dotfiles/modules/nixos/guests/torrent/default.nix

{
  config,
  flake,
  pkgs,
  ...
}:
let
  inherit (flake.config.people) user0;
  inherit (flake.config.services) instances;
  serviceCfg = instances.torrent;
  host = instances.torrent.domains.url0;
  dns0 = instances.web.dns.provider0;
  dns0Path = "dns/${dns0}";
  torrentPort = 51820;
  vpnEndpoint = "185.111.110.1";
  localNet = "192.168.50.0/24";
in
{
  microvm.vms.${serviceCfg.name} = {
    autostart = true;
    config = {
      system.stateVersion = "25.05";

      # VPN Killswitch - configured BEFORE networking starts
      boot.kernel.sysctl = {
        "net.ipv4.ip_forward" = 1;
      };

      networking = {
        # Disable default firewall - we're doing it manually
        firewall.enable = false;

        wg-quick.interfaces = {
          wg0 = {
            address = [ "10.2.0.2/32" ];
            dns = [ "10.2.0.1" ];
            privateKeyFile = "/run/secrets/wireguard-pass";

            peers = [
              {
                publicKey = "QPfiwJQmt5VLEOh1ufLbi1lj6LUnwQY0tgDSh3pWx1k=";
                endpoint = "${vpnEndpoint}:${toString torrentPort}";
                allowedIPs = [
                  "0.0.0.0/0"
                  "::/0"
                ];
                persistentKeepalive = 25;
              }
            ];

            # Now we can safely open the VPN tunnel for all traffic
            postUp = ''
              echo "VPN UP: Opening network for VPN and local traffic"

              # Allow ALL traffic through VPN interface
              ${pkgs.iptables}/bin/iptables -A INPUT -i wg0 -j ACCEPT
              ${pkgs.iptables}/bin/iptables -A OUTPUT -o wg0 -j ACCEPT

              # Allow local network traffic (WebUI, management)
              ${pkgs.iptables}/bin/iptables -A INPUT -i enp0s5 -s ${localNet} -j ACCEPT
              ${pkgs.iptables}/bin/iptables -A OUTPUT -o enp0s5 -d ${localNet} -j ACCEPT

              # NAT for VPN
              ${pkgs.iptables}/bin/iptables -t nat -A POSTROUTING -o wg0 -j MASQUERADE

              # Allow forwarding through VPN (for port forwarding)
              ${pkgs.iptables}/bin/iptables -A FORWARD -i wg0 -j ACCEPT
              ${pkgs.iptables}/bin/iptables -A FORWARD -o wg0 -j ACCEPT
              ${pkgs.iptables}/bin/iptables -A FORWARD -i enp0s5 -o wg0 -j ACCEPT
              ${pkgs.iptables}/bin/iptables -A FORWARD -o enp0s5 -i wg0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

              echo "VPN UP: Network opened for VPN and local traffic"
            '';

            preDown = ''
              echo "VPN DOWN: Removing VPN rules, killswitch remains active"
              ${pkgs.iptables}/bin/iptables -D INPUT -i wg0 -j ACCEPT 2>/dev/null || true
              ${pkgs.iptables}/bin/iptables -D OUTPUT -o wg0 -j ACCEPT 2>/dev/null || true

              ${pkgs.iptables}/bin/iptables -D INPUT -i enp0s5 -s ${localNet} -j ACCEPT 2>/dev/null || true
              ${pkgs.iptables}/bin/iptables -D OUTPUT -o enp0s5 -d ${localNet} -j ACCEPT 2>/dev/null || true

              ${pkgs.iptables}/bin/iptables -t nat -D POSTROUTING -o wg0 -j MASQUERADE 2>/dev/null || true

              ${pkgs.iptables}/bin/iptables -D FORWARD -i wg0 -j ACCEPT 2>/dev/null || true
              ${pkgs.iptables}/bin/iptables -D FORWARD -o wg0 -j ACCEPT 2>/dev/null || true
              ${pkgs.iptables}/bin/iptables -D FORWARD -i enp0s5 -o wg0 -j ACCEPT 2>/dev/null || true
              ${pkgs.iptables}/bin/iptables -D FORWARD -o enp0s5 -i wg0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT 2>/dev/null || true

              echo "VPN DOWN: Killswitch rules remain - no internet access"
            '';
          };
        };

        dhcpcd.enable = false;
        useNetworkd = true;
      };

      services = {
        qbittorrent = {
          enable = true;
          webuiPort = serviceCfg.ports.port0;
          torrentingPort = torrentPort;
          openFirewall = false; # We're managing firewall manually

          serverConfig = {
            LegalNotice.Accepted = true;

