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transmission/libtransmission/torrent-magnet.cc

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// This file Copyright © 2012-2022 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#include <algorithm>
#include <climits> /* INT_MAX */
#include <ctime>
#include <string>
#include <string_view>
#include <event2/buffer.h>
#include <fmt/core.h>
#include "transmission.h"
#include "crypto-utils.h" /* tr_sha1() */
#include "error.h"
#include "file.h"
#include "log.h"
#include "magnet-metainfo.h"
#include "resume.h"
#include "torrent-magnet.h"
#include "torrent-metainfo.h"
#include "torrent.h"
#include "tr-assert.h"
#include "utils.h"
#include "variant.h"
#include "web-utils.h"
using namespace std::literals;
/***
****
***/
/* don't ask for the same metadata piece more than this often */
static auto constexpr MinRepeatIntervalSecs = int{ 3 };
struct metadata_node
{
time_t requestedAt;
int piece;
};
struct tr_incomplete_metadata
{
char* metadata;
size_t metadata_size;
int pieceCount;
/** sorted from least to most recently requested */
struct metadata_node* piecesNeeded;
int piecesNeededCount;
};
static void incompleteMetadataFree(struct tr_incomplete_metadata* m)
{
tr_free(m->metadata);
tr_free(m->piecesNeeded);
tr_free(m);
}
bool tr_torrentSetMetadataSizeHint(tr_torrent* tor, int64_t size)
{
if (tor->hasMetainfo())
{
return false;
}
if (tor->incompleteMetadata != nullptr)
{
return false;
}
int const n = (size <= 0 || size > INT_MAX) ? -1 : size / METADATA_PIECE_SIZE + (size % METADATA_PIECE_SIZE != 0 ? 1 : 0);
tr_logAddDebugTor(tor, fmt::format("metadata is {} bytes in {} pieces", size, n));
if (n <= 0)
{
return false;
}
auto* const m = tr_new(struct tr_incomplete_metadata, 1);
if (m == nullptr)
{
return false;
}
m->pieceCount = n;
m->metadata = tr_new(char, size);
m->metadata_size = size;
m->piecesNeededCount = n;
m->piecesNeeded = tr_new(struct metadata_node, n);
if (m->metadata == nullptr || m->piecesNeeded == nullptr)
{
incompleteMetadataFree(m);
return false;
}
for (int i = 0; i < n; ++i)
{
m->piecesNeeded[i].piece = i;
m->piecesNeeded[i].requestedAt = 0;
}
tor->incompleteMetadata = m;
return true;
}
void* tr_torrentGetMetadataPiece(tr_torrent const* tor, int piece, size_t* len)
{
TR_ASSERT(tr_isTorrent(tor));
TR_ASSERT(piece >= 0);
TR_ASSERT(len != nullptr);
if (!tor->hasMetainfo())
{
return nullptr;
}
auto const fd = tr_sys_file_open(tor->torrentFile(), TR_SYS_FILE_READ, 0);
if (fd == TR_BAD_SYS_FILE)
{
return nullptr;
}
auto const info_dict_size = tor->infoDictSize();
TR_ASSERT(info_dict_size > 0);
char* ret = nullptr;
if (size_t o = piece * METADATA_PIECE_SIZE; tr_sys_file_seek(fd, tor->infoDictOffset() + o, TR_SEEK_SET, nullptr))
{
size_t const l = o + METADATA_PIECE_SIZE <= info_dict_size ? METADATA_PIECE_SIZE : info_dict_size - o;
if (0 < l && l <= METADATA_PIECE_SIZE)
{
auto* buf = tr_new(char, l);
