Hello Libtorrent : Publish Data (3) Start Seeder

#bittorrent #libtorrent #cpp #p2p

I had explained about how to start tracker server and how to create a meta data file.

In this section, I explain how to create seeder with libtorrent.

What is Seeder

Seeder is a peer uploading data. Seeder has many task.

Regist own ip address and own status to tracker server
Join the mainline dht network
Explore peers which want to data
Download and Upload Game
Upload Data

etc..

But,You can write so easy a seeder code with using libtorrent

Source Code

It's a completed code is below.

//LD_LIBRARY_PATH=/usr/local/lib/libtorrent-rasterbar.so g++ main_tiny_seeder.cpp -o tiny_seeder.out -ltorrent-rasterbar -lpthread

#include <iostream>
#include <libtorrent/session.hpp>
#include <libtorrent/alert_types.hpp>
#include <libtorrent/alert.hpp>


std::string my_listen_interfaces = "";             //<your ip>:6881";//,[::]:6881"  "{E4F0B674-0DFC-48BB-98A5-2AA730BDB6D6}:7777"
std::string target_torrentfile_path = "a.torrent"; // <your torrent file  path>
std::string target_folder_path = ".data";

int main(int argc, char *argv[])
try
{
    lt::session session();
    lt::add_torrent_params torrent_params; // = lt::parse_magnet_uri("<your magnet link>");
    torrent_params.save_path = ".data";    // save in current dir
    torrent_params.ti = std::make_shared<lt::torrent_info>(target_torrentfile_path);
    torrent_params.flags |= lt::torrent_flags::seed_mode; // May not be needed
    torrent_params.have_pieces.set_all();                 //　May not be needed
    torrent_params.verified_pieces.set_all();             // May not be needed

    lt::torrent_handle h = session.add_torrent(std::move(torrent_params));

    while (true)
    {
        std::vector<lt::alert *> alerts;
        session.pop_alerts(&alerts);

        lt::state_update_alert *st;
        for (lt::alert *a : alerts)
        {
            std::cout << "[" << a->type() << "](" << a->what() << ") " << a->message() << std::endl;
        }
        std::this_thread::sleep_for(std::chrono::milliseconds(1000));
    }
END:
    return 0;
}
catch (std::exception &e)
{
    std::cerr << "Error: " << e.what() << std::endl;
}

It's so Simple Code.

Create Session

Session object manage all state about downloading and uploading and exploring

lt::session session();

Add Torrent to Session Object

Once the torrent file information is added to the session object, the session object will start uploading, downloading, and exploring.

lt::add_torrent_params torrent_params; // = lt::parse_magnet_uri("<your magnet link>");
    torrent_params.save_path = ".data";    // save in current dir
torrent_params.ti = std::make_shared<lt::torrent_info>(target_torrentfile_path);
ssession.add_torrent(std::move(torrent_params));

Output Status

Session Object can notify alert any messages.

while (true)
{
    std::vector<lt::alert *> alerts;
    session.pop_alerts(&alerts);

    lt::state_update_alert *st;
    for (lt::alert *a : alerts)
    {
        std::cout << "[" << a->type() << "](" << a->what() << ") " << a->message() << std::endl;
    }   std::this_thread::sleep_for(std::chrono::milliseconds(1000));
}

Optional

If you has known ip address, you can set this

lt::settings_pack session_params;
session_params.set_int(lt::settings_pack::alert_mask, lt::alert_category::all);
    if (my_listen_interfaces.length() != 0)
    {
        session_params.set_str(lt::settings_pack::listen_interfaces, my_listen_interfaces);
    }
    lt::session session(session_params);

and libtorrent has seeder mode.

lt::add_torrent_params torrent_params; // = lt::parse_magnet_uri("<your magnet link>");
torrent_params.save_path = ".data";    // save in current dir
torrent_params.ti = std::make_shared<lt::torrent_info>(target_torrentfile_path);
torrent_params.flags |= lt::torrent_flags::seed_mode; // May not be needed
torrent_params.have_pieces.set_all();                 //　May not be needed
torrent_params.verified_pieces.set_all();             // May not be needed

and has super seeder mode too.