            BitTorrent = {
              Session = {
                Interface = "wg0";
                InterfaceName = "wg0";
                Port = torrentPort;
                MaxConnections = -1;
                MaxConnectionsPerTorrent = -1;
                MaxUploads = -1;
                MaxUploadsPerTorrent = -1;
                QueueingSystemEnabled = false;
                uTPRateLimited = false;
                uTPEnabled = true;
                AlternativeGlobalDLSpeedLimit = 0;
                AlternativeGlobalUPSpeedLimit = 0;
                GlobalMaxInactiveSeedingMinutes = 10224;
                GlobalMaxRatio = -1;
              };
            };

            Preferences = {
              WebUI = {
                Username = "user";
                Password_PBKDF2 = "@ByteArray(1bJKXLVSLU6kgCHbCS2lDg==:BmyrMaod6dbJqEe7Ud/JgKAxRMqzsAuEjHcTvLzIBgc5rc5Z7J2X9mbH0cDEAhXqc+O3gQxrckt8S2Gf+zlO9w==)";
              };

              General = {
                Locale = "en";
              };

              Downloads = {
                SavePath = "${serviceCfg.varPaths.path0}/downloads";
                TempPathEnabled = false;
                PreAllocation = false;
              };
            };
          };
        };

        openssh = {
          enable = true;
          settings.PasswordAuthentication = false;
        };
      };

      users.users.root.openssh.authorizedKeys.keys = flake.config.people.users.${user0}.sshKeys;

      systemd = {
        network = {
          enable = true;
          networks."10-enp" = {
            matchConfig.Name = "enp0s5";
            addresses = [ { Address = "${serviceCfg.interface.ip}/24"; } ];
            gateway = [ serviceCfg.interface.gate ];
          };
        };

        tmpfiles.rules = [
          "d ${serviceCfg.varPaths.path0} 755 ${serviceCfg.name} ${serviceCfg.name} -"
          "d ${serviceCfg.varPaths.path0}/downloads 755 ${serviceCfg.name} ${serviceCfg.name} -"
        ];

        services = {
          # Ensure qBittorrent ONLY starts after VPN is up
          qbittorrent = {
            after = [
              "wg-quick-wg0.service"
              "network-online.target"
            ];
            requires = [ "wg-quick-wg0.service" ];
            wants = [ "network-online.target" ];
            bindsTo = [ "wg-quick-wg0.service" ]; # Stop if VPN stops

            serviceConfig = {
              Restart = "on-failure";
              RestartSec = "10s";
            };
          };

          natpmp-portforward = {
            description = "NAT-PMP Port Forwarding for VPN";
            after = [
              "wg-quick-wg0.service"
              "qbittorrent.service"
            ];
            requires = [
              "wg-quick-wg0.service"
              "qbittorrent.service"
            ];
            wantedBy = [ "multi-user.target" ];

            serviceConfig = {
              Type = "simple";
              Restart = "always";
              RestartSec = "10s";
            };

            script = ''
              PASSWORD=$(cat /run/secrets/qbittorrent-pass)
              echo "Waiting for qBittorrent to start..."
              sleep 10

              while true; do
                echo "Requesting port forwarding from VPN..."
                
                UDP_OUTPUT=$(${pkgs.libnatpmp}/bin/natpmpc -a 1 0 udp 60 -g 10.2.0.1 2>&1)
                UDP_PORT=$(echo "$UDP_OUTPUT" | ${pkgs.gnugrep}/bin/grep "Mapped public port" | ${pkgs.gawk}/bin/awk '{print $4}' | head -1)
                
                TCP_OUTPUT=$(${pkgs.libnatpmp}/bin/natpmpc -a 1 0 tcp 60 -g 10.2.0.1 2>&1)
                TCP_PORT=$(echo "$TCP_OUTPUT" | ${pkgs.gnugrep}/bin/grep "Mapped public port" | ${pkgs.gawk}/bin/awk '{print $4}' | head -1)
                
                if [ -n "$UDP_PORT" ] && [ -n "$TCP_PORT" ]; then
                  echo "Port forwarding successful: UDP=$UDP_PORT, TCP=$TCP_PORT"
                  
