#!/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
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
from resources.libraries.python.PacketVerifier import RxQueue, TxQueue
from resources.libraries.python.TrafficScriptArg import TrafficScriptArg
from scapy.layers.inet6 import IPv6, ICMPv6ND_NA, ICMPv6NDOptDstLLAddr
from scapy.layers.inet6 import ICMPv6EchoRequest, ICMPv6EchoReply
from scapy.all import Ether


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
    ether = dst_rxq.recv(2, dst_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']

    # 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['ICMPv6 Echo Request']

    # 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 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
    ether = src_rxq.recv(2, src_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']

    # 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['ICMPv6 Echo Reply']

    # 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 tmp.cksum != cksum:
        raise RuntimeError(
            'Invalid checksum {0} should be {1}'.format(cksum, tmp.cksum))

    sys.exit(0)

if __name__ == "__main__":
    main()