def outgoing_packet_handler(src_port, dst_addr, dst_port, data):
udp_frag = udp.Packet(sport=src_port, dport=dst_port, data=data)
udp_assembled = udp.assemble(udp_frag, False)
pseudo_header = socket.inet_aton(local_ip) + socket.inet_aton(dst_addr) + '\x00\x11' + struct.pack('!H', len(udp_assembled))
cksum = inetutils.cksum(pseudo_header + udp_assembled)
udp_assembled_with_cksum = udp_assembled[:6] + struct.pack('H', cksum) + udp_assembled[8:]
out_sk.sendto(udp_assembled_with_cksum, (dst_addr, 0))
def _disassemble(self, raw_packet, cksum):
# The kernel computes the checksum, even on a raw packet.
packet = inetutils.net2iph(raw_packet)
b1 = ord(packet[0])
self.v = (b1 >> 4) & 0x0f
self.hl = b1 & 0x0f
if self.v != IPVERSION:
raise ValueError( "cannot handle IPv%d packets" % self.v )
hl = self.hl * 4
# verify the checksum
self.sum = struct.unpack('H', packet[10:12])[0] & 0xffff
if cksum:
our_cksum = inetutils.cksum(packet[:20])
if our_cksum != 0:
raise ValueError( packet )
# unpack the fields
elts = struct.unpack('ccHHHcc', packet[:hl-10])
# struct didn't do !<> when this was written
self.tos = ord(elts[1])
self.len = elts[2] & 0xffff
self.id = elts[3] & 0xffff
self.off = elts[4] & 0xffff
self.ttl = ord(elts[5])
self.p = ord(elts[6])
self.data = packet[hl:]
self.src = packet[hl-8:hl-4]
self.dst = packet[hl-4:hl]
self.__unparse_addrs()
def _disassemble(self, raw_packet, cksum):
# The kernel computes the checksum, even on a raw packet.
packet = inetutils.net2iph(raw_packet)
b1 = ord(packet[0])
self.v = (b1 >> 4) & 0x0f
self.hl = b1 & 0x0f
if self.v != IPVERSION:
raise ValueError, "cannot handle IPv%d packets" % self.v
hl = self.hl * 4
# verify the checksum
self.sum = struct.unpack('H', packet[10:12])[0] & 0xffff
if cksum:
our_cksum = inetutils.cksum(packet[:20])
if our_cksum != 0:
raise ValueError, packet
# unpack the fields
elts = struct.unpack('ccHHHcc', packet[:hl-10])
# struct didn't do !<> when this was written
self.tos = ord(elts[1])
self.len = elts[2] & 0xffff
self.id = elts[3] & 0xffff
self.off = elts[4] & 0xffff
self.ttl = ord(elts[5])
self.p = ord(elts[6])
self.data = packet[hl:]
self.src = packet[hl-8:hl-4]
self.dst = packet[hl-4:hl]
self.__unparse_addrs()
def _assemble(self, cksum):
"Get a packet suitable for sending over an IP socket."
# make sure all the data is ready
assert self.src, "src needed before assembling."
assert self.dst, "dst needed before assembling."
self.len = self.hl * 4 + len(self.data)
self.__parse_addrs()
# create the packet
header = struct.pack('!BBHHHBB',
((self.v & 0x0f) << 4
| (self.hl & 0x0f)), # 4bits each
(self.tos & 0xff),
self.len,
self.id,
(self.df & 0x01) << 14 | self.off,
(self.ttl & 0xff),
(self.p & 0xff))
# fill checksum field by two null bytes for checksum computing
pseudo_header = header + b'\000\000' + self.__src + self.__dst
# compute ip header checksum, checksum will be in network bytes order
self.sum = inetutils.cksum(pseudo_header)
# compose ip packet header (checksum already in network bytes order)
# order conversion doesn't require here
packet = header + struct.pack('H', self.sum) + self.__src + self.__dst
# compose ip packet
packet = packet + self.data
return packet
def _assemble(self, cksum):
"Get a packet suitable for sending over an IP socket."
# make sure all the data is ready
assert self.src, "src needed before assembling."
assert self.dst, "dst needed before assembling."
self.len = self.hl * 4 + len(self.data)
self.__parse_addrs()
# create the packet
header = struct.pack('ccHHHcc',
chr((self.v & 0x0f) << 4
| (self.hl & 0x0f)), # 4bits each
chr(self.tos & 0xff),
self.len,
self.id,
(self.df & 0x01) << 14
| self.off, # what about flags?
chr(self.ttl & 0xff),
chr(self.p & 0xff))
if cksum:
self.sum = inetutils.cksum(header + '\000\000' + self.__src +
self.__dst)
packet = header + struct.pack('H', self.sum) \
+ self.__src + self.__dst
else:
packet = header + '\000\000' + self.__src + self.__dst
packet = packet + self.data
self.__packet = inetutils.iph2net(packet)
return self.__packet
def _assemble(self, cksum):
"Get a packet suitable for sending over an IP socket."
