#!/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 for IPv6 Neighbor Solicitation test."""

import sys
import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
from resources.libraries.python.PacketVerifier import RxQueue, TxQueue,\
    checksum_equal
from resources.libraries.python.TrafficScriptArg import TrafficScriptArg
from scapy.layers.inet6 import IPv6, ICMPv6ND_NA, ICMPv6ND_NS
from scapy.layers.inet6 import ICMPv6NDOptDstLLAddr, ICMPv6NDOptSrcLLAddr
from scapy.all import Ether


def main():
    args = TrafficScriptArg(['src_mac', 'dst_mac', 'src_ip', 'dst_ip'])

    rxq = RxQueue(args.get_arg('rx_if'))
    txq = TxQueue(args.get_arg('tx_if'))

    src_mac = args.get_arg('src_mac')
    dst_mac = args.get_arg('dst_mac')
    src_ip = args.get_arg('src_ip')
    dst_ip = args.get_arg('dst_ip')

    sent_packets = []

    # send ICMPv6 neighbor solicitation message
    pkt_send = (Ether(src=src_mac, dst='ff:ff:ff:ff:ff:ff') /
                      IPv6(src=src_ip, dst='ff02::1:ff00:2') /
                      ICMPv6ND_NS(tgt=dst_ip) /
                      ICMPv6NDOptSrcLLAddr(lladdr=src_mac))
    sent_packets.append(pkt_send)
    txq.send(pkt_send)

    # receive ICMPv6 neighbor advertisement message
    ether = rxq.recv(2, sent_packets)
    if ether is None:
        raise RuntimeError('ICMPv6 echo reply Rx timeout')

    if not ether.haslayer(IPv6):
        raise RuntimeError('Unexpected packet with no IPv6 received {0}'.format(
            ether.__repr__()))

    ipv6 = ether['IPv6']

    if not ipv6.haslayer(ICMPv6ND_NA):
        raise RuntimeError(
            'Unexpected packet with no ICMPv6 ND-NA received {0}'.format(
                ipv6.__repr__()))

    icmpv6_na = ipv6['ICMPv6 Neighbor Discovery - Neighbor Advertisement']

    # verify target address
    if icmpv6_na.tgt != dst_ip:
        raise RuntimeError('Invalid target address {0} should be {1}'.format(
            icmpv6_na.tgt, dst_ip))

    if not icmpv6_na.haslayer(ICMPv6NDOptDstLLAddr):
        raise RuntimeError(
            'Missing Destination Link-Layer Address option in ICMPv6 ' +
            'Neighbor Advertisement {0}'.format(icmpv6_na.__repr__()))

    option = 'ICMPv6 Neighbor Discovery Option - Destination Link-Layer Address'
    dst_ll_addr = icmpv6_na[option]

    # verify destination link-layer address field
    if dst_ll_addr.lladdr != dst_mac:
        raise RuntimeError('Invalid lladdr {0} should be {1}'.format(
            dst_ll_addr.lladdr, dst_mac))

    # verify checksum
    cksum = icmpv6_na.cksum
    del icmpv6_na.cksum
    tmp = ICMPv6ND_NA(str(icmpv6_na))
    if not checksum_equal(tmp.cksum, cksum):
        raise RuntimeError(
            'Invalid checksum {0} should be {1}'.format(cksum, tmp.cksum))

    sys.exit(0)

if __name__ == "__main__":
    main()