def incoming_packet_handler(pktlen, data, timestamp):
if not data or data[12:14] != '\x08\x00':
return
ip_pkt = ip.disassemble(data[14:])
udp_frag = udp.disassemble(ip_pkt.data, False)
data_str = udp_frag.data.encode('hex') if udp_frag.data != '' else '-'
sys.stdout.write("{} {} {} {}\n".format(ip_pkt.src, udp_frag.sport, udp_frag.dport, data_str))
sys.stdout.flush()
def incoming_packet_handler(pktlen, data, timestamp):
if not data or data[12:14] != '\x08\x00':
return
ip_pkt = ip.disassemble(data[14:])
udp_frag = udp.disassemble(ip_pkt.data, False)
data_str = udp_frag.data.encode('hex') if udp_frag.data != '' else '-'
sys.stdout.write("{} {} {} {}\n".format(ip_pkt.src, udp_frag.sport,
udp_frag.dport, data_str))
sys.stdout.flush()
def testUdpPortWronlyParsed(self):
ip_reply = ip.disassemble(self.pkt)
icmp_reply = icmp.disassemble(ip_reply.data) #ICMP is payload of IP
inner_ip = icmp_reply.get_embedded_ip()
self.assertEqual('10.249.64.152', inner_ip.src)
self.assertEqual('207.68.173.76', inner_ip.dst)
udp_in_icmp = udp.disassemble(inner_ip.data, 0)
self.assertEqual(40164, udp_in_icmp.sport)
self.assertEqual(33435, udp_in_icmp.dport)
def testUdpPortWronlyParsed(self):
ip_reply = ip.disassemble(self.pkt)
icmp_reply = icmp.disassemble(ip_reply.data) #ICMP is payload of IP
inner_ip = icmp_reply.get_embedded_ip()
self.assertEqual('10.249.64.152', inner_ip.src)
self.assertEqual('207.68.173.76', inner_ip.dst)
udp_in_icmp = udp.disassemble(inner_ip.data, 0)
self.assertEqual(40164, udp_in_icmp.sport)
self.assertEqual(33435, udp_in_icmp.dport)
class UDPProbe(Probe):
def probe_packet(self):
""" Build the outgoing probe packet
"""
# build the packet, then set its length
probe_ip = ip.Packet()
probe_ip.src = self.src_addr
probe_ip.dst = self.dst_addr
probe_ip.p = socket.IPPROTO_UDP
probe_ip.ttl = self.ttl
probe_ip.df = self.dont_frag
# build UPD packet as the payload of IP packet
probe_udp = udp.Packet()
# Because more than 1 traceroute can be running at the same time, we need to
# distinguish the packets responding to this traceroute instance. We do this
# by setting source port in UDP header to our process id. As ICMP will include
# UDP header that triggers it in the payload, we will be able to compare the
# UDP source port embedded in returned ICMP packet with our process id and
# determine if the packet is of our interest.
probe_udp.sport = self.src_port
probe_udp.dport = self.dst_port
# calculate the length of UDP data
header_len = len(udp.assemble(probe_udp) + ip.assemble(probe_ip))
if self.packet_len <= header_len:
raise TraceError, "packet length must be > %d" % (header_len)
probe_udp.data = '\000' * (self.packet_len - header_len)
probe_ip.data = udp.assemble(probe_udp)
return ip.assemble(probe_ip, self.check_sum)
def received(self, pkt, gateway):
""" Upon received an incoming ICMP, determine if the packet is of our interest
If it is, populate related fields, and return 1
otherwise return 0
"""
ip_reply = ip.disassemble(pkt)
if icmp.HDR_SIZE_IN_BYTES > len(ip_reply.data):
return 0 #IP payload is not long enough to hold ICMP
try:
icmp_reply = icmp.disassemble(
ip_reply.data) #ICMP is payload of IP
except ValueError, msg:
if DEBUG:
stdout.write("Bad Packet received!")
return 0
if DEBUG:
stdout.write(
"recvfrom %s: ICMP_type: %d ICMP_code: %d" %
(gateway, icmp_reply.get_type(), icmp_reply.get_code()))
# 2 conditions interest us:
# 1. ICMP_TIMEEXCEED, probe packet dropped by gateway in the middle,
# which then send ICMP_TIMEEXCEED back to us
# 2. ICMP_UNREACH, probe packet reach destination host, which (we assume)
# is not listening on the port hence send ICMP_UNREACH back to us
if (isinstance(icmp_reply, icmp.TimeExceeded) \
and icmp_reply.get_code() == icmp.ICMP_TIMXCEED_INTRANS) \
or isinstance(icmp_reply, icmp.Unreachable) :
inner_ip = icmp_reply.get_embedded_ip()
if inner_ip.src != self.src_addr or inner_ip.dst != self.dst_addr:
return 0
if udp.HDR_SIZE_IN_BYTES > len(inner_ip.data):
return 0 #Not enough data for UDP
udp_in_icmp = udp.disassemble(inner_ip.data, 0)
if udp_in_icmp.sport == self.src_port \
and udp_in_icmp.dport == self.dst_port:
self.gateway = gateway
self.timestamp_received = time.time()
if icmp_reply.get_type() == icmp.ICMP_UNREACH:
self.dst_reached = 1
return 1
if self.verbose: # In verbose mode, ICMP packets other than IME_EXCEEDED and UNREACHABLE are listed
stdout.write(
"recvfrom %s: ICMP_type: %d ICMP_code: %d" %
(gateway, icmp_reply.get_type(), icmp_reply.get_code()))
return 0
def testSimplePacket(self):
buf = udp.assemble(self.simple, 1)
new = udp.disassemble(buf, 1)
self.assertEqual(self.simple, new)
def testSimplePacket(self):
buf = udp.assemble(self.simple, 1)
new = udp.disassemble(buf, 1)
self.assertEqual(self.simple, new)
