sbt_client工具（Linux下的BT下載和種子製作工具）

用於建立bt種子檔案和下載的命令列bt客戶端工具
簡單的下載：

sbt_client -d xxx.torrent

種子製作：

sbt_client -f xxx.tgz -t http://xxx.6969/announce -o xxx.tgz.torrent

編譯命令：

g++ -std=gnu++11 simple_client.cpp -o sbt_client -L/usr/lib -lssl -lcrypto -L/usr/local/lib /usr/local/lib/libtorrent-rasterbar.so.10.0.0 -lboost_system -lpthread

原始碼：

#include <cstdlib>
#include <iostream>
#include <functional>
#include <cstdio>
#include <sstream>
#include <fstream>

#include "libtorrent/entry.hpp"
#include "libtorrent/bencode.hpp"
#include "libtorrent/session.hpp"
#include "libtorrent/torrent_info.hpp"
#include "libtorrent/storage.hpp"
#include "libtorrent/hasher.hpp"
#include "libtorrent/create_torrent.hpp"
#include "libtorrent/aux_/max_path.hpp" // for TORRENT_MAX_PATH

#include <chrono>
#include <libtorrent/alert_types.hpp>
#include <libtorrent/error_code.hpp>
#include <libtorrent/torrent_status.hpp>

#ifdef TORRENT_WINDOWS
#include <direct.h> // for _getcwd
#endif

using namespace std::placeholders;

std::vector<char> load_file(std::string const& filename)
{
	std::fstream in;
	in.exceptions(std::ifstream::failbit);
	in.open(filename.c_str(), std::ios_base::in | std::ios_base::binary);
	in.seekg(0, std::ios_base::end);
	size_t const size = size_t(in.tellg());
	in.seekg(0, std::ios_base::beg);
	std::vector<char> ret(size);
	in.read(ret.data(), ret.size());
	return ret;
}

std::string branch_path(std::string const& f)
{
	if (f.empty()) return f;

#ifdef TORRENT_WINDOWS
	if (f == "\\\\") return "";
#endif
	if (f == "/") return "";

	int len = int(f.size());
	// if the last character is / or \ ignore it
	if (f[len - 1] == '/' || f[len - 1] == '\\') --len;
	while (len > 0) {
		--len;
		if (f[len] == '/' || f[len] == '\\')
			break;
	}

	if (f[len] == '/' || f[len] == '\\') ++len;
	return std::string(f.c_str(), len);
}

bool file_filter(std::string const& f)
{
	if (f.empty()) return false;

	char const* first = f.c_str();
	char const* sep = strrchr(first, '/');
#if defined(TORRENT_WINDOWS) || defined(TORRENT_OS2)
	char const* altsep = strrchr(first, '\\');
	if (sep == nullptr || altsep > sep) sep = altsep;
#endif
	// if there is no parent path, just set 'sep'
	// to point to the filename.
	// if there is a parent path, skip the '/' character
	if (sep == nullptr) sep = first;
	else ++sep;

	// return false if the first character of the filename is a .
	if (sep[0] == '.') return false;

	std::cerr << f << "\n";
	return true;
}

void print_usage()
{
	std::cerr << R"(usage: sbt_client [OPTIONS]

[*]Download files from a torrent file
[*]Generates a torrent file from the specified file
   or directory and writes it to standard out


OPTIONS:
-d file       download files from a torrent file
-f file       generate torrent from a file
-m file       generate a merkle hash tree torrent.
              merkle torrents require client support
              the resulting full merkle tree is written to
              the specified file
-w url        adds a web seed to the torrent with
              the specified url
-t url        adds the specified tracker to the
              torrent. For multiple trackers, specify more
              -t options
-c comment    sets the comment to the specified string
-C creator    sets the created-by field to the specified string
-p bytes      enables padding files. Files larger
              than bytes will be piece-aligned
-s bytes      specifies a piece size for the torrent
              This has to be a multiple of 16 kiB
-l            Don't follow symlinks, instead encode them as
              links in the torrent file
-o file       specifies the output filename of the torrent file
              If this is not specified, the torrent file is
              printed to the standard out, except on windows
              where the filename defaults to a.torrent
-r file       add root certificate to the torrent, to verify
              the HTTPS tracker
-S info-hash  add a similar torrent by info-hash. The similar
              torrent is expected to share some files with this one
-L collection add a collection name to this torrent. Other torrents
              in the same collection is expected to share files
              with this one.
-M            make the torrent compatible with mutable torrents
              this means aligning large files and pad them in order
              for piece hashes to uniquely indentify a file without
              overlap
)";
}

using clk = std::chrono::steady_clock;

