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transmission/libtransmission/peer-mgr.cc

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// This file Copyright © 2007-2022 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 <cerrno> /* error codes ERANGE, ... */
#include <climits> /* INT_MAX */
#include <cmath>
#include <cstdint>
#include <cstdlib> /* qsort */
#include <ctime> // time_t
#include <deque>
#include <iterator> // std::back_inserter
#include <memory>
#include <numeric> // std::accumulate
#include <optional>
#include <tuple> // std::tie
#include <utility>
#include <vector>
#include <event2/event.h>
#include <fmt/format.h>
#define LIBTRANSMISSION_PEER_MODULE
#include "transmission.h"
#include "announcer.h"
#include "bandwidth.h"
#include "blocklist.h"
#include "cache.h"
#include "clients.h"
#include "completion.h"
#include "crypto-utils.h"
#include "handshake.h"
#include "log.h"
#include "net.h"
#include "peer-io.h"
#include "peer-mgr-active-requests.h"
#include "peer-mgr-wishlist.h"
#include "peer-mgr.h"
#include "peer-msgs.h"
#include "session.h"
#include "stats.h" /* tr_statsAddUploaded, tr_statsAddDownloaded */
#include "torrent.h"
#include "tr-assert.h"
#include "tr-utp.h"
#include "utils.h"
#include "webseed.h"
// use for bitwise operations w/peer_atom.flags2
static auto constexpr MyflagBanned = int{ 1 };
// use for bitwise operations w/peer_atom.flags2
// unreachable for now... but not banned.
// if they try to connect to us it's okay
static auto constexpr MyflagUnreachable = int{ 2 };
static auto constexpr CancelHistorySec = int{ 60 };
/**
***
**/
/**
* Peer information that should be kept even before we've connected and
* after we've disconnected. These are kept in a pool of peer_atoms to decide
* which ones would make good candidates for connecting to, and to watch out
* for banned peers.
*
* @see tr_peer
* @see tr_peerMsgs
*/
struct peer_atom
{
peer_atom(tr_address addr_in, tr_port port_in, uint8_t flags_in, uint8_t from)
: addr{ addr_in }
, port{ port_in }
, fromFirst{ from }
, fromBest{ from }
, flags{ flags_in }
{
}
#ifdef TR_ENABLE_ASSERTS
[[nodiscard]] bool isValid() const noexcept
{
return fromFirst < TR_PEER_FROM__MAX && fromBest < TR_PEER_FROM__MAX && tr_address_is_valid(&addr);
}
#endif
[[nodiscard]] constexpr auto isSeed() const noexcept
{
return (flags & ADDED_F_SEED_FLAG) != 0;
}
[[nodiscard]] auto readable() const
{
return addr.readable(port);
}
[[nodiscard]] bool isBlocklisted(tr_session const* session) const
{
if (blocklisted_)
{
return *blocklisted_;
}
auto const value = tr_sessionIsAddressBlocked(session, &addr);
blocklisted_ = value;
return value;
}
[[nodiscard]] int getReconnectIntervalSecs(time_t const now) const noexcept
{
auto sec = int{};
bool const unreachable = (this->flags2 & MyflagUnreachable) != 0;
/* if we were recently connected to this peer and transferring piece
* data, try to reconnect to them sooner rather that later -- we don't
* want network troubles to get in the way of a good peer. */
if (!unreachable && now - this->piece_data_time <= MinimumReconnectIntervalSecs * 2)
{
sec = MinimumReconnectIntervalSecs;
}
/* otherwise, the interval depends on how many times we've tried
* and failed to connect to the peer */
else
{
auto step = this->num_fails;
/* penalize peers that were unreachable the last time we tried */
if (unreachable)
{
step += 2;
}
switch (step)
{
case 0:
sec = 0;
break;
case 1:
sec = 10;
break;
case 2:
sec = 60 * 2;
break;
case 3:
sec = 60 * 15;
break;
case 4:
sec = 60 * 30;
break;
case 5:
sec = 60 * 60;
break;
default:
sec = 60 * 120;
break;
}
}
tr_logAddTrace(fmt::format("reconnect interval for {} is {} seconds", this->readable(), sec));
return sec;
}
void setBlocklistedDirty()
{
blocklisted_.reset();
}
std::optional<bool> isReachable() const
{
if ((flags2 & MyflagUnreachable) != 0)
{
return false;
}
if ((flags & ADDED_F_CONNECTABLE) != 0)
{
return true;
}
return std::nullopt;
}
tr_address const addr;
tr_port port = {};
uint16_t num_fails = {};
time_t time = {}; /* when the peer's connection status last changed */
time_t piece_data_time = {};
time_t lastConnectionAttemptAt = {};
time_t lastConnectionAt = {};
uint8_t const fromFirst; /* where the peer was first found */
uint8_t fromBest; /* the "best" value of where the peer has been found */
uint8_t flags = {}; /* these match the added_f flags */
uint8_t flags2 = {}; /* flags that aren't defined in added_f */
bool utp_failed = false; /* We recently failed to connect over uTP */
bool is_connected = false;
private:
mutable std::optional<bool> blocklisted_;
// the minimum we'll wait before attempting to reconnect to a peer
static auto constexpr MinimumReconnectIntervalSecs = int{ 5 };
};
// a container for keeping track of tr_handshakes
class Handshakes
{
public:
void add(tr_address const& address, tr_handshake* handshake)
{
TR_ASSERT(!contains(address));
handshakes_.emplace_back(address, handshake);
}
[[nodiscard]] bool contains(tr_address const& address) const noexcept
{
return std::any_of(
std::begin(handshakes_),
std::end(handshakes_),
[&address](auto const& pair) { return pair.first == address; });
}
void erase(tr_address const& address)
{
for (auto iter = std::begin(handshakes_), end = std::end(handshakes_); iter != end; ++iter)
{
if (iter->first == address)
{
handshakes_.erase(iter);
return;
}
}
}
[[nodiscard]] auto empty() const noexcept
{
return std::empty(handshakes_);
}
void abortAll()
{
// make a tmp copy so that calls to tr_handshakeAbort() won't
// be able to invalidate its loop iteration
auto tmp = handshakes_;
for (auto& [addr, handshake] : tmp)
{
tr_handshakeAbort(handshake);
}
handshakes_ = {};
}
private:
std::vector<std::pair<tr_address, tr_handshake*>> handshakes_;
};
#define tr_logAddDebugSwarm(swarm, msg) tr_logAddDebugTor((swarm)->tor, msg)
#define tr_logAddTraceSwarm(swarm, msg) tr_logAddTraceTor((swarm)->tor, msg)
static void peerCallbackFunc(tr_peer* /*peer*/, tr_peer_event const* /*e*/, void* /*vs*/);
/** @brief Opaque, per-torrent data structure for peer connection information */
class tr_swarm
{
public:
tr_swarm(tr_peerMgr* manager_in, tr_torrent* tor_in) noexcept
: manager{ manager_in }
, tor{ tor_in }
{
rebuildWebseeds();
}
void cancelOldRequests()
{
auto const now = tr_time();
auto const oldest = now - RequestTtlSecs;
for (auto const& [block, peer] : active_requests.sentBefore(oldest))
{
maybeSendCancelRequest(peer, block, nullptr);
active_requests.remove(block, peer);
}
}
void cancelAllRequestsForBlock(tr_block_index_t block, tr_peer const* no_notify)
{
for (auto* peer : active_requests.remove(block))
{
maybeSendCancelRequest(peer, block, no_notify);
}
}
[[nodiscard]] auto unique_lock() const
{
return tor->unique_lock();
}
[[nodiscard]] size_t countActiveWebseeds() const noexcept
{
if (!tor->isRunning || tor->isDone())
{
return {};
}
auto const now = tr_time_msec();
return std::count_if(
std::begin(webseeds),
std::end(webseeds),
[&now](auto const& webseed) { return webseed->isTransferringPieces(now, TR_DOWN, nullptr); });
}
[[nodiscard]] auto peerCount() const noexcept
{
return std::size(peers);
}
void stop()
{
auto const lock = unique_lock();
is_running = false;
removeAllPeers();
outgoing_handshakes.abortAll();
}
void removePeer(tr_peer* peer)
{
auto const lock = unique_lock();
auto* const atom = peer->atom;
TR_ASSERT(atom != nullptr);
atom->time = tr_time();
if (auto iter = std::find(std::begin(peers), std::end(peers), peer); iter != std::end(peers))
{
peers.erase(iter);
}
--stats.peer_count;
--stats.peer_from_count[atom->fromFirst];
TR_ASSERT(stats.peer_count == peerCount());
delete peer;
}
void removeAllPeers()
{
auto tmp = peers;
for (auto* peer : tmp)
{
removePeer(peer);
}
TR_ASSERT(stats.peer_count == 0);
