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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 <iterator> // std::back_inserter
#include <map>
#include <vector>
#include <event2/event.h>
#include <fmt/core.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 "ptrarray.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"
// how frequently to cull old atoms
static auto constexpr AtomPeriodMsec = int{ 60 * 1000 };
// how frequently to change which peers are choked
static auto constexpr RechokePeriodMsec = int{ 10 * 1000 };
// an optimistically unchoked peer is immune from rechoking
// for this many calls to rechokeUploads().
static auto constexpr OptimisticUnchokeMultiplier = int{ 4 };
// how frequently to reallocate bandwidth
static auto constexpr BandwidthPeriodMsec = int{ 500 };
// how frequently to age out old piece request lists
static auto constexpr RefillUpkeepPeriodMsec = int{ 10 * 1000 };
// how frequently to decide which peers live and die
static auto constexpr ReconnectPeriodMsec = int{ 500 };
// when many peers are available, keep idle ones this long
static auto constexpr MinUploadIdleSecs = int{ 60 };
// when few peers are available, keep idle ones this long
static auto constexpr MaxUploadIdleSecs = int{ 60 * 5 };
// 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 };
// number of bad pieces a peer is allowed to send before we ban them
static auto constexpr MaxBadPiecesPerPeer = int{ 5 };
// 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 };
// the minimum we'll wait before attempting to reconnect to a peer
static auto constexpr MinimumReconnectIntervalSecs = int{ 5 };
// how long we'll let requests we've made linger before we cancel them
static auto constexpr RequestTtlSecs = int{ 90 };
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
{
uint8_t 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 */
int8_t blocklisted; /* -1 for unknown, true for blocklisted, false for not blocklisted */
tr_port port;
bool utp_failed; /* We recently failed to connect over uTP */
uint16_t numFails;
time_t time; /* when the peer's connection status last changed */
time_t piece_data_time;
time_t lastConnectionAttemptAt;
time_t lastConnectionAt;
/* similar to a TTL field, but less rigid --
* if the swarm is small, the atom will be kept past this date. */
time_t shelf_date;
tr_peer* peer; /* will be nullptr if not connected */
tr_address addr;
[[nodiscard]] int compare(peer_atom const& that) const
{
return addr.compare(that.addr);
}
[[nodiscard]] bool operator==(peer_atom const& that) const
{
return compare(that) == 0;
}
[[nodiscard]] bool operator<(peer_atom const& that) const
{
return compare(that) < 0;
}
[[nodiscard]] bool operator>(peer_atom const& that) const
{
return compare(that) > 0;
}
};
#ifndef TR_ENABLE_ASSERTS
#define tr_isAtom(a) (true)
#else
static bool tr_isAtom(struct peer_atom const* atom)
{
return atom != nullptr && atom->fromFirst < TR_PEER_FROM__MAX && atom->fromBest < TR_PEER_FROM__MAX &&
tr_address_is_valid(&atom->addr);
}
#endif
static char const* tr_atomAddrStr(struct peer_atom const* atom)
{
static char addrstr[TR_ADDRSTRLEN];
return atom != nullptr ? tr_address_and_port_to_string(addrstr, sizeof(addrstr), &atom->addr, atom->port) : "[no atom]";
}
/** @brief Opaque, per-torrent data structure for peer connection information */
class tr_swarm
{
public:
tr_swarm(tr_peerMgr* manager_in, tr_torrent* tor_in)
: manager{ manager_in }
, tor{ tor_in }
{
}
public:
tr_swarm_stats stats = {};
std::map<tr_address, tr_handshake*> outgoing_handshakes;
tr_ptrArray pool = {}; /* struct peer_atom */
tr_ptrArray peers = {}; /* tr_peerMsgs */
tr_ptrArray webseeds = {}; /* tr_webseed */
tr_peerMgr* const manager;
tr_torrent* const tor;
tr_peerMsgs* optimistic = nullptr; /* the optimistic peer, or nullptr if none */
int optimisticUnchokeTimeScaler = 0;
bool poolIsAllSeeds = false;
bool poolIsAllSeedsDirty = true; /* true if poolIsAllSeeds needs to be recomputed */
bool isRunning = false;
bool needsCompletenessCheck = true;
bool endgame = false;
ActiveRequests active_requests;
int interestedCount = 0;
int maxPeers = 0;
time_t lastCancel = 0;
};
struct tr_peerMgr
{
explicit tr_peerMgr(tr_session* session_in)
: session{ session_in }
{
}
[[nodiscard]] auto unique_lock() const
{
return session->unique_lock();
}
tr_session* const session;
std::map<tr_address, tr_handshake*> incoming_handshakes;
event* bandwidthTimer = nullptr;
event* rechokeTimer = nullptr;
event* refillUpkeepTimer = nullptr;
event* atomTimer = nullptr;
};
#define tr_logAddDebugSwarm(swarm, msg) tr_logAddDebugTor((swarm)->tor, msg)
#define tr_logAddTraceSwarm(swarm, msg) tr_logAddTraceTor((swarm)->tor, msg)
/**
*** tr_peer virtual functions
**/
unsigned int tr_peerGetPieceSpeed_Bps(tr_peer const* peer, uint64_t now, tr_direction direction)
{
unsigned int Bps = 0;
peer->is_transferring_pieces(now, direction, &Bps);
return Bps;
}
tr_peer::tr_peer(tr_torrent const* tor, peer_atom* atom_in)
: session{ tor->session }
, atom{ atom_in }
, swarm{ tor->swarm }
, blame{ tor->blockCount() }
, have{ tor->pieceCount() }
{
}
tr_peer::~tr_peer()
{
if (swarm != nullptr)
{
swarm->active_requests.remove(this);
}
if (atom != nullptr)
{
atom->peer = nullptr;
}
}
/**
***
**/
static int comparePeerAtomToAddress(void const* va, void const* vb)
{
auto const* const a = static_cast<struct peer_atom const*>(va);
auto const* const b = static_cast<tr_address const*>(vb);
return tr_address_compare(&a->addr, b);
}
static int compareAtomsByAddress(void const* va, void const* vb)
{
auto const* const b = static_cast<struct peer_atom const*>(vb);
TR_ASSERT(tr_isAtom(b));
return comparePeerAtomToAddress(va, &b->addr);
}
/**
***
**/
tr_address const* tr_peerAddress(tr_peer const* peer)
{
return &peer->atom->addr;
