#!/usr/bin/env python3

import socket

import scapy.compat
from scapy.layers.l2 import Ether
from scapy.layers.inet import ICMP, IP, TCP, UDP
from scapy.layers.ipsec import SecurityAssociation, ESP

from util import ppp, ppc
from template_ipsec import TemplateIpsec
from vpp_ipsec import VppIpsecSA, VppIpsecSpd, VppIpsecSpdEntry,\
        VppIpsecSpdItfBinding
from vpp_ip_route import VppIpRoute, VppRoutePath
from vpp_ip import DpoProto
from vpp_papi import VppEnum


class IPSecNATTestCase(TemplateIpsec):
    """ IPSec/NAT

    TUNNEL MODE::

         public network  |   private network
         ---   encrypt  ---   plain   ---
        |pg0| <------- |VPP| <------ |pg1|
         ---            ---           ---

         ---   decrypt  ---   plain   ---
        |pg0| -------> |VPP| ------> |pg1|
         ---            ---           ---

    """

    tcp_port_in = 6303
    tcp_port_out = 6303
    udp_port_in = 6304
    udp_port_out = 6304
    icmp_id_in = 6305
    icmp_id_out = 6305

    @classmethod
    def setUpClass(cls):
        super(IPSecNATTestCase, cls).setUpClass()

    @classmethod
    def tearDownClass(cls):
        super(IPSecNATTestCase, cls).tearDownClass()

    def setUp(self):
        super(IPSecNATTestCase, self).setUp()
        self.tun_if = self.pg0

        self.tun_spd = VppIpsecSpd(self, self.tun_spd_id)
        self.tun_spd.add_vpp_config()
        VppIpsecSpdItfBinding(self, self.tun_spd,
                              self.tun_if).add_vpp_config()

        p = self.ipv4_params
        self.config_esp_tun(p)
        self.logger.info(self.vapi.ppcli("show ipsec all"))

        d = DpoProto.DPO_PROTO_IP6 if p.is_ipv6 else DpoProto.DPO_PROTO_IP4
        VppIpRoute(self,  p.remote_tun_if_host, p.addr_len,
                   [VppRoutePath(self.tun_if.remote_addr[p.addr_type],
                                 0xffffffff,
                                 proto=d)]).add_vpp_config()

    def tearDown(self):
        super(IPSecNATTestCase, self).tearDown()

    def create_stream_plain(self, src_mac, dst_mac, src_ip, dst_ip):
        return [
            # TCP
            Ether(src=src_mac, dst=dst_mac) /
            IP(src=src_ip, dst=dst_ip) /
            TCP(sport=self.tcp_port_in, dport=20),
            # UDP
            Ether(src=src_mac, dst=dst_mac) /
            IP(src=src_ip, dst=dst_ip) /
            UDP(sport=self.udp_port_in, dport=20),
            # ICMP
            Ether(src=src_mac, dst=dst_mac) /
            IP(src=src_ip, dst=dst_ip) /
            ICMP(id=self.icmp_id_in, type='echo-request')
        ]

    def create_stream_encrypted(self, src_mac, dst_mac, src_ip, dst_ip, sa):
        return [
            # TCP
            Ether(src=src_mac, dst=dst_mac) /
            sa.encrypt(IP(src=src_ip, dst=dst_ip) /
                       TCP(dport=self.tcp_port_out, sport=20)),
            # UDP
            Ether(src=src_mac, dst=dst_mac) /
            sa.encrypt(IP(src=src_ip, dst=dst_ip) /
                       UDP(dport=self.udp_port_out, sport=20)),
            # ICMP
            Ether(src=src_mac, dst=dst_mac) /
            sa.encrypt(IP(src=src_ip, dst=dst_ip) /
                       ICMP(id=self.icmp_id_out, type='echo-request'))
        ]