}
void updateEndgame()
{
/* we consider ourselves to be in endgame if the number of bytes
we've got requested is >= the number of bytes left to download */
is_endgame_ = uint64_t(std::size(active_requests)) * tr_block_info::BlockSize >= tor->leftUntilDone();
}
[[nodiscard]] auto constexpr isEndgame() const noexcept
{
return is_endgame_;
}
void addStrike(tr_peer* peer)
{
tr_logAddTraceSwarm(this, fmt::format("increasing peer {} strike count to {}", peer->readable(), peer->strikes + 1));
if (++peer->strikes >= MaxBadPiecesPerPeer)
{
peer->atom->flags2 |= MyflagBanned;
peer->do_purge = true;
tr_logAddTraceSwarm(this, fmt::format("banning peer {}", peer->readable()));
}
}
void rebuildWebseeds()
{
auto const n = tor->webseedCount();
webseeds.clear();
webseeds.reserve(n);
for (size_t i = 0; i < n; ++i)
{
webseeds.emplace_back(tr_webseedNew(tor, tor->webseed(i), peerCallbackFunc, this));
}
webseeds.shrink_to_fit();
stats.active_webseed_count = 0;
}
[[nodiscard]] auto isAllSeeds() const noexcept
{
if (!pool_is_all_seeds_)
{
pool_is_all_seeds_ = std::all_of(std::begin(pool), std::end(pool), [](auto const& atom) { return atom.isSeed(); });
}
return *pool_is_all_seeds_;
}
void markAllSeedsFlagDirty() noexcept
{
pool_is_all_seeds_.reset();
}
Handshakes outgoing_handshakes;
uint16_t interested_count = 0;
uint16_t max_peers = 0;
tr_swarm_stats stats = {};
uint8_t optimistic_unchoke_time_scaler = 0;
bool is_running = false;
bool needs_completeness_check = true;
tr_peerMgr* const manager;
tr_torrent* const tor;
std::vector<std::unique_ptr<tr_peer>> webseeds;
std::vector<tr_peerMsgs*> peers;
// tr_peers hold pointers to the items in this container,
// so use a deque instead of vector to prevent insertion from
// invalidating those pointers
std::deque<peer_atom> pool;
tr_peerMsgs* optimistic = nullptr; /* the optimistic peer, or nullptr if none */
time_t lastCancel = 0;
ActiveRequests active_requests;
private:
static void maybeSendCancelRequest(tr_peer* peer, tr_block_index_t block, tr_peer const* muted)
{
auto* msgs = dynamic_cast<tr_peerMsgs*>(peer);
if (msgs != nullptr && msgs != muted)
{
peer->cancels_sent_to_peer.add(tr_time(), 1);
msgs->cancel_block_request(block);
}
}
// number of bad pieces a peer is allowed to send before we ban them
static auto constexpr MaxBadPiecesPerPeer = int{ 5 };
// how long we'll let requests we've made linger before we cancel them
static auto constexpr RequestTtlSecs = int{ 90 };
mutable std::optional<bool> pool_is_all_seeds_;
bool is_endgame_ = false;
};
struct EventDeleter
{
void operator()(struct event* ev) const
{
event_free(ev);
}
};
using UniqueTimer = std::unique_ptr<struct event, EventDeleter>;
struct tr_peerMgr
{
explicit tr_peerMgr(tr_session* session_in)
: session{ session_in }
, bandwidth_timer_{ evtimer_new(session->event_base, bandwidthPulseMarshall, this) }
, rechoke_timer_{ evtimer_new(session->event_base, rechokePulseMarshall, this) }
, refill_upkeep_timer_{ evtimer_new(session->event_base, refillUpkeepMarshall, this) }
{
tr_timerAddMsec(*bandwidth_timer_, BandwidthPeriodMsec);
tr_timerAddMsec(*rechoke_timer_, RechokePeriodMsec);
tr_timerAddMsec(*refill_upkeep_timer_, RefillUpkeepPeriodMsec);
}
[[nodiscard]] auto unique_lock() const
{
return session->unique_lock();
}
~tr_peerMgr()
{
auto const lock = unique_lock();
incoming_handshakes.abortAll();
}
void rechokeSoon() noexcept
{
tr_timerAddMsec(*rechoke_timer_, 100);
}
void bandwidthPulse();
void rechokePulse() const;
void reconnectPulse();
void refillUpkeep() const;
void makeNewPeerConnections(size_t max);
tr_session* const session;
Handshakes incoming_handshakes;
private:
static void bandwidthPulseMarshall(evutil_socket_t, short /*reason*/, void* vmgr)
{
auto* const self = static_cast<tr_peerMgr*>(vmgr);
self->bandwidthPulse();
tr_timerAddMsec(*self->bandwidth_timer_, BandwidthPeriodMsec);
}
static void rechokePulseMarshall(evutil_socket_t, short /*reason*/, void* vmgr)
{
auto* const self = static_cast<tr_peerMgr*>(vmgr);
self->rechokePulse();
tr_timerAddMsec(*self->rechoke_timer_, RechokePeriodMsec);
}
static void refillUpkeepMarshall(evutil_socket_t, short /*reason*/, void* vmgr)
{
auto* const self = static_cast<tr_peerMgr*>(vmgr);
self->refillUpkeep();
tr_timerAddMsec(*self->refill_upkeep_timer_, RefillUpkeepPeriodMsec);
}
UniqueTimer const bandwidth_timer_;
UniqueTimer const rechoke_timer_;
UniqueTimer const refill_upkeep_timer_;
static auto constexpr BandwidthPeriodMsec = int{ 500 };
static auto constexpr RechokePeriodMsec = int{ 10 * 1000 };
static auto constexpr RefillUpkeepPeriodMsec = int{ 10 * 1000 };
// how frequently to decide which peers live and die
static auto constexpr ReconnectPeriodMsec = int{ 500 };
// max number of peers to ask for per second overall.
// this throttle is to avoid overloading the router
static auto constexpr MaxConnectionsPerSecond = size_t{ 12 };
};
/**
*** tr_peer virtual functions
**/
unsigned int tr_peerGetPieceSpeed_Bps(tr_peer const* peer, uint64_t now, tr_direction direction)
{
unsigned int Bps = 0;
peer->isTransferringPieces(now, direction, &Bps);
return Bps;
}
tr_peer::tr_peer(tr_torrent const* tor, peer_atom* atom_in)
: session{ tor->session }
, swarm{ tor->swarm }
, atom{ atom_in }
, blame{ tor->blockCount() }
{
}
tr_peer::~tr_peer()
{
if (swarm != nullptr)
{
swarm->active_requests.remove(this);
}
if (atom != nullptr)
{
atom->is_connected = false;
}
}
/**
***
**/
static tr_swarm* getExistingSwarm(tr_peerMgr* manager, tr_sha1_digest_t const& hash)
{
auto* const tor = manager->session->torrents().get(hash);
return tor == nullptr ? nullptr : tor->swarm;
}
static struct peer_atom* getExistingAtom(tr_swarm const* cswarm, tr_address const& addr)
{
auto* swarm = const_cast<tr_swarm*>(cswarm);
auto const test = [&addr](auto const& atom)
{
return atom.addr == addr;
};
auto const it = std::find_if(std::begin(swarm->pool), std::end(swarm->pool), test);
return it != std::end(swarm->pool) ? &*it : nullptr;
}
static bool peerIsInUse(tr_swarm const* cs, struct peer_atom const* atom)
{
auto const* const s = const_cast<tr_swarm*>(cs);
auto const lock = s->unique_lock();
return atom->is_connected || s->outgoing_handshakes.contains(atom->addr) ||
s->manager->incoming_handshakes.contains(atom->addr);
}
static void swarmFree(tr_swarm* s)
{
TR_ASSERT(s != nullptr);
auto const lock = s->unique_lock();
TR_ASSERT(!s->is_running);
TR_ASSERT(std::empty(s->outgoing_handshakes));
TR_ASSERT(s->peerCount() == 0);
s->stats = {};
delete s;
}
tr_peerMgr* tr_peerMgrNew(tr_session* session)
{
return new tr_peerMgr{ session };
}
void tr_peerMgrFree(tr_peerMgr* manager)
{
delete manager;
}
/***
****
***/
void tr_peerMgrOnBlocklistChanged(tr_peerMgr* mgr)
{
/* we cache whether or not a peer is blocklisted...
since the blocklist has changed, erase that cached value */
for (auto* const tor : mgr->session->torrents())
{
for (auto& atom : tor->swarm->pool)
{
atom.setBlocklistedDirty();
}
}
}
/***
****
***/
static void atomSetSeed(tr_swarm* swarm, peer_atom& atom)
{
tr_logAddTraceSwarm(swarm, fmt::format("marking peer {} as a seed", atom.readable()));
atom.flags |= ADDED_F_SEED_FLAG;
swarm->markAllSeedsFlagDirty();
}
bool tr_peerMgrPeerIsSeed(tr_torrent const* tor, tr_address const& addr)
{
if (auto const* atom = getExistingAtom(tor->swarm, addr); atom != nullptr)
{
return atom->isSeed();
}
return false;
}
void tr_peerMgrSetUtpSupported(tr_torrent* tor, tr_address const& addr)
{
if (auto* const atom = getExistingAtom(tor->swarm, addr); atom != nullptr)
{
atom->flags |= ADDED_F_UTP_FLAGS;
}
}
void tr_peerMgrSetUtpFailed(tr_torrent* tor, tr_address const& addr, bool failed)
{
if (auto* const atom = getExistingAtom(tor->swarm, addr); atom != nullptr)
{
atom->utp_failed = failed;
