Author: | Arvid Norberg, arvid@libtorrent.org |
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Version: | 1.2.7 |
Table of contents
examples
Except for the example programs in this manual, there's also a bigger example of a (little bit) more complete client, client_test. There are separate instructions for how to use it here if you'd like to try it.
simple client
This is a simple client. It doesn't have much output to keep it simple:
#include <cstdlib> #include "libtorrent/entry.hpp" #include "libtorrent/bencode.hpp" #include "libtorrent/session.hpp" #include "libtorrent/torrent_info.hpp" #include <iostream> int main(int argc, char* argv[]) try { if (argc != 2) { std::cerr << "usage: ./simple_client torrent-file\n" "to stop the client, press return.\n"; return 1; } lt::session s; lt::add_torrent_params p; p.save_path = "./"; p.ti = std::make_shared<lt::torrent_info>(argv[1]); s.add_torrent(p); // wait for the user to end char a; int ret = std::scanf("%c\n", &a); (void)ret; // ignore return 0; } catch (std::exception const& e) { std::cerr << "ERROR: " << e.what() << "\n"; }
make_torrent
Shows how to create a torrent from a directory tree:
#include "libtorrent/entry.hpp" #include "libtorrent/bencode.hpp" #include "libtorrent/torrent_info.hpp" #include "libtorrent/storage.hpp" #include "libtorrent/create_torrent.hpp" #include <functional> #include <cstdio> #include <sstream> #include <fstream> #include <iostream> #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); } // do not include files and folders whose // name starts with a . 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: make_torrent FILE [OPTIONS] Generates a torrent file from the specified file or directory and writes it to standard out OPTIONS: -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. Specify a dash character "-" as a tracker to indicate the following trackers should be in a higher tier. -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 )"; } int main(int argc_, char const* argv_[]) try { lt::span<char const*> args(argv_, size_t(argc_)); std::string creator_str = "libtorrent"; 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 = "a.torrent"; #endif std::string full_path = args[1]; args = args.subspan(2); for (; !args.empty(); args = args.subspan(1)) { if (args[0][0] != '-') { print_usage(); return 1; } char const flag = args[0][1]; switch (flag) { 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 '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 (full_path[0] != '/') #endif { char cwd[2048]; #ifdef TORRENT_WINDOWS #define getcwd_ _getcwd #else #define getcwd_ getcwd #endif char const* ret = getcwd_(cwd, sizeof(cwd)); if (ret == nullptr) { std::cerr << "failed to get current working directory: " << strerror(errno) << "\n"; return 1; } #undef getcwd_ #ifdef TORRENT_WINDOWS full_path = cwd + ("\\" + full_path); #else full_path = cwd + ("/" + full_path); #endif } lt::add_files(fs, 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) { if (tr == "-") ++tier; else t.add_tracker(tr, 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(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& e) { std::cerr << "ERROR: " << e.what() << "\n"; return 1; }
dump_torrent
This is an example of a program that will take a torrent-file as a parameter and print information about it to std out:
#include <cstdio> // for snprintf #include <cinttypes> // for PRId64 et.al. #include "libtorrent/entry.hpp" #include "libtorrent/bencode.hpp" #include "libtorrent/torrent_info.hpp" #include "libtorrent/announce_entry.hpp" #include "libtorrent/bdecode.hpp" #include "libtorrent/magnet_uri.hpp" #include <fstream> #include <iostream> 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(), size); return ret; } int main(int argc, char* argv[]) try { if (argc < 2 || argc > 5) { std::cerr << "usage: dump_torrent torrent-file [total-items-limit] [recursion-limit] [piece-count-limit]\n"; return 1; } lt::load_torrent_limits cfg; if (argc > 2) cfg.max_decode_tokens = atoi(argv[2]); if (argc > 3) cfg.max_decode_depth = atoi(argv[3]); if (argc > 4) cfg.max_pieces = atoi(argv[4]); std::vector<char> buf = load_file(argv[1]); int pos = -1; lt::error_code ec; std::cout << "decoding. recursion limit: " << cfg.max_decode_depth << " total item count limit: " << cfg.max_decode_tokens << "\n"; lt::bdecode_node const e = lt::bdecode(buf, ec, &pos, cfg.max_decode_depth , cfg.max_decode_tokens); std::printf("\n\n----- raw info -----\n\n%s\n", print_entry(e).c_str()); if (ec) { std::cerr << "failed to decode: '" << ec.message() << "' at character: " << pos<< "\n"; return 1; } lt::torrent_info const t(std::move(e), cfg); buf.clear(); // print info about torrent std::printf("\n\n----- torrent file info -----\n\nnodes:\n"); for (auto const& i : t.nodes()) std::printf("%s: %d\n", i.first.c_str(), i.second); puts("trackers:\n"); for (auto const& i : t.trackers()) std::printf("%2d: %s\n", i.tier, i.url.c_str()); std::stringstream ih; ih << t.info_hash(); std::printf("number of pieces: %d\n" "piece length: %d\n" "info hash: %s\n" "comment: %s\n" "created by: %s\n" "magnet link: %s\n" "name: %s\n" "number of files: %d\n" "files:\n" , t.num_pieces() , t.piece_length() , ih.str().c_str() , t.comment().c_str() , t.creator().c_str() , make_magnet_uri(t).c_str() , t.name().c_str() , t.num_files()); lt::file_storage const& st = t.files(); for (auto const i : st.file_range()) { auto const first = st.map_file(i, 0, 0).piece; auto const last = st.map_file(i, std::max(std::int64_t(st.file_size(i)) - 1, std::int64_t(0)), 0).piece; auto const flags = st.file_flags(i); std::stringstream file_hash; if (!st.hash(i).is_all_zeros()) file_hash << st.hash(i); std::printf(" %8" PRIx64 " %11" PRId64 " %c%c%c%c [ %5d, %5d ] %7u %s %s %s%s\n" , st.file_offset(i) , st.file_size(i) , ((flags & lt::file_storage::flag_pad_file)?'p':'-') , ((flags & lt::file_storage::flag_executable)?'x':'-') , ((flags & lt::file_storage::flag_hidden)?'h':'-') , ((flags & lt::file_storage::flag_symlink)?'l':'-') , static_cast<int>(first) , static_cast<int>(last) , std::uint32_t(st.mtime(i)) , file_hash.str().c_str() , st.file_path(i).c_str() , (flags & lt::file_storage::flag_symlink) ? "-> " : "" , (flags & lt::file_storage::flag_symlink) ? st.symlink(i).c_str() : ""); } std::printf("web seeds:\n"); for (auto const& ws : t.web_seeds()) { std::printf("%s %s\n" , ws.type == lt::web_seed_entry::url_seed ? "BEP19" : "BEP17" , ws.url.c_str()); } return 0; } catch (std::exception const& e) { std::cerr << "ERROR: " << e.what() << "\n"; }