}
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 int peerCompare(void const* va, void const* vb)
{
auto const* const a = static_cast<tr_peer const*>(va);
auto const* const b = static_cast<tr_peer const*>(vb);
return tr_address_compare(tr_peerAddress(a), tr_peerAddress(b));
}
static struct peer_atom* getExistingAtom(tr_swarm const* cswarm, tr_address const* addr)
{
auto* swarm = const_cast<tr_swarm*>(cswarm);
return static_cast<struct peer_atom*>(tr_ptrArrayFindSorted(&swarm->pool, addr, comparePeerAtomToAddress));
}
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->manager->unique_lock();
return atom->peer != nullptr || s->outgoing_handshakes.count(atom->addr) != 0 ||
s->manager->incoming_handshakes.count(atom->addr) != 0;
}
static void swarmFree(tr_swarm* s)
{
TR_ASSERT(s != nullptr);
auto const lock = s->manager->unique_lock();
TR_ASSERT(!s->isRunning);
TR_ASSERT(std::empty(s->outgoing_handshakes));
TR_ASSERT(tr_ptrArrayEmpty(&s->peers));
tr_ptrArrayDestruct(&s->webseeds, [](void* peer) { delete static_cast<tr_peer*>(peer); });
tr_ptrArrayDestruct(&s->pool, (PtrArrayForeachFunc)tr_free);
tr_ptrArrayDestruct(&s->peers, nullptr);
s->stats = {};
delete s;
}
static void peerCallbackFunc(tr_peer* /*peer*/, tr_peer_event const* /*e*/, void* /*vs*/);
static void rebuildWebseedArray(tr_swarm* s, tr_torrent* tor)
{
/* clear the array */
tr_ptrArrayDestruct(&s->webseeds, [](void* peer) { delete static_cast<tr_peer*>(peer); });
s->webseeds = {};
s->stats.activeWebseedCount = 0;
/* repopulate it */
for (size_t i = 0, n = tor->webseedCount(); i < n; ++i)
{
auto* const w = tr_webseedNew(tor, tor->webseed(i), peerCallbackFunc, s);
tr_ptrArrayAppend(&s->webseeds, w);
}
}
static tr_swarm* swarmNew(tr_peerMgr* manager, tr_torrent* tor)
{
auto* swarm = new tr_swarm{ manager, tor };
rebuildWebseedArray(swarm, tor);
return swarm;
}
static void ensureMgrTimersExist(struct tr_peerMgr* m);
tr_peerMgr* tr_peerMgrNew(tr_session* session)
{
auto* const m = new tr_peerMgr{ session };
ensureMgrTimersExist(m);
return m;
}
static void deleteTimer(struct event** t)
{
if (*t != nullptr)
{
event_free(*t);
*t = nullptr;
}
}
static void deleteTimers(struct tr_peerMgr* m)
{
deleteTimer(&m->atomTimer);
deleteTimer(&m->bandwidthTimer);
deleteTimer(&m->rechokeTimer);
deleteTimer(&m->refillUpkeepTimer);
}
void tr_peerMgrFree(tr_peerMgr* manager)
{
auto const lock = manager->unique_lock();
deleteTimers(manager);
/* free the handshakes. Abort invokes handshakeDoneCB(), which removes
* the item from manager->handshakes, so this is a little roundabout... */
while (!std::empty(manager->incoming_handshakes))
{
tr_handshakeAbort(std::begin(manager->incoming_handshakes)->second);
}
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())
{
tr_swarm* s = tor->swarm;
for (int i = 0, n = tr_ptrArraySize(&s->pool); i < n; ++i)
{
auto* const atom = static_cast<struct peer_atom*>(tr_ptrArrayNth(&s->pool, i));
atom->blocklisted = -1;
}
}
}
static bool isAtomBlocklisted(tr_session const* session, struct peer_atom* atom)
{
if (atom->blocklisted < 0)
{
atom->blocklisted = (int8_t)tr_sessionIsAddressBlocked(session, &atom->addr);
}
return atom->blocklisted != 0;
}
/***
****
***/
static constexpr bool atomIsSeed(struct peer_atom const* atom)
{
return (atom != nullptr) && ((atom->flags & ADDED_F_SEED_FLAG) != 0);
}
static void atomSetSeed(tr_swarm* s, struct peer_atom* atom)
{
tr_logAddTraceSwarm(s, fmt::format("marking peer {} as a seed", tr_atomAddrStr(atom)));
atom->flags |= ADDED_F_SEED_FLAG;
s->poolIsAllSeedsDirty = true;
}
bool tr_peerMgrPeerIsSeed(tr_torrent const* tor, tr_address const* addr)
{
bool isSeed = false;
if (auto const* atom = getExistingAtom(tor->swarm, addr); atom != nullptr)
{
isSeed = atomIsSeed(atom);
}
return isSeed;
}
void tr_peerMgrSetUtpSupported(tr_torrent* tor, tr_address const* addr)
{
struct peer_atom* atom = getExistingAtom(tor->swarm, addr);
if (atom != nullptr)
{
atom->flags |= ADDED_F_UTP_FLAGS;
}
}
void tr_peerMgrSetUtpFailed(tr_torrent* tor, tr_address const* addr, bool failed)
{
struct peer_atom* atom = getExistingAtom(tor->swarm, addr);
if (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
**/
static int countActiveWebseeds(tr_swarm* s)
{
int activeCount = 0;
if (s->tor->isRunning && !s->tor->isDone())
{
uint64_t const now = tr_time_msec();
for (int i = 0, n = tr_ptrArraySize(&s->webseeds); i < n; ++i)
{
if (static_cast<tr_peer const*>(tr_ptrArrayNth(&s->webseeds, i))->is_transferring_pieces(now, TR_DOWN, nullptr))
{
++activeCount;
}
}
}
return activeCount;
}
// 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);
}
}
static void updateEndgame(tr_swarm* s)
{
/* we consider ourselves to be in endgame if the number of bytes
we've got requested is >= the number of bytes left to download */
s->endgame = uint64_t(std::size(s->active_requests)) * tr_block_info::BlockSize >= s->tor->leftUntilDone();
}
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_->have.test(piece);
}
[[nodiscard]] bool isEndgame() const override
{
return swarm_->endgame;
}
[[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_;
};
auto* const swarm = torrent->swarm;
updateEndgame(swarm);
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);
}
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->cancelsSentToPeer.add(tr_time(), 1);
msgs->cancel_block_request(block);
}
}
static void cancelAllRequestsForBlock(tr_swarm* swarm, tr_block_index_t block, tr_peer const* no_notify)
{
for (auto* peer : swarm->active_requests.remove(block))
{
maybeSendCancelRequest(peer, block, no_notify);
}
}
static void tr_swarmCancelOldRequests(tr_swarm* swarm)
{
auto const now = tr_time();
auto const oldest = now - RequestTtlSecs;
for (auto const& [block, peer] : swarm->active_requests.sentBefore(oldest))
