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transmission/libtransmission/peer-msgs.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>
#include <cstdarg>
#include <cstring>
#include <ctime>
#include <memory> // std::unique_ptr
#include <optional>
#include <event2/buffer.h>
#include <event2/bufferevent.h>
#include <event2/event.h>
#include "transmission.h"
#include "cache.h"
#include "completion.h"
#include "file.h"
#include "log.h"
#include "peer-io.h"
#include "peer-mgr.h"
#include "peer-msgs.h"
#include "ptrarray.h"
#include "quark.h"
#include "session.h"
#include "torrent-magnet.h"
#include "torrent.h"
#include "tr-assert.h"
#include "tr-dht.h"
#include "utils.h"
#include "variant.h"
#include "version.h"
#ifndef EBADMSG
#define EBADMSG EINVAL
#endif
/**
***
**/
// these values are hardcoded by various BEPs as noted
namespace BtPeerMsgs
{
// http://bittorrent.org/beps/bep_0003.html#peer-messages
auto constexpr Choke = uint8_t{ 0 };
auto constexpr Unchoke = uint8_t{ 1 };
auto constexpr Interested = uint8_t{ 2 };
auto constexpr NotInterested = uint8_t{ 3 };
auto constexpr Have = uint8_t{ 4 };
auto constexpr Bitfield = uint8_t{ 5 };
auto constexpr Request = uint8_t{ 6 };
auto constexpr Piece = uint8_t{ 7 };
auto constexpr Cancel = uint8_t{ 8 };
auto constexpr Port = uint8_t{ 9 };
// https://www.bittorrent.org/beps/bep_0006.html
auto constexpr FextSuggest = uint8_t{ 13 };
auto constexpr FextHaveAll = uint8_t{ 14 };
auto constexpr FextHaveNone = uint8_t{ 15 };
auto constexpr FextReject = uint8_t{ 16 };
auto constexpr FextAllowedFast = uint8_t{ 17 };
// http://bittorrent.org/beps/bep_0010.html
// see also LtepMessageIds below
auto constexpr Ltep = uint8_t{ 20 };
} // namespace BtPeerMsgs
namespace LtepMessages
{
// http://bittorrent.org/beps/bep_0010.html
auto constexpr Handshake = uint8_t{ 0 };
} // namespace LtepMessages
// http://bittorrent.org/beps/bep_0010.html
// Client-defined extension message IDs that we tell peers about
// in the LTEP handshake and will respond to when sent in an LTEP
// message.
enum LtepMessageIds
{
// we support peer exchange (bep 11)
// https://www.bittorrent.org/beps/bep_0011.html
UT_PEX_ID = 1,
// we support sending metadata files (bep 9)
// https://www.bittorrent.org/beps/bep_0009.html
// see also MetadataMsgType below
UT_METADATA_ID = 3,
};
// http://bittorrent.org/beps/bep_0009.html
namespace MetadataMsgType
{
auto constexpr Request = int{ 0 };
auto constexpr Data = int{ 1 };
auto constexpr Reject = int{ 2 };
} // namespace MetadataMsgType
// seconds between sendPex() calls
static auto constexpr PexIntervalSecs = int{ 90 };
static auto constexpr MinChokePeriodSec = int{ 10 };
// idle seconds before we send a keepalive
static auto constexpr KeepaliveIntervalSecs = int{ 100 };
static auto constexpr MetadataReqQ = int{ 64 };
static auto constexpr ReqQ = int{ 512 };
// used in lowering the outMessages queue period
static auto constexpr ImmediatePriorityIntervalSecs = int{ 0 };
static auto constexpr HighPriorityIntervalSecs = int{ 2 };
static auto constexpr LowPriorityIntervalSecs = int{ 10 };
// how many blocks to keep prefetched per peer
static auto constexpr PrefetchSize = int{ 18 };
// when we're making requests from another peer,
// batch them together to send enough requests to
// meet our bandwidth goals for the next N seconds
static auto constexpr RequestBufSecs = int{ 10 };
namespace
{
auto constexpr MaxPexPeerCount = size_t{ 50 };
} // unnamed namespace
enum class AwaitingBt
{
Length,
Id,
Message,
Piece
};
enum class EncryptionPreference
{
Unknown,
Yes,
No
};
/**
***
**/
struct peer_request
{
uint32_t index;
uint32_t offset;
uint32_t length;
};
static peer_request blockToReq(tr_torrent const* tor, tr_block_index_t block)
{
auto ret = peer_request{};
tr_torrentGetBlockLocation(tor, block, &ret.index, &ret.offset, &ret.length);
return ret;
}
/**
***
**/
/* this is raw, unchanged data from the peer regarding
* the current message that it's sending us. */
struct tr_incoming
{
uint8_t id = 0;
uint32_t length = 0; /* includes the +1 for id length */
struct peer_request blockReq = {}; /* metadata for incoming blocks */
struct evbuffer* block = nullptr; /* piece data for incoming blocks */
};
class tr_peerMsgsImpl;
// TODO: make these to be member functions
static ReadState canRead(tr_peerIo* io, void* vmsgs, size_t* piece);
static void cancelAllRequestsToClient(tr_peerMsgsImpl* msgs);
static void didWrite(tr_peerIo* io, size_t bytesWritten, bool wasPieceData, void* vmsgs);
static void gotError(tr_peerIo* io, short what, void* vmsgs);
static void peerPulse(void* vmsgs);
static void pexPulse(evutil_socket_t fd, short what, void* vmsgs);
static void protocolSendCancel(tr_peerMsgsImpl* msgs, struct peer_request const& req);
static void protocolSendChoke(tr_peerMsgsImpl* msgs, bool choke);
static void protocolSendHave(tr_peerMsgsImpl* msgs, tr_piece_index_t index);
static void protocolSendPort(tr_peerMsgsImpl* msgs, uint16_t port);
static void sendInterest(tr_peerMsgsImpl* msgs, bool b);
static void sendLtepHandshake(tr_peerMsgsImpl* msgs);
static void tellPeerWhatWeHave(tr_peerMsgsImpl* msgs);
static void updateDesiredRequestCount(tr_peerMsgsImpl* msgs);
//zzz
struct EventDeleter
{
void operator()(struct event* ev) const
{
event_free(ev);
}
};
using UniqueTimer = std::unique_ptr<struct event, EventDeleter>;
/**
* Low-level communication state information about a connected peer.
*
* This structure remembers the low-level protocol states that we're
* in with this peer, such as active requests, pex messages, and so on.
* Its fields are all private to peer-msgs.c.
*
* Data not directly involved with sending & receiving messages is
* stored in tr_peer, where it can be accessed by both peermsgs and
* the peer manager.
*
* @see struct peer_atom
* @see tr_peer
*/
class tr_peerMsgsImpl : public tr_peerMsgs
{
public:
tr_peerMsgsImpl(tr_torrent* torrent_in, peer_atom* atom_in, tr_peerIo* io_in, tr_peer_callback callback, void* callbackData)
: tr_peerMsgs{ torrent_in, atom_in }
, outMessagesBatchPeriod{ LowPriorityIntervalSecs }
, torrent{ torrent_in }
, outMessages{ evbuffer_new() }
, io{ io_in }
, callback_{ callback }
, callbackData_{ callbackData }
{
if (torrent->allowsPex())
{
pex_timer.reset(evtimer_new(torrent->session->event_base, pexPulse, this));
tr_timerAdd(pex_timer.get(), PexIntervalSecs, 0);
}
if (tr_peerIoSupportsUTP(io))
{
tr_address const* addr = tr_peerIoGetAddress(io, nullptr);
tr_peerMgrSetUtpSupported(torrent, addr);
tr_peerMgrSetUtpFailed(torrent, addr, false);
}
if (tr_peerIoSupportsLTEP(io))
{
sendLtepHandshake(this);
}
tellPeerWhatWeHave(this);
if (tr_dhtEnabled(torrent->session) && tr_peerIoSupportsDHT(io))
{
/* Only send PORT over IPv6 when the IPv6 DHT is running (BEP-32). */
struct tr_address const* addr = tr_peerIoGetAddress(io, nullptr);
if (addr->type == TR_AF_INET || tr_globalIPv6(nullptr) != nullptr)
{
protocolSendPort(this, tr_dhtPort(torrent->session));
}
}
tr_peerIoSetIOFuncs(io, canRead, didWrite, gotError, this);
updateDesiredRequestCount(this);
}
~tr_peerMsgsImpl() override
{
set_active(TR_UP, false);
set_active(TR_DOWN, false);
if (this->incoming.block != nullptr)
{
evbuffer_free(this->incoming.block);
}
if (this->io != nullptr)
{
tr_peerIoClear(this->io);
tr_peerIoUnref(this->io); /* balanced by the ref in handshakeDoneCB() */
}
evbuffer_free(this->outMessages);
tr_free(this->pex6);
tr_free(this->pex);
}
bool is_transferring_pieces(uint64_t now, tr_direction direction, unsigned int* setme_Bps) const override
{
auto const Bps = tr_peerIoGetPieceSpeed_Bps(io, now, direction);
if (setme_Bps != nullptr)
{
*setme_Bps = Bps;
}
return Bps > 0;
}
[[nodiscard]] bool is_peer_choked() const override
{
return peer_is_choked_;
}
[[nodiscard]] bool is_peer_interested() const override
{
return peer_is_interested_;
}
[[nodiscard]] bool is_client_choked() const override
{
return client_is_choked_;
}
[[nodiscard]] bool is_client_interested() const override
{
return client_is_interested_;
}
[[nodiscard]] bool is_utp_connection() const override
{
return io->socket.type == TR_PEER_SOCKET_TYPE_UTP;
}
[[nodiscard]] bool is_encrypted() const override
{
return tr_peerIoIsEncrypted(io);
}
[[nodiscard]] bool is_incoming_connection() const override
{
return tr_peerIoIsIncoming(io);
}
[[nodiscard]] bool is_active(tr_direction direction) const override
{
TR_ASSERT(tr_isDirection(direction));
auto const active = is_active_[direction];
TR_ASSERT(active == calculate_active(direction));
