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transmission/libtransmission/peer-io.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 <cstdint>
#include <cstring>
#include <string>
#include <event2/event.h>
#include <event2/buffer.h>
#include <event2/bufferevent.h>
#include <libutp/utp.h>
#include <fmt/format.h>
#include "transmission.h"
#include "session.h"
#include "bandwidth.h"
#include "log.h"
#include "net.h"
#include "peer-io.h"
#include "tr-assert.h"
#include "tr-utp.h"
#include "trevent.h" /* tr_runInEventThread() */
#include "utils.h"
#ifdef _WIN32
#undef EAGAIN
#define EAGAIN WSAEWOULDBLOCK
#undef EINTR
#define EINTR WSAEINTR
#undef EINPROGRESS
#define EINPROGRESS WSAEINPROGRESS
#undef EPIPE
#define EPIPE WSAECONNRESET
#endif
/* The amount of read bufferring that we allow for uTP sockets. */
static auto constexpr UtpReadBufferSize = 256 * 1024;
#define tr_logAddErrorIo(io, msg) tr_logAddError(msg, (io)->addrStr())
#define tr_logAddWarnIo(io, msg) tr_logAddWarn(msg, (io)->addrStr())
#define tr_logAddDebugIo(io, msg) tr_logAddDebug(msg, (io)->addrStr())
#define tr_logAddTraceIo(io, msg) tr_logAddTrace(msg, (io)->addrStr())
static size_t guessPacketOverhead(size_t d)
{
/**
* http://sd.wareonearth.com/~phil/net/overhead/
*
* TCP over Ethernet:
* Assuming no header compression (e.g. not PPP)
* Add 20 IPv4 header or 40 IPv6 header (no options)
* Add 20 TCP header
* Add 12 bytes optional TCP timestamps
* Max TCP Payload data rates over ethernet are thus:
* (1500-40)/ (38+1500) = 94.9285 % IPv4, minimal headers
* (1500-52)/ (38+1500) = 94.1482 % IPv4, TCP timestamps
* (1500-52)/ (42+1500) = 93.9040 % 802.1q, IPv4, TCP timestamps
* (1500-60)/ (38+1500) = 93.6281 % IPv6, minimal headers
* (1500-72)/ (38+1500) = 92.8479 % IPv6, TCP timestamps
* (1500-72)/ (42+1500) = 92.6070 % 802.1q, IPv6, ICP timestamps
*/
double const assumed_payload_data_rate = 94.0;
return (unsigned int)(d * (100.0 / assumed_payload_data_rate) - d);
}
/***
****
***/
static void didWriteWrapper(tr_peerIo* io, unsigned int bytes_transferred)
{
while (bytes_transferred != 0 && tr_isPeerIo(io) && !std::empty(io->outbuf_info))
{
auto& [n_bytes_left, is_piece_data] = io->outbuf_info.front();
unsigned int const payload = std::min(uint64_t{ n_bytes_left }, uint64_t{ bytes_transferred });
/* For uTP sockets, the overhead is computed in utp_on_overhead. */
unsigned int const overhead = io->socket.type == TR_PEER_SOCKET_TYPE_TCP ? guessPacketOverhead(payload) : 0;
uint64_t const now = tr_time_msec();
io->bandwidth().notifyBandwidthConsumed(TR_UP, payload, is_piece_data, now);
if (overhead > 0)
{
io->bandwidth().notifyBandwidthConsumed(TR_UP, overhead, false, now);
}
if (io->didWrite != nullptr)
{
io->didWrite(io, payload, is_piece_data, io->userData);
}
if (!tr_isPeerIo(io))
{
break;
}
bytes_transferred -= payload;
n_bytes_left -= payload;
if (n_bytes_left == 0)
{
io->outbuf_info.pop_front();
}
}
}
static void canReadWrapper(tr_peerIo* io)
{
tr_logAddTraceIo(io, "canRead");
tr_peerIoRef(io);
tr_session const* const session = io->session;
/* try to consume the input buffer */
if (io->canRead != nullptr)
{
auto const lock = session->unique_lock();
auto const now = tr_time_msec();