{
maybeSendCancelRequest(peer, block, nullptr);
swarm->active_requests.remove(block, peer);
}
}
static void refillUpkeep(evutil_socket_t /*fd*/, short /*what*/, void* vmgr)
{
auto* mgr = static_cast<tr_peerMgr*>(vmgr);
auto const lock = mgr->unique_lock();
auto& torrents = mgr->session->torrents();
std::for_each(std::begin(torrents), std::end(torrents), [](auto* tor) { tr_swarmCancelOldRequests(tor->swarm); });
tr_timerAddMsec(mgr->refillUpkeepTimer, RefillUpkeepPeriodMsec);
}
static void addStrike(tr_swarm* s, tr_peer* peer)
{
tr_logAddTraceSwarm(s, fmt::format("increasing peer {} strike count to {}", tr_atomAddrStr(peer->atom), peer->strikes + 1));
if (++peer->strikes >= MaxBadPiecesPerPeer)
{
struct peer_atom* atom = peer->atom;
atom->flags2 |= MyflagBanned;
peer->doPurge = true;
tr_logAddTraceSwarm(s, fmt::format("banning peer {}", tr_atomAddrStr(atom)));
}
}
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 (int i = 0, n = tr_ptrArraySize(&s->peers); i < n; ++i)
{
auto* peer = static_cast<tr_peerMsgs*>(tr_ptrArrayNth(&s->peers, i));
// 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->needsCompletenessCheck = 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->manager->unique_lock();
switch (e->eventType)
{
case TR_PEER_PEER_GOT_PIECE_DATA:
{
time_t const now = tr_time();
tr_torrent* 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:
{
time_t const now = tr_time();
tr_torrent* 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);
cancelAllRequestsForBlock(s, loc.block, peer);
peer->blocksSentToClient.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->doPurge = true;
tr_logAddDebugSwarm(
s,
fmt::format(
"setting {} doPurge flag because we got an ERANGE, EMSGSIZE, or ENOTCONN error",
tr_atomAddrStr(peer->atom)));
}
else
{
tr_logAddDebugSwarm(s, fmt::format("unhandled error: {}", tr_strerror(e->err)));
}
break;
default:
TR_ASSERT_MSG(false, "%s", fmt::format("unhandled peer event type {}", e->eventType).c_str());
}
}
static int getDefaultShelfLife(uint8_t from)
{
/* in general, peers obtained from firsthand contact
* are better than those from secondhand, etc etc */
switch (from)
{
case TR_PEER_FROM_INCOMING:
return 60 * 60 * 6;
case TR_PEER_FROM_LTEP:
return 60 * 60 * 6;
case TR_PEER_FROM_TRACKER:
return 60 * 60 * 3;
case TR_PEER_FROM_DHT:
return 60 * 60 * 3;
case TR_PEER_FROM_PEX:
return 60 * 60 * 2;
case TR_PEER_FROM_RESUME:
return 60 * 60;
case TR_PEER_FROM_LPD:
return 10 * 60;
default:
return 60 * 60;
}
}
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)
{
int const jitter = tr_rand_int_weak(60 * 10);
a = tr_new0(struct peer_atom, 1);
a->addr = *addr;
a->port = port;
a->flags = flags;
a->fromFirst = from;
a->fromBest = from;
a->shelf_date = tr_time() + getDefaultShelfLife(from) + jitter;
a->blocklisted = -1;
tr_ptrArrayInsertSorted(&s->pool, a, compareAtomsByAddress);
tr_logAddTraceSwarm(s, fmt::format("got a new atom: {}", tr_atomAddrStr(a)));
}
else
{
if (from < a->fromBest)
{
a->fromBest = from;
}
a->flags |= flags;
}
s->poolIsAllSeedsDirty = true;
return a;
}
static int getMaxPeerCount(tr_torrent const* tor)
{
return tor->maxConnectedPeers;
}
static int getPeerCount(tr_swarm const* s)
{
return tr_ptrArraySize(&s->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->peer = peer;
tr_ptrArrayInsertSorted(&swarm->peers, peer, peerCompare);
++swarm->stats.peerCount;
++swarm->stats.peerFromCount[atom->fromFirst];
TR_ASSERT(swarm->stats.peerCount == tr_ptrArraySize(&swarm->peers));
TR_ASSERT(swarm->stats.peerFromCount[atom->fromFirst] <= swarm->stats.peerCount);
// 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 port = tr_port{};
auto const* const addr = tr_peerIoGetAddress(result.io, &port);
if (tr_peerIoIsIncoming(result.io))
{
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->isRunning)
{
if (s != nullptr)
{
struct peer_atom* atom = getExistingAtom(s, addr);
if (atom != nullptr)
{
++atom->numFails;
if (!result.readAnythingFromPeer)
{
tr_logAddTraceSwarm(
s,
fmt::format("marking peer {} as unreachable... numFails is {}", tr_atomAddrStr(atom), atom->numFails));
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 (!tr_peerIoIsIncoming(result.io))
{
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", tr_atomAddrStr(atom)));
}
else if (tr_peerIoIsIncoming(result.io) && getPeerCount(s) >= getMaxPeerCount(s->tor))
{
/* too many peers already */
}
else
{
tr_peer const* const peer = atom->peer;
if (peer != nullptr)
{
/* we already have this peer */
}
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);
tr_peerIoSetParent(stolen, &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.count(*addr) > 0)
{
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.try_emplace(*addr, handshake);
}
}
void tr_peerMgrSetSwarmIsAllSeeds(tr_torrent* tor)
{
auto const lock = tor->unique_lock();
auto* const swarm = tor->swarm;
auto atomCount = int{};
auto** atoms = (struct peer_atom**)tr_ptrArrayPeek(&swarm->pool, &atomCount);
for (int i = 0; i < atomCount; ++i)
{
atomSetSeed(swarm, atoms[i]);
}
swarm->poolIsAllSeeds = true;
swarm->poolIsAllSeedsDirty = false;
}
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<std::byte const*>(compact);
auto pex = std::vector<tr_pex>(n);
for (size_t i = 0; i < n; ++i)
{
pex[i].addr.type = TR_AF_INET;
std::copy_n(walk, 4, reinterpret_cast<std::byte*>(&pex[i].addr.addr));
walk += 4;
std::copy_n(walk, 2, reinterpret_cast<std::byte*>(&pex[i].port));
walk += 2;
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<std::byte const*>(compact);
auto pex = std::vector<tr_pex>(n);
for (size_t i = 0; i < n; ++i)
{
pex[i].addr.type = TR_AF_INET6;
std::copy_n(walk, 16, reinterpret_cast<std::byte*>(&pex[i].addr.addr.addr6.s6_addr));
walk += 16;
std::copy_n(walk, 2, reinterpret_cast<std::byte*>(&pex[i].port));
