543 lines
15 KiB
C++
543 lines
15 KiB
C++
// This file Copyright © 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 <cstdint> // uint64_t, uint32_t
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#include <ctime>
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#include <iterator>
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#include <memory>
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#include <numeric> // std::accumulate()
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#include <set>
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#include <string>
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#include <string_view>
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#include <utility>
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#include <event2/buffer.h>
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#include <fmt/core.h>
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#include "libtransmission/transmission.h"
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#include "libtransmission/bandwidth.h"
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#include "libtransmission/bitfield.h"
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#include "libtransmission/block-info.h"
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#include "libtransmission/cache.h"
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#include "libtransmission/peer-common.h"
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#include "libtransmission/peer-mgr.h"
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#include "libtransmission/session.h"
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#include "libtransmission/timer.h"
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#include "libtransmission/torrent.h"
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#include "libtransmission/tr-assert.h"
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#include "libtransmission/tr-macros.h"
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#include "libtransmission/tr-strbuf.h"
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#include "libtransmission/utils-ev.h"
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#include "libtransmission/utils.h"
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#include "libtransmission/web-utils.h"
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#include "libtransmission/web.h"
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#include "libtransmission/webseed.h"
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struct evbuffer;
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using namespace std::literals;
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using namespace libtransmission::Values;
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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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libtransmission::evhelpers::evbuffer_unique_ptr const content_{ evbuffer_new() };
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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->block_loc(blocks.end - 1).byte + tor->block_size(blocks.end - 1) }
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, loc{ tor->block_loc(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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constexpr void taskStarted() noexcept
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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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constexpr void gotData() noexcept
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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 noexcept
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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 noexcept
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{
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return paused_until > tr_time();
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}
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[[nodiscard]] constexpr size_t maxConnections() const noexcept
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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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void task_request_next_chunk(tr_webseed_task* task);
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void onBufferGotData(evbuffer* /*buf*/, evbuffer_cb_info const* info, void* vtask);
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class tr_webseed final : 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_webseed 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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, idle_timer_{ session->timerMaker().create([this]() { on_idle(this); }) }
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, have_{ tor->piece_count() }
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, bandwidth_{ &tor->bandwidth() }
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{
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have_.set_has_all();
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idle_timer_->start_repeating(IdleTimerInterval);
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}
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tr_webseed(tr_webseed&&) = delete;
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tr_webseed(tr_webseed const&) = delete;
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tr_webseed& operator=(tr_webseed&&) = delete;
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tr_webseed& operator=(tr_webseed const&) = delete;
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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]] Speed get_piece_speed(uint64_t now, tr_direction dir) const override
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{
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return dir == TR_DOWN ? bandwidth_.get_piece_speed(now, dir) : Speed{};
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}
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[[nodiscard]] TR_CONSTEXPR20 size_t activeReqCount(tr_direction dir) const noexcept override
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{
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if (dir == TR_CLIENT_TO_PEER) // blocks we've requested
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{
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return std::accumulate(
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std::begin(tasks),
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std::end(tasks),
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size_t{},
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[](size_t sum, auto const* task) { return sum + (task->blocks.end - task->blocks.begin); });
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}
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// webseed will never request blocks from us
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return {};
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}
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[[nodiscard]] std::string display_name() const override
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{
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if (auto const parsed = tr_urlParse(base_url); parsed)
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{
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return fmt::format("{:s}:{:d}", parsed->host, parsed->port);
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}
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return base_url;
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}
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[[nodiscard]] tr_bitfield const& has() const noexcept override
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{
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return have_;
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}
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void gotPieceData(uint32_t n_bytes)
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{
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bandwidth_.notify_bandwidth_consumed(TR_DOWN, n_bytes, true, tr_time_msec());
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publish(tr_peer_event::GotPieceData(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 const* const tor = getTorrent();
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for (auto block = block_span.begin; block < block_span.end; ++block)
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{
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publish(tr_peer_event::GotRejected(tor->block_info(), block));
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}
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}
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void requestBlocks(tr_block_span_t const* block_spans, size_t n_spans) override
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{
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auto* const tor = getTorrent();
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if (tor == nullptr || !tor->is_running() || tor->is_done())
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{
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return;
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}
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for (auto const *span = block_spans, *end = span + n_spans; span != end; ++span)
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{
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auto* const task = new tr_webseed_task{ tor, this, *span };
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evbuffer_add_cb(task->content(), onBufferGotData, task);
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tasks.insert(task);
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task_request_next_chunk(task);
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tr_peerMgrClientSentRequests(tor, this, *span);
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}
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}
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[[nodiscard]] RequestLimit canRequest() const noexcept override
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{
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auto const n_slots = connection_limiter.slotsAvailable();
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if (n_slots == 0)
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{
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return {};
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}
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if (auto const* const tor = getTorrent(); tor == nullptr || !tor->is_running() || tor->is_done())
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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;
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// we could probably be smarter about this.
