mirror of
https://github.com/transmission/transmission
synced 2024-12-26 09:37:56 +00:00
7238724318
* 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.
523 lines
13 KiB
C++
523 lines
13 KiB
C++
// This file Copyright © 2008-2022 Mnemosyne LLC.
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// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
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// or any future license endorsed by Mnemosyne LLC.
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// License text can be found in the licenses/ folder.
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#include <algorithm>
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#include <set>
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#include <string>
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#include <string_view>
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#include <event2/buffer.h>
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#include <event2/event.h>
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#include "transmission.h"
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#include "bandwidth.h"
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#include "cache.h"
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#include "peer-mgr.h"
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#include "torrent.h"
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#include "trevent.h" /* tr_runInEventThread() */
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#include "utils.h"
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#include "web-utils.h"
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#include "web.h"
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#include "webseed.h"
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using namespace std::literals;
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namespace
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{
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class tr_webseed;
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void on_idle(tr_webseed* w);
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class tr_webseed_task
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{
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private:
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std::shared_ptr<evbuffer> const content_{ evbuffer_new(), evbuffer_free };
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public:
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tr_webseed_task(tr_torrent* tor, tr_webseed* webseed_in, tr_block_span_t blocks_in)
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: webseed{ webseed_in }
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, session{ tor->session }
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, blocks{ blocks_in }
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, end_byte{ tor->blockLoc(blocks.end - 1).byte + tor->blockSize(blocks.end - 1) }
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, loc{ tor->blockLoc(blocks.begin) }
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{
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}
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tr_webseed* const webseed;
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[[nodiscard]] auto* content() const
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{
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return content_.get();
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}
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tr_session* const session;
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tr_block_span_t const blocks;
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uint64_t const end_byte;
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// the current position in the task; i.e., the next block to save
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tr_block_info::Location loc;
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bool dead = false;
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};
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/**
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* Manages how many web tasks should be running at a time.
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*
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* - When all is well, allow multiple tasks running in parallel.
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* - If we get an error, throttle down to only one at a time
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* until we get piece data.
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* - If we have too many errors in a row, put the peer in timeout
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* and don't allow _any_ connections for awhile.
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*/
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class ConnectionLimiter
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{
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public:
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void taskStarted()
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{
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++n_tasks;
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}
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void taskFinished(bool success)
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{
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if (!success)
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{
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taskFailed();
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}
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TR_ASSERT(n_tasks > 0);
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--n_tasks;
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}
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void gotData()
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{
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TR_ASSERT(n_tasks > 0);
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n_consecutive_failures = 0;
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paused_until = 0;
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}
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[[nodiscard]] size_t slotsAvailable() const
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{
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if (isPaused())
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{
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return 0;
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}
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auto const max = maxConnections();
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if (n_tasks >= max)
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{
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return 0;
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}
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return max - n_tasks;
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}
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private:
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[[nodiscard]] bool isPaused() const
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{
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return paused_until > tr_time();
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}
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[[nodiscard]] size_t maxConnections() const
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{
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return n_consecutive_failures > 0 ? 1 : MaxConnections;
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}
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void taskFailed()
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{
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TR_ASSERT(n_tasks > 0);
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if (++n_consecutive_failures >= MaxConsecutiveFailures)
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{
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paused_until = tr_time() + TimeoutIntervalSecs;
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}
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}
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static time_t constexpr TimeoutIntervalSecs = 120;
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static size_t constexpr MaxConnections = 4;
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static size_t constexpr MaxConsecutiveFailures = MaxConnections;
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size_t n_tasks = 0;
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size_t n_consecutive_failures = 0;
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time_t paused_until = 0;
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};
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class tr_webseed : public tr_peer
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{
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public:
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tr_webseed(struct tr_torrent* tor, std::string_view url, tr_peer_callback callback_in, void* callback_data_in)
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: tr_peer{ tor }
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, torrent_id{ tr_torrentId(tor) }
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, base_url{ url }
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, callback{ callback_in }
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, callback_data{ callback_data_in }
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, bandwidth(tor->bandwidth)
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, pulse_timer(evtimer_new(session->event_base, &tr_webseed::onTimer, this), event_free)
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{
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// init parent bits
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have.setHasAll();
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tr_peerUpdateProgress(tor, this);
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startTimer();
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}
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~tr_webseed() override
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{
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// flag all the pending tasks as dead
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std::for_each(std::begin(tasks), std::end(tasks), [](auto* task) { task->dead = true; });
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tasks.clear();
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}
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[[nodiscard]] tr_torrent* getTorrent() const
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{
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return tr_torrentFindFromId(session, torrent_id);
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}
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[[nodiscard]] bool is_transferring_pieces(uint64_t now, tr_direction direction, unsigned int* setme_Bps) const override
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{
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unsigned int Bps = 0;
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bool is_active = false;
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if (direction == TR_DOWN)
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{
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is_active = !std::empty(tasks);
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Bps = bandwidth.getPieceSpeedBytesPerSecond(now, direction);
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}
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if (setme_Bps != nullptr)
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{
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*setme_Bps = Bps;
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}
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return is_active;
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}
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void gotPieceData(uint32_t n_bytes)
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{
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bandwidth.notifyBandwidthConsumed(TR_DOWN, n_bytes, true, tr_time_msec());
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publishClientGotPieceData(n_bytes);
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connection_limiter.gotData();
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}