return active;
}
void update_active(tr_direction direction) override
{
TR_ASSERT(tr_isDirection(direction));
set_active(direction, calculate_active(direction));
}
[[nodiscard]] time_t get_connection_age() const override
{
return tr_peerIoGetAge(io);
}
void cancel_block_request(tr_block_index_t block) override
{
protocolSendCancel(this, blockToReq(torrent, block));
}
void set_choke(bool peer_is_choked) override
{
time_t const now = tr_time();
time_t const fibrillationTime = now - MinChokePeriodSec;
if (chokeChangedAt > fibrillationTime)
{
// TODO dbgmsg(msgs, "Not changing choke to %d to avoid fibrillation", peer_is_choked);
}
else if (peer_is_choked_ != peer_is_choked)
{
peer_is_choked_ = peer_is_choked;
if (peer_is_choked_)
{
cancelAllRequestsToClient(this);
}
protocolSendChoke(this, peer_is_choked_);
chokeChangedAt = now;
update_active(TR_CLIENT_TO_PEER);
}
}
void pulse() override
{
peerPulse(this);
}
void on_piece_completed(tr_piece_index_t piece) override
{
protocolSendHave(this, piece);
// since we have more pieces now, we might not be interested in this peer
update_interest();
}
void set_interested(bool interested) override
{
if (client_is_interested_ != interested)
{
client_is_interested_ = interested;
sendInterest(this, interested);
update_active(TR_PEER_TO_CLIENT);
}
}
void update_interest()
{
// TODO -- might need to poke the mgr on startup
}
// publishing events
void publishError(int err)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_ERROR;
e.err = err;
publish(e);
}
void publishGotBlock(struct peer_request const* req)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_BLOCK;
e.pieceIndex = req->index;
e.offset = req->offset;
e.length = req->length;
publish(e);
}
void publishGotRej(struct peer_request const* req)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_REJ;
e.pieceIndex = req->index;
e.offset = req->offset;
e.length = req->length;
publish(e);
}
void publishGotChoke()
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_CHOKE;
publish(e);
}
void publishClientGotHaveAll()
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_HAVE_ALL;
publish(e);
}
void publishClientGotHaveNone()
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_HAVE_NONE;
publish(e);
}
void publishClientGotPieceData(uint32_t length)
{
auto e = tr_peer_event{};
e.length = length;
e.eventType = TR_PEER_CLIENT_GOT_PIECE_DATA;
publish(e);
}
void publishPeerGotPieceData(uint32_t length)
{
auto e = tr_peer_event{};
e.length = length;
e.eventType = TR_PEER_PEER_GOT_PIECE_DATA;
publish(e);
}
void publishClientGotSuggest(tr_piece_index_t pieceIndex)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_SUGGEST;
e.pieceIndex = pieceIndex;
publish(e);
}
void publishClientGotPort(tr_port port)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_PORT;
e.port = port;
publish(e);
}
void publishClientGotAllowedFast(tr_piece_index_t pieceIndex)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_ALLOWED_FAST;
e.pieceIndex = pieceIndex;
publish(e);
}
void publishClientGotBitfield(tr_bitfield* bitfield)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_BITFIELD;
e.bitfield = bitfield;
publish(e);
}
void publishClientGotHave(tr_piece_index_t index)
{
auto e = tr_peer_event{};
e.eventType = TR_PEER_CLIENT_GOT_HAVE;
e.pieceIndex = index;
publish(e);
}
private:
[[nodiscard]] bool calculate_active(tr_direction direction) const
{
if (direction == TR_CLIENT_TO_PEER)
{
return is_peer_interested() && !is_peer_choked();
}
// TR_PEER_TO_CLIENT
if (!torrent->hasMetadata())
{
return true;
}
auto const active = is_client_interested() && !is_client_choked();
TR_ASSERT(!active || !torrent->isDone());
return active;
}
void set_active(tr_direction direction, bool active)
{
// TODO dbgmsg(msgs, "direction [%d] is_active [%d]", int(direction), int(is_active));
auto& val = is_active_[direction];
if (val != active)
{
val = active;
tr_swarmIncrementActivePeers(torrent->swarm, direction, active);
}
}
void publish(tr_peer_event const& e)
{
if (callback_ != nullptr)
{
(*callback_)(this, &e, callbackData_);
}
}
public:
/* Whether or not we've choked this peer. */
bool peer_is_choked_ = true;
/* whether or not the peer has indicated it will download from us. */
bool peer_is_interested_ = false;
/* whether or not the peer is choking us. */
bool client_is_choked_ = true;
/* whether or not we've indicated to the peer that we would download from them if unchoked. */
bool client_is_interested_ = false;
bool peerSupportsPex = false;
bool peerSupportsMetadataXfer = false;
bool clientSentLtepHandshake = false;
bool peerSentLtepHandshake = false;
size_t desired_request_count = 0;
int prefetchCount = 0;
/* how long the outMessages batch should be allowed to grow before
* it's flushed -- some messages (like requests >:) should be sent
* very quickly; others aren't as urgent. */
int8_t outMessagesBatchPeriod;
AwaitingBt state = AwaitingBt::Length;
uint8_t ut_pex_id = 0;
uint8_t ut_metadata_id = 0;
uint16_t pexCount = 0;
uint16_t pexCount6 = 0;
tr_port dht_port = 0;
EncryptionPreference encryption_preference = EncryptionPreference::Unknown;
size_t metadata_size_hint = 0;
#if 0
/* number of pieces we'll allow in our fast set */
static auto constexpr MAX_FAST_SET_SIZE = int{ 3 };
size_t fastsetSize;
tr_piece_index_t fastset[MAX_FAST_SET_SIZE];
#endif
tr_torrent* const torrent;
evbuffer* const outMessages; /* all the non-piece messages */
struct peer_request peerAskedFor[ReqQ] = {};
int peerAskedForMetadata[MetadataReqQ] = {};
int peerAskedForMetadataCount = 0;
tr_pex* pex = nullptr;
tr_pex* pex6 = nullptr;
time_t clientSentAnythingAt = 0;
time_t chokeChangedAt = 0;
/* when we started batching the outMessages */
time_t outMessagesBatchedAt = 0;
struct tr_incoming incoming = {};
/* if the peer supports the Extension Protocol in BEP 10 and
supplied a reqq argument, it's stored here. */
std::optional<size_t> reqq;
UniqueTimer pex_timer;
tr_peerIo* io = nullptr;
private:
bool is_active_[2] = { false, false };
tr_peer_callback const callback_;
void* const callbackData_;
};
tr_peerMsgs* tr_peerMsgsNew(tr_torrent* torrent, peer_atom* atom, tr_peerIo* io, tr_peer_callback callback, void* callbackData)
{
return new tr_peerMsgsImpl(torrent, atom, io, callback, callbackData);
}
/**
***
**/
static void myDebug(char const* file, int line, tr_peerMsgsImpl const* msgs, char const* fmt, ...) TR_GNUC_PRINTF(4, 5);
static void myDebug(char const* file, int line, tr_peerMsgsImpl const* msgs, char const* fmt, ...)
{
tr_sys_file_t const fp = tr_logGetFile();
if (fp != TR_BAD_SYS_FILE)
{
va_list args;
char timestr[64];
char addrstr[TR_ADDRSTRLEN];
struct evbuffer* buf = evbuffer_new();
char* base = tr_sys_path_basename(file, nullptr);
evbuffer_add_printf(
buf,
"[%s] %s - %s [%s]: ",
tr_logGetTimeStr(timestr, sizeof(timestr)),
tr_torrentName(msgs->torrent),
tr_peerIoGetAddrStr(msgs->io, addrstr, sizeof(addrstr)),
msgs->client.c_str());
va_start(args, fmt);
evbuffer_add_vprintf(buf, fmt, args);
va_end(args);
evbuffer_add_printf(buf, " (%s:%d)", base, line);
auto const message = evbuffer_free_to_str(buf);
tr_sys_file_write_line(fp, message, nullptr);
tr_free(base);
}
}
#define dbgmsg(msgs, ...) \
do \
{ \
if (tr_logGetDeepEnabled()) \
{ \
myDebug(__FILE__, __LINE__, msgs, __VA_ARGS__); \
} \
} while (0)
/**
***
**/
static void pokeBatchPeriod(tr_peerMsgsImpl* msgs, int interval)
{
if (msgs->outMessagesBatchPeriod > interval)
{
msgs->outMessagesBatchPeriod = interval;
dbgmsg(msgs, "lowering batch interval to %d seconds", interval);
}
}
static void dbgOutMessageLen(tr_peerMsgsImpl* msgs)
{
dbgmsg(msgs, "outMessage size is now %zu", evbuffer_get_length(msgs->outMessages));
}
static void protocolSendReject(tr_peerMsgsImpl* msgs, struct peer_request const* req)
{
TR_ASSERT(tr_peerIoSupportsFEXT(msgs->io));
struct evbuffer* out = msgs->outMessages;
evbuffer_add_uint32(out, sizeof(uint8_t) + 3 * sizeof(uint32_t));
evbuffer_add_uint8(out, BtPeerMsgs::FextReject);
evbuffer_add_uint32(out, req->index);
evbuffer_add_uint32(out, req->offset);
evbuffer_add_uint32(out, req->length);
dbgmsg(msgs, "rejecting %u:%u->%u...", req->index, req->offset, req->length);
dbgOutMessageLen(msgs);
}
static void protocolSendRequest(tr_peerMsgsImpl* msgs, struct peer_request const& req)
{
struct evbuffer* out = msgs->outMessages;
evbuffer_add_uint32(out, sizeof(uint8_t) + 3 * sizeof(uint32_t));
evbuffer_add_uint8(out, BtPeerMsgs::Request);
evbuffer_add_uint32(out, req.index);
evbuffer_add_uint32(out, req.offset);