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auto constexpr PreferredBlocksPerTask = size_t{ 64 };
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return { n_slots, n_slots * PreferredBlocksPerTask };
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}
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void publish(tr_peer_event const& peer_event)
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{
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if (callback != nullptr)
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{
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(*callback)(this, peer_event, callback_data);
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}
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}
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tr_torrent_id_t const torrent_id;
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std::string const base_url;
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tr_peer_callback_webseed const callback;
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void* const callback_data;
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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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static auto constexpr IdleTimerInterval = 2s;
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std::unique_ptr<libtransmission::Timer> const idle_timer_;
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tr_bitfield have_;
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tr_bandwidth bandwidth_;
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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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libtransmission::evhelpers::evbuffer_unique_ptr const content_{ evbuffer_new() };
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public:
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write_block_data(
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tr_session* session,
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tr_torrent_id_t tor_id,
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tr_block_index_t block,
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std::unique_ptr<Cache::BlockData> data,
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tr_webseed* webseed)
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: session_{ session }
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, tor_id_{ tor_id }
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, block_{ block }
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, data_{ std::move(data) }
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, webseed_{ webseed }
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{
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}
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void write_block_func()
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{
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if (auto const* const tor = tr_torrentFindFromId(session_, tor_id_); tor != nullptr)
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{
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session_->cache->write_block(tor_id_, block_, std::move(data_));
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webseed_->publish(tr_peer_event::GotBlock(tor->block_info(), block_));
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}
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delete this;
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}
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private:
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tr_session* const session_;
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tr_torrent_id_t const tor_id_;
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tr_block_index_t const block_;
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std::unique_ptr<Cache::BlockData> data_;
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tr_webseed* const webseed_;
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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->block_size(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->has_block(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 block_buf = std::make_unique<Cache::BlockData>(block_size);
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evbuffer_remove(task->content(), std::data(*block_buf), std::size(*block_buf));
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auto* const data = new write_block_data{ session, tor->id(), task->loc.block, std::move(block_buf), webseed };
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session->run_in_session_thread(&write_block_data::write_block_func, data);
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}
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task->loc = tor->byte_loc(task->loc.byte + block_size);
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TR_ASSERT(task->loc.byte <= task->end_byte);
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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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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 lock = task->session->unique_lock();
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task->webseed->gotPieceData(n_added);
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}
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void on_idle(tr_webseed* webseed)
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{
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auto const [max_spans, max_blocks] = webseed->canRequest();
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if (max_spans == 0 || max_blocks == 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 spans = tr_peerMgrGetNextRequests(webseed->getTorrent(), webseed, max_blocks);
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if (std::size(spans) > max_spans)
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{
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spans.resize(max_spans);
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}
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webseed->requestBlocks(std::data(spans), std::size(spans));
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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, primary_ip, 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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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 webseed = task->webseed;
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webseed->connection_limiter.taskFinished(success);
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if (auto const* const tor = webseed->getTorrent(); 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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useFetchedBlocks(task);
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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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TR_ASSERT(task->loc.byte == task->end_byte);
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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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template<typename OutputIt>
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void makeUrl(tr_webseed const* const webseed, std::string_view name, OutputIt out)
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{
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auto const& url = webseed->base_url;
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out = std::copy(std::begin(url), std::end(url), out);
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if (tr_strv_ends_with(url, "/"sv) && !std::empty(name))
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{
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tr_urlPercentEncode(out, name, false);
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}
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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* 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 loc = tor->byte_loc(task->loc.byte + evbuffer_get_length(task->content()));
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auto const [file_index, file_offset] = tor->file_offset(loc);
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auto const left_in_file = tor->file_size(file_index) - file_offset;
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auto const left_in_task = task->end_byte - loc.byte;
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auto const this_chunk = std::min(left_in_file, left_in_task);
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TR_ASSERT(this_chunk > 0U);
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webseed->connection_limiter.taskStarted();
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auto url = tr_urlbuf{};
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makeUrl(webseed, tor->file_subpath(file_index), std::back_inserter(url));
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auto options = tr_web::FetchOptions{ url.sv(), onPartialDataFetched, task };
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options.range = fmt::format("{:d}-{:d}", file_offset, file_offset + this_chunk - 1);
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options.speed_limit_tag = tor->id();
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options.buffer = task->content();
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tor->session->fetch(std::move(options));
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}
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} // namespace
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// ---
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tr_peer* tr_webseedNew(tr_torrent* torrent, std::string_view url, tr_peer_callback_webseed 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* const webseed = dynamic_cast<tr_webseed const*>(peer);
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if (webseed == nullptr)
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{
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return {};
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}
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auto const is_downloading = !std::empty(webseed->tasks);
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auto const speed = peer->get_piece_speed(tr_time_msec(), TR_DOWN);
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return { webseed->base_url.c_str(), is_downloading, speed.base_quantity() };
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}
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