auto done = bool{ false };
auto err = bool{ false };
while (!done && !err)
{
size_t piece = 0;
size_t const oldLen = evbuffer_get_length(io->inbuf.get());
int const ret = io->canRead(io, io->userData, &piece);
size_t const used = oldLen - evbuffer_get_length(io->inbuf.get());
unsigned int const overhead = guessPacketOverhead(used);
if (piece != 0 || piece != used)
{
if (piece != 0)
{
io->bandwidth().notifyBandwidthConsumed(TR_DOWN, piece, true, now);
}
if (used != piece)
{
io->bandwidth().notifyBandwidthConsumed(TR_DOWN, used - piece, false, now);
}
}
if (overhead > 0)
{
io->bandwidth().notifyBandwidthConsumed(TR_UP, overhead, false, now);
}
switch (ret)
{
case READ_NOW:
if (evbuffer_get_length(io->inbuf.get()) != 0)
{
continue;
}
done = true;
break;
case READ_LATER:
done = true;
break;
case READ_ERR:
err = true;
break;
}
TR_ASSERT(tr_isPeerIo(io));
}
}
tr_peerIoUnref(io);
}
static void event_read_cb(evutil_socket_t fd, short /*event*/, void* vio)
{
auto* io = static_cast<tr_peerIo*>(vio);
TR_ASSERT(tr_isPeerIo(io));
TR_ASSERT(io->socket.type == TR_PEER_SOCKET_TYPE_TCP);
/* Limit the input buffer to 256K, so it doesn't grow too large */
tr_direction const dir = TR_DOWN;
unsigned int const max = 256 * 1024;
io->pendingEvents &= ~EV_READ;
unsigned int const curlen = evbuffer_get_length(io->inbuf.get());
unsigned int howmuch = curlen >= max ? 0 : max - curlen;
howmuch = io->bandwidth().clamp(TR_DOWN, howmuch);
tr_logAddTraceIo(io, "libevent says this peer is ready to read");
/* if we don't have any bandwidth left, stop reading */
if (howmuch < 1)
{
tr_peerIoSetEnabled(io, dir, false);
return;
}
EVUTIL_SET_SOCKET_ERROR(0);
auto const res = evbuffer_read(io->inbuf.get(), fd, (int)howmuch);
int const e = EVUTIL_SOCKET_ERROR();
if (res > 0)
{
tr_peerIoSetEnabled(io, dir, true);
/* Invoke the user callback - must always be called last */
canReadWrapper(io);
}
else
{
short what = BEV_EVENT_READING;
if (res == 0) /* EOF */
{
what |= BEV_EVENT_EOF;
}
else if (res == -1)
{
if (e == EAGAIN || e == EINTR)
{
tr_peerIoSetEnabled(io, dir, true);
return;
}
what |= BEV_EVENT_ERROR;
}
tr_logAddDebugIo(
io,
fmt::format("event_read_cb err: res:{}, what:{}, errno:{} ({})", res, what, e, tr_net_strerror(e)));
if (io->gotError != nullptr)
{
io->gotError(io, what, io->userData);
}
}
}
static int tr_evbuffer_write(tr_peerIo* io, int fd, size_t howmuch)
{
EVUTIL_SET_SOCKET_ERROR(0);
int const n = evbuffer_write_atmost(io->outbuf.get(), fd, howmuch);
int const e = EVUTIL_SOCKET_ERROR();
tr_logAddTraceIo(io, fmt::format("wrote {} to peer ({})", n, (n == -1 ? tr_net_strerror(e).c_str() : "")));
return n;
}
static void event_write_cb(evutil_socket_t fd, short /*event*/, void* vio)
{
auto* io = static_cast<tr_peerIo*>(vio);
TR_ASSERT(tr_isPeerIo(io));
TR_ASSERT(io->socket.type == TR_PEER_SOCKET_TYPE_TCP);
auto const dir = TR_UP;
auto res = int{ 0 };
auto what = short{ BEV_EVENT_WRITING };
io->pendingEvents &= ~EV_WRITE;
tr_logAddTraceIo(io, "libevent says this peer is ready to write");
/* Write as much as possible, since the socket is non-blocking, write() will
* return if it can't write any more data without blocking */
size_t const howmuch = io->bandwidth().clamp(dir, evbuffer_get_length(io->outbuf.get()));