if (auto n = uint64_t{}; tr_sys_file_read(fd, buf, l, &n) && n == l)
{
*len = l;
ret = buf;
buf = nullptr;
}
tr_free(buf);
}
}
tr_sys_file_close(fd);
TR_ASSERT(ret == nullptr || *len > 0);
return ret;
}
static int getPieceNeededIndex(struct tr_incomplete_metadata const* m, int piece)
{
for (int i = 0; i < m->piecesNeededCount; ++i)
{
if (m->piecesNeeded[i].piece == piece)
{
return i;
}
}
return -1;
}
static int getPieceLength(struct tr_incomplete_metadata const* m, int piece)
{
return piece + 1 == m->pieceCount ? // last piece
m->metadata_size - (piece * METADATA_PIECE_SIZE) :
METADATA_PIECE_SIZE;
}
static void tr_buildMetainfoExceptInfoDict(tr_torrent_metainfo const& tm, tr_variant* top)
{
tr_variantInitDict(top, 6);
if (auto const& val = tm.comment(); !std::empty(val))
{
tr_variantDictAddStr(top, TR_KEY_comment, val);
}
if (auto const& val = tm.source(); !std::empty(val))
{
tr_variantDictAddStr(top, TR_KEY_source, val);
}
if (auto const& val = tm.creator(); !std::empty(val))
{
tr_variantDictAddStr(top, TR_KEY_created_by, val);
}
if (auto const val = tm.dateCreated(); val != 0)
{
tr_variantDictAddInt(top, TR_KEY_creation_date, val);
}
if (auto const& announce_list = tm.announceList(); !std::empty(announce_list))
{
auto const n = std::size(announce_list);
if (n == 1)
{
tr_variantDictAddStr(top, TR_KEY_announce, announce_list.at(0).announce_str.sv());
}
else
{
auto* const announce_list_variant = tr_variantDictAddList(top, TR_KEY_announce_list, n);
tr_variant* tier_variant = nullptr;
auto current_tier = std::optional<tr_tracker_tier_t>{};
for (auto const& tracker : announce_list)
{
if (!current_tier || *current_tier != tracker.tier)
{
tier_variant = tr_variantListAddList(announce_list_variant, n);
}
tr_variantListAddStr(tier_variant, tracker.announce_str.sv());
}
}
}
if (auto const n_webseeds = tm.webseedCount(); n_webseeds > 0)
{
auto* const webseeds_variant = tr_variantDictAddList(top, TR_KEY_url_list, n_webseeds);
for (size_t i = 0; i < n_webseeds; ++i)
{
tr_variantListAddStr(webseeds_variant, tm.webseed(i));
}
}
}
static bool useNewMetainfo(tr_torrent* tor, tr_incomplete_metadata const* m, tr_error** error)
{
// test the info_dict checksum
auto const sha1 = tr_sha1(std::string_view{ m->metadata, m->metadata_size });
if (bool const checksum_passed = sha1 && *sha1 == tor->infoHash(); !checksum_passed)
{
return false;
}
// checksum passed; now try to parse it as benc
auto info_dict_v = tr_variant{};
if (!tr_variantFromBuf(
&info_dict_v,
TR_VARIANT_PARSE_BENC | TR_VARIANT_PARSE_INPLACE,
{ m->metadata, m->metadata_size },
nullptr,
error))
{
return false;
}
// yay we have an info dict. Let's make a torrent file
auto top_v = tr_variant{};
tr_buildMetainfoExceptInfoDict(tor->metainfo_, &top_v);
tr_variantMergeDicts(tr_variantDictAddDict(&top_v, TR_KEY_info, 0), &info_dict_v);
auto const benc = tr_variantToStr(&top_v, TR_VARIANT_FMT_BENC);
tr_variantFree(&top_v);
tr_variantFree(&info_dict_v);
// does this synthetic torrent file parse?