walk += 2;
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)
{
tr_swarm* s = tor->swarm;
uint32_t const byteCount = tor->pieceSize(pieceIndex);
for (int i = 0, n = tr_ptrArraySize(&s->peers); i != n; ++i)
{
auto* const peer = static_cast<tr_peer*>(tr_ptrArrayNth(&s->peers, i));
if (peer->blame.test(pieceIndex))
{
tr_logAddTraceSwarm(
s,
fmt::format(
"peer {} contributed to corrupt piece ({}); now has {} strikes",
tr_atomAddrStr(peer->atom),
pieceIndex,
peer->strikes + 1));
addStrike(s, peer);
}
}
tr_announcerAddBytes(tor, TR_ANN_CORRUPT, byteCount);
}
int tr_pexCompare(void const* va, void const* vb)
{
auto const* const a = static_cast<tr_pex const*>(va);
auto const* const b = static_cast<tr_pex const*>(vb);
TR_ASSERT(tr_isPex(a));
TR_ASSERT(tr_isPex(b));
if (auto const i = tr_address_compare(&a->addr, &b->addr); i != 0)
{
return i;
}
if (a->port != b->port)
{
return a->port < b->port ? -1 : 1;
}
return 0;
}
/* better goes first */
static int compareAtomsByUsefulness(void const* va, void const* vb)
{
struct peer_atom const* a = *(struct peer_atom const* const*)va;
struct peer_atom const* b = *(struct peer_atom const* const*)vb;
TR_ASSERT(tr_isAtom(a));
TR_ASSERT(tr_isAtom(b));
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->numFails != b->numFails)
{
return a->numFails < b->numFails ? -1 : 1;
}
return 0;
}
static bool isAtomInteresting(tr_torrent const* tor, struct peer_atom* atom)
{
if (tor->isDone() && atomIsSeed(atom))
{
return false;
}
if (peerIsInUse(tor->swarm, atom))
{
return true;
}
if (isAtomBlocklisted(tor->session, atom))
{
return false;
}
if ((atom->flags2 & MyflagBanned) != 0)
{
return false;
}
return true;
}
// TODO: return a std::vector
int tr_peerMgrGetPeers(tr_torrent const* tor, tr_pex** setme_pex, uint8_t af, uint8_t list_mode, int maxCount)
{
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
TR_ASSERT(setme_pex != nullptr);
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 atomCount = int{};
struct peer_atom** atoms = nullptr;
if (list_mode == TR_PEERS_CONNECTED) /* connected peers only */
{
auto const** peers = (tr_peer const**)tr_ptrArrayBase(&s->peers);
atomCount = tr_ptrArraySize(&s->peers);
atoms = tr_new(struct peer_atom*, atomCount);
for (int i = 0; i < atomCount; ++i)
{
atoms[i] = peers[i]->atom;
}
}
else /* TR_PEERS_INTERESTING */
{
auto** atomBase = (struct peer_atom**)tr_ptrArrayBase(&s->pool);
int const n = tr_ptrArraySize(&s->pool);
atoms = tr_new(struct peer_atom*, n);
for (int i = 0; i < n; ++i)
{
if (isAtomInteresting(tor, atomBase[i]))
{
atoms[atomCount++] = atomBase[i];
}
}
}
qsort(atoms, atomCount, sizeof(struct peer_atom*), compareAtomsByUsefulness);
/**
*** add the first N of them into our return list
**/
int const n = std::min(atomCount, maxCount);
auto* const pex = tr_new0(tr_pex, n);
tr_pex* walk = pex;
auto count = int{};
for (int i = 0; i < atomCount && count < n; ++i)
{
auto const* const atom = atoms[i];
if (atom->addr.type == af)
{
TR_ASSERT(tr_address_is_valid(&atom->addr));
walk->addr = atom->addr;
walk->port = atom->port;
walk->flags = atom->flags;
++count;
++walk;
}
}
qsort(pex, count, sizeof(tr_pex), tr_pexCompare);
TR_ASSERT(walk - pex == count);
*setme_pex = pex;
/* cleanup */
tr_free(atoms);
return count;
}
static void atomPulse(evutil_socket_t, short /*unused*/, void* /*vmgr*/);
static void bandwidthPulse(evutil_socket_t, short /*unused*/, void* /*vmgr*/);
static void rechokePulse(evutil_socket_t, short /*unused*/, void* /*vmgr*/);
static void reconnectPulse(evutil_socket_t, short /*unused*/, void* /*vmgr*/);
static struct event* createTimer(tr_session* session, int msec, event_callback_fn callback, void* cbdata)
{
struct event* timer = evtimer_new(session->event_base, callback, cbdata);
tr_timerAddMsec(timer, msec);
return timer;
}
static void ensureMgrTimersExist(struct tr_peerMgr* m)
{
if (m->atomTimer == nullptr)
{
m->atomTimer = createTimer(m->session, AtomPeriodMsec, atomPulse, m);
}
if (m->bandwidthTimer == nullptr)
{
m->bandwidthTimer = createTimer(m->session, BandwidthPeriodMsec, bandwidthPulse, m);
}
if (m->rechokeTimer == nullptr)
{
m->rechokeTimer = createTimer(m->session, RechokePeriodMsec, rechokePulse, m);
}
if (m->refillUpkeepTimer == nullptr)
{
m->refillUpkeepTimer = createTimer(m->session, RefillUpkeepPeriodMsec, refillUpkeep, m);
}
}
void tr_peerMgrStartTorrent(tr_torrent* tor)
{
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
tr_swarm* s = tor->swarm;
ensureMgrTimersExist(s->manager);
s->isRunning = true;
s->maxPeers = tor->maxConnectedPeers;
// rechoke soon
tr_timerAddMsec(s->manager->rechokeTimer, 100);
}
static void removeAllPeers(tr_swarm* /*swarm*/);
static void stopSwarm(tr_swarm* swarm)
{
swarm->isRunning = false;
removeAllPeers(swarm);
/* disconnect the handshakes. handshakeAbort calls handshakeDoneCB(),
* which removes the handshake from t->outgoing_handshakes... */
while (!std::empty(swarm->outgoing_handshakes))
{
tr_handshakeAbort(std::begin(swarm->outgoing_handshakes)->second);
}
}
void tr_peerMgrStopTorrent(tr_torrent* tor)
{
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
stopSwarm(tor->swarm);
}
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 = swarmNew(manager, tor);
}
void tr_peerMgrRemoveTorrent(tr_torrent* tor)
{
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
stopSwarm(tor->swarm);
swarmFree(tor->swarm);
}
void tr_peerUpdateProgress(tr_torrent* tor, tr_peer* peer)
{
if (auto const* have = &peer->have; have->hasAll())
{
peer->progress = 1.0;
}
else if (have->hasNone())
{
peer->progress = 0.0;
}
else
{
float const true_count = have->count();
if (tor->hasMetainfo())
{
peer->progress = true_count / float(tor->pieceCount());
}
else // without pieceCount, this result is only a best guess...