# make sure all the data is ready
assert self.src, "src needed before assembling."
assert self.dst, "dst needed before assembling."
self.len = self.hl * 4 + len(self.data)
self.__parse_addrs()
# create the packet
header = struct.pack('ccHHHcc',
chr((self.v & 0x0f) << 4
| (self.hl & 0x0f)), # 4bits each
chr(self.tos & 0xff),
self.len,
self.id,
(self.df & 0x01) << 14
| self.off, # what about flags?
chr(self.ttl & 0xff),
chr(self.p & 0xff))
if cksum:
self.sum = inetutils.cksum(header + '\000\000' + self.__src +
self.__dst)
packet = header + struct.pack('H', self.sum) \
+ self.__src + self.__dst
else:
packet = header + '\000\000' + self.__src + self.__dst
packet = packet + self.data
self.__packet = inetutils.iph2net(packet)
return self.__packet
def _disassemble(self, raw_packet, cksum=1):
packet = inetutils.net2updh(raw_packet)
if cksum and packet[6:8] != '\000\000':
our_cksum = inetutils.cksum(packet)
if our_cksum != 0:
raise ValueError, packet
elts = map(lambda x:x & 0xffff, struct.unpack('HHHH', packet[:8]))
[self.sport, self.dport, self.ulen, self.sum] = elts
self.data = packet[8:]
def _assemble(self, cksum=1):
self.ulen = 8 + len(self.data)
begin = struct.pack('HHH', self.sport, self.dport, self.ulen)
packet = begin + '\000\000' + self.data
if cksum:
self.sum = inetutils.cksum(packet)
packet = begin + struct.pack('H', self.sum) + self.data
self.__packet = inetutils.udph2net(packet)
return self.__packet
def outgoing_packet_handler(src_port, dst_addr, dst_port, data):
udp_frag = udp.Packet(sport=src_port, dport=dst_port, data=data)
udp_assembled = udp.assemble(udp_frag, False)
pseudo_header = socket.inet_aton(local_ip) + socket.inet_aton(
dst_addr) + '\x00\x11' + struct.pack('!H', len(udp_assembled))
cksum = inetutils.cksum(pseudo_header + udp_assembled)
udp_assembled_with_cksum = udp_assembled[:6] + struct.pack(
'H', cksum) + udp_assembled[8:]
out_sk.sendto(udp_assembled_with_cksum, (dst_addr, 0))
def _disassemble(self, buffer, cksum):
type, code = ord(buffer[0]), ord(buffer[1])
# when this method is called, type and code should be set correctly already
assert self.get_type() == type, "Mismatched type %d : %d" % (self.get_type(), type)
assert self.get_code() == code, "Mismatched code %d : %d" % (self.get_code(), code)
#only field let to puplate is cksum
if cksum and 0 != inetutils.cksum(buffer):
raise ValueError("CheckSum Error!")
self.__cksum = buffer[2:4]
self.__raw_packet = buffer
def create_ip_packet(src, dst, icmp_id, sequence_number):
"""Create a new echo request packet based on the given id."""
# Header is type (8), code (8), checksum (16), id (16), sequence (16)
sent_time = time.time()
icmp = struct.pack('!BBHHHd', ICMP_ECHO_REQUEST, 0, 0, icmp_id, sequence_number, sent_time)
# inetutils.cksum return unsigned short in network bytes order
icmp_checksum = inetutils.cksum(icmp)
# therefore we must convert it to host endianess than convert all icmp header to bytes array in network endianess
icmp = struct.pack('!BBHHHd', ICMP_ECHO_REQUEST, 0, socket.ntohs(icmp_checksum), icmp_id, sequence_number, sent_time)
# Build ip packet
# Give ipv4 destination and source address and data (icmp packet) as arguments
packet = ip.Packet(src=src, dst=dst, ttl=64, p=socket.IPPROTO_ICMP, data=icmp)
return packet._assemble(cksum=True)
def _assemble(self, cksum):
""" method to assemble into a byte sequence that is ready for being sent
This method will call the virtual method _get_icmp_data from its concrete
sub-class to get its payload
"""
packet = chr(self.get_type()) + chr(self.get_code()) + '\000\000' + self._get_icmp_data()
if cksum:
self.__cksum = struct.pack('H', inetutils.cksum(packet))
else:
self.__cksum = '\000\000'
self.__raw_packet = chr(self.get_type()) + chr(self.get_code()) + self.get_cksum() + self._get_icmp_data()
# Don't need to do any byte-swapping, because idseq is
# appplication defined and others are single byte values.
return self.__raw_packet
