lokinet/llarp/dns/platform.hpp

#pragma once
#include <string>
#include <memory>
#include <llarp/net/sock_addr.hpp>
#include <llarp/util/logging.hpp>
#include <stdexcept>

#ifndef _WIN32
#include <net/if.h>
#endif

namespace llarp::dns
{
  /// sets dns settings in a platform dependant way
  class I_Platform
  {
   public:
    virtual ~I_Platform() = default;

    /// Attempts to set lokinet as the DNS server.
    /// throws if unsupported or fails.
    ///
    ///
    /// \param if_index -- the interface index to which we add the DNS servers, this can be gotten
    /// from the interface name e.g. lokitun0 (Typically tun_endpoint.GetIfName().) and then put
    /// through if_nametoindex().
    /// \param dns -- the listening address of the lokinet DNS server
    /// \param global -- whether to set up lokinet for all DNS queries (true) or just .loki & .snode
    /// addresses (false).
    virtual void
    set_resolver(unsigned int if_index, llarp::SockAddr dns, bool global) = 0;
  };

  /// a dns platform does silently does nothing, successfully
  class Null_Platform : public I_Platform
  {
   public:
    ~Null_Platform() override = default;
    void
    set_resolver(unsigned int, llarp::SockAddr, bool) override
    {}
  };

  /// a collection of dns platforms that are tried in order when setting dns
  class Multi_Platform : public I_Platform
  {
    std::vector<std::unique_ptr<I_Platform>> m_Impls;

   public:
    ~Multi_Platform() override = default;
    /// add a platform to be owned
    void
    add_impl(std::unique_ptr<I_Platform> impl);

    /// try all owned platforms to set the resolver, throws if none of them work
    void
    set_resolver(unsigned int if_index, llarp::SockAddr dns, bool global) override;
  };
}  // namespace llarp::dns