bittorrent.h

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#pragma once
 
#include "librats/util/rats_export.h"
#include "librats/node/peer_network.h"          // Subsystem, NodeContext (fwd)
#include "librats/bittorrent/client.h"          // bittorrent::Client, TorrentInfo, InfoHash
#include "librats/dht/dht.h"                     // DhtClient, SpiderAnnounceCallback
 
#include <condition_variable>
#include <cstddef>
#include <cstdint>
#include <functional>
#include <memory>
#include <mutex>
#include <string>
 
namespace librats {
 
class ServiceRegistry;
 
class RATS_API Bittorrent final : public Subsystem {
public:
    struct Config {
        bittorrent::Client::Config client;       
        bool                       use_node_dht = true;  
    };
 
    Bittorrent() = default;
    explicit Bittorrent(Config config);
    explicit Bittorrent(const bittorrent::Client::Config& client_config);
    ~Bittorrent() override;
 
    Bittorrent(const Bittorrent&) = delete;
    Bittorrent& operator=(const Bittorrent&) = delete;
 
    // — Subsystem —
    void attach(NodeContext& ctx) override;
    void start() override;
    void stop() override;
 
    bittorrent::Client*       client() noexcept { return client_.get(); }
    const bittorrent::Client* client() const noexcept { return client_.get(); }
 
    bool is_running()     const { return client_ && client_->is_running(); }
    bool using_node_dht() const noexcept { return shared_dht_; }
 
    //=========================================================================
    // Spider mode (rats-search) — DHT-wide infohash crawling.
    // Delegates to the active DHT (the shared node DHT). No-op before start()
    // or when no DHT is shared.
    //
    // Guarded to match dht.h, which declares SpiderAnnounceCallback behind the
    // same macro: the whole subsystem needs RATS_SEARCH_FEATURES to link, but the
    // header must still *parse* without it (IDE indexers, a consumer probing the
    // installed tree) rather than fail on an undeclared type.
    //=========================================================================
#ifdef RATS_SEARCH_FEATURES
    void   set_spider_mode(bool enable);
    bool   is_spider_mode() const;
    void   set_spider_announce_callback(SpiderAnnounceCallback callback);
    void   set_spider_ignore(bool ignore);
    bool   is_spider_ignoring() const;
    void   spider_walk();
    size_t spider_pool_size() const;
    size_t spider_visited_count() const;
    void   clear_spider_state();
#endif
 
    //=========================================================================
    // Metadata-only fetch (BEP 9). Adds a temporary metadata-only magnet torrent,
    // waits up to timeout_ms for its info dict to arrive, removes the temporary
    // torrent, then invokes `callback` with the result (success=false on timeout).
    // `callback` runs on an internal worker thread; it is invoked exactly once.
    //=========================================================================
    using MetadataCallback = std::function<void(const bittorrent::TorrentInfo& info, bool success,
                                                const std::string& error)>;
 
    void get_torrent_metadata(const std::string& info_hash_hex,
                              MetadataCallback callback, int timeout_ms = 60000);
 
    void get_torrent_metadata_from_peer(const std::string& info_hash_hex,
                                        const std::string& ip, uint16_t port,
                                        MetadataCallback callback, int timeout_ms = 60000);
 
private:
    DhtClient* active_dht() const;
 
    void fetch_metadata_impl(const std::string& info_hash_hex, const std::string& ip,
                             uint16_t port, bool direct, MetadataCallback callback, int timeout_ms);
 
    Config                              config_;
    ServiceRegistry*                    services_ = nullptr;
    std::unique_ptr<bittorrent::Client> client_;
    bool                                shared_dht_ = false;
 
    // In-flight metadata watchers; stop() drains them before tearing down client_.
    std::mutex              meta_mutex_;
    std::condition_variable meta_cv_;        
    std::condition_variable meta_drain_cv_;  
    bool                    meta_stopping_ = false;
    int                     meta_inflight_ = 0;
};
 
} // namespace librats