}
}
/**
*** REQUESTS
***
*** There are two data structures associated with managing block requests:
***
*** 1. tr_swarm::active_requests, an opaque class that tracks what requests
*** we currently have, i.e. which blocks and from which peers.
*** This is used for cancelling requests that have been waiting
*** for too long and avoiding duplicate requests.
***
*** 2. tr_swarm::pieces, an array of "struct weighted_piece" which lists the
*** pieces that we want to request. It's used to decide which blocks to
*** return next when tr_peerMgrGetBlockRequests() is called.
**/
/**
*** struct block_request
**/
// TODO: if we keep this, add equivalent API to ActiveRequest
void tr_peerMgrClientSentRequests(tr_torrent* torrent, tr_peer* peer, tr_block_span_t span)
{
auto const now = tr_time();
for (tr_block_index_t block = span.begin; block < span.end; ++block)
{
torrent->swarm->active_requests.add(block, peer, now);
}
}
std::vector<tr_block_span_t> tr_peerMgrGetNextRequests(tr_torrent* torrent, tr_peer const* peer, size_t numwant)
{
class MediatorImpl final : public Wishlist::Mediator
{
public:
MediatorImpl(tr_torrent const* torrent_in, tr_peer const* peer_in)
: torrent_{ torrent_in }
, swarm_{ torrent_in->swarm }
, peer_{ peer_in }
{
}
~MediatorImpl() override = default;
[[nodiscard]] bool clientCanRequestBlock(tr_block_index_t block) const override
{
return !torrent_->hasBlock(block) && !swarm_->active_requests.has(block, peer_);
}
[[nodiscard]] bool clientCanRequestPiece(tr_piece_index_t piece) const override
{
return torrent_->pieceIsWanted(piece) && peer_->hasPiece(piece);
}
[[nodiscard]] bool isEndgame() const override
{
return swarm_->isEndgame();
}
[[nodiscard]] size_t countActiveRequests(tr_block_index_t block) const override
{
return swarm_->active_requests.count(block);
}
[[nodiscard]] size_t countMissingBlocks(tr_piece_index_t piece) const override
{
return torrent_->countMissingBlocksInPiece(piece);
}
[[nodiscard]] tr_block_span_t blockSpan(tr_piece_index_t piece) const override
{
return torrent_->blockSpanForPiece(piece);
}
[[nodiscard]] tr_piece_index_t countAllPieces() const override
{
return torrent_->pieceCount();
}
[[nodiscard]] tr_priority_t priority(tr_piece_index_t piece) const override
{
return torrent_->piecePriority(piece);
}
private:
tr_torrent const* const torrent_;
tr_swarm const* const swarm_;
tr_peer const* const peer_;
};
torrent->swarm->updateEndgame();
return Wishlist::next(MediatorImpl(torrent, peer), numwant);
}
/****
*****
***** Piece List Manipulation / Accessors
*****
****/
bool tr_peerMgrDidPeerRequest(tr_torrent const* tor, tr_peer const* peer, tr_block_index_t block)
{
return tor->swarm->active_requests.has(block, peer);
}
size_t tr_peerMgrCountActiveRequestsToPeer(tr_torrent const* tor, tr_peer const* peer)
{
return tor->swarm->active_requests.count(peer);
}
void tr_peerMgr::refillUpkeep() const
{
auto const lock = unique_lock();
for (auto* const tor : session->torrents())
{
tor->swarm->cancelOldRequests();
}
}
static void peerSuggestedPiece(tr_swarm* /*s*/, tr_peer* /*peer*/, tr_piece_index_t /*pieceIndex*/, bool /*isFastAllowed*/)
{
#if 0
TR_ASSERT(t != nullptr);
TR_ASSERT(peer != nullptr);
TR_ASSERT(peer->msgs != nullptr);
/* is this a valid piece? */
if (pieceIndex >= t->tor->pieceCount())
{
return;
}
/* don't ask for it if we've already got it */
if (t->tor->hasPiece(pieceIndex))
{
return;
}
/* don't ask for it if they don't have it */
if (!peer->have.readBit(pieceIndex))
{
return;
}
/* don't ask for it if we're choked and it's not fast */
if (!isFastAllowed && peer->clientIsChoked)
{
return;
}
/* request the blocks that we don't have in this piece */
{
tr_torrent const* tor = t->tor;
auto const [begin, end] = tor->blockSpanForPiece(pieceIndex);
for (tr_block_index_t b = begin; b < end; ++b)
{
if (tor->hasBlock(b))
{
uint32_t const offset = getBlockOffsetInPiece(tor, b);
uint32_t const length = tor->blockSize(b);
tr_peerMsgsAddRequest(peer->msgs, pieceIndex, offset, length);
incrementPieceRequests(t, pieceIndex);
}
}
}
#endif
}
void tr_peerMgrPieceCompleted(tr_torrent* tor, tr_piece_index_t p)
{
bool pieceCameFromPeers = false;
tr_swarm* const s = tor->swarm;
/* walk through our peers */
for (auto* const peer : s->peers)
{
// notify the peer that we now have this piece
peer->on_piece_completed(p);
if (!pieceCameFromPeers)
{
pieceCameFromPeers = peer->blame.test(p);
}
}
if (pieceCameFromPeers) /* webseed downloads don't belong in announce totals */
{
tr_announcerAddBytes(tor, TR_ANN_DOWN, tor->pieceSize(p));
}
/* bookkeeping */
s->needs_completeness_check = true;
}
static void peerCallbackFunc(tr_peer* peer, tr_peer_event const* e, void* vs)
{
TR_ASSERT(peer != nullptr);
auto* s = static_cast<tr_swarm*>(vs);
auto const lock = s->unique_lock();
switch (e->eventType)
{
case TR_PEER_PEER_GOT_PIECE_DATA:
{
auto const now = tr_time();
auto* const tor = s->tor;
tor->uploadedCur += e->length;
tr_announcerAddBytes(tor, TR_ANN_UP, e->length);
tor->setDateActive(now);
tor->setDirty();
tr_statsAddUploaded(tor->session, e->length);
if (peer->atom != nullptr)
{
peer->atom->piece_data_time = now;
}
break;
}
case TR_PEER_CLIENT_GOT_PIECE_DATA:
{
auto const now = tr_time();
auto* const tor = s->tor;
tor->downloadedCur += e->length;
tor->setDateActive(now);
tor->setDirty();
tr_statsAddDownloaded(tor->session, e->length);
if (peer->atom != nullptr)
{
peer->atom->piece_data_time = now;
}
break;
}
case TR_PEER_CLIENT_GOT_HAVE:
case TR_PEER_CLIENT_GOT_HAVE_ALL:
case TR_PEER_CLIENT_GOT_HAVE_NONE:
case TR_PEER_CLIENT_GOT_BITFIELD:
/* TODO: if we don't need these, should these events be removed? */
/* noop */
break;
case TR_PEER_CLIENT_GOT_REJ:
s->active_requests.remove(s->tor->pieceLoc(e->pieceIndex, e->offset).block, peer);
break;
case TR_PEER_CLIENT_GOT_CHOKE:
s->active_requests.remove(peer);
break;
case TR_PEER_CLIENT_GOT_PORT:
if (peer->atom != nullptr)
{
peer->atom->port = e->port;
}
break;
case TR_PEER_CLIENT_GOT_SUGGEST:
peerSuggestedPiece(s, peer, e->pieceIndex, false);
break;
case TR_PEER_CLIENT_GOT_ALLOWED_FAST:
peerSuggestedPiece(s, peer, e->pieceIndex, true);
break;
case TR_PEER_CLIENT_GOT_BLOCK:
{
auto* const tor = s->tor;
auto const loc = tor->pieceLoc(e->pieceIndex, e->offset);
s->cancelAllRequestsForBlock(loc.block, peer);
peer->blocks_sent_to_client.add(tr_time(), 1);
tr_torrentGotBlock(tor, loc.block);
break;
}
case TR_PEER_ERROR:
if (e->err == ERANGE || e->err == EMSGSIZE || e->err == ENOTCONN)
{
/* some protocol error from the peer */
peer->do_purge = true;
tr_logAddDebugSwarm(
s,
fmt::format(
"setting {} do_purge flag because we got an ERANGE, EMSGSIZE, or ENOTCONN error",
peer->readable()));
}
else
{
tr_logAddDebugSwarm(s, fmt::format("unhandled error: {}", tr_strerror(e->err)));
}
break;
default:
TR_ASSERT_MSG(false, fmt::format(FMT_STRING("unhandled peer event type {:d}"), e->eventType));
}
}
static struct peer_atom* ensureAtomExists(
tr_swarm* s,
tr_address const& addr,
tr_port const port,
uint8_t const flags,
uint8_t const from)
{
TR_ASSERT(tr_address_is_valid(&addr));
TR_ASSERT(from < TR_PEER_FROM__MAX);
struct peer_atom* a = getExistingAtom(s, addr);
if (a == nullptr)
{
a = &s->pool.emplace_back(addr, port, flags, from);
}
else
{
a->fromBest = std::min(a->fromBest, from);
a->flags |= flags;
}
s->markAllSeedsFlagDirty();
return a;
}
[[nodiscard]] static constexpr auto getMaxPeerCount(tr_torrent const* tor) noexcept
{
return tor->max_connected_peers;
}
static void createBitTorrentPeer(tr_torrent* tor, tr_peerIo* io, struct peer_atom* atom, tr_quark client)
{
TR_ASSERT(atom != nullptr);
TR_ASSERT(tr_isTorrent(tor));
TR_ASSERT(tor->swarm != nullptr);
tr_swarm* swarm = tor->swarm;
auto* peer = tr_peerMsgsNew(tor, atom, io, peerCallbackFunc, swarm);
peer->client = client;
atom->is_connected = true;
swarm->peers.push_back(peer);
++swarm->stats.peer_count;
++swarm->stats.peer_from_count[atom->fromFirst];
TR_ASSERT(swarm->stats.peer_count == swarm->peerCount());
TR_ASSERT(swarm->stats.peer_from_count[atom->fromFirst] <= swarm->stats.peer_count);
// TODO is this needed?
