lokinet/llarp/vpn/platform.hpp

#pragma once

#include <llarp/net/ip_range.hpp>
#include <llarp/net/ip_packet.hpp>
#include <oxenc/variant.h>

#include "i_packet_io.hpp"

#include <set>

namespace llarp
{
  struct Context;
  struct AbstractRouter;
}  // namespace llarp

namespace llarp::vpn
{
  struct InterfaceAddress
  {
    constexpr InterfaceAddress(IPRange r, int f = AF_INET) : range{std::move(r)}, fam{f}
    {}
    IPRange range;
    int fam;
    bool
    operator<(const InterfaceAddress& other) const
    {
      return std::tie(range, fam) < std::tie(other.range, other.fam);
    }
  };

  struct InterfaceInfo
  {
    std::string ifname;
    unsigned int index;
    huint32_t dnsaddr;
    std::vector<InterfaceAddress> addrs;

    /// get address number N
    inline net::ipaddr_t
    operator[](size_t idx) const
    {
      const auto& range = addrs[idx].range;
      if (range.IsV4())
        return ToNet(net::TruncateV6(range.addr));
      return ToNet(range.addr);
    }
  };

  /// a vpn network interface
  class NetworkInterface : public I_Packet_IO
  {
   protected:
    InterfaceInfo m_Info;

   public:
    NetworkInterface(InterfaceInfo info) : m_Info{std::move(info)}
    {}
    NetworkInterface(const NetworkInterface&) = delete;
    NetworkInterface(NetworkInterface&&) = delete;

    const InterfaceInfo&
    Info() const
    {
      return m_Info;
    }

    /// idempotently wake up the upper layers as needed (platform dependant)
    virtual void
    MaybeWakeUpperLayers() const {};
  };

  class IRouteManager
  {
   public:
    IRouteManager() = default;
    IRouteManager(const IRouteManager&) = delete;
    IRouteManager(IRouteManager&&) = delete;
    virtual ~IRouteManager() = default;

    virtual const llarp::net::Platform*
    Net_ptr() const;

    inline const llarp::net::Platform&
    Net() const
    {
      return *Net_ptr();
    }

    virtual void
    AddRoute(net::ipaddr_t ip, net::ipaddr_t gateway) = 0;

    virtual void
    DelRoute(net::ipaddr_t ip, net::ipaddr_t gateway) = 0;

    virtual void
    AddDefaultRouteViaInterface(NetworkInterface& vpn) = 0;

    virtual void
    DelDefaultRouteViaInterface(NetworkInterface& vpn) = 0;

    virtual void
    AddRouteViaInterface(NetworkInterface& vpn, IPRange range) = 0;

    virtual void
    DelRouteViaInterface(NetworkInterface& vpn, IPRange range) = 0;

    virtual std::vector<net::ipaddr_t>
    GetGatewaysNotOnInterface(NetworkInterface& vpn) = 0;

    virtual void
    AddBlackhole(){};

    virtual void
    DelBlackhole(){};
  };

  /// a vpn platform
  /// responsible for obtaining vpn interfaces
  class Platform
  {
   protected:
    /// get a new network interface fully configured given the interface info
    /// blocks until ready, throws on error
    virtual std::shared_ptr<NetworkInterface>
    ObtainInterface(InterfaceInfo info, AbstractRouter* router) = 0;

   public:
    Platform() = default;
    Platform(const Platform&) = delete;
    Platform(Platform&&) = delete;
    virtual ~Platform() = default;

    /// create and start a network interface
    inline std::shared_ptr<NetworkInterface>
    CreateInterface(InterfaceInfo info, AbstractRouter* router)
    {
      if (auto netif = ObtainInterface(std::move(info), router))
      {
        netif->Start();
        return netif;
      }
      return nullptr;
    }

    /// get owned ip route manager for managing routing table
    virtual IRouteManager&
    RouteManager() = 0;

    /// create a packet io that will read (and optionally write) packets on a network interface the
    /// lokinet process does not own
    /// @param index the interface index of the network interface to use or 0 for all
    /// interfaces on the system
    virtual std::shared_ptr<I_Packet_IO>
    create_packet_io(
        [[maybe_unused]] unsigned int ifindex,
        [[maybe_unused]] const std::optional<SockAddr>& dns_upstream_src)
    {
      throw std::runtime_error{"raw packet io is unimplemented"};
    }
  };

  /// create native vpn platform
  std::shared_ptr<Platform>
  MakeNativePlatform(llarp::Context* ctx);

}  // namespace llarp::vpn