{
peer->progress = true_count / float(have->size() + 1);
}
}
peer->progress = std::clamp(peer->progress, 0.0F, 1.0F);
if (peer->atom != nullptr && peer->progress >= 1.0F)
{
atomSetSeed(tor->swarm, peer->atom);
}
}
void tr_peerMgrOnTorrentGotMetainfo(tr_torrent* tor)
{
/* the webseed list may have changed... */
rebuildWebseedArray(tor->swarm, tor);
/* some peer_msgs' progress fields may not be accurate if we
didn't have the metadata before now... so refresh them all... */
int const peerCount = tr_ptrArraySize(&tor->swarm->peers);
auto** const peers = (tr_peer**)tr_ptrArrayBase(&tor->swarm->peers);
for (int i = 0; i < peerCount; ++i)
{
tr_peerUpdateProgress(tor, peers[i]);
}
/* update the bittorrent peers' willingnes... */
for (int i = 0; i < peerCount; ++i)
{
auto* msgs = static_cast<tr_peerMsgs*>(peers[i]);
msgs->update_active(TR_UP);
msgs->update_active(TR_DOWN);
}
}
void tr_peerMgrTorrentAvailability(tr_torrent const* tor, int8_t* tab, unsigned int tabCount)
{
TR_ASSERT(tr_isTorrent(tor));
TR_ASSERT(tab != nullptr);
TR_ASSERT(tabCount > 0);
std::fill_n(tab, tabCount, int8_t{});
if (tor->hasMetainfo())
{
int const peerCount = tr_ptrArraySize(&tor->swarm->peers);
auto const** peers = (tr_peer const**)tr_ptrArrayBase(&tor->swarm->peers);
float const interval = tor->pieceCount() / (float)tabCount;
auto const isSeed = tor->isSeed();
for (tr_piece_index_t i = 0; i < tabCount; ++i)
{
int const piece = i * interval;
if (isSeed || tor->hasPiece(piece))
{
tab[i] = -1;
}
else if (peerCount != 0)
{
for (int j = 0; j < peerCount; ++j)
{
if (peers[j]->have.test(piece))
{
++tab[i];
}
}
}
}
}
}
void tr_swarmGetStats(tr_swarm const* swarm, tr_swarm_stats* setme)
{
TR_ASSERT(swarm != nullptr);
TR_ASSERT(setme != nullptr);
*setme = swarm->stats;
}
void tr_swarmIncrementActivePeers(tr_swarm* swarm, tr_direction direction, bool is_active)
{
int n = swarm->stats.activePeerCount[direction];
if (is_active)
{
++n;
}
else
{
--n;
}
TR_ASSERT(n >= 0);
TR_ASSERT(n <= swarm->stats.peerCount);
swarm->stats.activePeerCount[direction] = n;
}
bool tr_peerIsSeed(tr_peer const* peer)
{
return (peer != nullptr) && ((peer->progress >= 1.0) || atomIsSeed(peer->atom));
}
/* 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->isRunning)
{
return 0;
}
size_t const n_peers = tr_ptrArraySize(&s->peers);
if (n_peers == 0)
{
return 0;
}
auto const** const peers = (tr_peer const**)tr_ptrArrayBase(&s->peers);
for (size_t i = 0; i < n_peers; ++i)
{
if (peers[i]->atom != nullptr && atomIsSeed(peers[i]->atom))
{
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 (size_t i = 0; i < n_peers; ++i)
{
auto const* const peer = peers[i];
for (size_t j = 0; j < n_pieces; ++j)
{
if (peer->have.test(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 = tr_ptrArraySize(&tor->swarm->webseeds);
TR_ASSERT(i < n);
return i >= n ? tr_webseed_view{} : tr_webseedView(static_cast<tr_peer const*>(tr_ptrArrayNth(&tor->swarm->webseeds, i)));
}
static auto getPeerStats(tr_peerMsgs const* peer, time_t now, uint64_t now_msec)
{
auto stats = tr_peer_stat{};
auto const* const atom = peer->atom;
tr_address_to_string_with_buf(&atom->addr, stats.addr, sizeof(stats.addr));
stats.client = peer->client.c_str();
stats.port = ntohs(peer->atom->port);
stats.from = atom->fromFirst;
stats.progress = peer->progress;
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 = tr_peerIsSeed(peer);
stats.blocksToPeer = peer->blocksSentToPeer.count(now, CancelHistorySec);
stats.blocksToClient = peer->blocksSentToClient.count(now, CancelHistorySec);
stats.cancelsToPeer = peer->cancelsSentToPeer.count(now, CancelHistorySec);
stats.cancelsToClient = peer->cancelsSentToClient.count(now, CancelHistorySec);
stats.pendingReqsToPeer = peer->swarm->active_requests.count(peer);
stats.pendingReqsToClient = peer->pendingReqsToClient;
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;
}
struct tr_peer_stat* tr_peerMgrPeerStats(tr_torrent const* tor, int* setmeCount)
{
TR_ASSERT(tr_isTorrent(tor));
TR_ASSERT(tor->swarm->manager != nullptr);
auto** peers = (tr_peerMsgs**)tr_ptrArrayBase(&tor->swarm->peers);
int const size = tr_ptrArraySize(&tor->swarm->peers);
auto* const ret = tr_new0(tr_peer_stat, size);
time_t const now = tr_time();
uint64_t const now_msec = tr_time_msec();
for (int i = 0; i < size; ++i)
{
ret[i] = getPeerStats(peers[i], now, now_msec);
}
*setmeCount = size;
return ret;
}
/***
****
****
***/
void tr_peerMgrClearInterest(tr_torrent* tor)
{
TR_ASSERT(tr_isTorrent(tor));
auto const lock = tor->unique_lock();
tr_swarm* s = tor->swarm;
int const peerCount = tr_ptrArraySize(&s->peers);
for (int i = 0; i < peerCount; ++i)
{
static_cast<tr_peerMsgs*>(tr_ptrArrayNth(&s->peers, i))->set_interested(false);
}
}
/* does this peer have any pieces that we want? */
static bool isPeerInteresting(tr_torrent* const tor, bool const* const piece_is_interesting, tr_peer const* const peer)
{
/* these cases should have already been handled by the calling code... */
TR_ASSERT(!tor->isDone());
TR_ASSERT(tor->clientCanDownload());
if (tr_peerIsSeed(peer))
{
return true;
}
for (tr_piece_index_t i = 0; i < tor->pieceCount(); ++i)
{
if (piece_is_interesting[i] && peer->have.test(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;
};
static 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;
}
/* determines who we send "interested" messages to */
static void rechokeDownloads(tr_swarm* s)
{
int maxPeers = 0;
int rechoke_count = 0;
struct tr_rechoke_info* rechoke = nullptr;