// isn't it already initialized in tr_peerMsgsImpl's ctor?
peer->update_active(TR_UP);
peer->update_active(TR_DOWN);
}
/* FIXME: this is kind of a mess. */
static bool on_handshake_done(tr_handshake_result const& result)
{
TR_ASSERT(result.io != nullptr);
bool ok = result.isConnected;
bool success = false;
auto* manager = static_cast<tr_peerMgr*>(result.userData);
auto const hash = tr_peerIoGetTorrentHash(result.io);
tr_swarm* const s = hash ? getExistingSwarm(manager, *hash) : nullptr;
auto const [addr, port] = result.io->socketAddress();
if (result.io->isIncoming())
{
manager->incoming_handshakes.erase(addr);
}
else if (s != nullptr)
{
s->outgoing_handshakes.erase(addr);
}
auto const lock = manager->unique_lock();
if (!ok || s == nullptr || !s->is_running)
{
if (s != nullptr)
{
struct peer_atom* atom = getExistingAtom(s, addr);
if (atom != nullptr)
{
++atom->num_fails;
if (!result.readAnythingFromPeer)
{
tr_logAddTraceSwarm(
s,
fmt::format("marking peer {} as unreachable... num_fails is {}", atom->readable(), atom->num_fails));
atom->flags2 |= MyflagUnreachable;
}
}
}
}
else /* looking good */
{
struct peer_atom* atom = ensureAtomExists(s, addr, port, 0, TR_PEER_FROM_INCOMING);
atom->time = tr_time();
atom->piece_data_time = 0;
atom->lastConnectionAt = tr_time();
if (!result.io->isIncoming())
{
atom->flags |= ADDED_F_CONNECTABLE;
atom->flags2 &= ~MyflagUnreachable;
}
/* In principle, this flag specifies whether the peer groks uTP,
not whether it's currently connected over uTP. */
if (result.io->socket.type == TR_PEER_SOCKET_TYPE_UTP)
{
atom->flags |= ADDED_F_UTP_FLAGS;
}
if ((atom->flags2 & MyflagBanned) != 0)
{
tr_logAddTraceSwarm(s, fmt::format("banned peer {} tried to reconnect", atom->readable()));
}
else if (result.io->isIncoming() && s->peerCount() >= getMaxPeerCount(s->tor))
{
/* too many peers already */
}
else if (atom->is_connected)
{
// we're already connected to this peer; do nothing
}
else
{
auto client = tr_quark{ TR_KEY_NONE };
if (result.peer_id)
{
char buf[128] = {};
tr_clientForId(buf, sizeof(buf), *result.peer_id);
client = tr_quark_new(buf);
}
/* this steals its refcount too, which is balanced by our unref in peerDelete() */
tr_peerIo* stolen = tr_handshakeStealIO(result.handshake);
stolen->setParent(&s->tor->bandwidth_);
createBitTorrentPeer(s->tor, stolen, atom, client);
success = true;
}
}
return success;
}
void tr_peerMgrAddIncoming(tr_peerMgr* manager, tr_address const* addr, tr_port port, struct tr_peer_socket const socket)
{
TR_ASSERT(tr_isSession(manager->session));
auto const lock = manager->unique_lock();
tr_session* session = manager->session;
if (tr_sessionIsAddressBlocked(session, addr))
{
tr_logAddTrace(fmt::format("Banned IP address '{}' tried to connect to us", tr_address_to_string(addr)));
tr_netClosePeerSocket(session, socket);
}
else if (manager->incoming_handshakes.contains(*addr))
{
tr_netClosePeerSocket(session, socket);
}
else /* we don't have a connection to them yet... */
{
tr_peerIo* const io = tr_peerIoNewIncoming(session, &session->top_bandwidth_, addr, port, tr_time(), socket);
tr_handshake* const handshake = tr_handshakeNew(io, session->encryptionMode, on_handshake_done, manager);
tr_peerIoUnref(io); /* balanced by the implicit ref in tr_peerIoNewIncoming() */
manager->incoming_handshakes.add(*addr, handshake);
}
}
void tr_peerMgrSetSwarmIsAllSeeds(tr_torrent* tor)
{
auto const lock = tor->unique_lock();
auto* const swarm = tor->swarm;
for (auto& atom : swarm->pool)
{
atomSetSeed(swarm, atom);
}
swarm->markAllSeedsFlagDirty();
}
size_t tr_peerMgrAddPex(tr_torrent* tor, uint8_t from, tr_pex const* pex, size_t n_pex)
{
size_t n_used = 0;
tr_swarm* s = tor->swarm;
auto const lock = s->manager->unique_lock();
for (tr_pex const* const end = pex + n_pex; pex != end; ++pex)
{
if (tr_isPex(pex) && /* safeguard against corrupt data */
!tr_sessionIsAddressBlocked(s->manager->session, &pex->addr) &&
tr_address_is_valid_for_peers(&pex->addr, pex->port))
{
ensureAtomExists(s, pex->addr, pex->port, pex->flags, from);
++n_used;
}
}
return n_used;
}
std::vector<tr_pex> tr_peerMgrCompactToPex(void const* compact, size_t compactLen, uint8_t const* added_f, size_t added_f_len)
{
size_t n = compactLen / 6;
auto const* walk = static_cast<uint8_t const*>(compact);
auto pex = std::vector<tr_pex>(n);
for (size_t i = 0; i < n; ++i)
{
std::tie(pex[i].addr, walk) = tr_address::fromCompact4(walk);
std::tie(pex[i].port, walk) = tr_port::fromCompact(walk);
if (added_f != nullptr && n == added_f_len)
{
pex[i].flags = added_f[i];
}
}
return pex;
}
std::vector<tr_pex> tr_peerMgrCompact6ToPex(void const* compact, size_t compactLen, uint8_t const* added_f, size_t added_f_len)
{
size_t n = compactLen / 18;
auto const* walk = static_cast<uint8_t const*>(compact);
auto pex = std::vector<tr_pex>(n);
for (size_t i = 0; i < n; ++i)
{
std::tie(pex[i].addr, walk) = tr_address::fromCompact6(walk);
std::tie(pex[i].port, walk) = tr_port::fromCompact(walk);
if (added_f != nullptr && n == added_f_len)
{
pex[i].flags = added_f[i];
}
}
return pex;
}
/**
***
**/
void tr_peerMgrGotBadPiece(tr_torrent* tor, tr_piece_index_t pieceIndex)
{
auto* const swarm = tor->swarm;
auto const byteCount = tor->pieceSize(pieceIndex);
for (auto* const peer : swarm->peers)
{
if (peer->blame.test(pieceIndex))
{
tr_logAddTraceSwarm(
swarm,
fmt::format(
"peer {} contributed to corrupt piece ({}); now has {} strikes",
peer->readable(),
pieceIndex,
peer->strikes + 1));
swarm->addStrike(peer);
}
}
tr_announcerAddBytes(tor, TR_ANN_CORRUPT, byteCount);
}
namespace get_peers_helpers
{
/* better goes first */
struct CompareAtomsByUsefulness
{
[[nodiscard]] constexpr static int compare(peer_atom const& a, peer_atom const& b) noexcept // <=>
{
if (a.piece_data_time != b.piece_data_time)
{
return a.piece_data_time > b.piece_data_time ? -1 : 1;
}
if (a.fromBest != b.fromBest)
{
return a.fromBest < b.fromBest ? -1 : 1;
}
if (a.num_fails != b.num_fails)
{
return a.num_fails < b.num_fails ? -1 : 1;
}
return 0;
}
[[nodiscard]] constexpr bool operator()(peer_atom const& a, peer_atom const& b) const noexcept
{
return compare(a, b) < 0;
}
[[nodiscard]] constexpr bool operator()(peer_atom const* a, peer_atom const* b) const noexcept
{
return compare(*a, *b) < 0;
}
};
[[nodiscard]] bool isAtomInteresting(tr_torrent const* tor, peer_atom const& atom)
{
if (tor->isDone() && atom.isSeed())
{
return false;
}
if (peerIsInUse(tor->swarm, &atom))
{
return true;
}
if (atom.isBlocklisted(tor->session))
{
return false;
}
if ((atom.flags2 & MyflagBanned) != 0)
{
return false;
}
return true;
}
} // namespace get_peers_helpers
std::vector<tr_pex> tr_peerMgrGetPeers(tr_torrent const* tor, uint8_t af, uint8_t list_mode, size_t max_count)
{
using namespace get_peers_helpers;
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
TR_ASSERT(af == TR_AF_INET || af == TR_AF_INET6);
TR_ASSERT(list_mode == TR_PEERS_CONNECTED || list_mode == TR_PEERS_INTERESTING);
tr_swarm const* s = tor->swarm;
/**
*** build a list of atoms
**/
auto atoms = std::vector<peer_atom const*>{};
if (list_mode == TR_PEERS_CONNECTED) /* connected peers only */
{
atoms.reserve(s->peerCount());
std::transform(
std::begin(s->peers),
std::end(s->peers),
std::back_inserter(atoms),
[](auto const* peer) { return peer->atom; });
}
else /* TR_PEERS_INTERESTING */
{
for (auto const& atom : s->pool)
{
if (isAtomInteresting(tor, atom))
{
atoms.push_back(&atom);
}
}
}
std::sort(std::begin(atoms), std::end(atoms), CompareAtomsByUsefulness{});
/**
*** add the first N of them into our return list
**/
auto const n = std::min(std::size(atoms), max_count);
auto pex = std::vector<tr_pex>{};
pex.reserve(n);
for (size_t i = 0; i < std::size(atoms) && std::size(pex) < n; ++i)
{
auto const* const atom = atoms[i];
if (atom->addr.type == af)
{
TR_ASSERT(tr_address_is_valid(&atom->addr));
pex.emplace_back(atom->addr, atom->port, atom->flags);
}
}
std::sort(std::begin(pex), std::end(pex));
return pex;
}
void tr_peerMgrStartTorrent(tr_torrent* tor)
{
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
tr_swarm* const swarm = tor->swarm;
swarm->is_running = true;
swarm->max_peers = getMaxPeerCount(tor);
swarm->manager->rechokeSoon();
}
void tr_peerMgrStopTorrent(tr_torrent* tor)
