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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 <array>
#include <cerrno>
#include <cstdint>
#include <cstring>
#include <string>
#include <event2/event.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 "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 µTP sockets. */
static constexpr auto 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())
#ifdef TR_ENABLE_ASSERTS
[[nodiscard]] static constexpr auto isSupportedSocket(tr_peer_socket const& sock)
{
#ifdef WITH_UTP
return sock.type == TR_PEER_SOCKET_TYPE_TCP || sock.type == TR_PEER_SOCKET_TYPE_UTP;
#else
return sock.type == TR_PEER_SOCKET_TYPE_TCP;
#endif
}
#endif // TR_ENABLE_ASSERTS
static constexpr size_t guessPacketOverhead(size_t d)
{
/**
* https://web.archive.org/web/20140912230020/http://sd.wareonearth.com:80/~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, TCP timestamps
*/
double const assumed_payload_data_rate = 94.0;
return (size_t)(d * (100.0 / assumed_payload_data_rate) - d);
}
/***
****
***/
static void didWriteWrapper(tr_peerIo* io, size_t 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();
size_t const payload = std::min(uint64_t{ n_bytes_left }, uint64_t{ bytes_transferred });
/* For µTP sockets, the overhead is computed in utp_on_overhead. */
size_t 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_in)
{
auto const io = io_in->shared_from_this();
tr_logAddTraceIo(io, "canRead");
tr_session const* const session = io->session;
/* try to consume the input buffer */
if (io->canRead == nullptr)
{
return;
}
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;
auto const old_len = io->readBufferSize();
auto const read_state = io->canRead == nullptr ? READ_ERR : io->canRead(io.get(), io->userData, &piece);
auto const used = old_len - io->readBufferSize();
auto 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 (read_state)
{
case READ_NOW:
if (io->readBufferSize() != 0)
{
continue;
}
done = true;
break;
case READ_LATER:
done = true;
break;
case READ_ERR:
err = true;
break;
}
}
}
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;
size_t const max = 256 * 1024;
io->pendingEvents &= ~EV_READ;
auto const curlen = io->readBufferSize();
auto 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)
{
io->setEnabled(dir, false);
return;
}
tr_error* error = nullptr;
if (auto const res = io->inbuf.addSocket(fd, howmuch, &error); res > 0)
{
io->setEnabled(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;
}
if (error != nullptr)
{
if (error->code == EAGAIN || error->code == EINTR)
{
io->setEnabled(dir, true);
return;
}
what |= BEV_EVENT_ERROR;
tr_logAddDebugIo(
io,
fmt::format("event_read_cb err: res:{}, what:{}, errno:{} ({})", res, what, error->code, error->message));
}
io->call_error_callback(what);
}
tr_error_clear(&error);
}
// Helps us to ignore errors that say "try again later"
// since that's what peer-io does by default anyway.
[[nodiscard]] static auto constexpr canRetryFromError(int error_code)
{
return error_code == 0 || error_code == EAGAIN || error_code == EINTR || error_code == EINPROGRESS;
}
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);
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 */
auto constexpr Dir = TR_UP;
auto const howmuch = io->bandwidth().clamp(Dir, std::size(io->outbuf));
// if we don't have any bandwidth left, stop writing
if (howmuch < 1)
{
io->setEnabled(Dir, false);
return;
}
tr_error* error = nullptr;
auto const n_written = io->outbuf.toSocket(fd, howmuch, &error);
auto const should_retry = (error == nullptr) || canRetryFromError(error->code);
// schedule another write if we have more data to write & think future writes would succeed
if (!std::empty(io->outbuf) && (n_written > 0 || should_retry))
{
