IPv4/6 reassembly
Change-Id: Ic5dcadd13c88b8a5e7896dab82404509c081614a Signed-off-by: Klement Sekera <ksekera@cisco.com>
This commit is contained in:
Klement Sekera
committed by
Florin Coras
Florin Coras
parent
2b9453c55a
commit
75e7d13014
195
test/util.py
195
test/util.py
@ -8,10 +8,10 @@ from scapy.layers.inet6 import in6_mactoifaceid
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from scapy.layers.l2 import Ether
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from scapy.packet import Raw
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from scapy.layers.inet import IP, UDP, TCP
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from scapy.layers.inet6 import IPv6, ICMPv6Unknown, ICMPv6EchoRequest
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from scapy.packet import Packet
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from socket import inet_pton, AF_INET, AF_INET6
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from scapy.layers.inet import IP
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from scapy.layers.inet6 import IPv6, IPv6ExtHdrFragment, IPv6ExtHdrRouting,\
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IPv6ExtHdrHopByHop
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from socket import AF_INET6
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def ppp(headline, packet):
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@ -37,8 +37,7 @@ def ppc(headline, capture, limit=10):
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tail = ""
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if limit < len(capture):
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tail = "\nPrint limit reached, %s out of %s packets printed" % (
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len(capture), limit)
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limit = len(capture)
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limit, len(capture))
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body = "".join([ppp("Packet #%s:" % count, p)
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for count, p in zip(range(0, limit), capture)])
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return "%s\n%s%s" % (headline, body, tail)
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@ -174,6 +173,7 @@ class ForeignAddressFactory(object):
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class L4_Conn():
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""" L4 'connection' tied to two VPP interfaces """
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def __init__(self, testcase, if1, if2, af, l4proto, port1, port2):
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self.testcase = testcase
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self.ifs = [None, None]
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@ -189,7 +189,7 @@ class L4_Conn():
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def pkt(self, side, l4args={}, payload="x"):
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is_ip6 = 1 if self.address_family == AF_INET6 else 0
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s0 = side
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s1 = 1-side
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s1 = 1 - side
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src_if = self.ifs[s0]
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dst_if = self.ifs[s1]
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layer_3 = [IP(src=src_if.remote_ip4, dst=dst_if.remote_ip4),
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@ -208,7 +208,7 @@ class L4_Conn():
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l4args['flags'] = flags
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self.ifs[side].add_stream(self.pkt(side,
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l4args=l4args, payload=payload))
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self.ifs[1-side].enable_capture()
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self.ifs[1 - side].enable_capture()
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self.testcase.pg_start()
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def recv(self, side):
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@ -217,15 +217,190 @@ class L4_Conn():
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def send_through(self, side, flags=None, payload=""):
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self.send(side, flags, payload)
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p = self.recv(1-side)
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p = self.recv(1 - side)
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return p
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def send_pingpong(self, side, flags1=None, flags2=None):
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p1 = self.send_through(side, flags1)
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p2 = self.send_through(1-side, flags2)
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p2 = self.send_through(1 - side, flags2)
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return [p1, p2]
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class L4_CONN_SIDE:
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L4_CONN_SIDE_ZERO = 0
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L4_CONN_SIDE_ONE = 1
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class LoggerWrapper(object):
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def __init__(self, logger=None):
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self._logger = logger
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def debug(self, *args, **kwargs):
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if self._logger:
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self._logger.debug(*args, **kwargs)
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def error(self, *args, **kwargs):
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if self._logger:
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self._logger.error(*args, **kwargs)
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def fragment_rfc791(packet, fragsize, _logger=None):
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"""
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Fragment an IPv4 packet per RFC 791
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:param packet: packet to fragment
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:param fragsize: size at which to fragment
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:note: IP options are not supported
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:returns: list of fragments
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"""
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logger = LoggerWrapper(_logger)
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logger.debug(ppp("Fragmenting packet:", packet))
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packet = packet.__class__(str(packet)) # recalculate all values
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if len(packet[IP].options) > 0:
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raise Exception("Not implemented")
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if len(packet) <= fragsize:
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return [packet]
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pre_ip_len = len(packet) - len(packet[IP])
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ip_header_len = packet[IP].ihl * 4
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hex_packet = str(packet)
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hex_headers = hex_packet[:(pre_ip_len + ip_header_len)]
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hex_payload = hex_packet[(pre_ip_len + ip_header_len):]
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pkts = []
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ihl = packet[IP].ihl
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otl = len(packet[IP])
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nfb = (fragsize - pre_ip_len - ihl * 4) / 8
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fo = packet[IP].frag
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p = packet.__class__(hex_headers + hex_payload[:nfb * 8])
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p[IP].flags = "MF"
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p[IP].frag = fo
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p[IP].len = ihl * 4 + nfb * 8
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del p[IP].chksum
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pkts.append(p)
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p = packet.__class__(hex_headers + hex_payload[nfb * 8:])
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p[IP].len = otl - nfb * 8
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p[IP].frag = fo + nfb
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del p[IP].chksum
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more_fragments = fragment_rfc791(p, fragsize, _logger)
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pkts.extend(more_fragments)
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return pkts
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def fragment_rfc8200(packet, identification, fragsize, _logger=None):
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"""
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Fragment an IPv6 packet per RFC 8200
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:param packet: packet to fragment
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:param fragsize: size at which to fragment
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:note: IP options are not supported
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:returns: list of fragments
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"""
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logger = LoggerWrapper(_logger)
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packet = packet.__class__(str(packet)) # recalculate all values
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if len(packet) <= fragsize:
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return [packet]
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logger.debug(ppp("Fragmenting packet:", packet))
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pkts = []
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counter = 0
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routing_hdr = None
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hop_by_hop_hdr = None
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upper_layer = None
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seen_ipv6 = False
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ipv6_nr = -1
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l = packet.getlayer(counter)
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while l is not None:
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if l.__class__ is IPv6:
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if seen_ipv6:
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# ignore 2nd IPv6 header and everything below..