/* if we don't have any bandwidth left, stop writing */
if (howmuch < 1)
{
tr_peerIoSetEnabled(io, dir, false);
return;
}
EVUTIL_SET_SOCKET_ERROR(0);
res = tr_evbuffer_write(io, fd, howmuch);
int const e = EVUTIL_SOCKET_ERROR();
if (res == -1)
{
if (e == 0 || e == EAGAIN || e == EINTR || e == EINPROGRESS)
{
goto RESCHEDULE;
}
/* error case */
what |= BEV_EVENT_ERROR;
}
else if (res == 0)
{
/* eof case */
what |= BEV_EVENT_EOF;
}
if (res <= 0)
{
goto FAIL;
}
if (evbuffer_get_length(io->outbuf.get()) != 0)
{
tr_peerIoSetEnabled(io, dir, true);
}
didWriteWrapper(io, res);
return;
RESCHEDULE:
if (evbuffer_get_length(io->outbuf.get()) != 0)
{
tr_peerIoSetEnabled(io, dir, true);
}
return;
FAIL:
auto const errmsg = tr_net_strerror(e);
tr_logAddDebugIo(io, fmt::format("event_write_cb got an err. res:{}, what:{}, errno:{} ({})", res, what, e, errmsg));
if (io->gotError != nullptr)
{
io->gotError(io, what, io->userData);
}
}
/**
***
**/
static void maybeSetCongestionAlgorithm(tr_socket_t socket, std::string const& algorithm)
{
if (!std::empty(algorithm))
{
tr_netSetCongestionControl(socket, algorithm.c_str());
}
}
#ifdef WITH_UTP
/* UTP callbacks */
void tr_peerIo::readBufferAdd(void const* data, size_t n_bytes)
{
if (auto const rc = evbuffer_add(inbuf.get(), data, n_bytes); rc < 0)
{
tr_logAddWarn(_("Couldn't write to peer"));
return;
}
tr_peerIoSetEnabled(this, TR_DOWN, true);
canReadWrapper(this);
}
static size_t utp_get_rb_size(tr_peerIo* const io)
{
size_t const bytes = io->bandwidth().clamp(TR_DOWN, UtpReadBufferSize);
tr_logAddTraceIo(io, fmt::format("utp_get_rb_size is saying it's ready to read {} bytes", bytes));
return UtpReadBufferSize - bytes;
}
static int tr_peerIoTryWrite(tr_peerIo* io, size_t howmuch);
static void utp_on_writable(tr_peerIo* io)
{
tr_logAddTraceIo(io, "libutp says this peer is ready to write");
int const n = tr_peerIoTryWrite(io, SIZE_MAX);
tr_peerIoSetEnabled(io, TR_UP, n != 0 && evbuffer_get_length(io->outbuf.get()) != 0);
}
static void utp_on_state_change(tr_peerIo* const io, int const state)
{
if (state == UTP_STATE_CONNECT)
{
tr_logAddTraceIo(io, "utp_on_state_change -- changed to connected");
io->utp_supported_ = true;
}
else if (state == UTP_STATE_WRITABLE)
{
tr_logAddTraceIo(io, "utp_on_state_change -- changed to writable");
if ((io->pendingEvents & EV_WRITE) != 0)
{
utp_on_writable(io);
}
}
else if (state == UTP_STATE_EOF)
{
if (io->gotError != nullptr)
{
io->gotError(io, BEV_EVENT_EOF, io->userData);
}
}
else if (state == UTP_STATE_DESTROYING)
{
tr_logAddErrorIo(io, "Impossible state UTP_STATE_DESTROYING");
}
else
{
tr_logAddErrorIo(io, fmt::format(_("Unknown state: {state}"), fmt::arg("state", state)));
}
}
static void utp_on_error(tr_peerIo* const io, int const errcode)
{
tr_logAddDebugIo(io, fmt::format("utp_on_error -- errcode is {}", errcode));
if (io->gotError != nullptr)
{
errno = errcode;
io->gotError(io, BEV_EVENT_ERROR, io->userData);
}
}
static void utp_on_overhead(tr_peerIo* const io, bool const send, size_t const count, int /*type*/)
{
tr_logAddTraceIo(io, fmt::format("utp_on_overhead -- count is {}", count));
io->bandwidth().notifyBandwidthConsumed(send ? TR_UP : TR_DOWN, count, false, tr_time_msec());
