_ip(pac[:4]) self.req_type = ord(pac[4]) if self.req_type<=0 or self.req_type>5: self.isvalid = 0 return if self.req_type < 4: #they bore a format shown above #get the data length if len(pac)<6: self.isvalid = 0 return len_dat = ord(pac[5])*256 + ord(pac[6]) #check if length is within the bounds if len_dat+7 >= len(pac): self.isvalid = 0 return self.dat = pac[7:7+len_dat] #get the key length key_len = ord(pac[7+len_dat])*256 + ord(pac[7+len_dat+1]) #check the format of the packet if len(self.packet)!= 4+1+2+2+len_dat+key_len: self.isvalid = 0 return self.key = pac[7+len_dat+2: 7+len_dat+2+key_len] else: #this will have simple format self.dat = pac[5:]
def makePacket(self):
pac = ''
#ip address
pac += Converter.get_encoded_ip(self.src_ip)
# print pac,'*',len(pac)
#request-type
pac += chr(self.req_type)
# print pac,'*',len(pac)
#length of payload...
pac += chr(len(self.dat) / 256)
pac += chr(len(self.dat) % 256)
# print pac,'*',len(pac)
#append the payload
pac += self.dat
#append key-size
pac += chr(len(self.key) / 256)
pac += chr(len(self.key) % 256)
# print pac,'*',len(pac)
#append key
pac += self.key
# print pac,'*',len(pac)
self.packet = pac
def makePacket(self): pac = '' #ip address pac += Converter.get_encoded_ip(self.src_ip) # print pac,'*',len(pac) #request-type pac += chr(self.req_type) # print pac,'*',len(pac) #length of payload... pac += chr(len(self.dat)/256) pac += chr(len(self.dat)%256) # print pac,'*',len(pac) #append the payload pac += self.dat #append key-size pac += chr(len(self.key)/256) pac += chr(len(self.key)%256) # print pac,'*',len(pac) #append key pac += self.key # print pac,'*',len(pac) self.packet = pac
def setPacketByFields(self, typ, src, payload):
self.packet = Converter.get_encoded_ip(src) +\
chr(typ) + payload
def setPacketByFields(self, typ, src, payload): self.packet = Converter.get_encoded_ip(src) +\ chr(typ) + payload