#!/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.
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# distributed under the License is distributed on an "AS IS" BASIS,
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"""Traffic script that sends an ICMP/ICMPv6 packet out one interface, receives
a LISPGPE-encapsulated packet on the other interface and verifies received
packet.
"""

import sys

from scapy.all import bind_layers, Packet
from scapy.fields import FlagsField, BitField, XBitField, IntField
from scapy.layers.inet import ICMP, IP, UDP
from scapy.layers.inet6 import ICMPv6EchoRequest
from scapy.layers.inet6 import IPv6, ICMPv6ND_NS, ICMPv6MLReport2, ICMPv6ND_RA
from scapy.layers.l2 import Ether
from scapy.packet import Raw

from ..PacketVerifier import RxQueue, TxQueue
from ..TrafficScriptArg import TrafficScriptArg
from ..ValidIp import valid_ipv4, valid_ipv6


class LispGPEHeader(Packet):
    """Scapy header for the Lisp GPE Layer."""

    name = "Lisp GPE Header"
    fields_desc = [
        FlagsField(
            u"flags", None, 8, [u"N", u"L", u"E", u"V", u"I", u"P", u"R", u"O"]
        ),
        BitField(u"version", 0, size=2),
        BitField(u"reserved", 0, size=14),
        XBitField(u"next_protocol", 0, size=8),
        IntField(u"instance_id/locator_status_bits", 0)
    ]

    def guess_payload_class(self, payload):
        protocol = {
            0x1: LispGPEInnerIP,
            0x2: LispGPEInnerIPv6,
            0x3: LispGPEInnerEther,
            0x4: LispGPEInnerNSH
        }
        return protocol[self.next_protocol]


class LispGPEInnerIP(IP):
    """Scapy inner LISP GPE layer for IPv4-in-IPv4."""

    name = u"Lisp GPE Inner Layer - IPv4"


class LispGPEInnerIPv6(IPv6):
    """Scapy inner LISP GPE layer for IPv6-in-IPv6."""

    name = u"Lisp GPE Inner Layer - IPv6"


class LispGPEInnerEther(Ether):
    """Scapy inner LISP GPE layer for Lisp-L2."""

    name = u"Lisp GPE Inner Layer - Ethernet"


class LispGPEInnerNSH(Packet):
    """Scapy inner LISP GPE layer for Lisp-NSH.

    Parsing not implemented.
    """


def main():
    """Send IP ICMP packet from one traffic generator interface to the other.

    :raises RuntimeError: If the received packet is not correct."""

    args = TrafficScriptArg(
        [
            u"tg_src_mac", u"tg_dst_mac", u"src_ip", u"dst_ip", u"dut_if1_mac",
            u"dut_if2_mac", u"src_rloc", u"dst_rloc"
        ],
        [u"ot_mode"]
    )

    tx_src_mac = args.get_arg(u"tg_src_mac")
    tx_dst_mac = args.get_arg(u"dut_if1_mac")
    rx_dst_mac = args.get_arg(u"tg_dst_mac")
    rx_src_mac = args.get_arg(u"dut_if2_mac")
    src_ip = args.get_arg(u"src_ip")
    dst_ip = args.get_arg(u"dst_ip")
    src_rloc = args.get_arg(u"src_rloc")
    dst_rloc = args.get_arg(u"dst_rloc")
    tx_if = args.get_arg(u"tx_if")
    rx_if = args.get_arg(u"rx_if")
    ot_mode = args.get_arg(u"ot_mode")

    rxq = RxQueue(rx_if)
    txq = TxQueue(tx_if)

    pkt_raw = Ether(src=tx_src_mac, dst=tx_dst_mac)

    if valid_ipv4(src_ip) and valid_ipv4(dst_ip):
        pkt_raw /= IP(src=src_ip, dst=dst_ip)
        pkt_raw /= ICMP()
        ip_format = IP
    elif valid_ipv6(src_ip) and valid_ipv6(dst_ip):
        pkt_raw /= IPv6(src=src_ip, dst=dst_ip)
        pkt_raw /= ICMPv6EchoRequest()
        ip_format = IPv6
    else:
        raise ValueError(u"IP not in correct format")

    bind_layers(UDP, LispGPEHeader, dport=4341)

    pkt_raw /= Raw()
    sent_packets = list()
    sent_packets.append(pkt_raw)
    txq.send(pkt_raw)

    while True:
        if tx_if == rx_if:
            ether = rxq.recv(2, ignore=sent_packets)
        else:
            ether = rxq.recv(2)

        if ether is None:
            raise RuntimeError(u"ICMP echo Rx timeout")

        if ether.haslayer(ICMPv6ND_NS):
            # read another packet in the queue if the current one is ICMPv6ND_NS
            continue
        if ether.haslayer(ICMPv6ND_RA):
            # read another packet in the queue if the current one is ICMPv6ND_RA
            continue
        elif ether.haslayer(ICMPv6MLReport2):
            # read another packet in the queue if the current one is
            # ICMPv6MLReport2
            continue

        # otherwise process the current packet
        break

    if rx_dst_mac == ether[Ether].dst and rx_src_mac == ether[Ether].src:
        print(u"MAC addresses match.")
    else:
        raise RuntimeError(f"Matching packet unsuccessful: {ether!r}")

    ip = ether.payload

    if ot_mode == u"6to4":
        if not isinstance(ip, IP):
            raise RuntimeError(f"Not an IP packet received {ip!r}")
    elif ot_mode == u"4to6":
        if not isinstance(ip, IPv6):
            raise RuntimeError(f"Not an IP packet received {ip!r}")
    elif not isinstance(ip, ip_format):
        raise RuntimeError(f"Not an IP packet received {ip!r}")

    lisp = ether.getlayer(LispGPEHeader).underlayer
    if not lisp:
        raise RuntimeError(u"Lisp layer not present or parsing failed.")

    # Compare data from packets
    if src_ip == lisp.src:
        print(u"Source IP matches source EID.")
    else:
        raise RuntimeError(
            f"Matching Src IP unsuccessful: {src_ip} != {lisp.src}"
        )

    if dst_ip == lisp.dst:
        print(u"Destination IP matches destination EID.")
    else:
        raise RuntimeError(
            f"Matching Dst IP unsuccessful: {dst_ip} != {lisp.dst}"
        )

    if src_rloc == ip.src:
        print(u"Source RLOC matches configuration.")
    else:
        raise RuntimeError(
            f"Matching Src RLOC unsuccessful: {src_rloc} != {ip.src}"
        )

    if dst_rloc == ip.dst:
        print(u"Destination RLOC matches configuration.")
    else:
        raise RuntimeError(
            f"Matching dst RLOC unsuccessful: {dst_rloc} != {ip.dst}"
        )

    sys.exit(0)


if __name__ == u"__main__":
    main()