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refactor: webseed (#2689) 

* refactor: reduce nested conditional webseed logic

* refactor: use tr_block_info::Location in webseed

* request larger chunks at a time from webseeds

* fix: CURLOPT_MAXREDIRS to safeguard against loops

Discussion at https://trac.transmissionbt.com/ticket/6110 .
Reported by @x190 and @cfpp2p a few years back.
This commit is contained in:
Charles Kerr 2022-02-23 07:38:18 -06:00 committed by GitHub
parent bee5c1016a
commit 7238724318
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 206 additions and 233 deletions
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8
libtransmission/block-info.h
View File

@ -7,6 +7,8 @@
#include "transmission.h"
#include "tr-assert.h"
struct tr_block_info
{
uint64_t total_size = 0;
@ -99,6 +101,8 @@ struct tr_block_info
// Location of the first byte in `block`.
[[nodiscard]] Location constexpr blockLoc(tr_block_index_t block) const
{
TR_ASSERT(block < n_blocks);
return byteLoc(uint64_t{ block } * blockSize());
}
@ -116,6 +120,8 @@ struct tr_block_info
// Location of the first byte (+ optional offset and length) in `piece`
[[nodiscard]] Location constexpr pieceLoc(tr_piece_index_t piece, uint32_t offset = 0, uint32_t length = 0) const
{
TR_ASSERT(piece < n_pieces);
return byteLoc(uint64_t{ piece } * pieceSize() + offset + length);
}
@ -133,6 +139,8 @@ struct tr_block_info
// Location of the torrent's nth byte
[[nodiscard]] Location constexpr byteLoc(uint64_t byte) const
{
TR_ASSERT(byte <= total_size);
if (!isInitialized())
{
return {};

6
libtransmission/cache.cc
View File

@ -315,9 +315,11 @@ int tr_cacheWriteBlock(
struct evbuffer* writeme)
{
TR_ASSERT(tr_amInEventThread(torrent->session));
TR_ASSERT(loc.block_offset == 0);
TR_ASSERT(torrent->blockSize(loc.block) == length);
TR_ASSERT(torrent->blockSize(loc.block) <= evbuffer_get_length(writeme));
struct cache_block* cb = findBlock(cache, torrent, loc);
auto* cb = findBlock(cache, torrent, loc);
if (cb == nullptr)
{
cb = tr_new(struct cache_block, 1);

5
libtransmission/peer-msgs.cc
View File

@ -167,9 +167,8 @@ struct peer_request
static peer_request blockToReq(tr_torrent const* tor, tr_block_index_t block)
{
auto ret = peer_request{};
tr_torrentGetBlockLocation(tor, block, &ret.index, &ret.offset, &ret.length);
return ret;
auto const loc = tor->blockLoc(block);
return peer_request{ loc.piece, loc.piece_offset, tor->blockSize(block) };
}
/**

16
libtransmission/torrent.cc
View File

@ -1939,22 +1939,6 @@ uint16_t tr_torrentGetPeerLimit(tr_torrent const* tor)
****
***/
void tr_torrentGetBlockLocation(
tr_torrent const* tor,
tr_block_index_t block,
tr_piece_index_t* piece,
uint32_t* offset,
uint32_t* length)
{
uint64_t pos = block;
pos *= tor->blockSize();
*piece = pos / tor->pieceSize();
uint64_t piece_begin = tor->pieceSize();
piece_begin *= *piece;
*offset = pos - piece_begin;
*length = tor->blockSize(block);
}
bool tr_torrentReqIsValid(tr_torrent const* tor, tr_piece_index_t index, uint32_t offset, uint32_t length)
{
TR_ASSERT(tr_isTorrent(tor));

7
libtransmission/torrent.h
View File

@ -73,13 +73,6 @@ tr_torrent* tr_torrentFindFromObfuscatedHash(tr_session* session, tr_sha1_digest
bool tr_torrentReqIsValid(tr_torrent const* tor, tr_piece_index_t index, uint32_t offset, uint32_t length);
void tr_torrentGetBlockLocation(
tr_torrent const* tor,
tr_block_index_t block,
tr_piece_index_t* piece,
uint32_t* offset,
uint32_t* length);
tr_block_span_t tr_torGetFileBlockSpan(tr_torrent const* tor, tr_file_index_t file);
void tr_torrentCheckSeedLimit(tr_torrent* tor);