    def verify_capture_plain(self, capture):
        for packet in capture:
            try:
                self.assert_packet_checksums_valid(packet)
                self.assert_equal(packet[IP].src, self.tun_if.remote_ip4,
                                  "decrypted packet source address")
                self.assert_equal(packet[IP].dst, self.pg1.remote_ip4,
                                  "decrypted packet destination address")
                if packet.haslayer(TCP):
                    self.assertFalse(
                        packet.haslayer(UDP),
                        "unexpected UDP header in decrypted packet")
                    self.assert_equal(packet[TCP].dport, self.tcp_port_in,
                                      "decrypted packet TCP destination port")
                elif packet.haslayer(UDP):
                    if packet[UDP].payload:
                        self.assertFalse(
                            packet[UDP][1].haslayer(UDP),
                            "unexpected UDP header in decrypted packet")
                    self.assert_equal(packet[UDP].dport, self.udp_port_in,
                                      "decrypted packet UDP destination port")
                else:
                    self.assertFalse(
                        packet.haslayer(UDP),
                        "unexpected UDP header in decrypted packet")
                    self.assert_equal(packet[ICMP].id, self.icmp_id_in,
                                      "decrypted packet ICMP ID")
            except Exception:
                self.logger.error(
                    ppp("Unexpected or invalid plain packet:", packet))
                raise

    def verify_capture_encrypted(self, capture, sa):
        for packet in capture:
            try:
                copy = packet.__class__(scapy.compat.raw(packet))
                del copy[UDP].len
                copy = packet.__class__(scapy.compat.raw(copy))
                self.assert_equal(packet[UDP].len, copy[UDP].len,
                                  "UDP header length")
                self.assert_packet_checksums_valid(packet)
                self.assertIn(ESP, packet[IP])
                decrypt_pkt = sa.decrypt(packet[IP])
                self.assert_packet_checksums_valid(decrypt_pkt)
                self.assert_equal(decrypt_pkt[IP].src, self.pg1.remote_ip4,
                                  "encrypted packet source address")
                self.assert_equal(decrypt_pkt[IP].dst, self.tun_if.remote_ip4,
                                  "encrypted packet destination address")
            except Exception:
                self.logger.error(
                    ppp("Unexpected or invalid encrypted packet:", packet))
                raise

    def config_esp_tun(self, params):
        addr_type = params.addr_type
        scapy_tun_sa_id = params.scapy_tun_sa_id
        scapy_tun_spi = params.scapy_tun_spi
        vpp_tun_sa_id = params.vpp_tun_sa_id
        vpp_tun_spi = params.vpp_tun_spi
        auth_algo_vpp_id = params.auth_algo_vpp_id
        auth_key = params.auth_key
        crypt_algo_vpp_id = params.crypt_algo_vpp_id
        crypt_key = params.crypt_key
        addr_any = params.addr_any
        addr_bcast = params.addr_bcast
        flags = (VppEnum.vl_api_ipsec_sad_flags_t.
                 IPSEC_API_SAD_FLAG_UDP_ENCAP)
        e = VppEnum.vl_api_ipsec_spd_action_t

        VppIpsecSA(self, scapy_tun_sa_id, scapy_tun_spi,
                   auth_algo_vpp_id, auth_key,
                   crypt_algo_vpp_id, crypt_key,
                   self.vpp_esp_protocol,
                   self.pg1.remote_addr[addr_type],
                   self.tun_if.remote_addr[addr_type],
                   flags=flags).add_vpp_config()
        VppIpsecSA(self, vpp_tun_sa_id, vpp_tun_spi,
                   auth_algo_vpp_id, auth_key,
                   crypt_algo_vpp_id, crypt_key,
                   self.vpp_esp_protocol,
                   self.tun_if.remote_addr[addr_type],
                   self.pg1.remote_addr[addr_type],
                   flags=flags).add_vpp_config()