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break
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ipv6_nr = counter
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seen_ipv6 = True
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elif l.__class__ is IPv6ExtHdrFragment:
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raise Exception("Already fragmented")
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elif l.__class__ is IPv6ExtHdrRouting:
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routing_hdr = counter
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elif l.__class__ is IPv6ExtHdrHopByHop:
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hop_by_hop_hdr = counter
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elif seen_ipv6 and not upper_layer and \
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not l.__class__.__name__.startswith('IPv6ExtHdr'):
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upper_layer = counter
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counter = counter + 1
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l = packet.getlayer(counter)
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logger.debug(
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"Layers seen: IPv6(#%s), Routing(#%s), HopByHop(#%s), upper(#%s)" %
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(ipv6_nr, routing_hdr, hop_by_hop_hdr, upper_layer))
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if upper_layer is None:
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raise Exception("Upper layer header not found in IPv6 packet")
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last_per_fragment_hdr = ipv6_nr
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if routing_hdr is None:
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if hop_by_hop_hdr is not None:
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last_per_fragment_hdr = hop_by_hop_hdr
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else:
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last_per_fragment_hdr = routing_hdr
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logger.debug("Last per-fragment hdr is #%s" % (last_per_fragment_hdr))
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per_fragment_headers = packet.copy()
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per_fragment_headers[last_per_fragment_hdr].remove_payload()
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logger.debug(ppp("Per-fragment headers:", per_fragment_headers))
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ext_and_upper_layer = packet.getlayer(last_per_fragment_hdr)[1]
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hex_payload = str(ext_and_upper_layer)
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logger.debug("Payload length is %s" % len(hex_payload))
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logger.debug(ppp("Ext and upper layer:", ext_and_upper_layer))
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fragment_ext_hdr = IPv6ExtHdrFragment()
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logger.debug(ppp("Fragment header:", fragment_ext_hdr))
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if len(per_fragment_headers) + len(fragment_ext_hdr) +\
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len(ext_and_upper_layer) - len(ext_and_upper_layer.payload)\
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> fragsize:
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raise Exception("Cannot fragment this packet - MTU too small "
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"(%s, %s, %s, %s, %s)" % (
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len(per_fragment_headers), len(fragment_ext_hdr),
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len(ext_and_upper_layer),
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len(ext_and_upper_layer.payload), fragsize))
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orig_nh = packet[IPv6].nh
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p = per_fragment_headers
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del p[IPv6].plen
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del p[IPv6].nh
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p = p / fragment_ext_hdr
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del p[IPv6ExtHdrFragment].nh
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first_payload_len_nfb = (fragsize - len(p)) / 8
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p = p / Raw(hex_payload[:first_payload_len_nfb * 8])
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del p[IPv6].plen
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p[IPv6ExtHdrFragment].nh = orig_nh
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p[IPv6ExtHdrFragment].id = identification
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p[IPv6ExtHdrFragment].offset = 0
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p[IPv6ExtHdrFragment].m = 1
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p = p.__class__(str(p))
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logger.debug(ppp("Fragment %s:" % len(pkts), p))
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pkts.append(p)
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offset = first_payload_len_nfb * 8
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logger.debug("Offset after first fragment: %s" % offset)
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while len(hex_payload) > offset:
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p = per_fragment_headers
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del p[IPv6].plen
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del p[IPv6].nh
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p = p / fragment_ext_hdr
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del p[IPv6ExtHdrFragment].nh
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l_nfb = (fragsize - len(p)) / 8
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p = p / Raw(hex_payload[offset:offset + l_nfb * 8])
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p[IPv6ExtHdrFragment].nh = orig_nh
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p[IPv6ExtHdrFragment].id = identification
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p[IPv6ExtHdrFragment].offset = offset / 8
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p[IPv6ExtHdrFragment].m = 1
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p = p.__class__(str(p))
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logger.debug(ppp("Fragment %s:" % len(pkts), p))
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pkts.append(p)
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offset = offset + l_nfb * 8
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pkts[-1][IPv6ExtHdrFragment].m = 0 # reset more-flags in last fragment
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return pkts
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