2
libtransmission/web.cc
View File

@ -240,6 +240,7 @@ private:
static auto constexpr BandwidthPauseMsec = long{ 500 };
static auto constexpr DnsCacheTimeoutSecs = long{ 60 * 60 };
static auto constexpr MaxRedirects = long{ 10 };
bool const curl_verbose = tr_env_key_exists("TR_CURL_VERBOSE");
bool const curl_ssl_verify = !tr_env_key_exists("TR_CURL_SSL_NO_VERIFY");
@ -364,6 +365,7 @@ private:
(void)curl_easy_setopt(e, CURLOPT_VERBOSE, impl->curl_verbose ? 1L : 0L);
(void)curl_easy_setopt(e, CURLOPT_WRITEDATA, task);
(void)curl_easy_setopt(e, CURLOPT_WRITEFUNCTION, onDataReceived);
(void)curl_easy_setopt(e, CURLOPT_MAXREDIRS, MaxRedirects);
if (auto const addrstr = impl->mediator.publicAddress(); addrstr)
{

395
libtransmission/webseed.cc
View File

@ -28,7 +28,7 @@ using namespace std::literals;
namespace
{
struct tr_webseed;
class tr_webseed;
void on_idle(tr_webseed* w);
@ -38,14 +38,12 @@ private:
std::shared_ptr<evbuffer> const content_{ evbuffer_new(), evbuffer_free };
public:
tr_webseed_task(tr_torrent* tor, tr_webseed* webseed_in, tr_block_span_t span)
tr_webseed_task(tr_torrent* tor, tr_webseed* webseed_in, tr_block_span_t blocks_in)
: webseed{ webseed_in }
, session{ tor->session }
, block{ span.begin } // TODO(ckerr): just own the loc
, piece_index{ tor->blockLoc(this->block).piece }
, piece_offset{ tor->blockLoc(this->block).piece_offset }
, block_size{ tor->blockSize() }
, length{ (span.end - 1 - span.begin) * tor->blockSize() + tor->blockSize(span.end - 1) }
, blocks{ blocks_in }
, end_byte{ tor->blockLoc(blocks.end - 1).byte + tor->blockSize(blocks.end - 1) }
, loc{ tor->blockLoc(blocks.begin) }
{
}
@ -57,14 +55,13 @@ public:
}
tr_session* const session;
tr_block_index_t const block;
tr_piece_index_t const piece_index;
uint32_t const piece_offset;
uint32_t const block_size;
uint32_t const length;
tr_block_span_t const blocks;
uint64_t const end_byte;
// the current position in the task; i.e., the next block to save
tr_block_info::Location loc;
bool dead = false;
tr_block_index_t blocks_done = 0;
};
/**
@ -148,7 +145,7 @@ private:
time_t paused_until = 0;
};
struct tr_webseed : public tr_peer
class tr_webseed : public tr_peer
{
public:
tr_webseed(struct tr_torrent* tor, std::string_view url, tr_peer_callback callback_in, void* callback_data_in)
@ -174,7 +171,12 @@ public:
tasks.clear();
}
bool is_transferring_pieces(uint64_t now, tr_direction direction, unsigned int* setme_Bps) const override
[[nodiscard]] tr_torrent* getTorrent() const
{
return tr_torrentFindFromId(session, torrent_id);
}
[[nodiscard]] bool is_transferring_pieces(uint64_t now, tr_direction direction, unsigned int* setme_Bps) const override
{
unsigned int Bps = 0;
bool is_active = false;
@ -193,6 +195,40 @@ public:
return is_active;
}
void gotPieceData(uint32_t n_bytes)
{
bandwidth.notifyBandwidthConsumed(TR_DOWN, n_bytes, true, tr_time_msec());
publishClientGotPieceData(n_bytes);
connection_limiter.gotData();
}
void publishRejection(tr_block_span_t block_span)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_REJ;
for (auto block = block_span.begin; block < block_span.end; ++block)
{
auto const loc = getTorrent()->blockLoc(block);
e.pieceIndex = loc.piece;
e.offset = loc.piece_offset;
publish(&e);
}
}
void publishGotBlock(tr_torrent const* tor, tr_block_info::Location loc)
{
TR_ASSERT(loc.block_offset == 0);
TR_ASSERT(loc.block < tor->blockCount());
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_BLOCK;
e.pieceIndex = loc.piece;
e.offset = loc.piece_offset;
e.length = tor->blockSize(loc.block);
publish(&e);
}
int const torrent_id;
std::string const base_url;
tr_peer_callback const callback;
@ -203,6 +239,22 @@ public:
std::set<tr_webseed_task*> tasks;
private:
void publish(tr_peer_event* event)
{