io->setEnabled(Dir, true);
}
if (n_written > 0)
{
didWriteWrapper(io, n_written);
}
else
{
auto const what = BEV_EVENT_WRITING | (error != nullptr ? BEV_EVENT_ERROR : BEV_EVENT_EOF);
tr_logAddDebugIo(
io,
fmt::format(
"event_write_cb got an err. n_written:{}, what:{}, errno:{} ({})",
n_written,
what,
(error != nullptr ? error->code : 0),
(error != nullptr ? error->message : "EOF")));
io->call_error_callback(what);
}
tr_error_clear(&error);
}
/**
***
**/
static void maybeSetCongestionAlgorithm(tr_socket_t socket, std::string const& algorithm)
{
if (!std::empty(algorithm))
{
tr_netSetCongestionControl(socket, algorithm.c_str());
}
}
#ifdef WITH_UTP
/* µTP callbacks */
void tr_peerIo::readBufferAdd(void const* data, size_t n_bytes)
{
inbuf.add(data, n_bytes);
setEnabled(TR_DOWN, true);
canReadWrapper(this);
}
static size_t utp_get_rb_size(tr_peerIo* const io)
{
auto 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 size_t tr_peerIoTryWrite(tr_peerIo* io, size_t howmuch, tr_error** error = nullptr);
static void utp_on_writable(tr_peerIo* io)
{
tr_logAddTraceIo(io, "libutp says this peer is ready to write");
auto const n = tr_peerIoTryWrite(io, SIZE_MAX);
io->setEnabled(TR_UP, n != 0 && !std::empty(io->outbuf));
}
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)
{
io->call_error_callback(BEV_EVENT_EOF);
}
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)
{
if (errcode == UTP_ETIMEDOUT)
{
// high frequency error: we log as trace
tr_logAddTraceIo(io, fmt::format("utp_on_error -- UTP_ETIMEDOUT"));
}
else
{
tr_logAddDebugIo(io, fmt::format("utp_on_error -- {}", utp_error_code_names[errcode]));
}
if (io->gotError != nullptr)
{
errno = errcode;
io->call_error_callback(BEV_EVENT_ERROR);
}
}
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("[µTP] [{}:{}] [{}] 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 */
std::shared_ptr<tr_peerIo> tr_peerIo::create(
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);
auto lock = session->unique_lock();
TR_ASSERT(isSupportedSocket(socket));
TR_ASSERT(session->allowsTCP() || socket.type != TR_PEER_SOCKET_TYPE_TCP);
if (socket.type == TR_PEER_SOCKET_TYPE_TCP)
{
session->setSocketTOS(socket.handle.tcp, addr->type);
maybeSetCongestionAlgorithm(socket.handle.tcp, session->peerCongestionAlgorithm());
}
auto io = std::shared_ptr<tr_peerIo>{
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.reset(event_new(session->eventBase(), socket.handle.tcp, EV_READ, event_read_cb, io.get()));
io->event_write.reset(event_new(session->eventBase(), socket.handle.tcp, EV_WRITE, event_write_cb, io.get()));
break;
#ifdef WITH_UTP
case TR_PEER_SOCKET_TYPE_UTP:
tr_logAddTraceIo(io, fmt::format("socket (µTP) is {}", fmt::ptr(socket.handle.utp)));
utp_set_userdata(socket.handle.utp, io.get());
break;
#endif
default:
TR_ASSERT_MSG(false, fmt::format("unsupported peer socket type {:d}", static_cast<int>(socket.type)));
}
return io;
}
void tr_peerIo::utpInit([[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
}
std::shared_ptr<tr_peerIo> tr_peerIo::newIncoming(
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_peerIo::create(session, parent, addr, port, current_time, nullptr, true, false, socket);
}
std::shared_ptr<tr_peerIo> tr_peerIo::newOutgoing(
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));
TR_ASSERT(utp || session->allowsTCP());
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 create(session, parent, addr, port, current_time, &torrent_hash, false, is_seed, socket);
}
/***
****
***/
static void event_enable(tr_peerIo* io, short event)
{
TR_ASSERT(io->session != nullptr);
bool const need_events = io->socket.type == TR_PEER_SOCKET_TYPE_TCP;
TR_ASSERT(!need_events || io->event_read);
TR_ASSERT(!need_events || 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.get(), 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.get(), nullptr);