{
TR_ASSERT(tr_isTorrent(tor));
tor->swarm->stop();
}
void tr_peerMgrAddTorrent(tr_peerMgr* manager, tr_torrent* tor)
{
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
TR_ASSERT(tor->swarm == nullptr);
tor->swarm = new tr_swarm{ manager, tor };
}
void tr_peerMgrRemoveTorrent(tr_torrent* tor)
{
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
tor->swarm->stop();
swarmFree(tor->swarm);
}
void tr_peerMgrOnTorrentGotMetainfo(tr_torrent* tor)
{
/* the webseed list may have changed... */
tor->swarm->rebuildWebseeds();
/* some peer_msgs' progress fields may not be accurate if we
didn't have the metadata before now... so refresh them all... */
for (auto* peer : tor->swarm->peers)
{
peer->onTorrentGotMetainfo();
if (peer->isSeed())
{
atomSetSeed(tor->swarm, *peer->atom);
}
}
/* update the bittorrent peers' willingness... */
for (auto* peer : tor->swarm->peers)
{
peer->update_active(TR_UP);
peer->update_active(TR_DOWN);
}
}
int8_t tr_peerMgrPieceAvailability(tr_torrent const* tor, tr_piece_index_t piece)
{
if (!tor->hasMetainfo())
{
return 0;
}
if (tor->isSeed() || tor->hasPiece(piece))
{
return -1;
}
auto const& peers = tor->swarm->peers;
return std::count_if(std::begin(peers), std::end(peers), [piece](auto const* peer) { return peer->hasPiece(piece); });
}
void tr_peerMgrTorrentAvailability(tr_torrent const* tor, int8_t* tab, unsigned int n_tabs)
{
TR_ASSERT(tr_isTorrent(tor));
TR_ASSERT(tab != nullptr);
TR_ASSERT(n_tabs > 0);
std::fill_n(tab, n_tabs, int8_t{});
auto const interval = tor->pieceCount() / static_cast<float>(n_tabs);
for (tr_piece_index_t i = 0; i < n_tabs; ++i)
{
auto const piece = static_cast<tr_piece_index_t>(i * interval);
tab[i] = tr_peerMgrPieceAvailability(tor, piece);
}
}
tr_swarm_stats tr_swarmGetStats(tr_swarm const* swarm)
{
TR_ASSERT(swarm != nullptr);
return swarm->stats;
}
void tr_swarmIncrementActivePeers(tr_swarm* swarm, tr_direction direction, bool is_active)
{
int n = swarm->stats.active_peer_count[direction];
if (is_active)
{
++n;
}
else
{
--n;
}
TR_ASSERT(n >= 0);
TR_ASSERT(n <= swarm->stats.peer_count);
swarm->stats.active_peer_count[direction] = n;
}
/* count how many bytes we want that connected peers have */
uint64_t tr_peerMgrGetDesiredAvailable(tr_torrent const* tor)
{
TR_ASSERT(tr_isTorrent(tor));
// common shortcuts...
if (!tor->isRunning || tor->isStopping || tor->isDone() || !tor->hasMetainfo())
{
return 0;
}
tr_swarm const* const s = tor->swarm;
if (s == nullptr || !s->is_running)
{
return 0;
}
auto const n_peers = s->peerCount();
if (n_peers == 0)
{
return 0;
}
for (auto const* const peer : s->peers)
{
if (peer->atom != nullptr && peer->atom->isSeed())
{
return tor->leftUntilDone();
}
}
// do it the hard way
auto desired_available = uint64_t{};
auto const n_pieces = tor->pieceCount();
auto have = std::vector<bool>(n_pieces);
for (auto const* const peer : s->peers)
{
for (size_t j = 0; j < n_pieces; ++j)
{
if (peer->hasPiece(j))
{
have[j] = true;
}
}
}
for (size_t i = 0; i < n_pieces; ++i)
{
if (tor->pieceIsWanted(i) && have.at(i))
{
desired_available += tor->countMissingBytesInPiece(i);
}
}
TR_ASSERT(desired_available <= tor->totalSize());
return desired_available;
}
tr_webseed_view tr_peerMgrWebseed(tr_torrent const* tor, size_t i)
{
TR_ASSERT(tr_isTorrent(tor));
TR_ASSERT(tor->swarm != nullptr);
size_t const n = std::size(tor->swarm->webseeds);
TR_ASSERT(i < n);
return i >= n ? tr_webseed_view{} : tr_webseedView(tor->swarm->webseeds[i].get());
}
namespace peer_stat_helpers
{
[[nodiscard]] auto getPeerStats(tr_peerMsgs const* peer, time_t now, uint64_t now_msec)
{
auto stats = tr_peer_stat{};
auto const* const atom = peer->atom;
auto const [addr, port] = peer->socketAddress();
tr_address_to_string_with_buf(&addr, stats.addr, sizeof(stats.addr));
stats.client = peer->client.c_str();
stats.port = port.host();
stats.from = atom->fromFirst;
stats.progress = peer->percentDone();
stats.isUTP = peer->is_utp_connection();
stats.isEncrypted = peer->is_encrypted();
stats.rateToPeer_KBps = tr_toSpeedKBps(tr_peerGetPieceSpeed_Bps(peer, now_msec, TR_CLIENT_TO_PEER));
stats.rateToClient_KBps = tr_toSpeedKBps(tr_peerGetPieceSpeed_Bps(peer, now_msec, TR_PEER_TO_CLIENT));
stats.peerIsChoked = peer->is_peer_choked();
stats.peerIsInterested = peer->is_peer_interested();
stats.clientIsChoked = peer->is_client_choked();
stats.clientIsInterested = peer->is_client_interested();
stats.isIncoming = peer->is_incoming_connection();
stats.isDownloadingFrom = peer->is_active(TR_PEER_TO_CLIENT);
stats.isUploadingTo = peer->is_active(TR_CLIENT_TO_PEER);
stats.isSeed = peer->isSeed();
stats.blocksToPeer = peer->blocks_sent_to_peer.count(now, CancelHistorySec);
stats.blocksToClient = peer->blocks_sent_to_client.count(now, CancelHistorySec);
stats.cancelsToPeer = peer->cancels_sent_to_peer.count(now, CancelHistorySec);
stats.cancelsToClient = peer->cancels_sent_to_client.count(now, CancelHistorySec);
stats.activeReqsToPeer = peer->activeReqCount(TR_CLIENT_TO_PEER);
stats.activeReqsToClient = peer->activeReqCount(TR_PEER_TO_CLIENT);
char* pch = stats.flagStr;
if (stats.isUTP)
{
*pch++ = 'T';
}
if (peer->swarm->optimistic == peer)
{
*pch++ = 'O';
}
if (stats.isDownloadingFrom)
{
*pch++ = 'D';
}
else if (stats.clientIsInterested)
{
*pch++ = 'd';
}
if (stats.isUploadingTo)
{
*pch++ = 'U';
}
else if (stats.peerIsInterested)
{
*pch++ = 'u';
}
if (!stats.clientIsChoked && !stats.clientIsInterested)
{
*pch++ = 'K';
}
if (!stats.peerIsChoked && !stats.peerIsInterested)
{
*pch++ = '?';
}
if (stats.isEncrypted)
{
*pch++ = 'E';
}
if (stats.from == TR_PEER_FROM_DHT)
{
*pch++ = 'H';
}
else if (stats.from == TR_PEER_FROM_PEX)
{
*pch++ = 'X';
}
if (stats.isIncoming)
{
*pch++ = 'I';
}
*pch = '\0';
return stats;
}
} // namespace peer_stat_helpers
tr_peer_stat* tr_peerMgrPeerStats(tr_torrent const* tor, int* setme_count)
{
using namespace peer_stat_helpers;
TR_ASSERT(tr_isTorrent(tor));
TR_ASSERT(tor->swarm->manager != nullptr);
auto const n = tor->swarm->peerCount();
auto* const ret = tr_new0(tr_peer_stat, n);
auto const now = tr_time();
auto const now_msec = tr_time_msec();
std::transform(
std::begin(tor->swarm->peers),
std::end(tor->swarm->peers),
ret,
[&now, &now_msec](auto const* peer) { return getPeerStats(peer, now, now_msec); });
*setme_count = n;
return ret;
}
void tr_peerMgrClearInterest(tr_torrent* tor)
{
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
auto& peers = tor->swarm->peers;
std::for_each(std::begin(peers), std::end(peers), [](auto* const peer) { peer->set_interested(false); });
}
namespace rechoke_downloads_helpers
{
namespace
{
/* does this peer have any pieces that we want? */
[[nodiscard]] bool isPeerInteresting(
tr_torrent* const tor,
bool const* const piece_is_interesting,
tr_peerMsgs const* const peer)
{
/* these cases should have already been handled by the calling code... */
TR_ASSERT(!tor->isDone());
TR_ASSERT(tor->clientCanDownload());
if (peer->isSeed())
{
return true;
}
for (tr_piece_index_t i = 0; i < tor->pieceCount(); ++i)
{
if (piece_is_interesting[i] && peer->hasPiece(i))
{
return true;
}
}
return false;
}
enum tr_rechoke_state
{
RECHOKE_STATE_GOOD,
RECHOKE_STATE_UNTESTED,
RECHOKE_STATE_BAD
};
struct tr_rechoke_info
{
tr_peerMsgs* peer;
int salt;
int rechoke_state;
};
[[nodiscard]] constexpr int compare_rechoke_info(void const* va, void const* vb)
{
auto const* const a = static_cast<struct tr_rechoke_info const*>(va);
auto const* const b = static_cast<struct tr_rechoke_info const*>(vb);
if (a->rechoke_state != b->rechoke_state)
{
return a->rechoke_state - b->rechoke_state;
}
return a->salt - b->salt;
}
} // namespace
/* determines who we send "interested" messages to */
void rechokeDownloads(tr_swarm* s)
{
static auto constexpr MinInterestingPeers = uint16_t{ 5 };
auto const peerCount = s->peerCount();
auto const& peers = s->peers;
auto const now = tr_time();
uint16_t max_peers = 0;
uint16_t rechoke_count = 0;
struct tr_rechoke_info* rechoke = nullptr;
/* some cases where this function isn't necessary */
if (s->tor->isDone() || !s->tor->clientCanDownload())
{
return;
}
/* decide HOW MANY peers to be interested in */
{
int blocks = 0;
int cancels = 0;
/* Count up how many blocks & cancels each peer has.