if (callback != nullptr)
{
(*callback)(this, event, callback_data);
}
}
void publishClientGotPieceData(uint32_t length)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_PIECE_DATA;
e.length = length;
publish(&e);
}
void startTimer()
{
tr_timerAddMsec(pulse_timer.get(), IdleTimerMsec);
@ -223,73 +275,19 @@ private:
****
***/
void publish(tr_webseed* w, tr_peer_event* e)
{
if (w->callback != nullptr)
{
(*w->callback)(w, e, w->callback_data);
}
}
void fire_client_got_rejs(tr_torrent* tor, tr_webseed* w, tr_block_index_t block, tr_block_index_t count)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_REJ;
tr_torrentGetBlockLocation(tor, block, &e.pieceIndex, &e.offset, &e.length);
for (tr_block_index_t i = 1; i <= count; i++)
{
if (i == count)
{
e.length = tor->blockSize(block + count - 1);
}
publish(w, &e);
e.offset += e.length;
}
}
void fire_client_got_blocks(tr_torrent* tor, tr_webseed* w, tr_block_index_t block, tr_block_index_t count)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_BLOCK;
tr_torrentGetBlockLocation(tor, block, &e.pieceIndex, &e.offset, &e.length);
for (tr_block_index_t i = 1; i <= count; i++)
{
if (i == count)
{
e.length = tor->blockSize(block + count - 1);
}
publish(w, &e);
e.offset += e.length;
}
}
void fire_client_got_piece_data(tr_webseed* w, uint32_t length)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_PIECE_DATA;
e.length = length;
publish(w, &e);
}
/***
****
***/
struct write_block_data
{
private:
std::shared_ptr<evbuffer> const content_{ evbuffer_new(), evbuffer_free };
public:
write_block_data(tr_session* session_in, int torrent_id_in, tr_webseed* webseed_in)
write_block_data(tr_session* session_in, int torrent_id_in, tr_webseed* webseed_in, tr_block_info::Location loc_in)
: session{ session_in }
, torrent_id{ torrent_id_in }
, webseed{ webseed_in }
, loc{ loc_in }
{
TR_ASSERT(loc.block_offset == 0);
}
[[nodiscard]] auto* content() const
@ -297,106 +295,121 @@ public:
return content_.get();
}
static void write_block_func(void* vdata)
{
auto* const data = static_cast<write_block_data*>(vdata);
auto* const webseed = data->webseed;
auto* const buf = data->content();
auto* const tor = tr_torrentFindFromId(data->session, data->torrent_id);
if (tor == nullptr)
{
delete data;
return;
}
auto const len = evbuffer_get_length(buf);
TR_ASSERT(tor->blockSize(data->loc.block) == len);
tr_cacheWriteBlock(tor->session->cache, tor, data->loc, len, buf);
webseed->publishGotBlock(tor, data->loc);
TR_ASSERT(evbuffer_get_length(buf) == 0);
delete data;
}
private:
tr_session* const session;
int const torrent_id;
tr_webseed* const webseed;
tr_piece_index_t piece_index;
tr_block_index_t block_index;
tr_block_index_t count;
uint32_t block_offset;
tr_block_info::Location const loc;
};
void write_block_func(void* vdata)
void useFetchedBlocks(tr_webseed_task* task)
{
auto* const data = static_cast<write_block_data*>(vdata);
struct tr_webseed* const w = data->webseed;
auto* const buf = data->content();
auto* const session = task->session;
auto const lock = session->unique_lock();
auto* const tor = tr_torrentFindFromId(data->session, data->torrent_id);
if (tor != nullptr)
auto* const webseed = task->webseed;
auto const* const tor = webseed->getTorrent();
if (tor == nullptr)
{
uint32_t const block_size = tor->blockSize();
uint32_t len = evbuffer_get_length(buf);
uint32_t const offset_end = data->block_offset + len;
tr_cache* cache = data->session->cache;
tr_piece_index_t const piece = data->piece_index;
if (!tor->hasPiece(piece))
{
while (len > 0)
{
uint32_t const bytes_this_pass = std::min(len, block_size);
tr_cacheWriteBlock(cache, tor, tor->pieceLoc(piece, offset_end - len), bytes_this_pass, buf);
len -= bytes_this_pass;
}
fire_client_got_blocks(tor, w, data->block_index, data->count);