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void publishRejection(tr_block_span_t block_span)
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{
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auto e = tr_peer_event{};
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e.eventType = TR_PEER_CLIENT_GOT_REJ;
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for (auto block = block_span.begin; block < block_span.end; ++block)
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{
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auto const loc = getTorrent()->blockLoc(block);
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e.pieceIndex = loc.piece;
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e.offset = loc.piece_offset;
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publish(&e);
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}
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}
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void publishGotBlock(tr_torrent const* tor, tr_block_info::Location loc)
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{
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TR_ASSERT(loc.block_offset == 0);
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TR_ASSERT(loc.block < tor->blockCount());
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auto e = tr_peer_event{};
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e.eventType = TR_PEER_CLIENT_GOT_BLOCK;
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e.pieceIndex = loc.piece;
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e.offset = loc.piece_offset;
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e.length = tor->blockSize(loc.block);
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publish(&e);
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}
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int const torrent_id;
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std::string const base_url;
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tr_peer_callback const callback;
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void* const callback_data;
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Bandwidth bandwidth;
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ConnectionLimiter connection_limiter;
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std::set<tr_webseed_task*> tasks;
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private:
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void publish(tr_peer_event* event)
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{
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if (callback != nullptr)
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{
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(*callback)(this, event, callback_data);
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}
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}
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void publishClientGotPieceData(uint32_t length)
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{
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auto e = tr_peer_event{};
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e.eventType = TR_PEER_CLIENT_GOT_PIECE_DATA;
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e.length = length;
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publish(&e);
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}
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void startTimer()
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{
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tr_timerAddMsec(pulse_timer.get(), IdleTimerMsec);
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}
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static void onTimer(evutil_socket_t /*fd*/, short /*what*/, void* vwebseed)
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{
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auto* const webseed = static_cast<tr_webseed*>(vwebseed);
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on_idle(webseed);
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webseed->startTimer();
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}
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std::shared_ptr<event> const pulse_timer;
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static int constexpr IdleTimerMsec = 2000;
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};
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/***
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****
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***/
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struct write_block_data
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{
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private:
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std::shared_ptr<evbuffer> const content_{ evbuffer_new(), evbuffer_free };
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public:
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write_block_data(tr_session* session_in, int torrent_id_in, tr_webseed* webseed_in, tr_block_info::Location loc_in)
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: session{ session_in }
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, torrent_id{ torrent_id_in }
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, webseed{ webseed_in }
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, loc{ loc_in }
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{
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TR_ASSERT(loc.block_offset == 0);
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}
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[[nodiscard]] auto* content() const
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{
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return content_.get();
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}
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static void write_block_func(void* vdata)
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{
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auto* const data = static_cast<write_block_data*>(vdata);
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auto* const webseed = data->webseed;
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auto* const buf = data->content();
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auto* const tor = tr_torrentFindFromId(data->session, data->torrent_id);
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if (tor == nullptr)
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{
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delete data;
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return;
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}
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auto const len = evbuffer_get_length(buf);
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TR_ASSERT(tor->blockSize(data->loc.block) == len);
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tr_cacheWriteBlock(tor->session->cache, tor, data->loc, len, buf);
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webseed->publishGotBlock(tor, data->loc);
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TR_ASSERT(evbuffer_get_length(buf) == 0);
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delete data;
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}
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private:
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tr_session* const session;
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int const torrent_id;
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tr_webseed* const webseed;
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tr_block_info::Location const loc;
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};
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void useFetchedBlocks(tr_webseed_task* task)
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{
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auto* const session = task->session;
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auto const lock = session->unique_lock();
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auto* const webseed = task->webseed;
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auto const* const tor = webseed->getTorrent();
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if (tor == nullptr)
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{
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return;
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}
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auto* const buf = task->content();
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for (;;)
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{
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auto const block_size = tor->blockSize(task->loc.block);
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if (evbuffer_get_length(buf) < block_size)
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{
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break;
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}
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if (tor->hasBlock(task->loc.block))
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{
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evbuffer_drain(buf, block_size);
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}
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else
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{
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auto* const data = new write_block_data{ session, tor->uniqueId, webseed, task->loc };
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evbuffer_remove_buffer(task->content(), data->content(), block_size);
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tr_runInEventThread(session, write_block_data::write_block_func, data);
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}
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task->loc = tor->byteLoc(task->loc.byte + block_size);
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TR_ASSERT(task->loc.byte == task->end_byte || task->loc.block_offset == 0);
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}
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}
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/***
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****
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***/
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void onBufferGotData(evbuffer* /*buf*/, evbuffer_cb_info const* info, void* vtask)
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{
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size_t const n_added = info->n_added;
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auto* const task = static_cast<tr_webseed_task*>(vtask);
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if (n_added == 0 || task->dead)
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{
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return;
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}
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auto* const session = task->session;
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auto const lock = session->unique_lock();
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auto* const webseed = task->webseed;
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webseed->gotPieceData(n_added);
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useFetchedBlocks(task);
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}
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void task_request_next_chunk(tr_webseed_task* task);
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void on_idle(tr_webseed* w)
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{
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auto* const tor = w->getTorrent();
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if (tor == nullptr || !tor->isRunning || tor->isDone())
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{
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return;
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}
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auto const slots_available = w->connection_limiter.slotsAvailable();
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if (slots_available == 0)
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{
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return;
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}
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// Prefer to request large, contiguous chunks from webseeds.
