#!/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 IP ICMPv4 or ICMPv6."""

import sys
import ipaddress

from scapy.layers.inet import ICMP, IP
from scapy.layers.inet6 import IPv6, ICMPv6EchoRequest
from scapy.all import Ether

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


def is_icmp_reply(pkt, ipformat):
    """Return True if pkt is echo reply, else return False. If exception occurs
    return False.

    :param pkt: Packet.
    :param ipformat: Dictionary of names to distinguish IPv4 and IPv6.
    :type pkt: dict
    :type ipformat: dict
    :rtype: bool
    """
    #pylint: disable=bare-except
    try:
        if pkt[ipformat['IPType']][ipformat['ICMP_rep']].type == \
                ipformat['Type']:
            return True
        else:
            return False
    except:
        return False


def address_check(request, reply, ipformat):
    """Compare request packet source address with reply destination address
    and vice versa. If exception occurs return False.

    :param request: Sent packet containing request.
    :param reply: Received packet containing reply.
    :param ipformat: Dictionary of names to distinguish IPv4 and IPv6.
    :type request: dict
    :type reply: dict
    :type ipformat: dict
    :rtype: bool
    """
    #pylint: disable=bare-except
    try:
        r_src = reply[ipformat['IPType']].src == request[ipformat['IPType']].dst
        r_dst = reply[ipformat['IPType']].dst == request[ipformat['IPType']].src
        return r_src and r_dst
    except:
        return False


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(unicode(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(unicode(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(['dst_mac', 'src_mac', 'dst_ip', 'src_ip',
                             'timeout'])

    dst_mac = args.get_arg('dst_mac')
    src_mac = args.get_arg('src_mac')
    dst_ip = args.get_arg('dst_ip')
    src_ip = args.get_arg('src_ip')
    tx_if = args.get_arg('tx_if')
    rx_if = args.get_arg('rx_if')
    timeout = int(args.get_arg('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):
        icmp_request = (Ether(src=src_mac, dst=dst_mac) /
                        IP(src=src_ip, dst=dst_ip) /
                        ICMP())
        ip_format = {'IPType': 'IP', 'ICMP_req': 'ICMP',
                     'ICMP_rep': 'ICMP', 'Type': 0}
    elif valid_ipv6(src_ip) and valid_ipv6(dst_ip):
        icmp_request = (Ether(src=src_mac, dst=dst_mac) /
                        IPv6(src=src_ip, dst=dst_ip) /
                        ICMPv6EchoRequest())
        ip_format = {'IPType': 'IPv6', 'ICMP_req': 'ICMPv6 Echo Request',
                     'ICMP_rep': 'ICMPv6 Echo Reply', 'Type': 129}
    else:
        raise ValueError("IP not in correct format")

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

    for _ in range(1000):
        icmp_reply = rxq.recv(wait_step, ignore=sent_packets)
        if icmp_reply is None:
            timeout -= wait_step
            if timeout < 0:
                raise RuntimeError("ICMP echo Rx timeout")
        elif is_icmp_reply(icmp_reply, ip_format):
            if address_check(icmp_request, icmp_reply, ip_format):
                break
    else:
        raise RuntimeError("Max packet count limit reached")

    print "ICMP echo reply received."

    sys.exit(0)

if __name__ == "__main__":
    main()