evbuffer_add_uint32(out, req.length);
dbgmsg(msgs, "requesting %u:%u->%u...", req.index, req.offset, req.length);
dbgOutMessageLen(msgs);
pokeBatchPeriod(msgs, ImmediatePriorityIntervalSecs);
}
static void protocolSendCancel(tr_peerMsgsImpl* msgs, peer_request const& req)
{
struct evbuffer* out = msgs->outMessages;
evbuffer_add_uint32(out, sizeof(uint8_t) + 3 * sizeof(uint32_t));
evbuffer_add_uint8(out, BtPeerMsgs::Cancel);
evbuffer_add_uint32(out, req.index);
evbuffer_add_uint32(out, req.offset);
evbuffer_add_uint32(out, req.length);
dbgmsg(msgs, "cancelling %u:%u->%u...", req.index, req.offset, req.length);
dbgOutMessageLen(msgs);
pokeBatchPeriod(msgs, ImmediatePriorityIntervalSecs);
}
static void protocolSendPort(tr_peerMsgsImpl* msgs, uint16_t port)
{
struct evbuffer* out = msgs->outMessages;
dbgmsg(msgs, "sending Port %u", port);
evbuffer_add_uint32(out, 3);
evbuffer_add_uint8(out, BtPeerMsgs::Port);
evbuffer_add_uint16(out, port);
}
static void protocolSendHave(tr_peerMsgsImpl* msgs, tr_piece_index_t index)
{
struct evbuffer* out = msgs->outMessages;
evbuffer_add_uint32(out, sizeof(uint8_t) + sizeof(uint32_t));
evbuffer_add_uint8(out, BtPeerMsgs::Have);
evbuffer_add_uint32(out, index);
dbgmsg(msgs, "sending Have %u", index);
dbgOutMessageLen(msgs);
pokeBatchPeriod(msgs, LowPriorityIntervalSecs);
}
#if 0
static void protocolSendAllowedFast(tr_peerMsgs* msgs, uint32_t pieceIndex)
{
TR_ASSERT(tr_peerIoSupportsFEXT(msgs->io));
tr_peerIo* io = msgs->io;
struct evbuffer* out = msgs->outMessages;
evbuffer_add_uint32(io, out, sizeof(uint8_t) + sizeof(uint32_t));
evbuffer_add_uint8(io, out, BtPeerMsgs::FextAllowedFast);
evbuffer_add_uint32(io, out, pieceIndex);
dbgmsg(msgs, "sending Allowed Fast %u...", pieceIndex);
dbgOutMessageLen(msgs);
}
#endif
static void protocolSendChoke(tr_peerMsgsImpl* msgs, bool choke)
{
struct evbuffer* out = msgs->outMessages;
evbuffer_add_uint32(out, sizeof(uint8_t));
evbuffer_add_uint8(out, choke ? BtPeerMsgs::Choke : BtPeerMsgs::Unchoke);
dbgmsg(msgs, "sending %s...", choke ? "Choke" : "Unchoke");
dbgOutMessageLen(msgs);
pokeBatchPeriod(msgs, ImmediatePriorityIntervalSecs);
}
static void protocolSendHaveAll(tr_peerMsgsImpl* msgs)
{
TR_ASSERT(tr_peerIoSupportsFEXT(msgs->io));
struct evbuffer* out = msgs->outMessages;
evbuffer_add_uint32(out, sizeof(uint8_t));
evbuffer_add_uint8(out, BtPeerMsgs::FextHaveAll);
dbgmsg(msgs, "sending HAVE_ALL...");
dbgOutMessageLen(msgs);
pokeBatchPeriod(msgs, ImmediatePriorityIntervalSecs);
}
static void protocolSendHaveNone(tr_peerMsgsImpl* msgs)
{
TR_ASSERT(tr_peerIoSupportsFEXT(msgs->io));
struct evbuffer* out = msgs->outMessages;
evbuffer_add_uint32(out, sizeof(uint8_t));
evbuffer_add_uint8(out, BtPeerMsgs::FextHaveNone);
dbgmsg(msgs, "sending HAVE_NONE...");
dbgOutMessageLen(msgs);
pokeBatchPeriod(msgs, ImmediatePriorityIntervalSecs);
}
/**
*** ALLOWED FAST SET
*** For explanation, see http://www.bittorrent.org/beps/bep_0006.html
**/
#if 0
size_t tr_generateAllowedSet(tr_piece_index_t* setmePieces, size_t desiredSetSize, size_t pieceCount, uint8_t const* infohash,
tr_address const* addr)
{
TR_ASSERT(setmePieces != nullptr);
TR_ASSERT(desiredSetSize <= pieceCount);
TR_ASSERT(desiredSetSize != 0);
TR_ASSERT(pieceCount != 0);
TR_ASSERT(infohash != nullptr);
TR_ASSERT(addr != nullptr);
size_t setSize = 0;
if (addr->type == TR_AF_INET)
{
uint8_t w[SHA_DIGEST_LENGTH + 4];
uint8_t* walk = w;
uint8_t x[SHA_DIGEST_LENGTH];
uint32_t ui32 = ntohl(htonl(addr->addr.addr4.s_addr) & 0xffffff00); /* (1) */
memcpy(w, &ui32, sizeof(uint32_t));
walk += sizeof(uint32_t);
memcpy(walk, infohash, SHA_DIGEST_LENGTH); /* (2) */
walk += SHA_DIGEST_LENGTH;
tr_sha1(x, w, walk - w, nullptr); /* (3) */
TR_ASSERT(sizeof(w) == walk - w);
while (setSize < desiredSetSize)
{
for (int i = 0; i < 5 && setSize < desiredSetSize; ++i) /* (4) */
{
uint32_t j = i * 4; /* (5) */
uint32_t y = ntohl(*(uint32_t*)(x + j)); /* (6) */
uint32_t index = y % pieceCount; /* (7) */
bool found = false;
for (size_t k = 0; !found && k < setSize; ++k) /* (8) */
{
found = setmePieces[k] == index;
}
if (!found)
{
setmePieces[setSize++] = index; /* (9) */
}
}
tr_sha1(x, x, sizeof(x), nullptr); /* (3) */
}
}
return setSize;
}
static void updateFastSet(tr_peerMsgs*)
{
bool const fext = tr_peerIoSupportsFEXT(msgs->io);
bool const peerIsNeedy = msgs->peer->progress < 0.10;
if (fext && peerIsNeedy && !msgs->haveFastSet)
{
struct tr_address const* addr = tr_peerIoGetAddress(msgs->io, nullptr);
tr_info const* inf = &msgs->torrent->info;
size_t const numwant = std::min(MAX_FAST_SET_SIZE, inf->pieceCount);
/* build the fast set */
msgs->fastsetSize = tr_generateAllowedSet(msgs->fastset, numwant, inf->pieceCount, inf->hash, addr);
msgs->haveFastSet = true;
/* send it to the peer */
for (size_t i = 0; i < msgs->fastsetSize; ++i)
{
protocolSendAllowedFast(msgs, msgs->fastset[i]);
}
}
}
#endif
/**
*** INTEREST
**/
static void sendInterest(tr_peerMsgsImpl* msgs, bool b)
{
TR_ASSERT(msgs != nullptr);
struct evbuffer* out = msgs->outMessages;
dbgmsg(msgs, "Sending %s", b ? "Interested" : "Not Interested");
evbuffer_add_uint32(out, sizeof(uint8_t));
evbuffer_add_uint8(out, b ? BtPeerMsgs::Interested : BtPeerMsgs::NotInterested);
pokeBatchPeriod(msgs, HighPriorityIntervalSecs);
dbgOutMessageLen(msgs);
}
static bool popNextMetadataRequest(tr_peerMsgsImpl* msgs, int* piece)
{
if (msgs->peerAskedForMetadataCount == 0)
{
return false;
}
*piece = msgs->peerAskedForMetadata[0];
tr_removeElementFromArray(msgs->peerAskedForMetadata, 0, sizeof(int), msgs->peerAskedForMetadataCount);
--msgs->peerAskedForMetadataCount;
return true;
}
static bool popNextRequest(tr_peerMsgsImpl* msgs, struct peer_request* setme)
{
if (msgs->pendingReqsToClient == 0)
{
return false;
}
*setme = msgs->peerAskedFor[0];
tr_removeElementFromArray(msgs->peerAskedFor, 0, sizeof(struct peer_request), msgs->pendingReqsToClient);
--msgs->pendingReqsToClient;
return true;
}
static void cancelAllRequestsToClient(tr_peerMsgsImpl* msgs)
{
struct peer_request req;
bool const mustSendCancel = tr_peerIoSupportsFEXT(msgs->io);
while (popNextRequest(msgs, &req))
{
if (mustSendCancel)
{
protocolSendReject(msgs, &req);
}
}
}
/**
***
**/
static bool reqIsValid(tr_peerMsgsImpl const* peer, uint32_t index, uint32_t offset, uint32_t length)
{
return tr_torrentReqIsValid(peer->torrent, index, offset, length);
}
static bool requestIsValid(tr_peerMsgsImpl const* msgs, struct peer_request const* req)
{
return reqIsValid(msgs, req->index, req->offset, req->length);
}
/**
***
**/
static void sendLtepHandshake(tr_peerMsgsImpl* msgs)
{
evbuffer* const out = msgs->outMessages;
unsigned char const* ipv6 = tr_globalIPv6(msgs->io->session);
static tr_quark version_quark = 0;
if (msgs->clientSentLtepHandshake)
{
return;
}
if (version_quark == 0)
{
version_quark = tr_quark_new(TR_NAME " " USERAGENT_PREFIX);
}
dbgmsg(msgs, "sending an ltep handshake");
msgs->clientSentLtepHandshake = true;
/* decide if we want to advertise metadata xfer support (BEP 9) */
bool const allow_metadata_xfer = msgs->torrent->isPublic();
/* decide if we want to advertise pex support */
auto allow_pex = bool{};
if (!msgs->torrent->allowsPex())
{
allow_pex = false;
}
else if (msgs->peerSentLtepHandshake)
{
allow_pex = msgs->peerSupportsPex;
}
else
{
allow_pex = true;
}
auto val = tr_variant{};
tr_variantInitDict(&val, 8);
tr_variantDictAddBool(&val, TR_KEY_e, msgs->session->encryptionMode != TR_CLEAR_PREFERRED);
if (ipv6 != nullptr)
{
tr_variantDictAddRaw(&val, TR_KEY_ipv6, ipv6, 16);
}
// http://bittorrent.org/beps/bep_0009.html
// It also adds "metadata_size" to the handshake message (not the
// "m" dictionary) specifying an integer value of the number of
// bytes of the metadata.
auto const info_dict_size = msgs->torrent->infoDictSize();
if (allow_metadata_xfer && msgs->torrent->hasMetadata() && info_dict_size > 0)
{
tr_variantDictAddInt(&val, TR_KEY_metadata_size, info_dict_size);
}
// http://bittorrent.org/beps/bep_0010.html
// Local TCP listen port. Allows each side to learn about the TCP
// port number of the other side. Note that there is no need for the
// receiving side of the connection to send this extension message,
// since its port number is already known.
tr_variantDictAddInt(&val, TR_KEY_p, tr_sessionGetPublicPeerPort(msgs->session));
// http://bittorrent.org/beps/bep_0010.html
// An integer, the number of outstanding request messages this
// client supports without dropping any. The default in in
// libtorrent is 250.