*
* There are two situations where we send out cancels --
*
* 1. We've got unresponsive peers, which is handled by deciding
* -which- peers to be interested in.
*
* 2. We've hit our bandwidth cap, which is handled by deciding
* -how many- peers to be interested in.
*
* We're working on 2. here, so we need to ignore unresponsive
* peers in our calculations lest they confuse Transmission into
* thinking it's hit its bandwidth cap.
*/
for (auto const* const peer : peers)
{
auto const b = peer->blocks_sent_to_client.count(now, CancelHistorySec);
if (b == 0) /* ignore unresponsive peers, as described above */
{
continue;
}
blocks += b;
cancels += peer->cancels_sent_to_peer.count(now, CancelHistorySec);
}
if (cancels > 0)
{
/* cancelRate: of the block requests we've recently made, the percentage we cancelled.
* higher values indicate more congestion. */
double const cancelRate = cancels / (double)(cancels + blocks);
double const mult = 1 - std::min(cancelRate, 0.5);
max_peers = s->interested_count * mult;
tr_logAddTraceSwarm(
s,
fmt::format(
"cancel rate is {} -- reducing the number of peers we're interested in by {} percent",
cancelRate,
mult * 100));
s->lastCancel = now;
}
time_t const timeSinceCancel = now - s->lastCancel;
if (timeSinceCancel != 0)
{
int const maxIncrease = 15;
time_t const maxHistory = 2 * CancelHistorySec;
double const mult = std::min(timeSinceCancel, maxHistory) / (double)maxHistory;
int const inc = maxIncrease * mult;
max_peers = s->max_peers + inc;
tr_logAddTraceSwarm(
s,
fmt::format(
"time since last cancel is {} -- increasing the number of peers we're interested in by {}",
timeSinceCancel,
inc));
}
}
/* don't let the previous section's number tweaking go too far... */
max_peers = std::clamp(max_peers, MinInterestingPeers, s->tor->max_connected_peers);
s->max_peers = max_peers;
if (peerCount > 0)
{
auto const* const tor = s->tor;
int const n = tor->pieceCount();
/* build a bitfield of interesting pieces... */
auto* const piece_is_interesting = tr_new(bool, n);
for (int i = 0; i < n; ++i)
{
piece_is_interesting[i] = tor->pieceIsWanted(i) && !tor->hasPiece(i);
}
/* decide WHICH peers to be interested in (based on their cancel-to-block ratio) */
for (auto* const peer : peers)
{
if (!isPeerInteresting(s->tor, piece_is_interesting, peer))
{
peer->set_interested(false);
}
else
{
auto rechoke_state = tr_rechoke_state{};
auto const blocks = peer->blocks_sent_to_client.count(now, CancelHistorySec);
auto const cancels = peer->cancels_sent_to_peer.count(now, CancelHistorySec);
if (blocks == 0 && cancels == 0)
{
rechoke_state = RECHOKE_STATE_UNTESTED;
}
else if (cancels == 0)
{
rechoke_state = RECHOKE_STATE_GOOD;
}
else if (blocks == 0)
{
rechoke_state = RECHOKE_STATE_BAD;
}
else if (cancels * 10 < blocks)
{
rechoke_state = RECHOKE_STATE_GOOD;
}
else
{
rechoke_state = RECHOKE_STATE_BAD;
}
if (rechoke == nullptr)
{
rechoke = tr_new(struct tr_rechoke_info, peerCount);
}
rechoke[rechoke_count].peer = peer;
rechoke[rechoke_count].rechoke_state = rechoke_state;
rechoke[rechoke_count].salt = tr_rand_int_weak(INT_MAX);
rechoke_count++;
}
}
tr_free(piece_is_interesting);
}
if ((rechoke != nullptr) && (rechoke_count > 0))
{
qsort(rechoke, rechoke_count, sizeof(struct tr_rechoke_info), compare_rechoke_info);
}
/* now that we know which & how many peers to be interested in... update the peer interest */
s->interested_count = std::min(max_peers, rechoke_count);
for (int i = 0; i < rechoke_count; ++i)
{
rechoke[i].peer->set_interested(i < s->interested_count);
}
/* cleanup */
tr_free(rechoke);
}
} // namespace rechoke_downloads_helpers
/**
***
**/
[[nodiscard]] static inline bool isBandwidthMaxedOut(tr_bandwidth const& b, uint64_t const now_msec, tr_direction dir)
{
if (!b.isLimited(dir))
{
return false;
}
unsigned int const got = b.getPieceSpeedBytesPerSecond(now_msec, dir);
unsigned int const want = b.getDesiredSpeedBytesPerSecond(dir);
return got >= want;
}
namespace rechoke_uploads_helpers
{
namespace
{
struct ChokeData
{
bool isInterested;
bool wasChoked;
bool isChoked;
int rate;
int salt;
tr_peerMsgs* msgs;
};
[[nodiscard]] constexpr int compareChoke(void const* va, void const* vb) noexcept
{
auto const* const a = static_cast<struct ChokeData const*>(va);
auto const* const b = static_cast<struct ChokeData const*>(vb);
if (a->rate != b->rate) // prefer higher overall speeds
{
return a->rate > b->rate ? -1 : 1;
}
if (a->wasChoked != b->wasChoked) // prefer unchoked
{
return a->wasChoked ? 1 : -1;
}
if (a->salt != b->salt) // random order
{
return a->salt - b->salt;
}
return 0;
}
/* is this a new connection? */
[[nodiscard]] bool isNew(tr_peerMsgs const* msgs)
{
auto constexpr CutoffSecs = time_t{ 45 };
return msgs != nullptr && !msgs->is_connection_older_than(tr_time() - CutoffSecs);
}
/* get a rate for deciding which peers to choke and unchoke. */
[[nodiscard]] auto getRateBps(tr_torrent const* tor, tr_peer const* peer, uint64_t now)
{
if (tor->isDone())
{
return tr_peerGetPieceSpeed_Bps(peer, now, TR_CLIENT_TO_PEER);
}
/* downloading a private torrent... take upload speed into account
* because there may only be a small window of opportunity to share */
if (tor->isPrivate())
{
return tr_peerGetPieceSpeed_Bps(peer, now, TR_PEER_TO_CLIENT) + tr_peerGetPieceSpeed_Bps(peer, now, TR_CLIENT_TO_PEER);
}
/* downloading a public torrent */
return tr_peerGetPieceSpeed_Bps(peer, now, TR_PEER_TO_CLIENT);
}
// an optimistically unchoked peer is immune from rechoking
// for this many calls to rechokeUploads().
auto constexpr OptimisticUnchokeMultiplier = uint8_t{ 4 };
} // namespace
void rechokeUploads(tr_swarm* s, uint64_t const now)
{
auto const lock = s->unique_lock();
auto const peerCount = s->peerCount();
auto& peers = s->peers;
auto* const choke = tr_new0(struct ChokeData, peerCount);
auto const* const session = s->manager->session;
bool const chokeAll = !s->tor->clientCanUpload();
bool const isMaxedOut = isBandwidthMaxedOut(s->tor->bandwidth_, now, TR_UP);
/* an optimistic unchoke peer's "optimistic"
* state lasts for N calls to rechokeUploads(). */
if (s->optimistic_unchoke_time_scaler > 0)
{
--s->optimistic_unchoke_time_scaler;
}
else
{
s->optimistic = nullptr;
}
int size = 0;
/* sort the peers by preference and rate */
for (auto* const peer : peers)
{
if (peer->isSeed())
{
/* choke seeds and partial seeds */
peer->set_choke(true);
}
else if (chokeAll)
{
/* choke everyone if we're not uploading */
peer->set_choke(true);
}
else if (peer != s->optimistic)
{
struct ChokeData* n = &choke[size++];
n->msgs = peer;
n->isInterested = peer->is_peer_interested();
n->wasChoked = peer->is_peer_choked();
n->rate = getRateBps(s->tor, peer, now);
n->salt = tr_rand_int_weak(INT_MAX);
n->isChoked = true;
}
}
qsort(choke, size, sizeof(struct ChokeData), compareChoke);
/**
* Reciprocation and number of uploads capping is managed by unchoking
* the N peers which have the best upload rate and are interested.