}
static uint64 utp_callback(utp_callback_arguments* args)
{
auto* const io = static_cast<tr_peerIo*>(utp_get_userdata(args->socket));
if (io == nullptr)
{
#ifdef TR_UTP_TRACE
if (args->callback_type != UTP_ON_STATE_CHANGE || args->u1.state != UTP_STATE_DESTROYING)
{
fmt::print(
stderr,
FMT_STRING("[utp] [{}:{}] [{}] io is null! buf={}, len={}, flags={}, send/error_code/state={}, type={}\n"),
fmt::ptr(args->context),
fmt::ptr(args->socket),
utp_callback_names[args->callback_type],
fmt::ptr(args->buf),
args->len,
args->flags,
args->u1.send,
args->u2.type);
}
#endif
return 0;
}
TR_ASSERT(tr_isPeerIo(io));
TR_ASSERT(io->socket.handle.utp == args->socket);
switch (args->callback_type)
{
case UTP_ON_READ:
io->readBufferAdd(args->buf, args->len);
break;
case UTP_GET_READ_BUFFER_SIZE:
return utp_get_rb_size(io);
case UTP_ON_STATE_CHANGE:
utp_on_state_change(io, args->u1.state);
break;
case UTP_ON_ERROR:
utp_on_error(io, args->u1.error_code);
break;
case UTP_ON_OVERHEAD_STATISTICS:
utp_on_overhead(io, args->u1.send != 0, args->len, args->u2.type);
break;
}
return 0;
}
#endif /* #ifdef WITH_UTP */
tr_peerIo* tr_peerIoNew(
tr_session* session,
tr_bandwidth* parent,
tr_address const* addr,
tr_port port,
time_t current_time,
tr_sha1_digest_t const* torrent_hash,
bool is_incoming,
bool is_seed,
struct tr_peer_socket const socket)
{
TR_ASSERT(session != nullptr);
TR_ASSERT(session->events != nullptr);
auto lock = session->unique_lock();
#ifdef WITH_UTP
TR_ASSERT(socket.type == TR_PEER_SOCKET_TYPE_TCP || socket.type == TR_PEER_SOCKET_TYPE_UTP);
#else
TR_ASSERT(socket.type == TR_PEER_SOCKET_TYPE_TCP);
#endif
if (socket.type == TR_PEER_SOCKET_TYPE_TCP)
{
session->setSocketTOS(socket.handle.tcp, addr->type);
maybeSetCongestionAlgorithm(socket.handle.tcp, session->peerCongestionAlgorithm());
}
auto* io = new tr_peerIo{ session, torrent_hash, is_incoming, *addr, port, is_seed, current_time, parent };
io->socket = socket;
io->bandwidth().setPeer(io);
tr_logAddTraceIo(io, fmt::format("bandwidth is {}; its parent is {}", fmt::ptr(&io->bandwidth()), fmt::ptr(parent)));
switch (socket.type)
{
case TR_PEER_SOCKET_TYPE_TCP:
tr_logAddTraceIo(io, fmt::format("socket (tcp) is {}", socket.handle.tcp));
io->event_read = event_new(session->event_base, socket.handle.tcp, EV_READ, event_read_cb, io);
io->event_write = event_new(session->event_base, socket.handle.tcp, EV_WRITE, event_write_cb, io);
break;
#ifdef WITH_UTP
case TR_PEER_SOCKET_TYPE_UTP:
tr_logAddTraceIo(io, fmt::format("socket (utp) is {}", fmt::ptr(socket.handle.utp)));
utp_set_userdata(socket.handle.utp, io);
break;
#endif
default:
TR_ASSERT_MSG(false, fmt::format(FMT_STRING("unsupported peer socket type {:d}"), socket.type));
}
return io;
}
void tr_peerIoUtpInit([[maybe_unused]] struct_utp_context* ctx)
{
#ifdef WITH_UTP
utp_set_callback(ctx, UTP_ON_READ, &utp_callback);
utp_set_callback(ctx, UTP_GET_READ_BUFFER_SIZE, &utp_callback);
utp_set_callback(ctx, UTP_ON_STATE_CHANGE, &utp_callback);
utp_set_callback(ctx, UTP_ON_ERROR, &utp_callback);
utp_set_callback(ctx, UTP_ON_OVERHEAD_STATISTICS, &utp_callback);
utp_context_set_option(ctx, UTP_RCVBUF, UtpReadBufferSize);
#endif
}