tr_variantDictAddInt(&val, TR_KEY_reqq, ReqQ);
// http://bittorrent.org/beps/bep_0010.html
// Client name and version (as a utf-8 string). This is a much more
// reliable way of identifying the client than relying on the
// peer id encoding.
tr_variantDictAddQuark(&val, TR_KEY_v, version_quark);
// http://bittorrent.org/beps/bep_0021.html
// A peer that is a partial seed SHOULD include an extra header in
// the extension handshake 'upload_only'. Setting the value of this
// key to 1 indicates that this peer is not interested in downloading
// anything.
tr_variantDictAddBool(&val, TR_KEY_upload_only, msgs->torrent->isDone());
if (allow_metadata_xfer || allow_pex)
{
tr_variant* m = tr_variantDictAddDict(&val, TR_KEY_m, 2);
if (allow_metadata_xfer)
{
tr_variantDictAddInt(m, TR_KEY_ut_metadata, UT_METADATA_ID);
}
if (allow_pex)
{
tr_variantDictAddInt(m, TR_KEY_ut_pex, UT_PEX_ID);
}
}
auto* const payload = tr_variantToBuf(&val, TR_VARIANT_FMT_BENC);
evbuffer_add_uint32(out, 2 * sizeof(uint8_t) + evbuffer_get_length(payload));
evbuffer_add_uint8(out, BtPeerMsgs::Ltep);
evbuffer_add_uint8(out, LtepMessages::Handshake);
evbuffer_add_buffer(out, payload);
pokeBatchPeriod(msgs, ImmediatePriorityIntervalSecs);
dbgOutMessageLen(msgs);
/* cleanup */
evbuffer_free(payload);
tr_variantFree(&val);
}
static void parseLtepHandshake(tr_peerMsgsImpl* msgs, uint32_t len, struct evbuffer* inbuf)
{
auto* const tmp = tr_new(char, len);
tr_peerIoReadBytes(msgs->io, inbuf, tmp, len);
msgs->peerSentLtepHandshake = true;
auto val = tr_variant{};
if (!tr_variantFromBuf(&val, TR_VARIANT_PARSE_BENC | TR_VARIANT_PARSE_INPLACE, { tmp, len }) || !tr_variantIsDict(&val))
{
dbgmsg(msgs, "GET extended-handshake, couldn't get dictionary");
tr_free(tmp);
return;
}
/* arbitrary limit, should be more than enough */
if (len <= 4096)
{
dbgmsg(msgs, "here is the handshake: [%*.*s]", TR_ARG_TUPLE(int(len), int(len), tmp));
}
else
{
dbgmsg(msgs, "handshake length is too big (%" PRIu32 "), printing skipped", len);
}
/* does the peer prefer encrypted connections? */
auto i = int64_t{};
auto pex = tr_pex{};
if (tr_variantDictFindInt(&val, TR_KEY_e, &i))
{
msgs->encryption_preference = i != 0 ? EncryptionPreference::Yes : EncryptionPreference::No;
if (msgs->encryption_preference == EncryptionPreference::Yes)
{
pex.flags |= ADDED_F_ENCRYPTION_FLAG;
}
}
/* check supported messages for utorrent pex */
msgs->peerSupportsPex = false;
msgs->peerSupportsMetadataXfer = false;
if (tr_variant* sub = nullptr; tr_variantDictFindDict(&val, TR_KEY_m, &sub))
{
if (tr_variantDictFindInt(sub, TR_KEY_ut_pex, &i))
{
msgs->peerSupportsPex = i != 0;
msgs->ut_pex_id = (uint8_t)i;
dbgmsg(msgs, "msgs->ut_pex is %d", int(msgs->ut_pex_id));
}
if (tr_variantDictFindInt(sub, TR_KEY_ut_metadata, &i))
{
msgs->peerSupportsMetadataXfer = i != 0;
msgs->ut_metadata_id = (uint8_t)i;
dbgmsg(msgs, "msgs->ut_metadata_id is %d", int(msgs->ut_metadata_id));
}
if (tr_variantDictFindInt(sub, TR_KEY_ut_holepunch, &i))
{
/* Mysterious µTorrent extension that we don't grok. However,
it implies support for µTP, so use it to indicate that. */
tr_peerMgrSetUtpFailed(msgs->torrent, tr_peerIoGetAddress(msgs->io, nullptr), false);
}
}
/* look for metainfo size (BEP 9) */
if (tr_variantDictFindInt(&val, TR_KEY_metadata_size, &i) && tr_torrentSetMetadataSizeHint(msgs->torrent, i))
{
msgs->metadata_size_hint = (size_t)i;
}
/* look for upload_only (BEP 21) */
if (tr_variantDictFindInt(&val, TR_KEY_upload_only, &i))
{
pex.flags |= ADDED_F_SEED_FLAG;
}
/* get peer's listening port */
if (tr_variantDictFindInt(&val, TR_KEY_p, &i))
{
pex.port = htons((uint16_t)i);
msgs->publishClientGotPort(pex.port);
dbgmsg(msgs, "peer's port is now %d", int(i));
}
uint8_t const* addr = nullptr;
auto addr_len = size_t{};
if (tr_peerIoIsIncoming(msgs->io) && tr_variantDictFindRaw(&val, TR_KEY_ipv4, &addr, &addr_len) && addr_len == 4)
{
pex.addr.type = TR_AF_INET;
memcpy(&pex.addr.addr.addr4, addr, 4);
tr_peerMgrAddPex(msgs->torrent, TR_PEER_FROM_LTEP, &pex, 1);
}
if (tr_peerIoIsIncoming(msgs->io) && tr_variantDictFindRaw(&val, TR_KEY_ipv6, &addr, &addr_len) && addr_len == 16)
{
pex.addr.type = TR_AF_INET6;
memcpy(&pex.addr.addr.addr6, addr, 16);
tr_peerMgrAddPex(msgs->torrent, TR_PEER_FROM_LTEP, &pex, 1);
}
/* get peer's maximum request queue size */
if (tr_variantDictFindInt(&val, TR_KEY_reqq, &i))
{
msgs->reqq = i;
}
tr_variantFree(&val);
tr_free(tmp);
}
static void parseUtMetadata(tr_peerMsgsImpl* msgs, uint32_t msglen, struct evbuffer* inbuf)
{
int64_t msg_type = -1;
int64_t piece = -1;
int64_t total_size = 0;
auto* const tmp = tr_new(char, msglen);
tr_peerIoReadBytes(msgs->io, inbuf, tmp, msglen);
char const* const msg_end = (char const*)tmp + msglen;
auto dict = tr_variant{};
char const* benc_end = nullptr;
if (tr_variantFromBuf(&dict, TR_VARIANT_PARSE_BENC | TR_VARIANT_PARSE_INPLACE, { tmp, msglen }, &benc_end))
{
(void)tr_variantDictFindInt(&dict, TR_KEY_msg_type, &msg_type);
(void)tr_variantDictFindInt(&dict, TR_KEY_piece, &piece);
(void)tr_variantDictFindInt(&dict, TR_KEY_total_size, &total_size);
tr_variantFree(&dict);
}
dbgmsg(msgs, "got ut_metadata msg: type %d, piece %d, total_size %d", int(msg_type), int(piece), int(total_size));
if (msg_type == MetadataMsgType::Reject)
{
/* NOOP */
}
if (msg_type == MetadataMsgType::Data && !msgs->torrent->hasMetadata() && msg_end - benc_end <= METADATA_PIECE_SIZE &&
piece * METADATA_PIECE_SIZE + (msg_end - benc_end) <= total_size)
{
int const pieceLen = msg_end - benc_end;
tr_torrentSetMetadataPiece(msgs->torrent, piece, benc_end, pieceLen);
}
if (msg_type == MetadataMsgType::Request)
{
if (piece >= 0 && msgs->torrent->hasMetadata() && msgs->torrent->isPublic() &&
msgs->peerAskedForMetadataCount < MetadataReqQ)
{
msgs->peerAskedForMetadata[msgs->peerAskedForMetadataCount++] = piece;
}
else
{
evbuffer* const out = msgs->outMessages;
/* build the rejection message */
auto v = tr_variant{};
tr_variantInitDict(&v, 2);
tr_variantDictAddInt(&v, TR_KEY_msg_type, MetadataMsgType::Reject);
tr_variantDictAddInt(&v, TR_KEY_piece, piece);
evbuffer* const payload = tr_variantToBuf(&v, TR_VARIANT_FMT_BENC);
/* write it out as a LTEP message to our outMessages buffer */
evbuffer_add_uint32(out, 2 * sizeof(uint8_t) + evbuffer_get_length(payload));
evbuffer_add_uint8(out, BtPeerMsgs::Ltep);
evbuffer_add_uint8(out, msgs->ut_metadata_id);
evbuffer_add_buffer(out, payload);
pokeBatchPeriod(msgs, HighPriorityIntervalSecs);
dbgOutMessageLen(msgs);
/* cleanup */
evbuffer_free(payload);
tr_variantFree(&v);
}
}
tr_free(tmp);
}
static void parseUtPex(tr_peerMsgsImpl* msgs, uint32_t msglen, struct evbuffer* inbuf)
{
tr_torrent* tor = msgs->torrent;
if (!tor->allowsPex())
{
return;
}
auto* tmp = tr_new(char, msglen);
tr_peerIoReadBytes(msgs->io, inbuf, tmp, msglen);
if (tr_variant val; tr_variantFromBuf(&val, TR_VARIANT_PARSE_BENC | TR_VARIANT_PARSE_INPLACE, { tmp, msglen }))
{
uint8_t const* added = nullptr;
auto added_len = size_t{};
if (tr_variantDictFindRaw(&val, TR_KEY_added, &added, &added_len))
{
uint8_t const* added_f = nullptr;
auto added_f_len = size_t{};
if (!tr_variantDictFindRaw(&val, TR_KEY_added_f, &added_f, &added_f_len))
{
added_f_len = 0;
added_f = nullptr;