auto constexpr MinInterestingPeers = 5;
int const peerCount = tr_ptrArraySize(&s->peers);
time_t const now = tr_time();
/* 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 (int i = 0; i < peerCount; ++i)
{
auto const* const peer = static_cast<tr_peer const*>(tr_ptrArrayNth(&s->peers, i));
auto const b = peer->blocksSentToClient.count(now, CancelHistorySec);
auto const c = peer->cancelsSentToPeer.count(now, CancelHistorySec);
if (b == 0) /* ignore unresponsive peers, as described above */
{
continue;
}
blocks += b;
cancels += c;
}
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);
maxPeers = s->interestedCount * 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;
maxPeers = s->maxPeers + 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... */
maxPeers = std::clamp(maxPeers, MinInterestingPeers, int(s->tor->maxConnectedPeers));
s->maxPeers = maxPeers;
if (peerCount > 0)
{
tr_torrent 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 (int i = 0; i < peerCount; ++i)
{
auto* const peer = static_cast<tr_peerMsgs*>(tr_ptrArrayNth(&s->peers, i));
if (!isPeerInteresting(s->tor, piece_is_interesting, peer))
{
peer->set_interested(false);
}
else
{
auto rechoke_state = tr_rechoke_state{};
auto const blocks = peer->blocksSentToClient.count(now, CancelHistorySec);
auto const cancels = peer->cancelsSentToPeer.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->interestedCount = std::min(maxPeers, rechoke_count);
for (int i = 0; i < rechoke_count; ++i)
{
rechoke[i].peer->set_interested(i < s->interestedCount);
}
/* cleanup */
tr_free(rechoke);
}
/**
***
**/
struct ChokeData
{
bool isInterested;
bool wasChoked;
bool isChoked;
int rate;
int salt;
tr_peerMsgs* msgs;
};
static int compareChoke(void const* va, void const* vb)
{
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? */
static 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. */
static int getRate(tr_torrent const* tor, struct peer_atom const* atom, uint64_t now)
{
auto Bps = unsigned{};
if (tor->isDone())
{
Bps = tr_peerGetPieceSpeed_Bps(atom->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 */
else if (tor->isPrivate())
{
Bps = tr_peerGetPieceSpeed_Bps(atom->peer, now, TR_PEER_TO_CLIENT) +
tr_peerGetPieceSpeed_Bps(atom->peer, now, TR_CLIENT_TO_PEER);
}
/* downloading a public torrent */
else
{
Bps = tr_peerGetPieceSpeed_Bps(atom->peer, now, TR_PEER_TO_CLIENT);
}
/* convert it to bytes per second */
return Bps;
}
static inline bool isBandwidthMaxedOut(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;
}
static void rechokeUploads(tr_swarm* s, uint64_t const now)
{
auto const lock = s->manager->unique_lock();
int const peerCount = tr_ptrArraySize(&s->peers);
auto** peers = (tr_peerMsgs**)tr_ptrArrayBase(&s->peers);
auto* const choke = tr_new0(struct ChokeData, peerCount);
tr_session 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->optimisticUnchokeTimeScaler > 0)
{
s->optimisticUnchokeTimeScaler--;
}
else
{
s->optimistic = nullptr;
}
int size = 0;
/* sort the peers by preference and rate */
for (int i = 0; i < peerCount; ++i)
{
auto* const peer = peers[i];
struct peer_atom* const atom = peer->atom;
if (tr_peerIsSeed(peer))
{
/* 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 = getRate(s->tor, atom, 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->optimisticUnchokeTimeScaler = OptimisticUnchokeMultiplier;
}
}
for (int i = 0; i < size; ++i)
{
choke[i].msgs->set_choke(choke[i].isChoked);
}
/* cleanup */
tr_free(choke);
}
static void rechokePulse(evutil_socket_t /*fd*/, short /*what*/, void* vmgr)
{
auto* mgr = static_cast<tr_peerMgr*>(vmgr);
auto const lock = mgr->unique_lock();
uint64_t const now = tr_time_msec();
for (auto* const tor : mgr->session->torrents())
{
if (tor->isRunning)
{
tr_swarm* s = tor->swarm;
if (s->stats.peerCount > 0)
{
rechokeUploads(s, now);
rechokeDownloads(s);
}
}
}
tr_timerAddMsec(mgr->rechokeTimer, RechokePeriodMsec);
}
/***
****
**** Life and Death
****
***/
static bool shouldPeerBeClosed(tr_swarm const* s, tr_peer const* peer, int peerCount, time_t const now)
{
tr_torrent const* tor = s->tor;
struct peer_atom const* atom = peer->atom;
/* if it's marked for purging, close it */
if (peer->doPurge)
{
tr_logAddTraceSwarm(s, fmt::format("purging peer {} because its doPurge flag is set", tr_atomAddrStr(atom)));
return true;
}
/* disconnect if we're both seeds and enough time has passed for PEX */
if (tor->isDone() && tr_peerIsSeed(peer))
{
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",
tr_atomAddrStr(atom),
idleTime));
return true;
}
}
return false;
}
static int getReconnectIntervalSecs(struct peer_atom const* atom, time_t const now)
{
auto sec = int{};
bool const unreachable = (atom->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 - atom->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
{
int step = atom->numFails;
/* 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", tr_atomAddrStr(atom), sec));
return sec;
}
static void removePeer(tr_peer* peer)
{
auto* const s = peer->swarm;
auto const lock = s->manager->unique_lock();
struct peer_atom* atom = peer->atom;
TR_ASSERT(atom != nullptr);
atom->time = tr_time();
tr_ptrArrayRemoveSortedPointer(&s->peers, peer, peerCompare);
--s->stats.peerCount;
--s->stats.peerFromCount[atom->fromFirst];
TR_ASSERT(s->stats.peerCount == tr_ptrArraySize(&s->peers));
TR_ASSERT(s->stats.peerFromCount[atom->fromFirst] >= 0);
delete peer;
}
static void closePeer(tr_peer* peer)
{
TR_ASSERT(peer != nullptr);
auto* const s = peer->swarm;