                  # Clean up old dynamic rules
                  ${pkgs.iptables}/bin/iptables -t nat -D PREROUTING -i enp0s5 -s ${localNet} -p tcp -j DNAT 2>/dev/null || true
                  ${pkgs.iptables}/bin/iptables -t nat -D PREROUTING -i enp0s5 -s ${localNet} -p udp -j DNAT 2>/dev/null || true
                  ${pkgs.iptables}/bin/iptables -D FORWARD -i enp0s5 -o wg0 -p tcp -j ACCEPT 2>/dev/null || true
                  ${pkgs.iptables}/bin/iptables -D FORWARD -i enp0s5 -o wg0 -p udp -j ACCEPT 2>/dev/null || true
                  ${pkgs.iptables}/bin/iptables -D FORWARD -i wg0 -o enp0s5 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT 2>/dev/null || true
                  
                  # DNAT: Forward LAN traffic to qBittorrent on WireGuard interface
                  ${pkgs.iptables}/bin/iptables -t nat -A PREROUTING -i enp0s5 -s ${localNet} -p tcp --dport "$TCP_PORT" -j DNAT --to-destination 10.2.0.2:"$TCP_PORT"
                  ${pkgs.iptables}/bin/iptables -t nat -A PREROUTING -i enp0s5 -s ${localNet} -p udp --dport "$UDP_PORT" -j DNAT --to-destination 10.2.0.2:"$UDP_PORT"
                  
                  # Allow forwarding for these specific ports
                  ${pkgs.iptables}/bin/iptables -A FORWARD -i enp0s5 -o wg0 -d 10.2.0.2 -p tcp --dport "$TCP_PORT" -j ACCEPT
                  ${pkgs.iptables}/bin/iptables -A FORWARD -i enp0s5 -o wg0 -d 10.2.0.2 -p udp --dport "$UDP_PORT" -j ACCEPT
                  ${pkgs.iptables}/bin/iptables -A FORWARD -i wg0 -o enp0s5 -s 10.2.0.2 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
                  
                  echo "Firewall forwarding rules updated for ports: UDP=$UDP_PORT, TCP=$TCP_PORT"
                  
                  # Update qBittorrent listening port via API
                  echo "Logging into qBittorrent API..."
                  COOKIE=$(${pkgs.curl}/bin/curl -s -i \
                      --header "Referer: http://localhost:${toString serviceCfg.ports.port0}" \
                      --data "username=user&password=$PASSWORD" \
                      "http://localhost:${toString serviceCfg.ports.port0}/api/v2/auth/login" | \
                      ${pkgs.gnugrep}/bin/grep -i "set-cookie" | ${pkgs.gawk}/bin/awk -F'SID=|;' '{print $2}')
                  
                  if [ -n "$COOKIE" ]; then
                    echo "Authentication successful, updating port..."
                    ${pkgs.curl}/bin/curl -s \
                      --cookie "SID=$COOKIE" \
                      --data "json={\"listen_port\":$UDP_PORT}" \
                      "http://localhost:${toString serviceCfg.ports.port0}/api/v2/app/setPreferences"
                    
                    echo "Updated qBittorrent listening port to $UDP_PORT"
                  else
                    echo "WARNING: Failed to authenticate with qBittorrent API"
                  fi
                else
                  echo "ERROR: Failed to get forwarded ports"
                  echo "UDP output: $UDP_OUTPUT"
                  echo "TCP output: $TCP_OUTPUT"
                fi
                
                sleep 45
              done
            '';
          };
          killswitch-init = {
            description = "Initialize VPN Killswitch Before Network";
            wantedBy = [ "network-pre.target" ];
            before = [
              "network-pre.target"
              "network.target"
            ];
            after = [ "systemd-modules-load.service" ];

            serviceConfig = {
              Type = "oneshot";
              RemainAfterExit = true;
            };

            script = ''
              echo "KILLSWITCH: Setting up firewall rules BEFORE network services"

              # Default DROP everything
              ${pkgs.iptables}/bin/iptables -P INPUT DROP
              ${pkgs.iptables}/bin/iptables -P OUTPUT DROP
              ${pkgs.iptables}/bin/iptables -P FORWARD DROP

              ${pkgs.iptables}/bin/iptables -F
              ${pkgs.iptables}/bin/iptables -t nat -F
              ${pkgs.iptables}/bin/iptables -X

