transmission/libtransmission/webseed.cc

539 lines
14 KiB
C++

// This file Copyright © 2008-2022 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 <set>
#include <string>
#include <string_view>
#include <event2/buffer.h>
#include <event2/event.h>
#include "transmission.h"
#include "bandwidth.h"
#include "cache.h"
#include "peer-mgr.h"
#include "torrent.h"
#include "trevent.h" /* tr_runInEventThread() */
#include "utils.h"
#include "web-utils.h"
#include "web.h"
#include "webseed.h"
using namespace std::literals;
namespace
{
struct tr_webseed;
void on_idle(tr_webseed* w);
class tr_webseed_task
{
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)
: 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) }
{
}
tr_webseed* const webseed;
[[nodiscard]] auto* content() const
{
return content_.get();
}
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;
bool dead = false;
tr_block_index_t blocks_done = 0;
};
/**
* Manages how many web tasks should be running at a time.
*
* - When all is well, allow multiple tasks running in parallel.
* - If we get an error, throttle down to only one at a time
* until we get piece data.
* - If we have too many errors in a row, put the peer in timeout
* and don't allow _any_ connections for awhile.
*/
class ConnectionLimiter
{
public:
void taskStarted()
{
++n_tasks;
}
void taskFinished(bool success)
{
if (!success)
{
taskFailed();
}
TR_ASSERT(n_tasks > 0);
--n_tasks;
}
void gotData()
{
TR_ASSERT(n_tasks > 0);
n_consecutive_failures = 0;
paused_until = 0;
}
[[nodiscard]] size_t slotsAvailable() const
{
if (isPaused())
{
return 0;
}
auto const max = maxConnections();
if (n_tasks >= max)
{
return 0;
}
return max - n_tasks;
}
private:
[[nodiscard]] bool isPaused() const
{
return paused_until > tr_time();
}
[[nodiscard]] size_t maxConnections() const
{
return n_consecutive_failures > 0 ? 1 : MaxConnections;
}
void taskFailed()
{
TR_ASSERT(n_tasks > 0);
if (++n_consecutive_failures >= MaxConsecutiveFailures)
{
paused_until = tr_time() + TimeoutIntervalSecs;
}
}
static time_t constexpr TimeoutIntervalSecs = 120;
static size_t constexpr MaxConnections = 4;
static size_t constexpr MaxConsecutiveFailures = MaxConnections;
size_t n_tasks = 0;
size_t n_consecutive_failures = 0;
time_t paused_until = 0;
};
struct 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)
: tr_peer{ tor }
, torrent_id{ tr_torrentId(tor) }
, base_url{ url }
, callback{ callback_in }
, callback_data{ callback_data_in }
, bandwidth(tor->bandwidth)
, pulse_timer(evtimer_new(session->event_base, &tr_webseed::onTimer, this), event_free)
{
// init parent bits
have.setHasAll();
tr_peerUpdateProgress(tor, this);
startTimer();
}
~tr_webseed() override
{
// flag all the pending tasks as dead
std::for_each(std::begin(tasks), std::end(tasks), [](auto* task) { task->dead = true; });
tasks.clear();
}
bool is_transferring_pieces(uint64_t now, tr_direction direction, unsigned int* setme_Bps) const override
{
unsigned int Bps = 0;
bool is_active = false;
if (direction == TR_DOWN)
{
is_active = !std::empty(tasks);
Bps = bandwidth.getPieceSpeedBytesPerSecond(now, direction);
}
if (setme_Bps != nullptr)
{
*setme_Bps = Bps;
}
return is_active;
}
int const torrent_id;
std::string const base_url;
tr_peer_callback const callback;
void* const callback_data;
Bandwidth bandwidth;
ConnectionLimiter connection_limiter;
std::set<tr_webseed_task*> tasks;
private:
void startTimer()
{
tr_timerAddMsec(pulse_timer.get(), IdleTimerMsec);
}
static void onTimer(evutil_socket_t /*fd*/, short /*what*/, void* vwebseed)
{
auto* const webseed = static_cast<tr_webseed*>(vwebseed);
on_idle(webseed);
webseed->startTimer();
}
std::shared_ptr<event> const pulse_timer;
static int constexpr IdleTimerMsec = 2000;
};
/***
****
***/
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)
: session{ session_in }
, torrent_id{ torrent_id_in }
, webseed{ webseed_in }
{
}
[[nodiscard]] auto* content() const
{
return content_.get();
}
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;
};
void write_block_func(void* vdata)
{
auto* const data = static_cast<write_block_data*>(vdata);
struct tr_webseed* const w = data->webseed;
auto* const buf = data->content();
auto* const tor = tr_torrentFindFromId(data->session, data->torrent_id);
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);
}
}
delete data;
}
/***
****
***/
void on_content_changed(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);
auto* const session = task->session;
auto const lock = session->unique_lock();
if (!task->dead && n_added > 0)
{
auto* const w = task->webseed;
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;
}
}
}
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);
if (tor == nullptr || !tor->isRunning || tor->isDone())
{
return;
}
for (auto const span : tr_peerMgrGetNextRequests(tor, w, w->connection_limiter.slotsAvailable()))
{
w->connection_limiter.taskStarted();
auto* const task = new tr_webseed_task{ tor, w, span };
evbuffer_add_cb(task->content(), on_content_changed, task);
w->tasks.insert(task);
task_request_next_chunk(task);
tr_peerMgrClientSentRequests(tor, w, span);
}
}
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;
w->connection_limiter.taskFinished(success);
if (t->dead)
{
delete t;
return;
}
tr_torrent* tor = tr_torrentFindFromId(session, w->torrent_id);
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);
}
}
}
}
std::string make_url(tr_webseed* w, std::string_view name)
{
auto url = w->base_url;
if (tr_strvEndsWith(url, "/"sv) && !std::empty(name))
{
tr_http_escape(url, name, false);
}
return url;
}
void task_request_next_chunk(tr_webseed_task* t)
{
tr_webseed* w = t->webseed;
tr_torrent* const tor = tr_torrentFindFromId(w->session, w->torrent_id);
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 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 [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));
options.speed_limit_tag = tor->uniqueId;
options.buffer = t->content();
tor->session->web->fetch(std::move(options));
}
} // namespace
/***
****
***/
tr_peer* tr_webseedNew(tr_torrent* torrent, std::string_view url, tr_peer_callback callback, void* callback_data)
{
return new tr_webseed(torrent, url, callback, callback_data);
}
tr_webseed_view tr_webseedView(tr_peer const* peer)
{
auto const* w = dynamic_cast<tr_webseed const*>(peer);
if (w == nullptr)
{
return {};
}
auto bytes_per_second = unsigned{ 0 };
auto const is_downloading = peer->is_transferring_pieces(tr_time_msec(), TR_DOWN, &bytes_per_second);
return { w->base_url.c_str(), is_downloading, bytes_per_second };
}