* This maximizes the client's download rate. These N peers are
* referred to as downloaders, because they are interested in downloading
* from the client.
*
* Peers which have a better upload rate (as compared to the downloaders)
* but aren't interested get unchoked. If they become interested, the
* downloader with the worst upload rate gets choked. If a client has
* a complete file, it uses its upload rate rather than its download
* rate to decide which peers to unchoke.
*
* If our bandwidth is maxed out, don't unchoke any more peers.
*/
int checkedChokeCount = 0;
int unchokedInterested = 0;
for (int i = 0; i < size && unchokedInterested < session->uploadSlotsPerTorrent; ++i)
{
choke[i].isChoked = isMaxedOut ? choke[i].wasChoked : false;
++checkedChokeCount;
if (choke[i].isInterested)
{
++unchokedInterested;
}
}
/* optimistic unchoke */
if (s->optimistic == nullptr && !isMaxedOut && checkedChokeCount < size)
{
auto randPool = std::vector<ChokeData*>{};
for (int i = checkedChokeCount; i < size; ++i)
{
if (choke[i].isInterested)
{
tr_peerMsgs const* msgs = choke[i].msgs;
int const x = isNew(msgs) ? 3 : 1;
for (int y = 0; y < x; ++y)
{
randPool.push_back(&choke[i]);
}
}
}
auto const n = std::size(randPool);
if (n != 0)
{
auto* c = randPool[tr_rand_int_weak(n)];
c->isChoked = false;
s->optimistic = c->msgs;
s->optimistic_unchoke_time_scaler = OptimisticUnchokeMultiplier;
}
}
for (int i = 0; i < size; ++i)
{
choke[i].msgs->set_choke(choke[i].isChoked);
}
/* cleanup */
tr_free(choke);
}
} // namespace rechoke_uploads_helpers
void tr_peerMgr::rechokePulse() const
{
using namespace rechoke_downloads_helpers;
using namespace rechoke_uploads_helpers;
auto const lock = unique_lock();
auto const now = tr_time_msec();
for (auto* const tor : session->torrents())
{
if (!tor->isRunning)
{
continue;
}
if (auto* const swarm = tor->swarm; swarm->stats.peer_count > 0)
{
rechokeUploads(swarm, now);
rechokeDownloads(swarm);
}
}
}
/***
****
**** Life and Death
****
***/
namespace disconnect_helpers
{
namespace
{
// when many peers are available, keep idle ones this long
auto constexpr MinUploadIdleSecs = int{ 60 };
// when few peers are available, keep idle ones this long
auto constexpr MaxUploadIdleSecs = int{ 60 * 5 };
[[nodiscard]] bool shouldPeerBeClosed(tr_swarm const* s, tr_peerMsgs const* peer, int peerCount, time_t const now)
{
/* if it's marked for purging, close it */
if (peer->do_purge)
{
tr_logAddTraceSwarm(s, fmt::format("purging peer {} because its do_purge flag is set", peer->readable()));
return true;
}
auto const* tor = s->tor;
auto const* const atom = peer->atom;
/* disconnect if we're both seeds and enough time has passed for PEX */
if (tor->isDone() && peer->isSeed())
{
return !tor->allowsPex() || now - atom->time >= 30;
}
/* disconnect if it's been too long since piece data has been transferred.
* this is on a sliding scale based on number of available peers... */
{
auto const relaxStrictnessIfFewerThanN = std::lround(getMaxPeerCount(tor) * 0.9);
/* if we have >= relaxIfFewerThan, strictness is 100%.
* if we have zero connections, strictness is 0% */
float const strictness = peerCount >= relaxStrictnessIfFewerThanN ? 1.0 :
peerCount / (float)relaxStrictnessIfFewerThanN;
int const lo = MinUploadIdleSecs;
int const hi = MaxUploadIdleSecs;
int const limit = hi - (hi - lo) * strictness;
int const idleTime = now - std::max(atom->time, atom->piece_data_time);
if (idleTime > limit)
{
tr_logAddTraceSwarm(
s,
fmt::format("purging peer {} because it's been {} secs since we shared anything", peer->readable(), idleTime));
return true;
}
}
return false;
}
void closePeer(tr_peer* peer)
{
TR_ASSERT(peer != nullptr);
auto const* const s = peer->swarm;
/* if we transferred piece data, then they might be good peers,
so reset their `num_fails' weight to zero. otherwise we connected
to them fruitlessly, so mark it as another fail */
if (auto* const atom = peer->atom; atom->piece_data_time != 0)
{
tr_logAddTraceSwarm(s, fmt::format("resetting atom {} num_fails to 0", peer->readable()));
atom->num_fails = 0;
}
else
{
++atom->num_fails;
tr_logAddTraceSwarm(s, fmt::format("incremented atom {} num_fails to {}", peer->readable(), atom->num_fails));
}
tr_logAddTraceSwarm(s, fmt::format("removing bad peer {}", peer->readable()));
peer->swarm->removePeer(peer);
}
struct ComparePeerByActivity
{
[[nodiscard]] constexpr static int compare(tr_peer const* a, tr_peer const* b) // <=>
{
if (a->do_purge != b->do_purge)
{
return a->do_purge ? 1 : -1;
}
/* the one to give us data more recently goes first */
if (a->atom->piece_data_time != b->atom->piece_data_time)
{
return a->atom->piece_data_time > b->atom->piece_data_time ? -1 : 1;
}
/* the one we connected to most recently goes first */
if (a->atom->time != b->atom->time)
{
return a->atom->time > b->atom->time ? -1 : 1;
}
return 0;
}
[[nodiscard]] constexpr bool operator()(tr_peer const* a, tr_peer const* b) const // less then
{
return compare(a, b) < 0;
}
};
[[nodiscard]] auto getPeersToClose(tr_swarm* swarm, time_t const now_sec)
{
auto peers_to_close = std::vector<tr_peer*>{};
auto const peer_count = swarm->peerCount();
for (auto* peer : swarm->peers)
{
if (shouldPeerBeClosed(swarm, peer, peer_count, now_sec))
{
peers_to_close.push_back(peer);
}
}
return peers_to_close;
}
} // namespace
void closeBadPeers(tr_swarm* s, time_t const now_sec)
{
auto const lock = s->unique_lock();
for (auto* peer : getPeersToClose(s, now_sec))
{
closePeer(peer);
}
}
void enforceTorrentPeerLimit(tr_swarm* swarm)
{
// do we have too many peers?
auto const n = swarm->peerCount();
auto const max = tr_torrentGetPeerLimit(swarm->tor);
if (n <= max)
{
return;
}
// close all but the `max` most active
auto peers = swarm->peers;
std::partial_sort(std::begin(peers), std::begin(peers) + max, std::end(peers), ComparePeerByActivity{});
std::for_each(std::begin(peers) + max, std::end(peers), closePeer);
}
void enforceSessionPeerLimit(tr_session* session)
{
// do we have too many peers?