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// The actual value of '64' is arbitrary here; we could probably
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// be smarter about this.
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auto constexpr PreferredBlocksPerTask = size_t{ 64 };
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auto const spans = tr_peerMgrGetNextRequests(tor, w, slots_available * PreferredBlocksPerTask);
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for (size_t i = 0; i < slots_available && i < std::size(spans); ++i)
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{
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auto const& span = spans[i];
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w->connection_limiter.taskStarted();
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auto* const task = new tr_webseed_task{ tor, w, span };
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evbuffer_add_cb(task->content(), onBufferGotData, task);
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w->tasks.insert(task);
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task_request_next_chunk(task);
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tr_peerMgrClientSentRequests(tor, w, span);
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}
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}
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void onPartialDataFetched(tr_web::FetchResponse const& web_response)
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{
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auto const& [status, body, did_connect, did_timeout, vtask] = web_response;
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bool const success = status == 206;
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auto* const task = static_cast<tr_webseed_task*>(vtask);
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auto* const webseed = task->webseed;
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webseed->connection_limiter.taskFinished(success);
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if (task->dead)
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{
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delete task;
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return;
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}
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auto* const tor = webseed->getTorrent();
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if (tor == nullptr)
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{
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return;
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}
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if (!success)
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{
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webseed->publishRejection({ task->loc.block, task->blocks.end });
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webseed->tasks.erase(task);
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delete task;
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return;
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}
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if (task->loc.byte < task->end_byte)
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{
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// Request finished successfully but there's still data missing.
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// That means we've reached the end of a file and need to request
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// the next one
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task_request_next_chunk(task);
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return;
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}
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TR_ASSERT(evbuffer_get_length(task->content()) == 0);
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webseed->tasks.erase(task);
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delete task;
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on_idle(webseed);
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}
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std::string make_url(tr_webseed* w, std::string_view name)
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{
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auto url = w->base_url;
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if (tr_strvEndsWith(url, "/"sv) && !std::empty(name))
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{
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tr_http_escape(url, name, false);
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}
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return url;
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}
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void task_request_next_chunk(tr_webseed_task* task)
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{
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auto* const webseed = task->webseed;
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auto* const tor = webseed->getTorrent();
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if (tor == nullptr)
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{
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return;
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}
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auto const [file_index, file_offset] = tor->fileOffset(task->loc);
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auto const left_in_file = tor->fileSize(file_index) - file_offset;
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auto const left_in_task = task->end_byte - task->loc.byte;
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auto const this_chunk = std::min(left_in_file, left_in_task);
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auto const url = make_url(webseed, tor->fileSubpath(file_index));
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auto options = tr_web::FetchOptions{ url, onPartialDataFetched, task };
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options.range = tr_strvJoin(std::to_string(file_offset), "-"sv, std::to_string(file_offset + this_chunk - 1));
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options.speed_limit_tag = tor->uniqueId;
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options.buffer = task->content();
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tor->session->web->fetch(std::move(options));
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}
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} // namespace
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/***
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****
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***/
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tr_peer* tr_webseedNew(tr_torrent* torrent, std::string_view url, tr_peer_callback callback, void* callback_data)
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{
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return new tr_webseed(torrent, url, callback, callback_data);
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}
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tr_webseed_view tr_webseedView(tr_peer const* peer)
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{
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auto const* w = dynamic_cast<tr_webseed const*>(peer);
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if (w == nullptr)
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{
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return {};
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}
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auto bytes_per_second = unsigned{ 0 };
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auto const is_downloading = peer->is_transferring_pieces(tr_time_msec(), TR_DOWN, &bytes_per_second);
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return { w->base_url.c_str(), is_downloading, bytes_per_second };
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}
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