tr_peerIo* tr_peerIoNewIncoming(
tr_session* session,
tr_bandwidth* parent,
tr_address const* addr,
tr_port port,
time_t current_time,
struct tr_peer_socket const socket)
{
TR_ASSERT(session != nullptr);
TR_ASSERT(tr_address_is_valid(addr));
return tr_peerIoNew(session, parent, addr, port, current_time, nullptr, true, false, socket);
}
tr_peerIo* tr_peerIoNewOutgoing(
tr_session* session,
tr_bandwidth* parent,
tr_address const* addr,
tr_port port,
time_t current_time,
tr_sha1_digest_t const& torrent_hash,
bool is_seed,
bool utp)
{
TR_ASSERT(session != nullptr);
TR_ASSERT(tr_address_is_valid(addr));
auto socket = tr_peer_socket{};
if (utp)
{
socket = tr_netOpenPeerUTPSocket(session, addr, port, is_seed);
}
if (socket.type == TR_PEER_SOCKET_TYPE_NONE)
{
socket = tr_netOpenPeerSocket(session, addr, port, is_seed);
tr_logAddDebug(fmt::format(
"tr_netOpenPeerSocket returned {}",
socket.type != TR_PEER_SOCKET_TYPE_NONE ? socket.handle.tcp : TR_BAD_SOCKET));
}
if (socket.type == TR_PEER_SOCKET_TYPE_NONE)
{
return nullptr;
}
return tr_peerIoNew(session, parent, addr, port, current_time, &torrent_hash, false, is_seed, socket);
}
/***
****
***/
static void event_enable(tr_peerIo* io, short event)
{
TR_ASSERT(tr_amInEventThread(io->session));
TR_ASSERT(io->session != nullptr);
TR_ASSERT(io->session->events != nullptr);
bool const need_events = io->socket.type == TR_PEER_SOCKET_TYPE_TCP;
if (need_events)
{
TR_ASSERT(event_initialized(io->event_read));
TR_ASSERT(event_initialized(io->event_write));
}
if ((event & EV_READ) != 0 && (io->pendingEvents & EV_READ) == 0)
{
tr_logAddTraceIo(io, "enabling ready-to-read polling");
if (need_events)
{
event_add(io->event_read, nullptr);
}
io->pendingEvents |= EV_READ;
}
if ((event & EV_WRITE) != 0 && (io->pendingEvents & EV_WRITE) == 0)
{
tr_logAddTraceIo(io, "enabling ready-to-write polling");
if (need_events)
{
event_add(io->event_write, nullptr);
}
io->pendingEvents |= EV_WRITE;
}
}
static void event_disable(tr_peerIo* io, short event)
{
TR_ASSERT(tr_amInEventThread(io->session));
TR_ASSERT(io->session != nullptr);
TR_ASSERT(io->session->events != nullptr);
bool const need_events = io->socket.type == TR_PEER_SOCKET_TYPE_TCP;
if (need_events)
{
TR_ASSERT(event_initialized(io->event_read));
TR_ASSERT(event_initialized(io->event_write));
}
if ((event & EV_READ) != 0 && (io->pendingEvents & EV_READ) != 0)
{
tr_logAddTraceIo(io, "disabling ready-to-read polling");
if (need_events)
{
event_del(io->event_read);
}
io->pendingEvents &= ~EV_READ;
}
if ((event & EV_WRITE) != 0 && (io->pendingEvents & EV_WRITE) != 0)
{
tr_logAddTraceIo(io, "disabling ready-to-write polling");
if (need_events)
{
event_del(io->event_write);
}
io->pendingEvents &= ~EV_WRITE;
}
}
void tr_peerIoSetEnabled(tr_peerIo* io, tr_direction dir, bool isEnabled)
{
TR_ASSERT(tr_isPeerIo(io));
TR_ASSERT(tr_isDirection(dir));
TR_ASSERT(tr_amInEventThread(io->session));
TR_ASSERT(io->session->events != nullptr);
short const event = dir == TR_UP ? EV_WRITE : EV_READ;
if (isEnabled)
{
event_enable(io, event);
}
else
{
event_disable(io, event);
}
}
/***
****
***/
static void io_close_socket(tr_peerIo* io)
{
switch (io->socket.type)
{
case TR_PEER_SOCKET_TYPE_NONE:
break;