        VppIpsecSpdEntry(self, self.tun_spd, scapy_tun_sa_id,
                         addr_any, addr_bcast,
                         addr_any, addr_bcast,
                         socket.IPPROTO_ESP).add_vpp_config()
        VppIpsecSpdEntry(self, self.tun_spd, scapy_tun_sa_id,
                         addr_any, addr_bcast,
                         addr_any, addr_bcast,
                         socket.IPPROTO_ESP,
                         is_outbound=0).add_vpp_config()
        VppIpsecSpdEntry(self, self.tun_spd, scapy_tun_sa_id,
                         addr_any, addr_bcast,
                         addr_any, addr_bcast,
                         socket.IPPROTO_UDP,
                         remote_port_start=4500,
                         remote_port_stop=4500).add_vpp_config()
        VppIpsecSpdEntry(self, self.tun_spd, scapy_tun_sa_id,
                         addr_any, addr_bcast,
                         addr_any, addr_bcast,
                         socket.IPPROTO_UDP,
                         remote_port_start=4500,
                         remote_port_stop=4500,
                         is_outbound=0).add_vpp_config()
        VppIpsecSpdEntry(self, self.tun_spd, vpp_tun_sa_id,
                         self.tun_if.remote_addr[addr_type],
                         self.tun_if.remote_addr[addr_type],
                         self.pg1.remote_addr[addr_type],
                         self.pg1.remote_addr[addr_type],
                         0, priority=10,
                         policy=e.IPSEC_API_SPD_ACTION_PROTECT,
                         is_outbound=0).add_vpp_config()
        VppIpsecSpdEntry(self, self.tun_spd, scapy_tun_sa_id,
                         self.pg1.remote_addr[addr_type],
                         self.pg1.remote_addr[addr_type],
                         self.tun_if.remote_addr[addr_type],
                         self.tun_if.remote_addr[addr_type],
                         0, policy=e.IPSEC_API_SPD_ACTION_PROTECT,
                         priority=10).add_vpp_config()

    def test_ipsec_nat_tun(self):
        """ IPSec/NAT tunnel test case """
        p = self.ipv4_params
        scapy_tun_sa = SecurityAssociation(ESP, spi=p.scapy_tun_spi,
                                           crypt_algo=p.crypt_algo,
                                           crypt_key=p.crypt_key,
                                           auth_algo=p.auth_algo,
                                           auth_key=p.auth_key,
                                           tunnel_header=IP(
                                               src=self.pg1.remote_ip4,
                                               dst=self.tun_if.remote_ip4),
                                           nat_t_header=UDP(
                                               sport=4500,
                                               dport=4500))
        # in2out - from private network to public
        pkts = self.create_stream_plain(
            self.pg1.remote_mac, self.pg1.local_mac,
            self.pg1.remote_ip4, self.tun_if.remote_ip4)
        self.pg1.add_stream(pkts)
        self.pg_enable_capture(self.pg_interfaces)
        self.pg_start()
        capture = self.tun_if.get_capture(len(pkts))
        self.verify_capture_encrypted(capture, scapy_tun_sa)

        vpp_tun_sa = SecurityAssociation(ESP,
                                         spi=p.vpp_tun_spi,
                                         crypt_algo=p.crypt_algo,
                                         crypt_key=p.crypt_key,
                                         auth_algo=p.auth_algo,
                                         auth_key=p.auth_key,
                                         tunnel_header=IP(
                                             src=self.tun_if.remote_ip4,
                                             dst=self.pg1.remote_ip4),
                                         nat_t_header=UDP(
                                             sport=4500,
                                             dport=4500))

        # out2in - from public network to private
        pkts = self.create_stream_encrypted(
            self.tun_if.remote_mac, self.tun_if.local_mac,
            self.tun_if.remote_ip4, self.pg1.remote_ip4, vpp_tun_sa)
        self.logger.info(ppc("Sending packets:", pkts))
        self.tun_if.add_stream(pkts)
        self.pg_enable_capture(self.pg_interfaces)
        self.pg_start()
        capture = self.pg1.get_capture(len(pkts))
        self.verify_capture_plain(capture)