#!/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.

"""Send ICMPv6 echo request from one TG port to another through DUT nodes and
   send reply back. Also verify hop limit processing."""

import sys
import logging

# pylint: disable=no-name-in-module
# pylint: disable=import-error
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)

from scapy.layers.inet6 import IPv6, ICMPv6ND_NA, ICMPv6ND_NS
from scapy.layers.inet6 import ICMPv6NDOptDstLLAddr
from scapy.layers.inet6 import ICMPv6EchoRequest, ICMPv6EchoReply
from scapy.all import Ether

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


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

    src_rxq = RxQueue(args.get_arg('rx_if'))
    src_txq = TxQueue(args.get_arg('rx_if'))
    dst_rxq = RxQueue(args.get_arg('tx_if'))
    dst_txq = TxQueue(args.get_arg('tx_if'))

    src_mac = args.get_arg('src_mac')
    dst_mac = args.get_arg('dst_mac')
    src_nh_mac = args.get_arg('src_nh_mac')
    dst_nh_mac = args.get_arg('dst_nh_mac')
    src_ip = args.get_arg('src_ip')
    dst_ip = args.get_arg('dst_ip')
    hop_num = int(args.get_arg('h_num'))
    hop_limit = 64
    echo_id = 0xa
    echo_seq = 0x1

    src_sent_packets = []
    dst_sent_packets = []

    # send ICMPv6 neighbor advertisement message
    pkt_send = (Ether(src=src_mac, dst='ff:ff:ff:ff:ff:ff') /
                IPv6(src=src_ip, dst='ff02::1:ff00:2') /
                ICMPv6ND_NA(tgt=src_ip, R=0) /
                ICMPv6NDOptDstLLAddr(lladdr=src_mac))
    src_sent_packets.append(pkt_send)
    src_txq.send(pkt_send)
    pkt_send = (Ether(src=dst_mac, dst='ff:ff:ff:ff:ff:ff') /
                IPv6(src=dst_ip, dst='ff02::1:ff00:2') /
                ICMPv6ND_NA(tgt=dst_ip, R=0) /
                ICMPv6NDOptDstLLAddr(lladdr=dst_mac))
    dst_sent_packets.append(pkt_send)
    dst_txq.send(pkt_send)

    # send ICMPv6 echo request from first TG interface
    pkt_send = (Ether(src=src_mac, dst=src_nh_mac) /
                IPv6(src=src_ip, dst=dst_ip, hlim=hop_limit) /
                ICMPv6EchoRequest(id=echo_id, seq=echo_seq))
    src_sent_packets.append(pkt_send)
    src_txq.send(pkt_send)

    # receive ICMPv6 echo request on second TG interface
    while True:
        ether = dst_rxq.recv(2, dst_sent_packets)
        if ether is None:
            raise RuntimeError('ICMPv6 echo reply 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 not ether.haslayer(IPv6):
        raise RuntimeError('Unexpected packet with no IPv6 received: {0}'.
                           format(ether.__repr__()))

    ipv6 = ether[IPv6]

    # verify hop limit processing
    if ipv6.hlim != (hop_limit - hop_num):
        raise RuntimeError('Invalid hop limit {0} should be {1}'.
                           format(ipv6.hlim,hop_limit - hop_num))

    if not ipv6.haslayer(ICMPv6EchoRequest):
        raise RuntimeError('Unexpected packet with no IPv6 ICMP received {0}'.
                           format(ipv6.__repr__()))

    icmpv6 = ipv6[ICMPv6EchoRequest]

    # check identifier and sequence number
    if icmpv6.id != echo_id or icmpv6.seq != echo_seq:
        raise RuntimeError('Invalid ICMPv6 echo reply received ID {0} '
                           'seq {1} should be ID {2} seq {3}'.
                           format(icmpv6.id, icmpv6.seq, echo_id, echo_seq))

    # verify checksum
    cksum = icmpv6.cksum
    del icmpv6.cksum
    tmp = ICMPv6EchoRequest(str(icmpv6))
    if not checksum_equal(tmp.cksum, cksum):
        raise RuntimeError('Invalid checksum {0} should be {1}'.
                           format(cksum, tmp.cksum))

    # send ICMPv6 echo reply from second TG interface
    pkt_send = (Ether(src=dst_mac, dst=dst_nh_mac) /
                IPv6(src=dst_ip, dst=src_ip) /
                ICMPv6EchoReply(id=echo_id, seq=echo_seq))
    dst_sent_packets.append(pkt_send)
    dst_txq.send(pkt_send)

    # receive ICMPv6 echo reply on first TG interface
    while True:
        ether = src_rxq.recv(2, src_sent_packets)
        if ether is None:
            raise RuntimeError('ICMPv6 echo reply 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 not ether.haslayer(IPv6):
        raise RuntimeError('Unexpected packet with no IPv6 layer received {0}'.
                           format(ether.__repr__()))

    ipv6 = ether[IPv6]

    # verify hop limit processing
    if ipv6.hlim != (hop_limit - hop_num):
        raise RuntimeError('Invalid hop limit {0} should be {1}'.
                           format(ipv6.hlim, hop_limit - hop_num))

    if not ipv6.haslayer(ICMPv6EchoReply):
        raise RuntimeError('Unexpected packet with no IPv6 ICMP received {0}'.
                           format(ipv6.__repr__()))

    icmpv6 = ipv6[ICMPv6EchoReply]

    # check identifier and sequence number
    if icmpv6.id != echo_id or icmpv6.seq != echo_seq:
        raise RuntimeError('Invalid ICMPv6 echo reply received ID {0} '
                           'seq {1} should be ID {2} seq {3}'.
                           format(icmpv6.id, icmpv6.seq, echo_id, echo_seq))

    # verify checksum
    cksum = icmpv6.cksum
    del icmpv6.cksum
    tmp = ICMPv6EchoReply(str(icmpv6))
    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()