}
auto pex = tr_peerMgrCompactToPex(added, added_len, added_f, added_f_len);
pex.resize(std::min(MaxPexPeerCount, std::size(pex)));
tr_peerMgrAddPex(tor, TR_PEER_FROM_PEX, std::data(pex), std::size(pex));
}
if (tr_variantDictFindRaw(&val, TR_KEY_added6, &added, &added_len))
{
uint8_t const* added_f = nullptr;
auto added_f_len = size_t{};
if (!tr_variantDictFindRaw(&val, TR_KEY_added6_f, &added_f, &added_f_len))
{
added_f_len = 0;
added_f = nullptr;
}
auto pex = tr_peerMgrCompact6ToPex(added, added_len, added_f, added_f_len);
pex.resize(std::min(MaxPexPeerCount, std::size(pex)));
tr_peerMgrAddPex(tor, TR_PEER_FROM_PEX, std::data(pex), std::size(pex));
}
tr_variantFree(&val);
}
tr_free(tmp);
}
static void sendPex(tr_peerMsgsImpl* msgs);
static void parseLtep(tr_peerMsgsImpl* msgs, uint32_t msglen, struct evbuffer* inbuf)
{
TR_ASSERT(msglen > 0);
auto ltep_msgid = uint8_t{};
tr_peerIoReadUint8(msgs->io, inbuf, &ltep_msgid);
msglen--;
if (ltep_msgid == LtepMessages::Handshake)
{
dbgmsg(msgs, "got ltep handshake");
parseLtepHandshake(msgs, msglen, inbuf);
if (tr_peerIoSupportsLTEP(msgs->io))
{
sendLtepHandshake(msgs);
sendPex(msgs);
}
}
else if (ltep_msgid == UT_PEX_ID)
{
dbgmsg(msgs, "got ut pex");
msgs->peerSupportsPex = true;
parseUtPex(msgs, msglen, inbuf);
}
else if (ltep_msgid == UT_METADATA_ID)
{
dbgmsg(msgs, "got ut metadata");
msgs->peerSupportsMetadataXfer = true;
parseUtMetadata(msgs, msglen, inbuf);
}
else
{
dbgmsg(msgs, "skipping unknown ltep message (%d)", int(ltep_msgid));
evbuffer_drain(inbuf, msglen);
}
}
static ReadState readBtLength(tr_peerMsgsImpl* msgs, struct evbuffer* inbuf, size_t inlen)
{
auto len = uint32_t{};
if (inlen < sizeof(len))
{
return READ_LATER;
}
tr_peerIoReadUint32(msgs->io, inbuf, &len);
if (len == 0) /* peer sent us a keepalive message */
{
dbgmsg(msgs, "got KeepAlive");
}
else
{
msgs->incoming.length = len;
msgs->state = AwaitingBt::Id;
}
return READ_NOW;
}
static ReadState readBtMessage(tr_peerMsgsImpl* /*msgs*/, struct evbuffer* /*inbuf*/, size_t /*inlen*/);
static ReadState readBtId(tr_peerMsgsImpl* msgs, struct evbuffer* inbuf, size_t inlen)
{
if (inlen < sizeof(uint8_t))
{
return READ_LATER;
}
auto id = uint8_t{};
tr_peerIoReadUint8(msgs->io, inbuf, &id);
msgs->incoming.id = id;
dbgmsg(msgs, "msgs->incoming.id is now %d; msgs->incoming.length is %zu", id, (size_t)msgs->incoming.length);
if (id == BtPeerMsgs::Piece)
{
msgs->state = AwaitingBt::Piece;
return READ_NOW;
}
if (msgs->incoming.length != 1)
{
msgs->state = AwaitingBt::Message;
return READ_NOW;
}
return readBtMessage(msgs, inbuf, inlen - 1);
}
static void updatePeerProgress(tr_peerMsgsImpl* msgs)
{
tr_peerUpdateProgress(msgs->torrent, msgs);
msgs->update_interest();
}
static void prefetchPieces(tr_peerMsgsImpl* msgs)
{
if (!msgs->session->isPrefetchEnabled)
{
return;
}
for (int i = msgs->prefetchCount; i < msgs->pendingReqsToClient && i < PrefetchSize; ++i)
{
struct peer_request const* req = msgs->peerAskedFor + i;
if (requestIsValid(msgs, req))
{
tr_cachePrefetchBlock(
msgs->session->cache,
msgs->torrent,
msgs->torrent->pieceLoc(req->index, req->offset),
req->length);
++msgs->prefetchCount;
}
}
}
static void peerMadeRequest(tr_peerMsgsImpl* msgs, struct peer_request const* req)
{
bool const fext = tr_peerIoSupportsFEXT(msgs->io);
bool const reqIsValid = requestIsValid(msgs, req);
bool const clientHasPiece = reqIsValid && msgs->torrent->hasPiece(req->index);
bool const peerIsChoked = msgs->peer_is_choked_;
bool allow = false;
if (!reqIsValid)
{
dbgmsg(msgs, "rejecting an invalid request.");
}
else if (!clientHasPiece)
{
dbgmsg(msgs, "rejecting request for a piece we don't have.");
}
else if (peerIsChoked)
{
dbgmsg(msgs, "rejecting request from choked peer");
}
else if (msgs->pendingReqsToClient + 1 >= ReqQ)
{
dbgmsg(msgs, "rejecting request ... reqq is full");
}
else
{
allow = true;
}
if (allow)
{
msgs->peerAskedFor[msgs->pendingReqsToClient++] = *req;
prefetchPieces(msgs);
}
else if (fext)
{
protocolSendReject(msgs, req);
}
}
static bool messageLengthIsCorrect(tr_peerMsgsImpl const* msg, uint8_t id, uint32_t len)
{
switch (id)
{
case BtPeerMsgs::Choke:
case BtPeerMsgs::Unchoke:
case BtPeerMsgs::Interested:
case BtPeerMsgs::NotInterested:
case BtPeerMsgs::FextHaveAll:
case BtPeerMsgs::FextHaveNone:
return len == 1;
case BtPeerMsgs::Have:
case BtPeerMsgs::FextSuggest:
case BtPeerMsgs::FextAllowedFast:
return len == 5;
case BtPeerMsgs::Bitfield:
if (msg->torrent->hasMetadata())
{
return len == (msg->torrent->pieceCount() >> 3) + ((msg->torrent->pieceCount() & 7) != 0 ? 1 : 0) + 1U;
}
/* we don't know the piece count yet,
so we can only guess whether to send true or false */
if (msg->metadata_size_hint > 0)
{
return len <= msg->metadata_size_hint;
}
return true;
case BtPeerMsgs::Request:
case BtPeerMsgs::Cancel:
case BtPeerMsgs::FextReject:
return len == 13;
case BtPeerMsgs::Piece:
return len > 9 && len <= 16393;
case BtPeerMsgs::Port:
return len == 3;
case BtPeerMsgs::Ltep:
return len >= 2;
default:
return false;
}
}
static int clientGotBlock(tr_peerMsgsImpl* msgs, struct evbuffer* block, struct peer_request const* req);
static ReadState readBtPiece(tr_peerMsgsImpl* msgs, struct evbuffer* inbuf, size_t inlen, size_t* setme_piece_bytes_read)
{
TR_ASSERT(evbuffer_get_length(inbuf) >= inlen);
dbgmsg(msgs, "In readBtPiece");
struct peer_request* req = &msgs->incoming.blockReq;
if (req->length == 0)
{
if (inlen < 8)
{
return READ_LATER;
}
tr_peerIoReadUint32(msgs->io, inbuf, &req->index);
tr_peerIoReadUint32(msgs->io, inbuf, &req->offset);
req->length = msgs->incoming.length - 9;
dbgmsg(msgs, "got incoming block header %u:%u->%u", req->index, req->offset, req->length);
return READ_NOW;
}
if (msgs->incoming.block == nullptr)
{
msgs->incoming.block = evbuffer_new();
}
struct evbuffer* const block_buffer = msgs->incoming.block;
/* read in another chunk of data */
size_t const nLeft = req->length - evbuffer_get_length(block_buffer);
size_t const n = std::min(nLeft, inlen);
tr_peerIoReadBytesToBuf(msgs->io, inbuf, block_buffer, n);
msgs->publishClientGotPieceData(n);
*setme_piece_bytes_read += n;
dbgmsg(
msgs,
"got %zu bytes for block %u:%u->%u ... %d remain",
n,
req->index,
req->offset,
req->length,
int(req->length - evbuffer_get_length(block_buffer)));
if (evbuffer_get_length(block_buffer) < req->length)
{
return READ_LATER;
}
/* pass the block along... */
int const err = clientGotBlock(msgs, block_buffer, req);
evbuffer_drain(block_buffer, evbuffer_get_length(block_buffer));
/* cleanup */
req->length = 0;
msgs->state = AwaitingBt::Length;
return err != 0 ? READ_ERR : READ_NOW;
}
static ReadState readBtMessage(tr_peerMsgsImpl* msgs, struct evbuffer* inbuf, size_t inlen)
{
uint8_t const id = msgs->incoming.id;
#ifdef TR_ENABLE_ASSERTS
size_t const startBufLen = evbuffer_get_length(inbuf);
#endif
bool const fext = tr_peerIoSupportsFEXT(msgs->io);
auto ui32 = uint32_t{};
auto msglen = uint32_t{ msgs->incoming.length };
TR_ASSERT(msglen > 0);
--msglen; /* id length */
dbgmsg(msgs, "got BT id %d, len %d, buffer size is %zu", int(id), int(msglen), inlen);
if (inlen < msglen)
{
return READ_LATER;
}
if (!messageLengthIsCorrect(msgs, id, msglen + 1))
{
