relay.h

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#pragma once

 
#include "librats/util/rats_export.h"
#include "librats/core/service_registry.h"
#include "librats/node/peer_network.h"
#include "librats/peer/peer_id.h"
#include "librats/subsystems/relay_service.h"
#include "librats/transport/relay_link.h"   // Circuit::kDefaultWindow
 
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <cstdint>
#include <memory>
#include <mutex>
#include <thread>
 
namespace librats {
 
class RATS_API Relay final : public Subsystem, public RelayService {
public:
    struct Config {
        // ── Using relays to reach peers we cannot dial ──────────────────────

        bool enable_client = true;

        size_t max_probes = 3;

        size_t max_outbound_circuits = 8;

        std::chrono::milliseconds open_timeout{8000};

        std::chrono::milliseconds cooldown{60000};
 
        // ── Accepting circuits opened to us ─────────────────────────────────

        bool accept_inbound = true;

        size_t max_inbound_circuits = 16;
 
        // ── Carrying other peers' traffic ───────────────────────────────────

        bool serve = false;

        size_t max_circuits = 32;

        size_t max_circuits_per_peer = 2;

        uint64_t max_circuit_rate_bps = 10'000'000;

        std::chrono::milliseconds circuit_burst{2000};

        std::chrono::seconds max_circuit_duration{3600};

        size_t                    request_budget = 8;
        std::chrono::milliseconds request_window{1000};
 
        // ── Both ends ───────────────────────────────────────────────────────

        uint32_t window = Circuit::kDefaultWindow;

        bool upgrade_with_hole_punch = true;

        std::chrono::milliseconds tick{250};
    };
 
    Relay();
    explicit Relay(Config config);
    ~Relay() override;
 
    void attach(NodeContext& ctx) override;
    void start() override;
    void stop() override;

    bool connect_via_relay(const PeerId& target) override;
    bool serves(const PeerId& peer) const override;
 
    // — diagnostics and tests —
    size_t circuits() const;
    size_t carried_circuits() const;
    size_t forwarded_circuits() const;
    uint64_t carried_bytes() const;
    size_t attempts() const;
 
private:
    struct State;
 
    Config                 config_;
    std::shared_ptr<State> state_;
    ServiceRegistry*       services_ = nullptr;
 
    std::thread             worker_;
    std::atomic<bool>       running_{false};
    std::mutex              worker_mutex_;
    std::condition_variable worker_cv_;
 
    void loop();
};
 
} // namespace librats