def calc_checksum(self):
"""Calculate and store the checksum for this UDP datagram.
The packet must be part of a chain.
We attempt to infer whether IPv4 or IPv6 encapsulation
is in use for the payload. The closest header wins the match.
The network layer header must immediately precede the UDP
datagram (for now)."""
from pcs.packets.ipv4 import ipv4
ip = None
ip6 = None
if self._head is not None:
(ip, iip) = self._head.find_preceding(self, pcs.packets.ipv4.ipv4)
(ip6, iip6) = self._head.find_preceding(self,
pcs.packets.ipv6.ipv6)
# Either this UDP header is not in a chain, or no IPv4/IPv6
# outer header was found.
if ip is None and ip6 is None:
self.checksum = 0
self.checksum = ipv4.ipv4_cksum(self.getbytes())
return
# If we found both IPv4 and IPv6 headers then we must break the tie.
# The closest outer header wins and is used for checksum calculation.
if ip is not None and ip6 is not None:
assert iip != iip6, "ipv4 and ipv6 cannot be at same index"
if iip6 > iip:
ip = None # ip6 is nearest outer header, ignore ip
else:
ip6 = None # ip is nearest outer header, ignore ip6
if ip is not None:
self.calc_checksum_v4(ip)
else:
self.calc_checksum_v6(ip6)
def calc_checksum(self):
"""Calculate and store the checksum for this TCP segment.
The packet must be part of a chain.
We attempt to infer whether IPv4 or IPv6 encapsulation
is in use for the payload. The closest header wins the match.
The network layer header must immediately precede the TCP
segment (for now)."""
from pcs.packets.ipv4 import ipv4
ip = None
ip6 = None
if self._head is not None:
(ip, iip) = self._head.find_preceding(self, pcs.packets.ipv4.ipv4)
(ip6, iip6) = self._head.find_preceding(self, pcs.packets.ipv6.ipv6)
# Either this TCP header is not in a chain, or no IPv4/IPv6
# outer header was found.
if ip is None and ip6 is None:
self.checksum = 0
self.checksum = ipv4.ipv4_cksum(self.getbytes())
return
# If we found both IPv4 and IPv6 headers then we must break the tie.
# The closest outer header wins and is used for checksum calculation.
if ip is not None and ip6 is not None:
assert iip != iip6, "ipv4 and ipv6 cannot be at same index"
if iip6 > iip:
ip = None # ip6 is nearest outer header, ignore ip
else:
ip6 = None # ip is nearest outer header, ignore ip6
if ip is not None:
self.calc_checksum_v4(ip)
else:
self.calc_checksum_v6(ip6)
def calc_checksum(self):
"""Calculate and store the checksum for this ICMP header.
ICMP checksums are computed over payloads, but not IP headers."""
self.checksum = 0
tmpbytes = self.getbytes()
if not self._head is None:
tmpbytes += self._head.collate_following(self)
from pcs.packets.ipv4 import ipv4
self.checksum = ipv4.ipv4_cksum(tmpbytes)
def calc_checksum(self):
"""Calculate and store the checksum for this ICMP header.
ICMP checksums are computed over payloads, but not IP headers."""
self.checksum = 0
tmpbytes = self.getbytes()
if not self._head is None:
tmpbytes += self._head.collate_following(self)
from pcs.packets.ipv4 import ipv4
self.checksum = ipv4.ipv4_cksum(tmpbytes)
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 cksum(self, ip, data = "", nx = 0):
"""Calculate the checksum for this ICMPv6 header, outside
of a chain."""
p6 = pseudoipv6.pseudoipv6()
p6.src = ip.src
p6.dst = ip.dst
p6.length = len(self.getbytes()) + len (data)
if nx:
p6.next_header = nx
else:
p6.next_header = ip.next_header
pkt = p6.getbytes() + self.getbytes() + data
return ipv4.ipv4_cksum(pkt)
def calc_checksum(self):
"""Calculate and store the checksum for this UDPv6 datagram.
The packet SHOULD be part of a chain, and have an IPv6 header.
udpv6 is a specialization of udp whose outer header must
always be ipv4, therefore we enforce this."""
from pcs.packets.ipv4 import ipv4
ip6 = None
if self._head is not None:
ip6 = self._head.find_preceding(self, pcs.packets.ipv6.ipv6)
if ip6 is None:
self.checksum = 0
self.checksum = ipv4.ipv4_cksum(self.getbytes())
return
pcs.packets.udp.udp.calc_checksum_v6(self, ip6)
def calc_checksum_v6(self, ip6):
"""Calculate and store the checksum for the TCP segment
when encapsulated as an IPv6 payload with the given header."""
from pcs.packets.ipv4 import ipv4
from pcs.packets.pseudoipv6 import pseudoipv6
self.checksum = 0
payload = self._head.collate_following(self)
pip6 = pseudoipv6()
pip6.src = ip6.src
pip6.dst = ip6.dst
pip6.next_header = ip6.next_header
pip6.length = len(self.getbytes()) + len(payload)
tmpbytes = pip6.getbytes() + self.getbytes() + payload
self.checksum = ipv4.ipv4_cksum(tmpbytes)
def calc_checksum_v6(self, ip6):
"""Calculate and store the checksum for the TCP segment
when encapsulated as an IPv6 payload with the given header."""
from pcs.packets.ipv4 import ipv4
from pcs.packets.pseudoipv6 import pseudoipv6
self.checksum = 0
payload = self._head.collate_following(self)
pip6 = pseudoipv6()
pip6.src = ip6.src
pip6.dst = ip6.dst
pip6.next_header = ip6.next_header
pip6.length = len(self.getbytes()) + len(payload)
tmpbytes = pip6.getbytes() + self.getbytes() + payload
self.checksum = 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 cksum(self, ip, data = "", nx = 0):
"""Calculate the checksum for this UDPv6 header, outside
of any existing chain."""
from pcs.packets.ipv4 import ipv4
from pcs.packets.pseudoipv6 import pseudoipv6
p6 = pseudoipv6()
p6.src = ip.src
p6.dst = ip.dst
p6.length = len(self.getbytes()) + len(data)
if nx:
p6.next_header = nx
else:
p6.next_header = ip.next_header
tmpbytes = p6.getbytes() + self.getbytes() + data
return 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 calc_checksum(self):
"""Calculate and store the checksum for this ICMPv6 header.
ICMPv6 checksums are computed over data payloads and
next-headers. The packet must be part of a chain."""
self.checksum = 0
if self._head is not None:
payload = self._head.collate_following(self)
ip6 = self._head.find_preceding(self, pcs.packets.ipv6.ipv6)[0]
assert ip6 is not None, "No preceding IPv6 header."
pip6 = pseudoipv6()
pip6.src = ip6.src
pip6.dst = ip6.dst
pip6.next_header = ip6.next_header
pip6.length = len(self.getbytes()) + len(payload)
tmpbytes = pip6.getbytes() + self.getbytes() + payload
else:
tmpbytes = self.getbytes()
self.checksum = ipv4.ipv4_cksum(tmpbytes)