case TR_PEER_SOCKET_TYPE_TCP:
tr_netClose(io->session, io->socket.handle.tcp);
break;
#ifdef WITH_UTP
case TR_PEER_SOCKET_TYPE_UTP:
utp_set_userdata(io->socket.handle.utp, nullptr);
utp_close(io->socket.handle.utp);
break;
#endif
default:
tr_logAddDebugIo(io, fmt::format("unsupported peer socket type {}", io->socket.type));
}
io->socket = {};
if (io->event_read != nullptr)
{
event_free(io->event_read);
io->event_read = nullptr;
}
if (io->event_write != nullptr)
{
event_free(io->event_write);
io->event_write = nullptr;
}
}
static void io_dtor(tr_peerIo* const io)
{
TR_ASSERT(tr_isPeerIo(io));
TR_ASSERT(tr_amInEventThread(io->session));
TR_ASSERT(io->session->events != nullptr);
tr_logAddTraceIo(io, "in tr_peerIo destructor");
event_disable(io, EV_READ | EV_WRITE);
io_close_socket(io);
io->magic_number = ~0;
delete io;
}
static void tr_peerIoFree(tr_peerIo* io)
{
if (io != nullptr)
{
tr_logAddTraceIo(io, "in tr_peerIoFree");
io->canRead = nullptr;
io->didWrite = nullptr;
io->gotError = nullptr;
tr_runInEventThread(io->session, io_dtor, io);
}
}
void tr_peerIoRefImpl(char const* file, int line, tr_peerIo* io)
{
TR_ASSERT(tr_isPeerIo(io));
tr_logAddTraceIo(
io,
fmt::format("{}:{} incrementing the IO's refcount from {} to {}", file, line, io->refCount, io->refCount + 1));
++io->refCount;
}
void tr_peerIoUnrefImpl(char const* file, int line, tr_peerIo* io)
{
TR_ASSERT(tr_isPeerIo(io));
tr_logAddTraceIo(
io,
fmt::format("{}:{} decrementing the IO's refcount from {} to {}", file, line, io->refCount, io->refCount - 1));
if (--io->refCount == 0)
{
tr_peerIoFree(io);
}
}
std::string tr_peerIo::addrStr() const
{
return tr_isPeerIo(this) ? this->addr_.readable(this->port_) : "error";
}
void tr_peerIoSetIOFuncs(tr_peerIo* io, tr_can_read_cb readcb, tr_did_write_cb writecb, tr_net_error_cb errcb, void* user_data)
{
io->canRead = readcb;
io->didWrite = writecb;
io->gotError = errcb;
io->userData = user_data;
}
void tr_peerIoClear(tr_peerIo* io)
{
tr_peerIoSetIOFuncs(io, nullptr, nullptr, nullptr, nullptr);
tr_peerIoSetEnabled(io, TR_UP, false);
tr_peerIoSetEnabled(io, TR_DOWN, false);
}
int tr_peerIoReconnect(tr_peerIo* io)
{
TR_ASSERT(tr_isPeerIo(io));
TR_ASSERT(!io->isIncoming());
tr_session* session = tr_peerIoGetSession(io);
short int const pendingEvents = io->pendingEvents;
event_disable(io, EV_READ | EV_WRITE);
io_close_socket(io);
auto const [addr, port] = io->socketAddress();
io->socket = tr_netOpenPeerSocket(session, &addr, port, io->isSeed());
if (io->socket.type != TR_PEER_SOCKET_TYPE_TCP)
{
return -1;
}
io->event_read = event_new(session->event_base, io->socket.handle.tcp, EV_READ, event_read_cb, io);
io->event_write = event_new(session->event_base, io->socket.handle.tcp, EV_WRITE, event_write_cb, io);
event_enable(io, pendingEvents);
io->session->setSocketTOS(io->socket.handle.tcp, addr.type);
maybeSetCongestionAlgorithm(io->socket.handle.tcp, session->peerCongestionAlgorithm());
return 0;
}
/**
***
**/
static unsigned int getDesiredOutputBufferSize(tr_peerIo const* io, uint64_t now)
{
/* this is all kind of arbitrary, but what seems to work well is
* being large enough to hold the next 20 seconds' worth of input,
* or a few blocks, whichever is bigger.