// return the name of a torrent status enum
char const* state(lt::torrent_status::state_t s)
{
	switch (s) {
	case lt::torrent_status::checking_files: return "checking";
	case lt::torrent_status::downloading_metadata: return "dl metadata";
	case lt::torrent_status::downloading: return "downloading";
	case lt::torrent_status::finished: return "finished";
	case lt::torrent_status::seeding: return "seeding";
	case lt::torrent_status::allocating: return "allocating";
	case lt::torrent_status::checking_resume_data: return "checking resume";
	default: return "<>";
	}
}

int bt_client(char* torrent) {
	lt::settings_pack pack;
	pack.set_int(lt::settings_pack::alert_mask
		, lt::alert::error_notification
		| lt::alert::storage_notification
		| lt::alert::status_notification);

	lt::session ses(pack);
	lt::add_torrent_params atp;
	clk::time_point last_save_resume = clk::now();

	// load resume data from disk and pass it in as we add the magnet link
	std::ifstream ifs(".resume_file", std::ios_base::binary);
	ifs.unsetf(std::ios_base::skipws);
	atp.resume_data.assign(std::istream_iterator<char>(ifs)
		, std::istream_iterator<char>());


	atp.save_path = "./";
	atp.ti = std::make_shared<lt::torrent_info>(torrent);
	ses.add_torrent(atp);

	// this is the handle we'll set once we get the notification of it being
	// added
	lt::torrent_handle h;
	for (;;) {
		std::vector<lt::alert*> alerts;
		ses.pop_alerts(&alerts);

		for (lt::alert const* a : alerts) {
			if (auto at = lt::alert_cast<lt::add_torrent_alert>(a)) {
				h = at->handle;
			}
			// if we receive the finished alert or an error, we're done
			if (lt::alert_cast<lt::torrent_finished_alert>(a)) {
				h.save_resume_data();
				goto done;
			}
			if (lt::alert_cast<lt::torrent_error_alert>(a)) {
				std::cout << a->message() << std::endl;
				goto err;
			}

			// when resume data is ready, save it
			if (auto rd = lt::alert_cast<lt::save_resume_data_alert>(a)) {
				std::ofstream of(".resume_file", std::ios_base::binary);
				of.unsetf(std::ios_base::skipws);
				lt::bencode(std::ostream_iterator<char>(of)
					, *rd->resume_data);
			}

			if (auto st = lt::alert_cast<lt::state_update_alert>(a)) {
				if (st->status.empty()) continue;

				// we only have a single torrent, so we know which one
				// the status is for
				lt::torrent_status const& s = st->status[0];
				std::cout << "\r" << state(s.state) << " "
					<< (s.download_payload_rate / 1000) << " kB/s "
					<< (s.total_done / 1000) << " kB ("
					<< (s.progress_ppm / 10000) << "%) downloaded\x1b[K";	
					std::cout.flush();
			}
		}
		std::this_thread::sleep_for(std::chrono::milliseconds(100));

		// ask the session to post a state_update_alert, to update our
		// state output for the torrent
		ses.post_torrent_updates();

		// save resume data once every 30 seconds
		if (clk::now() - last_save_resume > std::chrono::seconds(30)) {
			h.save_resume_data();
			last_save_resume = clk::now();
		}

	}

	// TODO: ideally we should save resume data here

err:
	std::cout << "\nError happened!!!" << std::endl;
	return 0;

done:
	std::cout << "\n100% downloaded!" << std::endl;
	std::cout << "Seeding..." << std::endl;
	// wait for the user to end
	char a;
	int ret = std::scanf("%c\n", &a);
	(void)ret; // ignore
	return 0;

}

int main(int argc, char* argv[]) try
{
	lt::span<char *> args(argv, size_t(argc));
	std::string creator_str = "sbtc";
	std::string comment_str;

	if (args.size() < 2) {
		print_usage();
		return 1;
	}

	std::vector<std::string> web_seeds;
	std::vector<std::string> trackers;
	std::vector<std::string> collections;
	std::vector<lt::sha1_hash> similar;
	int pad_file_limit = -1;
	int piece_size = 0;
	lt::create_flags_t flags = {};
	std::string root_cert;

	std::string outfile;
	std::string merklefile;
#ifdef TORRENT_WINDOWS
	// don't ever write binary data to the console on windows
	// it will just be interpreted as text and corrupted
	outfile = "new.torrent";
#endif

	struct ST
	{
		std::string full_path;
	};
	ST st;
	//std::string full_path = args[1];
	args = args.subspan(1);