dbgmsg(msgs, "bad packet - BT message #%d with a length of %d", int(id), int(msglen));
msgs->publishError(EMSGSIZE);
return READ_ERR;
}
switch (id)
{
case BtPeerMsgs::Choke:
dbgmsg(msgs, "got Choke");
msgs->client_is_choked_ = true;
if (!fext)
{
msgs->publishGotChoke();
}
msgs->update_active(TR_PEER_TO_CLIENT);
break;
case BtPeerMsgs::Unchoke:
dbgmsg(msgs, "got Unchoke");
msgs->client_is_choked_ = false;
msgs->update_active(TR_PEER_TO_CLIENT);
updateDesiredRequestCount(msgs);
break;
case BtPeerMsgs::Interested:
dbgmsg(msgs, "got Interested");
msgs->peer_is_interested_ = true;
msgs->update_active(TR_CLIENT_TO_PEER);
break;
case BtPeerMsgs::NotInterested:
dbgmsg(msgs, "got Not Interested");
msgs->peer_is_interested_ = false;
msgs->update_active(TR_CLIENT_TO_PEER);
break;
case BtPeerMsgs::Have:
tr_peerIoReadUint32(msgs->io, inbuf, &ui32);
dbgmsg(msgs, "got Have: %u", ui32);
if (msgs->torrent->hasMetadata() && ui32 >= msgs->torrent->pieceCount())
{
msgs->publishError(ERANGE);
return READ_ERR;
}
/* a peer can send the same HAVE message twice... */
if (!msgs->have.test(ui32))
{
msgs->have.set(ui32);
msgs->publishClientGotHave(ui32);
}
updatePeerProgress(msgs);
break;
case BtPeerMsgs::Bitfield:
{
auto* const tmp = tr_new(uint8_t, msglen);
dbgmsg(msgs, "got a bitfield");
tr_peerIoReadBytes(msgs->io, inbuf, tmp, msglen);
msgs->have.setRaw(tmp, msglen);
msgs->publishClientGotBitfield(&msgs->have);
updatePeerProgress(msgs);
tr_free(tmp);
break;
}
case BtPeerMsgs::Request:
{
struct peer_request r;
tr_peerIoReadUint32(msgs->io, inbuf, &r.index);
tr_peerIoReadUint32(msgs->io, inbuf, &r.offset);
tr_peerIoReadUint32(msgs->io, inbuf, &r.length);
dbgmsg(msgs, "got Request: %u:%u->%u", r.index, r.offset, r.length);
peerMadeRequest(msgs, &r);
break;
}
case BtPeerMsgs::Cancel:
{
struct peer_request r;
tr_peerIoReadUint32(msgs->io, inbuf, &r.index);
tr_peerIoReadUint32(msgs->io, inbuf, &r.offset);
tr_peerIoReadUint32(msgs->io, inbuf, &r.length);
msgs->cancelsSentToClient.add(tr_time(), 1);
dbgmsg(msgs, "got a Cancel %u:%u->%u", r.index, r.offset, r.length);
for (int i = 0; i < msgs->pendingReqsToClient; ++i)
{
struct peer_request const* req = msgs->peerAskedFor + i;
if (req->index == r.index && req->offset == r.offset && req->length == r.length)
{
tr_removeElementFromArray(msgs->peerAskedFor, i, sizeof(struct peer_request), msgs->pendingReqsToClient);
--msgs->pendingReqsToClient;
if (fext)
{
protocolSendReject(msgs, &r);
}
break;
}
}
break;
}
case BtPeerMsgs::Piece:
TR_ASSERT(false); /* handled elsewhere! */
break;
case BtPeerMsgs::Port:
dbgmsg(msgs, "Got a BtPeerMsgs::Port");
tr_peerIoReadUint16(msgs->io, inbuf, &msgs->dht_port);
if (msgs->dht_port > 0)
{
tr_dhtAddNode(msgs->session, tr_peerAddress(msgs), msgs->dht_port, false);
}
break;
case BtPeerMsgs::FextSuggest:
dbgmsg(msgs, "Got a BtPeerMsgs::FextSuggest");
tr_peerIoReadUint32(msgs->io, inbuf, &ui32);
if (fext)
{
msgs->publishClientGotSuggest(ui32);
}
else
{
msgs->publishError(EMSGSIZE);
return READ_ERR;
}
break;
case BtPeerMsgs::FextAllowedFast:
dbgmsg(msgs, "Got a BtPeerMsgs::FextAllowedFast");
tr_peerIoReadUint32(msgs->io, inbuf, &ui32);
if (fext)
{
msgs->publishClientGotAllowedFast(ui32);
}
else
{
msgs->publishError(EMSGSIZE);
return READ_ERR;
}
break;
case BtPeerMsgs::FextHaveAll:
dbgmsg(msgs, "Got a BtPeerMsgs::FextHaveAll");
if (fext)
{
msgs->have.setHasAll();
msgs->publishClientGotHaveAll();
updatePeerProgress(msgs);
}
else
{
msgs->publishError(EMSGSIZE);
return READ_ERR;
}
break;
case BtPeerMsgs::FextHaveNone:
dbgmsg(msgs, "Got a BtPeerMsgs::FextHaveNone");
if (fext)
{
msgs->have.setHasNone();
msgs->publishClientGotHaveNone();
updatePeerProgress(msgs);
}
else
{
msgs->publishError(EMSGSIZE);
return READ_ERR;
}
break;
case BtPeerMsgs::FextReject:
{
struct peer_request r;
dbgmsg(msgs, "Got a BtPeerMsgs::FextReject");
tr_peerIoReadUint32(msgs->io, inbuf, &r.index);
tr_peerIoReadUint32(msgs->io, inbuf, &r.offset);
tr_peerIoReadUint32(msgs->io, inbuf, &r.length);
if (fext)
{
msgs->publishGotRej(&r);
}
else
{
msgs->publishError(EMSGSIZE);
return READ_ERR;
}
break;
}
case BtPeerMsgs::Ltep:
dbgmsg(msgs, "Got a BtPeerMsgs::Ltep");
parseLtep(msgs, msglen, inbuf);
break;
default:
dbgmsg(msgs, "peer sent us an UNKNOWN: %d", int(id));
tr_peerIoDrain(msgs->io, inbuf, msglen);
break;
}
TR_ASSERT(msglen + 1 == msgs->incoming.length);
TR_ASSERT(evbuffer_get_length(inbuf) == startBufLen - msglen);
msgs->state = AwaitingBt::Length;
return READ_NOW;
}
/* returns 0 on success, or an errno on failure */
static int clientGotBlock(tr_peerMsgsImpl* msgs, struct evbuffer* data, struct peer_request const* req)
{
TR_ASSERT(msgs != nullptr);
TR_ASSERT(req != nullptr);
tr_torrent* const tor = msgs->torrent;
auto const block = tor->pieceLoc(req->index, req->offset).block;
if (!requestIsValid(msgs, req))
{
dbgmsg(msgs, "dropping invalid block %u:%u->%u", req->index, req->offset, req->length);
return EBADMSG;
}
if (req->length != msgs->torrent->blockSize(block))
{
dbgmsg(msgs, "wrong block size -- expected %u, got %d", msgs->torrent->blockSize(block), req->length);
return EMSGSIZE;
}
dbgmsg(msgs, "got block %u:%u->%u", req->index, req->offset, req->length);
if (!tr_peerMgrDidPeerRequest(msgs->torrent, msgs, block))
{
dbgmsg(msgs, "we didn't ask for this message...");
return 0;
}
if (msgs->torrent->hasPiece(req->index))
{
dbgmsg(msgs, "we did ask for this message, but the piece is already complete...");
return 0;
}
/**
*** Save the block
**/
if (int const
err = tr_cacheWriteBlock(msgs->session->cache, tor, tor->pieceLoc(req->index, req->offset), req->length, data);
err != 0)
{
return err;
}
msgs->blame.set(req->index);
msgs->publishGotBlock(req);
return 0;
}
static void didWrite(tr_peerIo* io, size_t bytesWritten, bool wasPieceData, void* vmsgs)
{
auto* msgs = static_cast<tr_peerMsgsImpl*>(vmsgs);
if (wasPieceData)
{
msgs->publishPeerGotPieceData(bytesWritten);
}
if (tr_isPeerIo(io) && io->userData != nullptr)
{
peerPulse(msgs);
}
}
static ReadState canRead(tr_peerIo* io, void* vmsgs, size_t* piece)
{
auto* msgs = static_cast<tr_peerMsgsImpl*>(vmsgs);
struct evbuffer* in = tr_peerIoGetReadBuffer(io);
size_t const inlen = evbuffer_get_length(in);
dbgmsg(msgs, "canRead: inlen is %zu, msgs->state is %d", inlen, int(msgs->state));
auto ret = ReadState{};
if (inlen == 0)
{
ret = READ_LATER;
}
else if (msgs->state == AwaitingBt::Piece)
{
ret = readBtPiece(msgs, in, inlen, piece);
}
else
{
switch (msgs->state)
{
case AwaitingBt::Length:
ret = readBtLength(msgs, in, inlen);
break;
case AwaitingBt::Id:
ret = readBtId(msgs, in, inlen);
break;
case AwaitingBt::Message:
ret = readBtMessage(msgs, in, inlen);
break;
default:
#ifdef TR_ENABLE_ASSERTS
TR_ASSERT_MSG(false, "unhandled peer messages state %d", int(msgs->state));
#else
ret = READ_ERR;
break;
#endif
}
}
dbgmsg(msgs, "canRead: ret is %d", int(ret));
return ret;
}
/**
***
**/
static void updateDesiredRequestCount(tr_peerMsgsImpl* msgs)
{
tr_torrent const* const torrent = msgs->torrent;
/* there are lots of reasons we might not want to request any blocks... */
if (torrent->isDone() || !torrent->hasMetadata() || msgs->client_is_choked_ || !msgs->client_is_interested_)
{
msgs->desired_request_count = 0;
}
else
{
/* Get the rate limit we should use.