}
return;
}
delete data;
auto* const buf = task->content();
for (;;)
{
auto const block_size = tor->blockSize(task->loc.block);
if (evbuffer_get_length(buf) < block_size)
{
break;
}
if (tor->hasBlock(task->loc.block))
{
evbuffer_drain(buf, block_size);
}
else
{
auto* const data = new write_block_data{ session, tor->uniqueId, webseed, task->loc };
evbuffer_remove_buffer(task->content(), data->content(), block_size);
tr_runInEventThread(session, write_block_data::write_block_func, data);
}
task->loc = tor->byteLoc(task->loc.byte + block_size);
TR_ASSERT(task->loc.byte == task->end_byte || task->loc.block_offset == 0);
}
}
/***
****
***/
void on_content_changed(evbuffer* buf, evbuffer_cb_info const* info, void* vtask)
void onBufferGotData(evbuffer* /*buf*/, evbuffer_cb_info const* info, void* vtask)
{
size_t const n_added = info->n_added;
auto* const task = static_cast<tr_webseed_task*>(vtask);
if (n_added == 0 || task->dead)
{
return;
}
auto* const session = task->session;
auto const lock = session->unique_lock();
if (!task->dead && n_added > 0)
{
auto* const w = task->webseed;
auto* const webseed = task->webseed;
webseed->gotPieceData(n_added);
w->bandwidth.notifyBandwidthConsumed(TR_DOWN, n_added, true, tr_time_msec());
fire_client_got_piece_data(w, n_added);
uint32_t const len = evbuffer_get_length(buf);
task->webseed->connection_limiter.gotData();
if (len >= task->block_size)
{
/* once we've got at least one full block, save it */
uint32_t const block_size = task->block_size;
tr_block_index_t const completed = len / block_size;
auto* const data = new write_block_data{ session, w->torrent_id, task->webseed };
data->piece_index = task->piece_index;
data->block_index = task->block + task->blocks_done;
data->count = completed;
data->block_offset = task->piece_offset + task->blocks_done * block_size;
/* we don't use locking on this evbuffer so we must copy out the data
that will be needed when writing the block in a different thread */
evbuffer_remove_buffer(task->content(), data->content(), (size_t)block_size * (size_t)completed);
tr_runInEventThread(w->session, write_block_func, data);
task->blocks_done += completed;
}
}
useFetchedBlocks(task);
}
void task_request_next_chunk(tr_webseed_task* task);
void on_idle(tr_webseed* w)
{
auto* const tor = tr_torrentFindFromId(w->session, w->torrent_id);
auto* const tor = w->getTorrent();
if (tor == nullptr || !tor->isRunning || tor->isDone())
{
return;
}
for (auto const span : tr_peerMgrGetNextRequests(tor, w, w->connection_limiter.slotsAvailable()))
auto const slots_available = w->connection_limiter.slotsAvailable();
if (slots_available == 0)
{
return;
}
// Prefer to request large, contiguous chunks from webseeds.
// The actual value of '64' is arbitrary here; we could probably
// be smarter about this.
auto constexpr PreferredBlocksPerTask = size_t{ 64 };
auto const spans = tr_peerMgrGetNextRequests(tor, w, slots_available * PreferredBlocksPerTask);
for (size_t i = 0; i < slots_available && i < std::size(spans); ++i)
{
auto const& span = spans[i];
w->connection_limiter.taskStarted();
auto* const task = new tr_webseed_task{ tor, w, span };
evbuffer_add_cb(task->content(), on_content_changed, task);
evbuffer_add_cb(task->content(), onBufferGotData, task);
w->tasks.insert(task);
task_request_next_chunk(task);
@ -409,68 +422,45 @@ void onPartialDataFetched(tr_web::FetchResponse const& web_response)
auto const& [status, body, did_connect, did_timeout, vtask] = web_response;
bool const success = status == 206;
auto* const t = static_cast<tr_webseed_task*>(vtask);
auto* const session = t->session;
auto* const w = t->webseed;
auto* const task = static_cast<tr_webseed_task*>(vtask);
auto* const webseed = task->webseed;
w->connection_limiter.taskFinished(success);
