#!/usr/bin/env python
# Copyright (c) 2016 Cisco and/or its affiliates.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# 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 that sends an empty IPv4 UDP datagram encapsulated in IPv6
and checks if is correctly re-encapsulated."""

import sys

from scapy.layers.l2 import Ether
from scapy.layers.inet6 import IPv6
from scapy.layers.inet import IP, UDP

from resources.libraries.python.PacketVerifier import RxQueue, TxQueue
from resources.libraries.python.TrafficScriptArg import TrafficScriptArg


def _is_ipv4_in_ipv6(pkt):
    """If IPv6 next header type in the given pkt is IPv4, return True,
    else return False. False is returned also if exception occurs."""
    ipv6_type = int('0x86dd', 16)  # IPv6
    try:
        if pkt.type == ipv6_type:
            if pkt.payload.nh == 4:
                return True
    except:  # pylint: disable=bare-except
        return False
    return False


def main():  # pylint: disable=too-many-statements, too-many-locals
    """Main function of the script file."""
    args = TrafficScriptArg(['tx_dst_mac',
                             'tx_dst_ipv6', 'tx_src_ipv6',
                             'tx_dst_ipv4', 'tx_src_ipv4',
                             'tx_dst_udp_port', 'tx_src_udp_port',
                             'rx_dst_mac', 'rx_src_mac',
                             'rx_dst_ipv6', 'rx_src_ipv6'])
    rx_if = args.get_arg('rx_if')
    tx_if = args.get_arg('tx_if')
    tx_dst_mac = args.get_arg('tx_dst_mac')
    tx_src_mac = '02:00:00:00:00:01'

    tx_dst_ipv6 = args.get_arg('tx_dst_ipv6')
    tx_src_ipv6 = args.get_arg('tx_src_ipv6')
    tx_dst_ipv4 = args.get_arg('tx_dst_ipv4')
    tx_src_ipv4 = args.get_arg('tx_src_ipv4')
    tx_dst_udp_port = int(args.get_arg('tx_dst_udp_port'))
    tx_src_udp_port = int(args.get_arg('tx_src_udp_port'))
    rx_dst_mac = args.get_arg('rx_dst_mac')
    rx_src_mac = args.get_arg('rx_src_mac')
    rx_dst_ipv6 = args.get_arg('rx_dst_ipv6')
    rx_src_ipv6 = args.get_arg('rx_src_ipv6')

    rxq = RxQueue(rx_if)
    txq = TxQueue(tx_if)
    sent_packets = []

    # Create empty UDP datagram in IPv4 and IPv6
    tx_pkt = Ether(dst=tx_dst_mac, src=tx_src_mac)
    tx_pkt /= IPv6(src=tx_src_ipv6, dst=tx_dst_ipv6)
    tx_pkt /= IP(src=tx_src_ipv4, dst=tx_dst_ipv4)
    tx_pkt /= UDP(sport=tx_src_udp_port, dport=tx_dst_udp_port)
    tx_pkt /= 'udp_payload'

    txq.send(tx_pkt)
    sent_packets.append(tx_pkt)

    for _ in range(5):
        pkt = rxq.recv(2, ignore=sent_packets)
        if _is_ipv4_in_ipv6(pkt):
            ether = pkt
            break
    else:
        raise RuntimeError("IPv4 in IPv6 Rx error.")

    # check ethernet
    if ether.dst != rx_dst_mac:
        raise RuntimeError("Destination MAC error {} != {}.".
                           format(ether.dst, rx_dst_mac))
    print "Destination MAC: OK."

    if ether.src != rx_src_mac:
        raise RuntimeError("Source MAC error {} != {}.".
                           format(ether.src, rx_src_mac))
    print "Source MAC: OK."

    ipv6 = ether.payload

    # check ipv6
    if ipv6.dst != rx_dst_ipv6:
        raise RuntimeError("Destination IPv6 error {} != {}.".
                           format(ipv6.dst, rx_dst_ipv6))
    print "Destination IPv6: OK."

    if ipv6.src != rx_src_ipv6:
        raise RuntimeError("Source IPv6 error {} != {}.".
                           format(ipv6.src, rx_src_ipv6))
    print "Source IPv6: OK."

    ipv4 = ipv6.payload

    # check ipv4
    if ipv4.dst != tx_dst_ipv4:
        raise RuntimeError("Destination IPv4 error {} != {}.".
                           format(ipv4.dst, tx_dst_ipv4))
    print "Destination IPv4: OK."

    if ipv4.src != tx_src_ipv4:
        raise RuntimeError("Source IPv4 error {} != {}.".
                           format(ipv4.src, tx_src_ipv4))
    print "Source IPv4: OK."

    if ipv4.proto != 17:  # UDP
        raise RuntimeError("IPv4 protocol error {} != UDP.".
                           format(ipv4.proto))
    print "IPv4 protocol: OK."

    udp = ipv4.payload

    # check udp
    if udp.dport != tx_dst_udp_port:
        raise RuntimeError("UDP dport error {} != {}.".
                           format(udp.dport, tx_dst_udp_port))
    print "UDP dport: OK."

    if udp.sport != tx_src_udp_port:
        raise RuntimeError("UDP sport error {} != {}.".
                           format(udp.sport, tx_src_udp_port))
    print "UDP sport: OK."

    sys.exit(0)

if __name__ == "__main__":
    main()