* TODO: this needs to consider all the other peers as well... */
uint64_t const now = tr_time_msec();
auto rate_Bps = tr_peerGetPieceSpeed_Bps(msgs, now, TR_PEER_TO_CLIENT);
if (tr_torrentUsesSpeedLimit(torrent, TR_PEER_TO_CLIENT))
{
rate_Bps = std::min(rate_Bps, torrent->speedLimitBps(TR_PEER_TO_CLIENT));
}
/* honor the session limits, if enabled */
auto irate_Bps = unsigned{};
if (tr_torrentUsesSessionLimits(torrent) &&
tr_sessionGetActiveSpeedLimit_Bps(torrent->session, TR_PEER_TO_CLIENT, &irate_Bps))
{
rate_Bps = std::min(rate_Bps, irate_Bps);
}
/* use this desired rate to figure out how
* many requests we should send to this peer */
size_t constexpr Floor = 32;
size_t constexpr Seconds = RequestBufSecs;
size_t const estimated_blocks_in_period = (rate_Bps * Seconds) / torrent->blockSize();
size_t const ceil = msgs->reqq ? *msgs->reqq : 250;
msgs->desired_request_count = std::clamp(estimated_blocks_in_period, Floor, ceil);
}
}
static void updateMetadataRequests(tr_peerMsgsImpl* msgs, time_t now)
{
auto piece = int{};
if (msgs->peerSupportsMetadataXfer && tr_torrentGetNextMetadataRequest(msgs->torrent, now, &piece))
{
evbuffer* const out = msgs->outMessages;
/* build the data message */
auto tmp = tr_variant{};
tr_variantInitDict(&tmp, 3);
tr_variantDictAddInt(&tmp, TR_KEY_msg_type, MetadataMsgType::Request);
tr_variantDictAddInt(&tmp, TR_KEY_piece, piece);
auto* const payload = tr_variantToBuf(&tmp, TR_VARIANT_FMT_BENC);
dbgmsg(msgs, "requesting metadata piece #%d", piece);
/* write it out as a LTEP message to our outMessages buffer */
evbuffer_add_uint32(out, 2 * sizeof(uint8_t) + evbuffer_get_length(payload));
evbuffer_add_uint8(out, BtPeerMsgs::Ltep);
evbuffer_add_uint8(out, msgs->ut_metadata_id);
evbuffer_add_buffer(out, payload);
pokeBatchPeriod(msgs, HighPriorityIntervalSecs);
dbgOutMessageLen(msgs);
/* cleanup */
evbuffer_free(payload);
tr_variantFree(&tmp);
}
}
static void updateBlockRequests(tr_peerMsgsImpl* msgs)
{
if (!msgs->torrent->clientCanDownload())
{
return;
}
auto const n_active = tr_peerMgrCountActiveRequestsToPeer(msgs->torrent, msgs);
if (n_active >= msgs->desired_request_count)
{
return;
}
auto const n_wanted = msgs->desired_request_count - n_active;
if (n_wanted == 0)
{
return;
}
TR_ASSERT(msgs->is_client_interested());
TR_ASSERT(!msgs->is_client_choked());
for (auto const span : tr_peerMgrGetNextRequests(msgs->torrent, msgs, n_wanted))
{
for (tr_block_index_t block = span.begin; block < span.end; ++block)
{
protocolSendRequest(msgs, blockToReq(msgs->torrent, block));
}
tr_peerMgrClientSentRequests(msgs->torrent, msgs, span);
}
}
static size_t fillOutputBuffer(tr_peerMsgsImpl* msgs, time_t now)
{
size_t bytesWritten = 0;
struct peer_request req;
bool const haveMessages = evbuffer_get_length(msgs->outMessages) != 0;
bool const fext = tr_peerIoSupportsFEXT(msgs->io);
/**
*** Protocol messages
**/
if (haveMessages && msgs->outMessagesBatchedAt == 0) /* fresh batch */
{
dbgmsg(msgs, "started an outMessages batch (length is %zu)", evbuffer_get_length(msgs->outMessages));
msgs->outMessagesBatchedAt = now;
}
else if (haveMessages && now - msgs->outMessagesBatchedAt >= msgs->outMessagesBatchPeriod)
{
size_t const len = evbuffer_get_length(msgs->outMessages);
/* flush the protocol messages */
dbgmsg(msgs, "flushing outMessages... to %p (length is %zu)", (void*)msgs->io, len);
tr_peerIoWriteBuf(msgs->io, msgs->outMessages, false);
msgs->clientSentAnythingAt = now;
msgs->outMessagesBatchedAt = 0;
msgs->outMessagesBatchPeriod = LowPriorityIntervalSecs;
bytesWritten += len;
}
/**
*** Metadata Pieces
**/
auto piece = int{};
if (tr_peerIoGetWriteBufferSpace(msgs->io, now) >= METADATA_PIECE_SIZE && popNextMetadataRequest(msgs, &piece))
{
auto ok = bool{ false };
auto dataLen = size_t{};
if (auto* data = static_cast<char*>(tr_torrentGetMetadataPiece(msgs->torrent, piece, &dataLen)); data != nullptr)
{
auto* const out = msgs->outMessages;
/* build the data message */
auto tmp = tr_variant{};
tr_variantInitDict(&tmp, 3);
tr_variantDictAddInt(&tmp, TR_KEY_msg_type, MetadataMsgType::Data);
tr_variantDictAddInt(&tmp, TR_KEY_piece, piece);
tr_variantDictAddInt(&tmp, TR_KEY_total_size, msgs->torrent->infoDictSize());
evbuffer* const payload = tr_variantToBuf(&tmp, TR_VARIANT_FMT_BENC);
/* write it out as a LTEP message to our outMessages buffer */
evbuffer_add_uint32(out, 2 * sizeof(uint8_t) + evbuffer_get_length(payload) + dataLen);
evbuffer_add_uint8(out, BtPeerMsgs::Ltep);
evbuffer_add_uint8(out, msgs->ut_metadata_id);
evbuffer_add_buffer(out, payload);
evbuffer_add(out, data, dataLen);
pokeBatchPeriod(msgs, HighPriorityIntervalSecs);
dbgOutMessageLen(msgs);
evbuffer_free(payload);
tr_variantFree(&tmp);
tr_free(data);
ok = true;
}
if (!ok) /* send a rejection message */
{
evbuffer* const out = msgs->outMessages;
/* build the rejection message */
auto tmp = tr_variant{};
tr_variantInitDict(&tmp, 2);
tr_variantDictAddInt(&tmp, TR_KEY_msg_type, MetadataMsgType::Reject);
tr_variantDictAddInt(&tmp, TR_KEY_piece, piece);
evbuffer* const payload = tr_variantToBuf(&tmp, TR_VARIANT_FMT_BENC);
/* write it out as a LTEP message to our outMessages buffer */
evbuffer_add_uint32(out, 2 * sizeof(uint8_t) + evbuffer_get_length(payload));
evbuffer_add_uint8(out, BtPeerMsgs::Ltep);
evbuffer_add_uint8(out, msgs->ut_metadata_id);
evbuffer_add_buffer(out, payload);
pokeBatchPeriod(msgs, HighPriorityIntervalSecs);
dbgOutMessageLen(msgs);
evbuffer_free(payload);
tr_variantFree(&tmp);
}
}
/**
*** Data Blocks
**/
if (tr_peerIoGetWriteBufferSpace(msgs->io, now) >= msgs->torrent->blockSize() && popNextRequest(msgs, &req))
{
--msgs->prefetchCount;
if (requestIsValid(msgs, &req) && msgs->torrent->hasPiece(req.index))
{
uint32_t const msglen = 4 + 1 + 4 + 4 + req.length;
struct evbuffer_iovec iovec[1];
auto* const out = evbuffer_new();
evbuffer_expand(out, msglen);
evbuffer_add_uint32(out, sizeof(uint8_t) + 2 * sizeof(uint32_t) + req.length);
evbuffer_add_uint8(out, BtPeerMsgs::Piece);
evbuffer_add_uint32(out, req.index);
evbuffer_add_uint32(out, req.offset);
evbuffer_reserve_space(out, req.length, iovec, 1);
bool err = tr_cacheReadBlock(
msgs->session->cache,
msgs->torrent,
msgs->torrent->pieceLoc(req.index, req.offset),
req.length,
static_cast<uint8_t*>(iovec[0].iov_base)) != 0;
iovec[0].iov_len = req.length;
evbuffer_commit_space(out, iovec, 1);
/* check the piece if it needs checking... */
if (!err)
{
err = !msgs->torrent->ensurePieceIsChecked(req.index);
if (err)
{
auto const errmsg = tr_strvJoin(
"Please Verify Local Data! Piece #",
std::to_string(req.index),
" is corrupt.");
msgs->torrent->setLocalError(errmsg);
}
}
if (err)
{
if (fext)
{
protocolSendReject(msgs, &req);
}
}
else
{
size_t const n = evbuffer_get_length(out);
dbgmsg(msgs, "sending block %u:%u->%u", req.index, req.offset, req.length);
TR_ASSERT(n == msglen);
tr_peerIoWriteBuf(msgs->io, out, true);
bytesWritten += n;
msgs->clientSentAnythingAt = now;
msgs->blocksSentToPeer.add(tr_time(), 1);
}
evbuffer_free(out);
if (err)
{
bytesWritten = 0;
msgs = nullptr;
}
}
else if (fext) /* peer needs a reject message */
{
protocolSendReject(msgs, &req);
}
if (msgs != nullptr)
{
prefetchPieces(msgs);
}
}
/**
*** Keepalive
**/
if (msgs != nullptr && msgs->clientSentAnythingAt != 0 && now - msgs->clientSentAnythingAt > KeepaliveIntervalSecs)
{
dbgmsg(msgs, "sending a keepalive message");
evbuffer_add_uint32(msgs->outMessages, 0);
pokeBatchPeriod(msgs, ImmediatePriorityIntervalSecs);
}
return bytesWritten;
}
static void peerPulse(void* vmsgs)
{
auto* msgs = static_cast<tr_peerMsgsImpl*>(vmsgs);
time_t const now = tr_time();
if (tr_isPeerIo(msgs->io))
{
updateDesiredRequestCount(msgs);
updateBlockRequests(msgs);
updateMetadataRequests(msgs, now);
}
for (;;)
{
if (fillOutputBuffer(msgs, now) < 1)
{
break;
}
}
}
static void gotError(tr_peerIo* /*io*/, short what, void* vmsgs)
{
auto* msgs = static_cast<tr_peerMsgsImpl*>(vmsgs);
if ((what & BEV_EVENT_TIMEOUT) != 0)
{
dbgmsg(msgs, "libevent got a timeout, what=%hd", what);
}
if ((what & (BEV_EVENT_EOF | BEV_EVENT_ERROR)) != 0)
{
dbgmsg(msgs, "libevent got an error! what=%hd, errno=%d (%s)", what, errno, tr_strerror(errno));
}
msgs->publishError(ENOTCONN);
}
static void sendBitfield(tr_peerMsgsImpl* msgs)
{
TR_ASSERT(msgs->torrent->hasMetadata());
struct evbuffer* out = msgs->outMessages;
auto bytes = msgs->torrent->createPieceBitfield();
evbuffer_add_uint32(out, sizeof(uint8_t) + bytes.size());