	for (; !args.empty(); args = args.subspan(1)) {
		//std::cout << "00" << args[0][0] << std::endl;
		//std::cout << "01" << args[0][1] << std::endl;
		if (args[0][0] != '-') {
			print_usage();
			//std::cout << "error" << std::endl;
			/*std::cout << args[0][0] << std::endl;*/
			return 1;
		}

		char const flag = args[0][1];

		switch (flag)
		{
		case 'd':
			bt_client(args[1]);
			break;
		case 'M':
			flags |= lt::create_torrent::mutable_torrent_support;
			pad_file_limit = 0x4000;
			continue;
		case 'l':
			flags |= lt::create_torrent::symlinks;
			continue;
		}

		if (args.size() < 2) {
			print_usage();
			return 1;
		}

		switch (flag)
		{
		case 'f':st.full_path = args[1]; break;
		case 'w': web_seeds.push_back(args[1]); break;
		case 't': trackers.push_back(args[1]); break;
		case 's': piece_size = atoi(args[1]); break;
		case 'o': outfile = args[1]; break;
		case 'C': creator_str = args[1]; break;
		case 'c': comment_str = args[1]; break;
		case 'r': root_cert = args[1]; break;
		case 'L': collections.push_back(args[1]); break;
		case 'p':
			pad_file_limit = atoi(args[1]);
			flags |= lt::create_torrent::optimize_alignment;
			break;
		case 'm':
			merklefile = args[1];
			flags |= lt::create_torrent::merkle;
			break;
		case 'S': {
			if (strlen(args[1]) != 40) {
				std::cerr << "invalid info-hash for -S. "
					"Expected 40 hex characters\n";
				print_usage();
				return 1;
			}
			std::stringstream hash(args[1]);
			lt::sha1_hash ih;
			hash >> ih;
			if (hash.fail()) {
				std::cerr << "invalid info-hash for -S\n";
				print_usage();
				return 1;
			}
			similar.push_back(ih);
			break;
		}
		default:
			print_usage();
			return 1;
		}
		args = args.subspan(1);
	}

	lt::file_storage fs;
#ifdef TORRENT_WINDOWS
	if (full_path[1] != ':')
#else
	if (st.full_path[0] != '/')
#endif
	{
		char cwd[TORRENT_MAX_PATH];
#ifdef TORRENT_WINDOWS
		_getcwd(cwd, sizeof(cwd));
		full_path = cwd + ("\\" + full_path);
#else
		char const* ret = getcwd(cwd, sizeof(cwd));
		if (ret == nullptr) {
			std::cerr << "failed to get current working directory: "
				<< strerror(errno) << "\n";
			return 1;
		}
		st.full_path = cwd + ("/" + st.full_path);
#endif
	}

	lt::add_files(fs, st.full_path, file_filter, flags);
	if (fs.num_files() == 0) {
		std::cerr << "no files specified.\n";
		return 1;
	}

	lt::create_torrent t(fs, piece_size, pad_file_limit, flags);
	int tier = 0;
	for (std::string const& tr : trackers) {
		t.add_tracker(tr, tier);
		++tier;
	}

	for (std::string const& ws : web_seeds)
		t.add_url_seed(ws);

	for (std::string const& c : collections)
		t.add_collection(c);

	for (lt::sha1_hash const& s : similar)
		t.add_similar_torrent(s);

	auto const num = t.num_pieces();
	lt::set_piece_hashes(t, branch_path(st.full_path)
		, [num](lt::piece_index_t const p) {
			std::cerr << "\r" << p << "/" << num;
		});

	std::cerr << "\n";
	t.set_creator(creator_str.c_str());
	if (!comment_str.empty()) {
		t.set_comment(comment_str.c_str());
	}

	if (!root_cert.empty()) {
		std::vector<char> const pem = load_file(root_cert);
		t.set_root_cert(std::string(&pem[0], pem.size()));
	}

	// create the torrent and print it to stdout
	std::vector<char> torrent;
	lt::bencode(back_inserter(torrent), t.generate());
	if (!outfile.empty()) {
		std::fstream out;
		out.exceptions(std::ifstream::failbit);
		out.open(outfile.c_str(), std::ios_base::out | std::ios_base::binary);
		out.write(torrent.data(), torrent.size());
	}
	else {
		std::cout.write(torrent.data(), torrent.size());
	}

	if (!merklefile.empty()) {
		std::fstream merkle;
		merkle.exceptions(std::ifstream::failbit);
		merkle.open(merklefile.c_str(), std::ios_base::out | std::ios_base::binary);
		auto const& tree = t.merkle_tree();
		merkle.write(reinterpret_cast<char const*>(tree.data()), tree.size() * 20);
	}
	return 0;
}

catch (std::exception const& e) {
	std::cerr << "ERROR: " << e.what() << "\n";
	return 1;
}