/* if we transferred piece data, then they might be good peers,
so reset their `numFails' 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 {} numFails to 0", tr_atomAddrStr(atom)));
atom->numFails = 0;
}
else
{
++atom->numFails;
tr_logAddTraceSwarm(s, fmt::format("incremented atom {} numFails to {}", tr_atomAddrStr(atom), atom->numFails));
}
tr_logAddTraceSwarm(s, fmt::format("removing bad peer {}", tr_atomAddrStr(peer->atom)));
removePeer(peer);
}
static void removeAllPeers(tr_swarm* swarm)
{
size_t const n = tr_ptrArraySize(&swarm->peers);
auto** base = (tr_peer**)tr_ptrArrayBase(&swarm->peers);
for (auto* peer : std::vector<tr_peer*>{ base, base + n })
{
removePeer(peer);
}
TR_ASSERT(swarm->stats.peerCount == 0);
}
static auto getPeersToClose(tr_swarm* s, time_t const now_sec)
{
auto peerCount = int{};
auto** const peers = (tr_peer**)tr_ptrArrayPeek(&s->peers, &peerCount);
auto peers_to_close = std::vector<tr_peer*>{};
auto test = [=](auto* peer)
{
return shouldPeerBeClosed(s, peer, peerCount, now_sec);
};
std::copy_if(peers, peers + peerCount, std::back_inserter(peers_to_close), test);
return peers_to_close;
}
static void closeBadPeers(tr_swarm* s, time_t const now_sec)
{
auto const lock = s->manager->unique_lock();
for (auto* peer : getPeersToClose(s, now_sec))
{
closePeer(peer);
}
}
struct ComparePeerByActivity
{
static int compare(tr_peer const* a, tr_peer const* b) // <=>
{
if (a->doPurge != b->doPurge)
{
return a->doPurge ? 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;
}
bool operator()(tr_peer const* a, tr_peer const* b) const // less then
{
return compare(a, b) < 0;
}
};
static void enforceTorrentPeerLimit(tr_swarm* s)
{
// do we have too many peers?
int n = tr_ptrArraySize(&s->peers);
int const max = tr_torrentGetPeerLimit(s->tor);
if (n <= max)
{
return;
}
// close all but the `max` most active
auto peers = std::vector<tr_peer*>{};
peers.reserve(n);
auto** base = (tr_peer**)tr_ptrArrayBase(&s->peers);
std::copy_n(base, n, std::back_inserter(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);
}
static 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 + tr_ptrArraySize(&tor->swarm->peers); });
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())
{
size_t const n = tr_ptrArraySize(&tor->swarm->peers);
auto** base = (tr_peer**)tr_ptrArrayBase(&tor->swarm->peers);
std::copy_n(base, n, std::back_inserter(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);
}
static void makeNewPeerConnections(tr_peerMgr* mgr, size_t max);
static void reconnectPulse(evutil_socket_t /*fd*/, short /*what*/, void* vmgr)
{
auto* mgr = static_cast<tr_peerMgr*>(vmgr);
time_t const now_sec = tr_time();
// remove crappy peers
for (auto* const tor : mgr->session->torrents())
{
if (!tor->swarm->isRunning)
{
removeAllPeers(tor->swarm);
}
else
{
closeBadPeers(tor->swarm, now_sec);
}
}
// if we're over the per-torrent peer limits, cull some peers
for (auto* const tor : mgr->session->torrents())
{
if (tor->isRunning)
{
enforceTorrentPeerLimit(tor->swarm);
}
}
// if we're over the per-session peer limits, cull some peers
enforceSessionPeerLimit(mgr->session);
// try to make new peer connections
auto const max_connections_per_pulse = int(MaxConnectionsPerSecond * (ReconnectPeriodMsec / 1000.0));
makeNewPeerConnections(mgr, max_connections_per_pulse);
}
/****
*****
***** BANDWIDTH ALLOCATION
*****
****/
static void pumpAllPeers(tr_peerMgr* mgr)
{
for (auto* const tor : mgr->session->torrents())
{
tr_swarm* s = tor->swarm;
for (int j = 0, n = tr_ptrArraySize(&s->peers); j < n; ++j)
{
static_cast<tr_peerMsgs*>(tr_ptrArrayNth(&s->peers, j))->pulse();
}
}
}
static 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);
}
}
}
}
static void bandwidthPulse(evutil_socket_t /*fd*/, short /*what*/, void* vmgr)
{
auto* mgr = static_cast<tr_peerMgr*>(vmgr);
auto const lock = mgr->unique_lock();
tr_session* session = mgr->session;
pumpAllPeers(mgr);
/* 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->needsCompletenessCheck)
{
tor->swarm->needsCompletenessCheck = 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.activeWebseedCount = countActiveWebseeds(tor->swarm);
}
/* pump the queues */
queuePulse(session, TR_UP);
queuePulse(session, TR_DOWN);
reconnectPulse(0, 0, mgr);
tr_timerAddMsec(mgr->bandwidthTimer, BandwidthPeriodMsec);
}
/***
****
***/
static int compareAtomPtrsByAddress(void const* va, void const* vb)
{
struct peer_atom const* a = *(struct peer_atom const* const*)va;
struct peer_atom const* b = *(struct peer_atom const* const*)vb;
TR_ASSERT(tr_isAtom(a));
TR_ASSERT(tr_isAtom(b));
return tr_address_compare(&a->addr, &b->addr);
}
/* best come first, worst go last */
static int compareAtomPtrsByShelfDate(void const* va, void const* vb)
{
struct peer_atom const* a = *(struct peer_atom const* const*)va;
struct peer_atom const* b = *(struct peer_atom const* const*)vb;
TR_ASSERT(tr_isAtom(a));
TR_ASSERT(tr_isAtom(b));
int const data_time_cutoff_secs = 60 * 60;
time_t const tr_now = tr_time();
/* primary key: the last piece data time *if* it was within the last hour */
time_t atime = a->piece_data_time;
if (atime + data_time_cutoff_secs < tr_now)
{
atime = 0;
}
time_t btime = b->piece_data_time;
if (btime + data_time_cutoff_secs < tr_now)
{
btime = 0;
}
if (atime != btime)
{
return atime > btime ? -1 : 1;
}
/* secondary key: shelf date. */
if (a->shelf_date != b->shelf_date)
{
return a->shelf_date > b->shelf_date ? -1 : 1;
}
return 0;
}
static int getMaxAtomCount(tr_torrent const* tor)