auto metainfo = tr_torrent_metainfo{};
if (!metainfo.parseBenc(benc))
{
return false;
}
// save it
if (!tr_saveFile(tor->torrentFile(), benc, error))
{
return false;
}
// remove .magnet file
tr_sys_path_remove(tor->magnetFile());
// tor should keep this metainfo
tor->setMetainfo(metainfo);
return true;
}
static void onHaveAllMetainfo(tr_torrent* tor, tr_incomplete_metadata* m)
{
tr_error* error = nullptr;
if (useNewMetainfo(tor, m, &error))
{
incompleteMetadataFree(tor->incompleteMetadata);
tor->incompleteMetadata = nullptr;
tor->isStopping = true;
tor->magnetVerify = true;
tor->startAfterVerify = !tr_sessionGetPaused(tor->session);
tor->markEdited();
}
else /* drat. */
{
int const n = m->pieceCount;
for (int i = 0; i < n; ++i)
{
m->piecesNeeded[i].piece = i;
m->piecesNeeded[i].requestedAt = 0;
}
m->piecesNeededCount = n;
char const* const msg = error != nullptr && error->message != nullptr ? error->message : "unknown error";
tr_logAddWarnTor(
tor,
fmt::format(
ngettext(
"Couldn't parse magnet metainfo: '{error}'. Redownloading {piece_count} piece",
"Couldn't parse magnet metainfo: '{error}'. Redownloading {piece_count} pieces",
n),
fmt::arg("error", msg),
fmt::arg("piece_count", n)));
tr_error_clear(&error);
}
}
void tr_torrentSetMetadataPiece(tr_torrent* tor, int piece, void const* data, int len)
{
TR_ASSERT(tr_isTorrent(tor));
TR_ASSERT(data != nullptr);
TR_ASSERT(len >= 0);
tr_logAddDebugTor(tor, fmt::format("got metadata piece {} of {} bytes", piece, len));
// are we set up to download metadata?
tr_incomplete_metadata* const m = tor->incompleteMetadata;
if (m == nullptr)
{
return;
}
// sanity test: is `piece` in range?
if ((piece < 0) || (piece >= m->pieceCount))
{
return;
}
// sanity test: is `len` the right size?
if (getPieceLength(m, piece) != len)
{
return;
}
// do we need this piece?
int const idx = getPieceNeededIndex(m, piece);
if (idx == -1)
{
return;
}
size_t const offset = piece * METADATA_PIECE_SIZE;
std::copy_n(reinterpret_cast<char const*>(data), len, m->metadata + offset);
tr_removeElementFromArray(m->piecesNeeded, idx, sizeof(struct metadata_node), m->piecesNeededCount);
--m->piecesNeededCount;
tr_logAddDebugTor(tor, fmt::format("saving metainfo piece {}... {} remain", piece, m->piecesNeededCount));
/* are we done? */
if (m->piecesNeededCount == 0)
{
tr_logAddDebugTor(tor, fmt::format("metainfo piece {} was the last one", piece));
onHaveAllMetainfo(tor, m);
}
}
bool tr_torrentGetNextMetadataRequest(tr_torrent* tor, time_t now, int* setme_piece)
{
TR_ASSERT(tr_isTorrent(tor));
bool have_request = false;
struct tr_incomplete_metadata* m = tor->incompleteMetadata;
if (m != nullptr && m->piecesNeededCount > 0 && m->piecesNeeded[0].requestedAt + MinRepeatIntervalSecs < now)
{
int const piece = m->piecesNeeded[0].piece;
tr_removeElementFromArray(m->piecesNeeded, 0, sizeof(struct metadata_node), m->piecesNeededCount);
int i = m->piecesNeededCount - 1;
m->piecesNeeded[i].piece = piece;
m->piecesNeeded[i].requestedAt = now;
tr_logAddDebugTor(tor, fmt::format("next piece to request: {}", piece));
*setme_piece = piece;
have_request = true;
}
return have_request;
}
double tr_torrentGetMetadataPercent(tr_torrent const* tor)
{
if (tor->hasMetainfo())
{
return 1.0;
}
auto const* const m = tor->incompleteMetadata;
return m == nullptr || m->pieceCount == 0 ? 0.0 : (m->pieceCount - m->piecesNeededCount) / (double)m->pieceCount;
}
char* tr_torrentGetMagnetLink(tr_torrent const* tor)
{
return tr_strvDup(tor->metainfo_.magnet());
}
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