              # Allow loopback
              ${pkgs.iptables}/bin/iptables -A INPUT -i lo -j ACCEPT
              ${pkgs.iptables}/bin/iptables -A OUTPUT -o lo -j ACCEPT

              # CRITICAL: Only allow WireGuard endpoint traffic before VPN is up
              ${pkgs.iptables}/bin/iptables -A OUTPUT -o enp0s5 -p udp --dport ${toString torrentPort} -d ${vpnEndpoint} -j ACCEPT
              ${pkgs.iptables}/bin/iptables -A INPUT -i enp0s5 -p udp --sport ${toString torrentPort} -s ${vpnEndpoint} -j ACCEPT

              # Allow SSH from local network (for management)
              ${pkgs.iptables}/bin/iptables -A INPUT -i enp0s5 -s ${localNet} -p tcp --dport 22 -j ACCEPT
              ${pkgs.iptables}/bin/iptables -A OUTPUT -o enp0s5 -d ${localNet} -p tcp --sport 22 -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT

              # Block IPv6 completely
              ${pkgs.iptables}/bin/ip6tables -P INPUT DROP 2>/dev/null || true
              ${pkgs.iptables}/bin/ip6tables -P OUTPUT DROP 2>/dev/null || true
              ${pkgs.iptables}/bin/ip6tables -P FORWARD DROP 2>/dev/null || true

              echo "KILLSWITCH: Initialized - Network locked down"
            '';
          };
        };
      };

      microvm = {
        vcpu = 1;
        mem = 1024 * 1;
        hypervisor = "qemu";

        interfaces = [
          {
            type = "tap";
            id = serviceCfg.interface.id;
            mac = serviceCfg.interface.mac;
          }
          {
            type = "user";
            id = serviceCfg.interface.idUser;
            mac = serviceCfg.interface.macUser;
          }
        ];

        forwardPorts = [
          {
            from = "host";
            host.port = serviceCfg.interface.ssh;
            guest.port = 22;
          }
        ];

        shares = [
          {
            source = "/nix/store";
            mountPoint = "/nix/.ro-store";
            tag = "ro-store";
            proto = "virtiofs";
          }
          {
            mountPoint = serviceCfg.varPaths.path0;
            proto = "virtiofs";
            source = serviceCfg.mntPaths.path0;
            tag = "${serviceCfg.name}_data";
          }
          {
            mountPoint = "/run/secrets";
            proto = "virtiofs";
            source = "/run/secrets/torrent";
            tag = "host_secrets";
          }
        ];
      };
      environment.systemPackages = builtins.attrValues {
        inherit (pkgs)
          conntrack-tools
          gawk
          iptables
          libnatpmp
          speedtest-go
          wireguard-tools
          ;
      };
    };
  };

  # Host configuration remains the same
  services = {
    caddy = {
      virtualHosts = {
        "${host}" = {
          extraConfig = ''
            basic_auth {
              {$CADDY_AUTH_USER} {$CADDY_AUTH_PASSWORD_HASH}
            }
            reverse_proxy ${serviceCfg.interface.ip}:${toString serviceCfg.ports.port0}

            tls ${serviceCfg.ssl.cert} ${serviceCfg.ssl.key}

            encode zstd gzip
          '';
        };
      };
    };
  };

  sops.secrets = {
    "caddy/share-auth" = {
      owner = "caddy";
      group = "caddy";
      mode = "0400";
    };
    "torrent/wireguard-pass" = {
      owner = "root";
      mode = "0400";
    };
    "torrent/qbittorrent-pass" = {
      owner = "root";
      mode = "0400";
    };
  };

  security.acme.certs."${host}" = {
    dnsProvider = dns0;
    environmentFile = config.sops.secrets.${dns0Path}.path;
    group = "caddy";
  };

  users.users.caddy.extraGroups = [ "acme" ];

  systemd = {
    services.caddy = {
      serviceConfig = {
        EnvironmentFile = config.sops.secrets."caddy/share-auth".path;
      };
    };

    tmpfiles.rules = [
      "d ${serviceCfg.mntPaths.path0} 0755 microvm wheel - -"
      "d ${serviceCfg.secretPaths.path0}/caddy 755 caddy caddy -"
      "d /var/log/caddy 755 caddy caddy -"
    ];
  };

  networking.firewall = {
    allowedTCPPorts = [
      38834
      torrentPort
    ];
    allowedUDPPorts = [
      38834
      torrentPort
    ];
  };
}