#!/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 - IPFIX listener."""

import sys
from ipaddress import IPv4Address, IPv6Address, AddressValueError

from scapy.layers.inet import IP, TCP, UDP
from scapy.layers.inet6 import IPv6
from scapy.layers.l2 import Ether

from resources.libraries.python.IPFIXUtil import IPFIXHandler, IPFIXData
from resources.libraries.python.PacketVerifier import RxQueue, TxQueue, auto_pad
from resources.libraries.python.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:
        IPv4Address(unicode(ip))
        return True
    except (AttributeError, 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:
        IPv6Address(unicode(ip))
        return True
    except (AttributeError, AddressValueError):
        return False


def verify_data(data, count, src_ip, dst_ip, protocol):
    """Compare data in IPFIX flow report against parameters used to send test
     packets.

     :param data: Dictionary of fields in IPFIX flow report.
     :param count: Number of packets expected.
     :param src_ip: Expected source IP address.
     :param dst_ip: Expected destination IP address.
     :param protocol: Expected protocol, TCP or UDP.
     :type data: dict
     :type count: int
     :type src_ip: str
     :type dst_ip: str
     :type protocol: scapy.layers
     """

    # verify packet count
    if data["packetTotalCount"] != count:
        raise RuntimeError(
            "IPFIX reported wrong packet count. Count was {0},"
            " but should be {1}".format(data["packetTotalCount"], count))
    # verify IP addresses
    keys = data.keys()
    e = "{0} mismatch. Packets used {1}, but were classified as {2}."
    if valid_ipv4(src_ip) and valid_ipv4(dst_ip):
        if "IPv4_src" in keys:
            if data["IPv4_src"] != src_ip:
                raise RuntimeError(
                    e.format("Source IP", src_ip, data["IPv4_src"]))
        if "IPv4_dst" in keys:
            if data["IPv4_dst"] != dst_ip:
                raise RuntimeError(
                    e.format("Destination IP", dst_ip, data["IPv4_dst"]))
    else:
        if "IPv6_src" in keys:
            if data["IPv6_src"] != src_ip:
                raise RuntimeError(
                    e.format("Source IP", src_ip, data["IPv6_src"]))
        if "IPv6_dst" in keys:
            if data["IPv6_dst"] != dst_ip:
                raise RuntimeError(
                    e.format("Source IP", src_ip, data["IPv6_dst"]))
    # verify protocol ID
    if "Protocol_ID" in keys:
        if protocol == TCP and int(data["Protocol_ID"]) != 6:
            raise RuntimeError(
                "TCP Packets were classified as not TCP.")
        if protocol == UDP and int(data["Protocol_ID"]) != 17:
            raise RuntimeError(
                "UDP Packets were classified as not UDP.")
    # return port number
    for item in ("src_port", "tcp_src_port", "udp_src_port",
                 "dst_port", "tcp_dst_port", "udp_dst_port"):
        if item in keys:
            return int(data[item])
        else:
            raise RuntimeError("Data contains no port information.")


def main():
    """Send packets to VPP, then listen for IPFIX flow report. Verify that
    the correct packet count was reported."""
    args = TrafficScriptArg(
        ['src_mac', 'dst_mac', 'src_ip', 'dst_ip', 'protocol', 'port', 'count',
         'sessions']
    )

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

    protocol = args.get_arg('protocol')
    source_port = int(args.get_arg('port'))
    destination_port = int(args.get_arg('port'))
    count = int(args.get_arg('count'))
    sessions = int(args.get_arg('sessions'))

    txq = TxQueue(tx_if)
    rxq = RxQueue(tx_if)

    # generate simple packet based on arguments
    ip_version = None
    if valid_ipv4(src_ip) and valid_ipv4(dst_ip):
        ip_version = IP
    elif valid_ipv6(src_ip) and valid_ipv6(dst_ip):
        ip_version = IPv6
    else:
        ValueError("Invalid IP version!")

    if protocol.upper() == 'TCP':
        protocol = TCP
    elif protocol.upper() == 'UDP':
        protocol = UDP
    else:
        raise ValueError("Invalid type of protocol!")

    packets = []
    for x in range(sessions):
        pkt = (Ether(src=src_mac, dst=dst_mac) /
               ip_version(src=src_ip, dst=dst_ip) /
               protocol(sport=x, dport=x))
        pkt = auto_pad(pkt)
        packets.append(pkt)

    # do not print details for sent packets
    verbose = False
    print("Sending more than one packet. Details will be filtered for\
    # all packets sent.")

    ignore = []
    for x in range(sessions):
        for _ in range(count):
            txq.send(packets[x], verbose=verbose)
            ignore.append(packets[x])

    # allow scapy to recognize IPFIX headers and templates
    ipfix = IPFIXHandler()

    # clear receive buffer
    while True:
        pkt = rxq.recv(1, ignore=packets, verbose=verbose)
        if pkt is None:
            break

    data = None
    ports = [x for x in range(sessions)]

    # get IPFIX template and data
    while True:
        pkt = rxq.recv(5)
        if pkt is None:
            raise RuntimeError("RX timeout")
        if pkt.haslayer("IPFIXHeader"):
            if pkt.haslayer("IPFIXTemplate"):
                # create or update template for IPFIX data packets
                ipfix.update_template(pkt)
            elif pkt.haslayer("IPFIXData"):
                for x in range(sessions):
                    try:
                        data = pkt.getlayer(IPFIXData, x+1).fields
                    except AttributeError:
                        raise RuntimeError("Could not find data layer "
                                           "#{0}".format(x+1))
                    port = verify_data(data, count, src_ip, dst_ip, protocol)
                    if port in ports:
                        ports.remove(port)
                    else:
                        raise RuntimeError("Unexpected or duplicate port {0} "
                                           "in flow report.".format(port))
                print("All {0} sessions verified "
                      "with packet count {1}.".format(sessions, count))
                sys.exit(0)
            else:
                raise RuntimeError("Unable to parse IPFIX template "
                                   "or data set.")
        else:
            raise RuntimeError("Received non-IPFIX packet or IPFIX header was"
                               "not recognized.")

if __name__ == "__main__":

    main()