evbuffer_add_uint8(out, BtPeerMsgs::Bitfield);
evbuffer_add(out, bytes.data(), std::size(bytes));
dbgmsg(msgs, "sending bitfield... outMessage size is now %zu", evbuffer_get_length(out));
pokeBatchPeriod(msgs, ImmediatePriorityIntervalSecs);
}
static void tellPeerWhatWeHave(tr_peerMsgsImpl* msgs)
{
bool const fext = tr_peerIoSupportsFEXT(msgs->io);
if (fext && msgs->torrent->hasAll())
{
protocolSendHaveAll(msgs);
}
else if (fext && msgs->torrent->hasNone())
{
protocolSendHaveNone(msgs);
}
else if (!msgs->torrent->hasNone())
{
sendBitfield(msgs);
}
}
/**
***
**/
/* some peers give us error messages if we send
more than this many peers in a single pex message
http://wiki.theory.org/BitTorrentPeerExchangeConventions */
static auto constexpr MaxPexAdded = int{ 50 };
static auto constexpr MaxPexDropped = int{ 50 };
struct PexDiffs
{
tr_pex* added;
tr_pex* dropped;
tr_pex* elements;
int addedCount;
int droppedCount;
int elementCount;
};
static void pexAddedCb(void const* vpex, void* userData)
{
auto* diffs = static_cast<PexDiffs*>(userData);
auto const* pex = static_cast<tr_pex const*>(vpex);
if (diffs->addedCount < MaxPexAdded)
{
diffs->added[diffs->addedCount++] = *pex;
diffs->elements[diffs->elementCount++] = *pex;
}
}
static constexpr void pexDroppedCb(void const* vpex, void* userData)
{
auto* diffs = static_cast<PexDiffs*>(userData);
auto const* pex = static_cast<tr_pex const*>(vpex);
if (diffs->droppedCount < MaxPexDropped)
{
diffs->dropped[diffs->droppedCount++] = *pex;
}
}
static constexpr void pexElementCb(void const* vpex, void* userData)
{
auto* diffs = static_cast<PexDiffs*>(userData);
auto const* pex = static_cast<tr_pex const*>(vpex);
diffs->elements[diffs->elementCount++] = *pex;
}
using tr_set_func = void (*)(void const* element, void* userData);
/**
* @brief find the differences and commonalities in two sorted sets
* @param a the first set
* @param aCount the number of elements in the set 'a'
* @param b the second set
* @param bCount the number of elements in the set 'b'
* @param compare the sorting method for both sets
* @param elementSize the sizeof the element in the two sorted sets
* @param in_a called for items in set 'a' but not set 'b'
* @param in_b called for items in set 'b' but not set 'a'
* @param in_both called for items that are in both sets
* @param userData user data passed along to in_a, in_b, and in_both
*/
static void tr_set_compare(
void const* va,
size_t aCount,
void const* vb,
size_t bCount,
tr_voidptr_compare_func compare,
size_t elementSize,
tr_set_func in_a_cb,
tr_set_func in_b_cb,
tr_set_func in_both_cb,
void* userData)
{
auto const* a = static_cast<uint8_t const*>(va);
auto const* b = static_cast<uint8_t const*>(vb);
uint8_t const* aend = a + elementSize * aCount;
uint8_t const* bend = b + elementSize * bCount;
while (a != aend || b != bend)
{
if (a == aend)
{
(*in_b_cb)(b, userData);
b += elementSize;
}
else if (b == bend)
{
(*in_a_cb)(a, userData);
a += elementSize;
}
else
{
int const val = (*compare)(a, b);
if (val == 0)
{
(*in_both_cb)(a, userData);
a += elementSize;
b += elementSize;
}
else if (val < 0)
{
(*in_a_cb)(a, userData);
a += elementSize;
}
else if (val > 0)
{
(*in_b_cb)(b, userData);
b += elementSize;
}
}
}
}
static void sendPex(tr_peerMsgsImpl* msgs)
{
if (msgs->peerSupportsPex && msgs->torrent->allowsPex())
{
PexDiffs diffs;
PexDiffs diffs6;
tr_pex* newPex = nullptr;
tr_pex* newPex6 = nullptr;
int const newCount = tr_peerMgrGetPeers(msgs->torrent, &newPex, TR_AF_INET, TR_PEERS_CONNECTED, MaxPexPeerCount);
int const newCount6 = tr_peerMgrGetPeers(msgs->torrent, &newPex6, TR_AF_INET6, TR_PEERS_CONNECTED, MaxPexPeerCount);
/* build the diffs */
diffs.added = tr_new(tr_pex, newCount);
diffs.addedCount = 0;
diffs.dropped = tr_new(tr_pex, msgs->pexCount);
diffs.droppedCount = 0;
diffs.elements = tr_new(tr_pex, newCount + msgs->pexCount);
diffs.elementCount = 0;
tr_set_compare(
msgs->pex,
msgs->pexCount,
newPex,
newCount,
tr_pexCompare,
sizeof(tr_pex),
pexDroppedCb,
pexAddedCb,
pexElementCb,
&diffs);
diffs6.added = tr_new(tr_pex, newCount6);
diffs6.addedCount = 0;
diffs6.dropped = tr_new(tr_pex, msgs->pexCount6);
diffs6.droppedCount = 0;
diffs6.elements = tr_new(tr_pex, newCount6 + msgs->pexCount6);
diffs6.elementCount = 0;
tr_set_compare(
msgs->pex6,
msgs->pexCount6,
newPex6,
newCount6,
tr_pexCompare,
sizeof(tr_pex),
pexDroppedCb,
pexAddedCb,
pexElementCb,
&diffs6);
dbgmsg(
msgs,
"pex: old peer count %d+%d, new peer count %d+%d, added %d+%d, removed %d+%d",
msgs->pexCount,
msgs->pexCount6,
newCount,
newCount6,
diffs.addedCount,
diffs6.addedCount,
diffs.droppedCount,
diffs6.droppedCount);
if (diffs.addedCount == 0 && diffs.droppedCount == 0 && diffs6.addedCount == 0 && diffs6.droppedCount == 0)
{
tr_free(diffs.elements);
tr_free(diffs6.elements);
}
else
{
uint8_t* tmp = nullptr;
uint8_t* walk = nullptr;
evbuffer* const out = msgs->outMessages;
/* update peer */
tr_free(msgs->pex);
msgs->pex = diffs.elements;
msgs->pexCount = diffs.elementCount;
tr_free(msgs->pex6);
msgs->pex6 = diffs6.elements;
msgs->pexCount6 = diffs6.elementCount;
/* build the pex payload */
auto val = tr_variant{};
tr_variantInitDict(&val, 3); /* ipv6 support: left as 3: speed vs. likelihood? */
if (diffs.addedCount > 0)
{
/* "added" */
tmp = walk = tr_new(uint8_t, diffs.addedCount * 6);
for (int i = 0; i < diffs.addedCount; ++i)
{
memcpy(walk, &diffs.added[i].addr.addr, 4);
walk += 4;
memcpy(walk, &diffs.added[i].port, 2);
walk += 2;
}
TR_ASSERT(walk - tmp == diffs.addedCount * 6);
tr_variantDictAddRaw(&val, TR_KEY_added, tmp, walk - tmp);
tr_free(tmp);
/* "added.f"
* unset each holepunch flag because we don't support it. */
tmp = walk = tr_new(uint8_t, diffs.addedCount);
for (int i = 0; i < diffs.addedCount; ++i)
{
*walk++ = diffs.added[i].flags & ~ADDED_F_HOLEPUNCH;
}
TR_ASSERT(walk - tmp == diffs.addedCount);
tr_variantDictAddRaw(&val, TR_KEY_added_f, tmp, walk - tmp);
tr_free(tmp);
}
if (diffs.droppedCount > 0)
{
/* "dropped" */
tmp = walk = tr_new(uint8_t, diffs.droppedCount * 6);
for (int i = 0; i < diffs.droppedCount; ++i)
{
memcpy(walk, &diffs.dropped[i].addr.addr, 4);
walk += 4;
memcpy(walk, &diffs.dropped[i].port, 2);
walk += 2;
}
TR_ASSERT(walk - tmp == diffs.droppedCount * 6);
tr_variantDictAddRaw(&val, TR_KEY_dropped, tmp, walk - tmp);
tr_free(tmp);
}
if (diffs6.addedCount > 0)
{
/* "added6" */
tmp = walk = tr_new(uint8_t, diffs6.addedCount * 18);
for (int i = 0; i < diffs6.addedCount; ++i)
{
memcpy(walk, &diffs6.added[i].addr.addr.addr6.s6_addr, 16);
walk += 16;
memcpy(walk, &diffs6.added[i].port, 2);
walk += 2;
}
TR_ASSERT(walk - tmp == diffs6.addedCount * 18);
tr_variantDictAddRaw(&val, TR_KEY_added6, tmp, walk - tmp);
tr_free(tmp);
/* "added6.f"
* unset each holepunch flag because we don't support it. */
tmp = walk = tr_new(uint8_t, diffs6.addedCount);
for (int i = 0; i < diffs6.addedCount; ++i)
{
*walk++ = diffs6.added[i].flags & ~ADDED_F_HOLEPUNCH;
}
TR_ASSERT(walk - tmp == diffs6.addedCount);
tr_variantDictAddRaw(&val, TR_KEY_added6_f, tmp, walk - tmp);
tr_free(tmp);
}
if (diffs6.droppedCount > 0)
{
/* "dropped6" */
tmp = walk = tr_new(uint8_t, diffs6.droppedCount * 18);
for (int i = 0; i < diffs6.droppedCount; ++i)
{
memcpy(walk, &diffs6.dropped[i].addr.addr.addr6.s6_addr, 16);
walk += 16;
memcpy(walk, &diffs6.dropped[i].port, 2);
walk += 2;
}
TR_ASSERT(walk - tmp == diffs6.droppedCount * 18);
tr_variantDictAddRaw(&val, TR_KEY_dropped6, tmp, walk - tmp);
tr_free(tmp);
}
/* write the pex message */
auto* const payload = tr_variantToBuf(&val, TR_VARIANT_FMT_BENC);
evbuffer_add_uint32(out, 2 * sizeof(uint8_t) + evbuffer_get_length(payload));
evbuffer_add_uint8(out, BtPeerMsgs::Ltep);
evbuffer_add_uint8(out, msgs->ut_pex_id);
evbuffer_add_buffer(out, payload);
pokeBatchPeriod(msgs, HighPriorityIntervalSecs);
dbgmsg(msgs, "sending a pex message; outMessage size is now %zu", evbuffer_get_length(out));
dbgOutMessageLen(msgs);
evbuffer_free(payload);
tr_variantFree(&val);
}
/* cleanup */
tr_free(diffs.added);
tr_free(diffs.dropped);
tr_free(newPex);
tr_free(diffs6.added);
tr_free(diffs6.dropped);
tr_free(newPex6);
}
}
static void pexPulse(evutil_socket_t /*fd*/, short /*what*/, void* vmsgs)
{
auto* msgs = static_cast<tr_peerMsgsImpl*>(vmsgs);
sendPex(msgs);
TR_ASSERT(msgs->pex_timer);
tr_timerAdd(msgs->pex_timer.get(), PexIntervalSecs, 0);
}
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