{
return std::min(50, tor->maxConnectedPeers * 3);
}
static void atomPulse(evutil_socket_t /*fd*/, short /*what*/, void* vmgr)
{
auto* mgr = static_cast<tr_peerMgr*>(vmgr);
auto const lock = mgr->unique_lock();
for (auto* const tor : mgr->session->torrents())
{
tr_swarm* s = tor->swarm;
int const maxAtomCount = getMaxAtomCount(tor);
auto atomCount = int{};
auto** const atoms = (peer_atom**)tr_ptrArrayPeek(&s->pool, &atomCount);
if (atomCount > maxAtomCount) /* we've got too many atoms... time to prune */
{
int keepCount = 0;
int testCount = 0;
auto** keep = tr_new(struct peer_atom*, atomCount);
auto** test = tr_new(struct peer_atom*, atomCount);
/* keep the ones that are in use */
for (int i = 0; i < atomCount; ++i)
{
struct peer_atom* atom = atoms[i];
if (peerIsInUse(s, atom))
{
keep[keepCount++] = atom;
}
else
{
test[testCount++] = atom;
}
}
/* if there's room, keep the best of what's left */
int i = 0;
if (keepCount < maxAtomCount)
{
qsort(test, testCount, sizeof(struct peer_atom*), compareAtomPtrsByShelfDate);
while (i < testCount && keepCount < maxAtomCount)
{
keep[keepCount++] = test[i++];
}
}
/* free the culled atoms */
while (i < testCount)
{
tr_free(test[i++]);
}
/* rebuild Torrent.pool with what's left */
tr_ptrArrayDestruct(&s->pool, nullptr);
s->pool = {};
qsort(keep, keepCount, sizeof(struct peer_atom*), compareAtomPtrsByAddress);
for (i = 0; i < keepCount; ++i)
{
tr_ptrArrayAppend(&s->pool, keep[i]);
}
tr_logAddTraceSwarm(
s,
fmt::format("max atom count is {}... pruned from {} to {}", maxAtomCount, atomCount, keepCount));
/* cleanup */
tr_free(test);
tr_free(keep);
}
}
tr_timerAddMsec(mgr->atomTimer, AtomPeriodMsec);
}
/***
****
****
****
***/
/* is this atom someone that we'd want to initiate a connection to? */
static bool isPeerCandidate(tr_torrent const* tor, struct peer_atom* atom, time_t const now)
{
/* not if we're both seeds */
if (tor->isDone() && atomIsSeed(atom))
{
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 < getReconnectIntervalSecs(atom, now))
{
return false;
}
/* not if they're blocklisted */
if (isAtomBlocklisted(tor->session, atom))
{
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;
struct peer_atom* atom;
};
static bool torrentWasRecentlyStarted(tr_torrent const* tor)
{
return difftime(tr_time(), tor->startDate) < 120;
}
static 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 */
static uint64_t getPeerCandidateScore(tr_torrent const* tor, struct 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;
}
static bool calculateAllSeeds(tr_swarm* swarm)
{
int nAtoms = 0;
auto** atoms = (struct peer_atom**)tr_ptrArrayPeek(&swarm->pool, &nAtoms);
for (int i = 0; i < nAtoms; ++i)
{
if (!atomIsSeed(atoms[i]))
{
return false;
}
}
return true;
}
static bool swarmIsAllSeeds(tr_swarm* swarm)
{
if (swarm->poolIsAllSeedsDirty)
{
swarm->poolIsAllSeeds = calculateAllSeeds(swarm);
swarm->poolIsAllSeedsDirty = false;
}
return swarm->poolIsAllSeeds;
}
/** @return an array of all the atoms we might want to connect to */
static std::vector<peer_candidate> getPeerCandidates(tr_session* session, size_t max)
{
time_t const now = tr_time();
uint64_t const now_msec = tr_time_msec();
/* leave 5% of connection slots for incoming connections -- ticket #2609 */
int const maxCandidates = tr_sessionGetPeerLimit(session) * 0.95;
/* count how many peers and atoms we've got */
int atomCount = 0;
int peerCount = 0;
for (auto const* tor : session->torrents())
{
atomCount += tr_ptrArraySize(&tor->swarm->pool);
peerCount += tr_ptrArraySize(&tor->swarm->peers);
}
/* don't start any new handshakes if we're full up */
if (maxCandidates <= peerCount)
{
return {};
}
auto candidates = std::vector<peer_candidate>{};
candidates.reserve(atomCount);
/* populate the candidate array */
for (auto* tor : session->torrents())
{
if (!tor->swarm->isRunning)
{
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 && swarmIsAllSeeds(tor->swarm) && tor->isPrivate())
{
continue;
}
/* if we've already got enough peers in this torrent... */
if (tr_torrentGetPeerLimit(tor) <= tr_ptrArraySize(&tor->swarm->peers))
{
continue;
}
/* if we've already got enough speed in this torrent... */
if (seeding && isBandwidthMaxedOut(tor->bandwidth_, now_msec, TR_UP))
{
continue;
}
auto nAtoms = int{};
auto** atoms = (peer_atom**)tr_ptrArrayPeek(&tor->swarm->pool, &nAtoms);
for (int i = 0; i < nAtoms; ++i)
{
struct peer_atom* atom = atoms[i];
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;
}
static void initiateConnection(tr_peerMgr* mgr, tr_swarm* s, struct 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", tr_atomAddrStr(atom)));
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", tr_atomAddrStr(atom)));
atom->flags2 |= MyflagUnreachable;
atom->numFails++;
}
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.try_emplace(atom->addr, handshake);
}
atom->lastConnectionAttemptAt = now;
atom->time = now;
}
static void initiateCandidateConnection(tr_peerMgr* mgr, peer_candidate& c)
{
#if 0
fprintf(stderr, "Starting an OUTGOING connection with %s - [%s] %s, %s\n", tr_atomAddrStr(c->atom),
tr_torrentName(c->tor), c->tor->isPrivate() ? "private" : "public",
c->tor->isDone() ? "seed" : "downloader");
#endif
initiateConnection(mgr, c.tor->swarm, c.atom);
}
static void makeNewPeerConnections(struct tr_peerMgr* mgr, size_t max)
{
for (auto& candidate : getPeerCandidates(mgr->session, max))
{
initiateCandidateConnection(mgr, candidate);
}
}
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