webseed->connection_limiter.taskFinished(success);
if (t->dead)
if (task->dead)
{
delete t;
delete task;
return;
}
tr_torrent* tor = tr_torrentFindFromId(session, w->torrent_id);
if (tor != nullptr)
auto* const tor = webseed->getTorrent();
if (tor == nullptr)
{
if (!success)
{
tr_block_index_t const blocks_remain = (t->length + tor->blockSize() - 1) / tor->blockSize() - t->blocks_done;
if (blocks_remain != 0)
{
fire_client_got_rejs(tor, w, t->block + t->blocks_done, blocks_remain);
}
w->tasks.erase(t);
delete t;
}
else
{
uint32_t const bytes_done = t->blocks_done * tor->blockSize();
uint32_t const buf_len = evbuffer_get_length(t->content());
if (bytes_done + buf_len < t->length)
{
/* request finished successfully but there's still data missing. that
means we've reached the end of a file and need to request the next one */
task_request_next_chunk(t);
}
else
{
if (buf_len != 0 && !tor->hasPiece(t->piece_index))
{
/* on_content_changed() will not write a block if it is smaller than
the torrent's block size, i.e. the torrent's very last block */
tr_cacheWriteBlock(
session->cache,
tor,
tor->pieceLoc(t->piece_index, t->piece_offset + bytes_done),
buf_len,
t->content());
fire_client_got_blocks(tor, t->webseed, t->block + t->blocks_done, 1);
}
w->tasks.erase(t);
delete t;
on_idle(w);
}
}
return;
}
if (!success)
{
webseed->publishRejection({ task->loc.block, task->blocks.end });
webseed->tasks.erase(task);
delete task;
return;
}
if (task->loc.byte < task->end_byte)
{
// Request finished successfully but there's still data missing.
// That means we've reached the end of a file and need to request
// the next one
task_request_next_chunk(task);
return;
}
TR_ASSERT(evbuffer_get_length(task->content()) == 0);
webseed->tasks.erase(task);
delete task;
on_idle(webseed);
}
std::string make_url(tr_webseed* w, std::string_view name)
@ -485,31 +475,26 @@ std::string make_url(tr_webseed* w, std::string_view name)
return url;
}
void task_request_next_chunk(tr_webseed_task* t)
void task_request_next_chunk(tr_webseed_task* task)
{
tr_webseed* w = t->webseed;
tr_torrent* const tor = tr_torrentFindFromId(w->session, w->torrent_id);
auto* const webseed = task->webseed;
auto* const tor = webseed->getTorrent();
if (tor == nullptr)
{
return;
}
auto const piece_size = tor->pieceSize();
uint64_t const remain = t->length - t->blocks_done * tor->blockSize() - evbuffer_get_length(t->content());
auto const [file_index, file_offset] = tor->fileOffset(task->loc);
auto const total_offset = tor->pieceLoc(t->piece_index, t->piece_offset, t->length - remain).byte;
tr_piece_index_t const step_piece = total_offset / piece_size;
uint64_t const step_piece_offset = total_offset - uint64_t(piece_size) * step_piece;
auto const left_in_file = tor->fileSize(file_index) - file_offset;
auto const left_in_task = task->end_byte - task->loc.byte;
auto const this_chunk = std::min(left_in_file, left_in_task);
auto const [file_index, file_offset] = tor->fileOffset(tor->pieceLoc(step_piece, step_piece_offset));
uint64_t this_pass = std::min(remain, tor->fileSize(file_index) - file_offset);
auto const url = make_url(t->webseed, tor->fileSubpath(file_index));
auto options = tr_web::FetchOptions{ url, onPartialDataFetched, t };
options.range = tr_strvJoin(std::to_string(file_offset), "-"sv, std::to_string(file_offset + this_pass - 1));
auto const url = make_url(webseed, tor->fileSubpath(file_index));
auto options = tr_web::FetchOptions{ url, onPartialDataFetched, task };
options.range = tr_strvJoin(std::to_string(file_offset), "-"sv, std::to_string(file_offset + this_chunk - 1));
options.speed_limit_tag = tor->uniqueId;
options.buffer = t->content();
options.buffer = task->content();
tor->session->web->fetch(std::move(options));
}