* It's okay to tweak this as needed */
unsigned int const currentSpeed_Bps = io->bandwidth().getPieceSpeedBytesPerSecond(now, TR_UP);
unsigned int const period = 15U; /* arbitrary */
/* the 3 is arbitrary; the .5 is to leave room for messages */
static auto const ceiling = (unsigned int)(tr_block_info::BlockSize * 3.5);
return std::max(ceiling, currentSpeed_Bps * period);
}
size_t tr_peerIoGetWriteBufferSpace(tr_peerIo const* io, uint64_t now)
{
size_t const desiredLen = getDesiredOutputBufferSize(io, now);
size_t const currentLen = evbuffer_get_length(io->outbuf.get());
size_t freeSpace = 0;
if (desiredLen > currentLen)
{
freeSpace = desiredLen - currentLen;
}
return freeSpace;
}
/**
***
**/
static inline void processBuffer(tr_peerIo& io, evbuffer* buffer, size_t offset, size_t size)
{
struct evbuffer_ptr pos;
struct evbuffer_iovec iovec;
evbuffer_ptr_set(buffer, &pos, offset, EVBUFFER_PTR_SET);
do
{
if (evbuffer_peek(buffer, size, &pos, &iovec, 1) <= 0)
{
break;
}
io.encrypt(iovec.iov_len, iovec.iov_base);
TR_ASSERT(size >= iovec.iov_len);
size -= iovec.iov_len;
} while (evbuffer_ptr_set(buffer, &pos, iovec.iov_len, EVBUFFER_PTR_ADD) == 0);
TR_ASSERT(size == 0);
}
void tr_peerIoWriteBuf(tr_peerIo* io, struct evbuffer* buf, bool isPieceData)
{
size_t const byteCount = evbuffer_get_length(buf);
if (io->isEncrypted())
{
processBuffer(*io, buf, 0, byteCount);
}
evbuffer_add_buffer(io->outbuf.get(), buf);
io->outbuf_info.emplace_back(byteCount, isPieceData);
}
void tr_peerIoWriteBytes(tr_peerIo* io, void const* writeme, size_t writeme_len, bool is_piece_data)
{
struct evbuffer_iovec iovec;
evbuffer_reserve_space(io->outbuf.get(), writeme_len, &iovec, 1);
iovec.iov_len = writeme_len;
memcpy(iovec.iov_base, writeme, iovec.iov_len);
if (io->isEncrypted())
{
io->encrypt(iovec.iov_len, iovec.iov_base);
}
evbuffer_commit_space(io->outbuf.get(), &iovec, 1);
io->outbuf_info.emplace_back(writeme_len, is_piece_data);
}
/***
****
***/
void evbuffer_add_uint8(struct evbuffer* outbuf, uint8_t addme)
{
evbuffer_add(outbuf, &addme, 1);
}
void evbuffer_add_uint16(struct evbuffer* outbuf, uint16_t addme_hs)
{
uint16_t const ns = htons(addme_hs);
evbuffer_add(outbuf, &ns, sizeof(ns));
}
void evbuffer_add_uint32(struct evbuffer* outbuf, uint32_t addme_hl)
{
uint32_t const nl = htonl(addme_hl);
evbuffer_add(outbuf, &nl, sizeof(nl));
}
void evbuffer_add_uint64(struct evbuffer* outbuf, uint64_t addme_hll)
{
uint64_t const nll = tr_htonll(addme_hll);
evbuffer_add(outbuf, &nll, sizeof(nll));
}
/***
****
***/
void tr_peerIoReadBytes(tr_peerIo* io, struct evbuffer* inbuf, void* bytes, size_t byteCount)
{
TR_ASSERT(tr_isPeerIo(io));
TR_ASSERT(evbuffer_get_length(inbuf) >= byteCount);
evbuffer_remove(inbuf, bytes, byteCount);
if (io->isEncrypted())
{
io->decrypt(byteCount, bytes);
}
}
void tr_peerIoReadUint16(tr_peerIo* io, struct evbuffer* inbuf, uint16_t* setme)
{
auto tmp = uint16_t{};
tr_peerIoReadBytes(io, inbuf, &tmp, sizeof(uint16_t));
*setme = ntohs(tmp);
}
void tr_peerIoReadUint32(tr_peerIo* io, struct evbuffer* inbuf, uint32_t* setme)
{
auto tmp = uint32_t{};
tr_peerIoReadBytes(io, inbuf, &tmp, sizeof(uint32_t));
*setme = ntohl(tmp);
}
void tr_peerIoDrain(tr_peerIo* io, struct evbuffer* inbuf, size_t byteCount)
{
char buf[4096];
size_t const buflen = sizeof(buf);
while (byteCount > 0)
{
size_t const thisPass = std::min(byteCount, buflen);
tr_peerIoReadBytes(io, inbuf, buf, thisPass);
byteCount -= thisPass;
}
}
/***
****
***/
static int tr_peerIoTryRead(tr_peerIo* io, size_t howmuch)
{
howmuch = io->bandwidth().clamp(TR_DOWN, howmuch);
if (howmuch == 0)
{
return 0;
}
auto res = int{};
switch (io->socket.type)
{
case TR_PEER_SOCKET_TYPE_UTP:
/* UTP_RBDrained notifies libutp that your read buffer is empty.
