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#!/usr/bin/env python3
# Copyright (c) 2021 Cisco and/or its affiliates.
#
# SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
#
# Licensed under the Apache License 2.0 or
# GNU General Public License v2.0 or later; you may not use this file
# except in compliance with one of these Licenses. You
# may obtain a copy of the Licenses at:
#
# http://www.apache.org/licenses/LICENSE-2.0
# https://www.gnu.org/licenses/old-licenses/gpl-2.0-standalone.html
#
# Note: If this file is linked with Scapy, which is GPLv2+, your use of it
# must be under GPLv2+. If at any point in the future it is no longer linked
# with Scapy (or other GPLv2+ licensed software), you are free to choose
# Apache 2.
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Traffic script for NAT verification."""
import sys
import ipaddress
from scapy.layers.inet import IP, TCP, UDP
from scapy.layers.inet6 import IPv6, ICMPv6ND_NS
from scapy.layers.l2 import Ether
from scapy.packet import Raw
from .PacketVerifier import RxQueue, TxQueue
from .TrafficScriptArg import TrafficScriptArg
def valid_ipv4(ip):
try:
ipaddress.IPv4Address(ip)
return True
except (AttributeError, ipaddress.AddressValueError):
return False
def valid_ipv6(ip):
try:
ipaddress.IPv6Address(ip)
return True
except (AttributeError, ipaddress.AddressValueError):
return False
def main():
"""Send, receive and check IP/IPv6 packets with UDP/TCP layer passing
through NAT.
"""
args = TrafficScriptArg(
[
u"tx_src_mac", u"rx_dst_mac", u"src_ip_in", u"src_ip_out",
u"dst_ip", u"tx_dst_mac", u"rx_src_mac", u"protocol",
u"src_port_in", u"src_port_out", u"dst_port"
]
)
tx_src_mac = args.get_arg(u"tx_src_mac")
tx_dst_mac = args.get_arg(u"tx_dst_mac")
rx_dst_mac = args.get_arg(u"rx_dst_mac")
rx_src_mac = args.get_arg(u"rx_src_mac")
src_ip_in = args.get_arg(u"src_ip_in")
src_ip_out = args.get_arg(u"src_ip_out")
dst_ip = args.get_arg(u"dst_ip")
protocol = args.get_arg(u"protocol")
sport_in = int(args.get_arg(u"src_port_in"))
try:
sport_out = int(args.get_arg(u"src_port_out"))
except ValueError:
sport_out = None
dst_port = int(args.get_arg(u"dst_port"))
tx_txq = TxQueue(args.get_arg(u"tx_if"))
tx_rxq = RxQueue(args.get_arg(u"tx_if"))
rx_txq = TxQueue(args.get_arg(u"rx_if"))
rx_rxq = RxQueue(args.get_arg(u"rx_if"))
sent_packets = list()
pkt_raw = Ether(src=tx_src_mac, dst=tx_dst_mac)
if valid_ipv4(src_ip_in) and valid_ipv4(dst_ip):
ip_layer = IP
elif valid_ipv6(src_ip_in) and valid_ipv6(dst_ip):
ip_layer = IPv6
else:
raise ValueError(u"IP not in correct format")
pkt_raw /= ip_layer(src=src_ip_in, dst=dst_ip)
if protocol == u"UDP":
pkt_raw /= UDP(sport=sport_in, dport=dst_port)
proto_layer = UDP
elif protocol == u"TCP":
# flags=0x2 => SYN flag set
pkt_raw /= TCP(sport=sport_in, dport=dst_port, flags=0x2)
proto_layer = TCP
else:
raise ValueError(u"Incorrect protocol")
pkt_raw /= Raw()
sent_packets.append(pkt_raw)
tx_txq.send(pkt_raw)
while True:
ether = rx_rxq.recv(2)
if ether is None:
raise RuntimeError(u"IP packet Rx timeout")
if ether.haslayer(ICMPv6ND_NS):
# read another packet in the queue if the current one is ICMPv6ND_NS
continue
else:
# otherwise process the current packet
break
if rx_dst_mac != ether[Ether].dst or rx_src_mac != ether[Ether].src:
raise RuntimeError(f"Matching packet unsuccessful: {ether!r}")
ip_pkt = ether.payload
if not isinstance(ip_pkt, ip_layer):
raise RuntimeError(f"Not an {ip_layer!s} packet received: {ip_pkt!r}")
if ip_pkt.src != src_ip_out:
raise RuntimeError(
f"Matching Src IP address unsuccessful: "
f"{src_ip_out} != {ip_pkt.src}"
)
if ip_pkt.dst != dst_ip:
raise RuntimeError(
f"Matching Dst IP address unsuccessful: {dst_ip} != {ip_pkt.dst}"
)
proto_pkt = ip_pkt.payload
if not isinstance(proto_pkt, proto_layer):
raise RuntimeError(
f"Not a {proto_layer!s} packet received: {proto_pkt!r}"
)
if sport_out is not None:
if proto_pkt.sport != sport_out:
raise RuntimeError(
f"Matching Src {proto_layer!s} port unsuccessful: "
f"{sport_out} != {proto_pkt.sport}"
)
else:
sport_out = proto_pkt.sport
if proto_pkt.dport != dst_port:
raise RuntimeError(
f"Matching Dst {proto_layer!s} port unsuccessful: "
f"{dst_port} != {proto_pkt.dport}"
)
if proto_layer == TCP:
if proto_pkt.flags != 0x2:
raise RuntimeError(
f"Not a TCP SYN packet received: {proto_pkt!r}"
)
pkt_raw = Ether(src=rx_dst_mac, dst=rx_src_mac)
pkt_raw /= ip_layer(src=dst_ip, dst=src_ip_out)
pkt_raw /= proto_layer(sport=dst_port, dport=sport_out)
if proto_layer == TCP:
# flags=0x12 => SYN, ACK flags set
pkt_raw[TCP].flags = 0x12
pkt_raw /= Raw()
rx_txq.send(pkt_raw)
while True:
ether = tx_rxq.recv(2, ignore=sent_packets)
if ether is None:
raise RuntimeError(u"IP packet Rx timeout")
if ether.haslayer(ICMPv6ND_NS):
# read another packet in the queue if the current one is ICMPv6ND_NS
continue
else:
# otherwise process the current packet
break
if ether[Ether].dst != tx_src_mac or ether[Ether].src != tx_dst_mac:
raise RuntimeError(f"Matching packet unsuccessful: {ether!r}")
ip_pkt = ether.payload
if not isinstance(ip_pkt, ip_layer):
raise RuntimeError(f"Not an {ip_layer!s} packet received: {ip_pkt!r}")
if ip_pkt.src != dst_ip:
raise RuntimeError(
f"Matching Src IP address unsuccessful: {dst_ip} != {ip_pkt.src}"
)
if ip_pkt.dst != src_ip_in:
raise RuntimeError(
f"Matching Dst IP address unsuccessful: {src_ip_in} != {ip_pkt.dst}"
)
proto_pkt = ip_pkt.payload
if not isinstance(proto_pkt, proto_layer):
raise RuntimeError(
f"Not a {proto_layer!s} packet received: {proto_pkt!r}"
)
if proto_pkt.sport != dst_port:
raise RuntimeError(
f"Matching Src {proto_layer!s} port unsuccessful: "
f"{dst_port} != {proto_pkt.sport}"
)
if proto_pkt.dport != sport_in:
raise RuntimeError(
f"Matching Dst {proto_layer!s} port unsuccessful: "
f"{sport_in} != {proto_pkt.dport}"
)
if proto_layer == TCP:
if proto_pkt.flags != 0x12:
raise RuntimeError(
f"Not a TCP SYN-ACK packet received: {proto_pkt!r}"
)
sys.exit(0)
if __name__ == u"__main__":
main()
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