# This test verifies that we can ping an IPv4-only server from an IPv6-only
# client via a NAT64 router using CLAT on the client. The hosts and networks
# are configured as follows:
#
#        +------
# Client | clat    Address: 192.0.0.1/32  (configured via clatd)
#        |         Route:   default
#        |
#        | eth1    Address: 2001:db8::2/64
#        |  |      Route:   default via 2001:db8::1
#        +--|---
#           | VLAN 3
#        +--|---
#        | eth2    Address: 2001:db8::1/64
# Router |
#        | nat64   Address: 64:ff9b::1/128
#        |         Route:   64:ff9b::/96
#        |         Address: 192.0.2.0/32
#        |         Route:   192.0.2.0/24
#        |
#        | eth1    Address: 100.64.0.1/24
#        +--|---
#           | VLAN 2
#        +--|---
# Server | eth1    Address: 100.64.0.2/24
#        |         Route:   192.0.2.0/24 via 100.64.0.1
#        +------

import ./make-test-python.nix ({ pkgs, lib, ... }:

{
  name = "clatd";
  meta = with pkgs.lib.maintainers; {
    maintainers = [ hax404 ];
  };

  nodes = {
    # The server is configured with static IPv4 addresses. RFC 6052 Section 3.1
    # disallows the mapping of non-global IPv4 addresses like RFC 1918 into the
    # Well-Known Prefix 64:ff9b::/96. TAYGA also does not allow the mapping of
    # documentation space (RFC 5737). To circumvent this, 100.64.0.2/24 from
    # RFC 6589 (Carrier Grade NAT) is used here.
    # To reach the IPv4 address pool of the NAT64 gateway, there is a static
    # route configured. In normal cases, where the router would also source NAT
    # the pool addresses to one IPv4 addresses, this would not be needed.
    server = {
      virtualisation.vlans = [
        2 # towards router
      ];
      networking = {
        useDHCP = false;
        interfaces.eth1 = lib.mkForce {};
      };
      systemd.network = {
        enable = true;
        networks."vlan1" = {
          matchConfig.Name = "eth1";
          address = [
            "100.64.0.2/24"
          ];
          routes = [
            { routeConfig = { Destination = "192.0.2.0/24"; Gateway = "100.64.0.1"; }; }
          ];
        };
      };
    };

    # The router is configured with static IPv4 addresses towards the server
    # and IPv6 addresses towards the client. For NAT64, the Well-Known prefix
    # 64:ff9b::/96 is used. NAT64 is done with TAYGA which provides the
    # tun-interface nat64 and does the translation over it. The IPv6 packets
    # are sent to this interfaces and received as IPv4 packets and vice versa.
    # As TAYGA only translates IPv6 addresses to dedicated IPv4 addresses, it
    # needs a pool of IPv4 addresses which must be at least as big as the
    # expected amount of clients. In this test, the packets from the pool are
    # directly routed towards the client. In normal cases, there would be a
    # second source NAT44 to map all clients behind one IPv4 address.
    router = {
      boot.kernel.sysctl = {
        "net.ipv4.ip_forward" = 1;
        "net.ipv6.conf.all.forwarding" = 1;
      };

      virtualisation.vlans = [
        2 # towards server
        3 # towards client
      ];

      networking = {
        useDHCP = false;
        useNetworkd = true;
        firewall.enable = false;
        interfaces.eth1 = lib.mkForce {
          ipv4 = {
            addresses = [ { address = "100.64.0.1"; prefixLength = 24; } ];
          };
        };
        interfaces.eth2 = lib.mkForce {
          ipv6 = {
            addresses = [ { address = "2001:db8::1"; prefixLength = 64; } ];
          };
        };
      };

      services.tayga = {
        enable = true;
        ipv4 = {
          address = "192.0.2.0";
          router = {
            address = "192.0.2.1";
          };
          pool = {
            address = "192.0.2.0";
            prefixLength = 24;
          };
        };
        ipv6 = {
          address = "2001:db8::1";
          router = {
            address = "64:ff9b::1";
          };
          pool = {
            address = "64:ff9b::";
            prefixLength = 96;
          };
        };
      };
    };

    # The client is configured with static IPv6 addresses. It has also a static
    # default route towards the router. To reach the IPv4-only server, the
    # client starts the clat daemon which starts and configures the local
    # IPv4 -> IPv6 translation via Tayga.
    client = {
      virtualisation.vlans = [
        3 # towards router
      ];

      networking = {
        useDHCP = false;
        interfaces.eth1 = lib.mkForce {};
      };

      systemd.network = {
        enable = true;
        networks."vlan1" = {
          matchConfig.Name = "eth1";
          address = [
            "2001:db8::2/64"
          ];
          routes = [
            { routeConfig = { Destination = "::/0"; Gateway = "2001:db8::1"; }; }
          ];
        };
      };

      services.clatd = {
        enable = true;
        settings.plat-prefix = "64:ff9b::/96";
      };

      environment.systemPackages = [ pkgs.mtr ];
    };
  };

  testScript = ''
    start_all()

    # wait for all machines to start up
    for machine in client, router, server:
      machine.wait_for_unit("network-online.target")

    with subtest("Wait for tayga and clatd"):
      router.wait_for_unit("tayga.service")
      client.wait_for_unit("clatd.service")
      # clatd checks if this system has IPv4 connectivity for 10 seconds
      client.wait_until_succeeds(
        'journalctl -u clatd -e | grep -q "Starting up TAYGA, using config file"'
      )

    with subtest("Test ICMP"):
      client.wait_until_succeeds("ping -c 3 100.64.0.2 >&2")

    with subtest("Test ICMP and show a traceroute"):
      client.wait_until_succeeds("mtr --show-ips --report-wide 100.64.0.2 >&2")

    client.log(client.execute("systemd-analyze security clatd.service")[1])
  '';
})