def cksum(self, ip, data = ""):
"""Calculate the TCP segment checksum outside of a chain."""
from pcs.packets.ipv4 import ipv4
from pcs.packets.ipv4 import pseudoipv4
from socket import IPPROTO_TCP
tmpip = pseudoipv4()
tmpip.src = ip.src
tmpip.dst = ip.dst
tmpip.protocol = IPPROTO_TCP
tmpip.length = len(self.getbytes()) + len(data)
pkt = tmpip.getbytes() + self.getbytes() + data
return ipv4.ipv4_cksum(pkt)
def cksum(self, ip, data=""):
"""Calculate the TCP segment checksum outside of a chain."""
from pcs.packets.ipv4 import ipv4
from pcs.packets.ipv4 import pseudoipv4
from socket import IPPROTO_TCP
tmpip = pseudoipv4()
tmpip.src = ip.src
tmpip.dst = ip.dst
tmpip.protocol = IPPROTO_TCP
tmpip.length = len(self.getbytes()) + len(data)
pkt = tmpip.getbytes() + self.getbytes() + data
return ipv4.ipv4_cksum(pkt)
def cksum(self, ip, data = ""):
"""Calculate the checksum for this UDPv4 header,
outside of a chain."""
from socket import IPPROTO_UDP
from pcs.packets.ipv4 import ipv4
from pcs.packets.ipv4 import pseudoipv4
tmpip = pseudoipv4()
tmpip.src = ip.src
tmpip.dst = ip.dst
tmpip.protocol = IPPROTO_UDP
tmpip.length = len(self.getbytes()) + len(data)
tmpbytes = tmpip.getbytes() + self.getbytes() + data
return ipv4.ipv4_cksum(tmpbytes)
def calc_checksum_v4(self, ip):
"""Calculate and store the checksum for the UDP datagram
when encapsulated as an IPv4 payload with the given header."""
#print "udp.calc_checksum_v4()"
from pcs.packets.ipv4 import ipv4
from pcs.packets.ipv4 import pseudoipv4
self.checksum = 0
payload = self._head.collate_following(self)
pip = pseudoipv4()
pip.src = ip.src
pip.dst = ip.dst
pip.protocol = socket.IPPROTO_UDP
pip.length = len(self.getbytes()) + len(payload)
tmpbytes = pip.getbytes() + self.getbytes() + payload
self.checksum = ipv4.ipv4_cksum(tmpbytes)
def calc_checksum_v4(self, ip):
"""Calculate and store the checksum for the TCP segment
when encapsulated as an IPv4 payload with the given header."""
from pcs.packets.ipv4 import ipv4
from pcs.packets.ipv4 import pseudoipv4
from socket import IPPROTO_TCP
self.checksum = 0
payload = self._head.collate_following(self)
pip = pseudoipv4()
pip.src = ip.src
pip.dst = ip.dst
pip.protocol = IPPROTO_TCP
pip.length = len(self.getbytes()) + len(payload)
tmpbytes = pip.getbytes() + self.getbytes() + payload
self.checksum = ipv4.ipv4_cksum(tmpbytes)
def tcp_cksum(self, ip, data=""): #TODO: add this method to pcs tcp.py
"""return tcpv4 checksum"""
import struct
total = 0
tmpip = ipv4.pseudoipv4()
tmpip.src = ip.src
tmpip.dst = ip.dst
tmpip.reserved = 0
tmpip.protocol = pcs.IPPROTO_TCP
tmpip.length = len(self.getbytes()) + len(data)
pkt = tmpip.getbytes() + self.getbytes() + data
if len(pkt) % 2 == 1:
pkt += "\0"
for i in range(len(pkt) / 2):
total += (struct.unpack("!H", pkt[2 * i:2 * i + 2])[0])
total = (total >> 16) + (total & 0xffff)
total += total >> 16
return ~total & 0xffff