auto const& torrents = session->torrents();
size_t const n_peers = std::accumulate(
std::begin(torrents),
std::end(torrents),
size_t{},
[](size_t sum, tr_torrent const* tor) { return sum + tor->swarm->peerCount(); });
size_t const max = tr_sessionGetPeerLimit(session);
if (n_peers <= max)
{
return;
}
// make a list of all the peers
auto peers = std::vector<tr_peer*>{};
peers.reserve(n_peers);
for (auto const* const tor : session->torrents())
{
peers.insert(std::end(peers), std::begin(tor->swarm->peers), std::end(tor->swarm->peers));
}
// close all but the `max` most active
std::partial_sort(std::begin(peers), std::begin(peers) + max, std::end(peers), ComparePeerByActivity{});
std::for_each(std::begin(peers) + max, std::end(peers), closePeer);
}
} // namespace disconnect_helpers
void tr_peerMgr::reconnectPulse()
{
using namespace disconnect_helpers;
auto const now_sec = tr_time();
// remove crappy peers
for (auto* const tor : session->torrents())
{
if (!tor->swarm->is_running)
{
tor->swarm->removeAllPeers();
}
else
{
closeBadPeers(tor->swarm, now_sec);
}
}
// if we're over the per-torrent peer limits, cull some peers
for (auto* const tor : session->torrents())
{
if (tor->isRunning)
{
enforceTorrentPeerLimit(tor->swarm);
}
}
// if we're over the per-session peer limits, cull some peers
enforceSessionPeerLimit(session);
// try to make new peer connections
auto const max_connections_per_pulse = int(MaxConnectionsPerSecond * (ReconnectPeriodMsec / 1000.0));
makeNewPeerConnections(max_connections_per_pulse);
}
/****
*****
***** BANDWIDTH ALLOCATION
*****
****/
namespace bandwidth_helpers
{
void pumpAllPeers(tr_peerMgr* mgr)
{
for (auto* const tor : mgr->session->torrents())
{
for (auto* const peer : tor->swarm->peers)
{
peer->pulse();
}
}
}
void queuePulse(tr_session* session, tr_direction dir)
{
TR_ASSERT(tr_isSession(session));
TR_ASSERT(tr_isDirection(dir));
if (tr_sessionGetQueueEnabled(session, dir))
{
auto const n = tr_sessionCountQueueFreeSlots(session, dir);
for (auto* tor : tr_sessionGetNextQueuedTorrents(session, dir, n))
{
tr_torrentStartNow(tor);
if (tor->queue_started_callback != nullptr)
{
(*tor->queue_started_callback)(tor, tor->queue_started_user_data);
}
}
}
}
} // namespace bandwidth_helpers
void tr_peerMgr::bandwidthPulse()
{
using namespace bandwidth_helpers;
auto const lock = unique_lock();
pumpAllPeers(this);
/* allocate bandwidth to the peers */
session->top_bandwidth_.allocate(TR_UP, BandwidthPeriodMsec);
session->top_bandwidth_.allocate(TR_DOWN, BandwidthPeriodMsec);
/* torrent upkeep */
for (auto* const tor : session->torrents())
{
/* possibly stop torrents that have seeded enough */
tr_torrentCheckSeedLimit(tor);
/* run the completeness check for any torrents that need it */
if (tor->swarm->needs_completeness_check)
{
tor->swarm->needs_completeness_check = false;
tor->recheckCompleteness();
}
/* stop torrents that are ready to stop, but couldn't be stopped
earlier during the peer-io callback call chain */
if (tor->isStopping)
{
tr_torrentStop(tor);
}
/* update the torrent's stats */
tor->swarm->stats.active_webseed_count = tor->swarm->countActiveWebseeds();
}
/* pump the queues */
queuePulse(session, TR_UP);
queuePulse(session, TR_DOWN);
reconnectPulse();
}
/***
****
****
****
***/
namespace connect_helpers
{
namespace
{
/* is this atom someone that we'd want to initiate a connection to? */
[[nodiscard]] bool isPeerCandidate(tr_torrent const* tor, peer_atom const& atom, time_t const now)
{
// have we already tried and failed to connect?
if (auto const reachable = atom.isReachable(); reachable && !*reachable)
{
return false;
}
// not if we're both seeds
if (tor->isDone() && atom.isSeed())
{
return false;
}
// not if we've already got a connection to them...
if (peerIsInUse(tor->swarm, &atom))
{
return false;
}
// not if we just tried them already
if (now - atom.time < atom.getReconnectIntervalSecs(now))
{
return false;
}
// not if they're blocklisted
if (atom.isBlocklisted(tor->session))
{
return false;
}
// not if they're banned...
if ((atom.flags2 & MyflagBanned) != 0)
{
return false;
}
return true;
}
struct peer_candidate
{
uint64_t score;
tr_torrent* tor;
peer_atom* atom;
};
[[nodiscard]] bool torrentWasRecentlyStarted(tr_torrent const* tor)
{
return difftime(tr_time(), tor->startDate) < 120;
}
[[nodiscard]] constexpr uint64_t addValToKey(uint64_t value, int width, uint64_t addme)
{
value = value << (uint64_t)width;
value |= addme;
return value;
}
/* smaller value is better */
[[nodiscard]] uint64_t getPeerCandidateScore(tr_torrent const* tor, peer_atom const& atom, uint8_t salt)
{
auto i = uint64_t{};
auto score = uint64_t{};
bool const failed = atom.lastConnectionAt < atom.lastConnectionAttemptAt;
/* prefer peers we've connected to, or never tried, over peers we failed to connect to. */
i = failed ? 1 : 0;
score = addValToKey(score, 1, i);
/* prefer the one we attempted least recently (to cycle through all peers) */
i = atom.lastConnectionAttemptAt;
score = addValToKey(score, 32, i);
/* prefer peers belonging to a torrent of a higher priority */
switch (tr_torrentGetPriority(tor))
{
case TR_PRI_HIGH:
i = 0;
break;
case TR_PRI_NORMAL:
i = 1;
break;
case TR_PRI_LOW:
i = 2;
break;
}
score = addValToKey(score, 4, i);
/* prefer recently-started torrents */
i = torrentWasRecentlyStarted(tor) ? 0 : 1;
score = addValToKey(score, 1, i);
/* prefer torrents we're downloading with */
i = tor->isDone() ? 1 : 0;
score = addValToKey(score, 1, i);
/* prefer peers that are known to be connectible */
i = (atom.flags & ADDED_F_CONNECTABLE) != 0 ? 0 : 1;
score = addValToKey(score, 1, i);
/* prefer peers that we might be able to upload to */
i = (atom.flags & ADDED_F_SEED_FLAG) == 0 ? 0 : 1;
score = addValToKey(score, 1, i);
/* Prefer peers that we got from more trusted sources.
* lower `fromBest' values indicate more trusted sources */
score = addValToKey(score, 4, atom.fromBest);
/* salt */
score = addValToKey(score, 8, salt);
return score;
}
} // namespace
/** @return an array of all the atoms we might want to connect to */
[[nodiscard]] std::vector<peer_candidate> getPeerCandidates(tr_session* session, size_t max)
{
auto const now = tr_time();
auto const now_msec = tr_time_msec();
// leave 5% of connection slots for incoming connections -- ticket #2609
auto const max_candidates = static_cast<size_t>(tr_sessionGetPeerLimit(session) * 0.95);
/* count how many peers and atoms we've got */
auto atom_count = size_t{};
auto peer_count = size_t{};
for (auto const* tor : session->torrents())
{
atom_count += std::size(tor->swarm->pool);
peer_count += tor->swarm->peerCount();
}
/* don't start any new handshakes if we're full up */
if (max_candidates <= peer_count)
{
return {};
}
auto candidates = std::vector<peer_candidate>{};
candidates.reserve(atom_count);
/* populate the candidate array */
for (auto* tor : session->torrents())
{
if (!tor->swarm->is_running)
{
continue;
}
/* if everyone in the swarm is seeds and pex is disabled because
* the torrent is private, then don't initiate connections */
bool const seeding = tor->isDone();
if (seeding && tor->swarm->isAllSeeds() && tor->isPrivate())
{
continue;
}
/* if we've already got enough peers in this torrent... */
if (tr_torrentGetPeerLimit(tor) <= tor->swarm->peerCount())
{
continue;
}
/* if we've already got enough speed in this torrent... */
if (seeding && isBandwidthMaxedOut(tor->bandwidth_, now_msec, TR_UP))
{
continue;
}
for (auto& atom : tor->swarm->pool)
{
if (isPeerCandidate(tor, atom, now))
{
uint8_t const salt = tr_rand_int_weak(1024);
candidates.push_back({ getPeerCandidateScore(tor, atom, salt), tor, &atom });
}
}
}
// only keep the best `max` candidates
if (std::size(candidates) > max)
{
std::partial_sort(
std::begin(candidates),
std::begin(candidates) + max,
std::end(candidates),
[](auto const& a, auto const& b) { return a.score < b.score; });
candidates.resize(max);
}
return candidates;
}
void initiateConnection(tr_peerMgr* mgr, tr_swarm* s, peer_atom& atom)
{
time_t const now = tr_time();
bool utp = tr_sessionIsUTPEnabled(mgr->session) && !atom.utp_failed;
if (atom.fromFirst == TR_PEER_FROM_PEX)
{
/* PEX has explicit signalling for uTP support. If an atom
originally came from PEX and doesn't have the uTP flag, skip the
uTP connection attempt. Are we being optimistic here? */
utp = utp && (atom.flags & ADDED_F_UTP_FLAGS) != 0;
}
tr_logAddTraceSwarm(s, fmt::format("Starting an OUTGOING {} connection with {}", utp ? " µTP" : "TCP", atom.readable()));
tr_peerIo* const io = tr_peerIoNewOutgoing(
mgr->session,
&mgr->session->top_bandwidth_,
&atom.addr,
atom.port,
tr_time(),
s->tor->infoHash(),
s->tor->completeness == TR_SEED,
utp);
if (io == nullptr)
{
tr_logAddTraceSwarm(s, fmt::format("peerIo not created; marking peer {} as unreachable", atom.readable()));
atom.flags2 |= MyflagUnreachable;
++atom.num_fails;
}
else
{
tr_handshake* handshake = tr_handshakeNew(io, mgr->session->encryptionMode, on_handshake_done, mgr);
TR_ASSERT(tr_peerIoGetTorrentHash(io));
tr_peerIoUnref(io); /* balanced by the initial ref in tr_peerIoNewOutgoing() */
s->outgoing_handshakes.add(atom.addr, handshake);
}
atom.lastConnectionAttemptAt = now;
atom.time = now;
}
} // namespace connect_helpers
void tr_peerMgr::makeNewPeerConnections(size_t max)
{
using namespace connect_helpers;
for (auto& candidate : getPeerCandidates(session, max))
{
initiateConnection(this, candidate.tor->swarm, *candidate.atom);
}
}
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