* It opens up the congestion window by sending an ACK (soonish)
* if one was not going to be sent. */
if (evbuffer_get_length(io->inbuf.get()) == 0)
{
utp_read_drained(io->socket.handle.utp);
}
break;
case TR_PEER_SOCKET_TYPE_TCP:
{
EVUTIL_SET_SOCKET_ERROR(0);
res = evbuffer_read(io->inbuf.get(), io->socket.handle.tcp, (int)howmuch);
int const e = EVUTIL_SOCKET_ERROR();
tr_logAddTraceIo(io, fmt::format("read {} from peer ({})", res, res == -1 ? tr_net_strerror(e).c_str() : ""));
if (evbuffer_get_length(io->inbuf.get()) != 0)
{
canReadWrapper(io);
}
if (res <= 0 && io->gotError != nullptr && e != EAGAIN && e != EINTR && e != EINPROGRESS)
{
short what = BEV_EVENT_READING | BEV_EVENT_ERROR;
if (res == 0)
{
what |= BEV_EVENT_EOF;
}
tr_logAddTraceIo(
io,
fmt::format("tr_peerIoTryRead err: res:{} what:{}, errno:{} ({})", res, what, e, tr_net_strerror(e)));
io->gotError(io, what, io->userData);
}
break;
}
default:
tr_logAddDebugIo(io, fmt::format("unsupported peer socket type {}", io->socket.type));
}
return res;
}
static int tr_peerIoTryWrite(tr_peerIo* io, size_t howmuch)
{
auto const old_len = size_t{ evbuffer_get_length(io->outbuf.get()) };
tr_logAddTraceIo(io, fmt::format("in tr_peerIoTryWrite {}", howmuch));
howmuch = std::min(howmuch, old_len);
howmuch = io->bandwidth().clamp(TR_UP, howmuch);
if (howmuch == 0)
{
return 0;
}
auto n = int{};
switch (io->socket.type)
{
case TR_PEER_SOCKET_TYPE_UTP:
n = utp_write(io->socket.handle.utp, evbuffer_pullup(io->outbuf.get(), howmuch), howmuch);
if (n > 0)
{
evbuffer_drain(io->outbuf.get(), n);
didWriteWrapper(io, n);
}
break;
case TR_PEER_SOCKET_TYPE_TCP:
{
EVUTIL_SET_SOCKET_ERROR(0);
n = tr_evbuffer_write(io, io->socket.handle.tcp, howmuch);
int const e = EVUTIL_SOCKET_ERROR();
if (n > 0)
{
didWriteWrapper(io, n);
}
if (n < 0 && io->gotError != nullptr && e != 0 && e != EPIPE && e != EAGAIN && e != EINTR && e != EINPROGRESS)
{
short const what = BEV_EVENT_WRITING | BEV_EVENT_ERROR;
tr_logAddTraceIo(
io,
fmt::format("tr_peerIoTryWrite err: res:{}, what:{}, errno:{} ({})", n, what, e, tr_net_strerror(e)));
io->gotError(io, what, io->userData);
}
break;
}
default:
tr_logAddDebugIo(io, fmt::format("unsupported peer socket type {}", io->socket.type));
}
return n;
}
int tr_peerIoFlush(tr_peerIo* io, tr_direction dir, size_t limit)
{
TR_ASSERT(tr_isPeerIo(io));
TR_ASSERT(tr_isDirection(dir));
int const bytes_used = dir == TR_DOWN ? tr_peerIoTryRead(io, limit) : tr_peerIoTryWrite(io, limit);
tr_logAddTraceIo(io, fmt::format("flushing peer-io, direction:{}, limit:{}, byte_used:{}", dir, limit, bytes_used));
return bytes_used;
}
int tr_peerIoFlushOutgoingProtocolMsgs(tr_peerIo* io)
{
size_t byteCount = 0;
/* count up how many bytes are used by non-piece-data messages
at the front of our outbound queue */
for (auto const& [n_bytes, is_piece_data] : io->outbuf_info)
{
if (is_piece_data)
{
break;
}
byteCount += n_bytes;
}
return tr_peerIoFlush(io, TR_UP, byteCount);
}
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