#!/usr/bin/env python3

# Copyright (c) 2020 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.
#
# 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 IP ICMPv4 or ICMPv6."""

import sys
import ipaddress

from scapy.layers.inet import ICMP, IP
from scapy.layers.inet6 import IPv6, ICMPv6EchoRequest, ICMPv6EchoReply,\
    ICMPv6ND_NS
from scapy.layers.l2 import Ether
from scapy.packet import Raw

from .PacketVerifier import RxQueue, TxQueue
from .TrafficScriptArg import TrafficScriptArg


def valid_ipv4(ip):
    """Check if IP address has the correct IPv4 address format.

    :param ip: IP address.
    :type ip: str
    :return: True in case of correct IPv4 address format,
             otherwise return False.
    :rtype: bool
    """
    try:
        ipaddress.IPv4Address(ip)
        return True
    except (AttributeError, ipaddress.AddressValueError):
        return False


def valid_ipv6(ip):
    """Check if IP address has the correct IPv6 address format.

    :param ip: IP address.
    :type ip: str
    :return: True in case of correct IPv6 address format,
             otherwise return False.
    :rtype: bool
    """
    try:
        ipaddress.IPv6Address(ip)
        return True
    except (AttributeError, ipaddress.AddressValueError):
        return False


def main():
    """Send ICMP echo request and wait for ICMP echo reply. It ignores all other
    packets."""
    args = TrafficScriptArg(
        [u"dst_mac", u"src_mac", u"dst_ip", u"src_ip", u"timeout"]
    )

    dst_mac = args.get_arg(u"dst_mac")
    src_mac = args.get_arg(u"src_mac")
    dst_ip = args.get_arg(u"dst_ip")
    src_ip = args.get_arg(u"src_ip")
    tx_if = args.get_arg(u"tx_if")
    rx_if = args.get_arg(u"rx_if")
    timeout = int(args.get_arg(u"timeout"))
    wait_step = 1

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

    # Create empty ip ICMP packet
    if valid_ipv4(src_ip) and valid_ipv4(dst_ip):
        ip_layer = IP
        icmp_req = ICMP
        icmp_resp = ICMP
        icmp_type = 0  # echo-reply
    elif valid_ipv6(src_ip) and valid_ipv6(dst_ip):
        ip_layer = IP
        icmp_req = ICMPv6EchoRequest
        icmp_resp = ICMPv6EchoReply
        icmp_type = 0  # Echo Reply
    else:
        raise ValueError(u"IP not in correct format")

    icmp_request = (
            Ether(src=src_mac, dst=dst_mac) /
            ip_layer(src=src_ip, dst=dst_ip) /
            icmp_req()
    )

    # Send created packet on the interface
    icmp_request /= Raw()
    sent_packets.append(icmp_request)
    txq.send(icmp_request)

    for _ in range(1000):
        while True:
            icmp_reply = rxq.recv(wait_step, ignore=sent_packets)
            if icmp_reply is None:
                timeout -= wait_step
                if timeout < 0:
                    raise RuntimeError(u"ICMP echo Rx timeout")

            elif icmp_reply.haslayer(ICMPv6ND_NS):
                # read another packet in the queue in case of ICMPv6ND_NS packet
                continue
            else:
                # otherwise process the current packet
                break

        if icmp_reply[ip_layer][icmp_resp].type == icmp_type:
            if icmp_reply[ip_layer].src == dst_ip and \
                    icmp_reply[ip_layer].dst == src_ip:
                break
    else:
        raise RuntimeError(u"Max packet count limit reached")

    print(u"ICMP echo reply received.")

    sys.exit(0)


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