}
io->pendingEvents |= EV_WRITE;
}
}
static void event_disable(tr_peerIo* io, short event)
{
bool const need_events = io->socket.type == TR_PEER_SOCKET_TYPE_TCP;
TR_ASSERT(!need_events || io->event_read);
TR_ASSERT(!need_events || 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.get());
}
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.get());
}
io->pendingEvents &= ~EV_WRITE;
}
}
void tr_peerIo::setEnabled(tr_direction dir, bool is_enabled)
{
TR_ASSERT(tr_isDirection(dir));
short const event = dir == TR_UP ? EV_WRITE : EV_READ;
if (is_enabled)
{
event_enable(this, event);
}
else
{
event_disable(this, 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 {}", static_cast<int>(io->socket.type)));
}
io->event_write.reset();
io->event_read.reset();
io->socket = {};
}
tr_peerIo::~tr_peerIo()
{
auto const lock = session->unique_lock();
clearCallbacks();
tr_logAddTraceIo(this, "in tr_peerIo destructor");
event_disable(this, EV_READ | EV_WRITE);
io_close_socket(this);
}
std::string tr_peerIo::addrStr() const
{
return tr_isPeerIo(this) ? this->addr_.readable(this->port_) : "error";
}
void tr_peerIo::setCallbacks(tr_can_read_cb readcb, tr_did_write_cb writecb, tr_net_error_cb errcb, void* user_data)
{
this->canRead = readcb;
this->didWrite = writecb;
this->gotError = errcb;
this->userData = user_data;
}
void tr_peerIo::clear()
{
clearCallbacks();
setEnabled(TR_UP, false);
setEnabled(TR_DOWN, false);
io_close_socket(this);
}
int tr_peerIo::reconnect()
{
TR_ASSERT(tr_isPeerIo(this));
TR_ASSERT(!this->isIncoming());
TR_ASSERT(this->session->allowsTCP());
short int const pending_events = this->pendingEvents;
event_disable(this, EV_READ | EV_WRITE);
io_close_socket(this);
auto const [addr, port] = this->socketAddress();
this->socket = tr_netOpenPeerSocket(session, &addr, port, this->isSeed());
if (this->socket.type != TR_PEER_SOCKET_TYPE_TCP)
{
return -1;
}
this->event_read.reset(event_new(session->eventBase(), this->socket.handle.tcp, EV_READ, event_read_cb, this));
this->event_write.reset(event_new(session->eventBase(), this->socket.handle.tcp, EV_WRITE, event_write_cb, this));
event_enable(this, pending_events);
this->session->setSocketTOS(this->socket.handle.tcp, addr.type);
maybeSetCongestionAlgorithm(this->socket.handle.tcp, session->peerCongestionAlgorithm());
return 0;
}
/**
***
**/
static size_t 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 */
auto const current_speed_bytes_per_second = 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 = static_cast<size_t>(tr_block_info::BlockSize * 3.5);
return std::max(ceiling, current_speed_bytes_per_second * period);
}
size_t tr_peerIo::getWriteBufferSpace(uint64_t now) const noexcept
{
size_t const desired_len = getDesiredOutputBufferSize(this, now);
size_t const current_len = std::size(outbuf);
return desired_len > current_len ? desired_len - current_len : 0U;
}
/**
***
**/
void tr_peerIo::write(libtransmission::Buffer& buf, bool is_piece_data)
{
for (auto& ch : buf)
{
encrypt(1, &ch);
}
outbuf_info.emplace_back(std::size(buf), is_piece_data);
outbuf.add(buf);
}
void tr_peerIo::writeBytes(void const* bytes, size_t n_bytes, bool is_piece_data)
{
auto const old_size = std::size(outbuf);
outbuf.reserve(old_size + n_bytes);
outbuf.add(bytes, n_bytes);
for (auto iter = std::begin(outbuf) + old_size, end = std::end(outbuf); iter != end; ++iter)
{
encrypt(1, &*iter);
}
outbuf_info.emplace_back(n_bytes, is_piece_data);
}
/***
****
***/
void tr_peerIo::readBytes(void* bytes, size_t byte_count)
{
TR_ASSERT(readBufferSize() >= byte_count);
inbuf.toBuf(bytes, byte_count);
if (isEncrypted())
{
decrypt(byte_count, bytes);
}
}
void tr_peerIo::readUint16(uint16_t* setme)
{
auto tmp = uint16_t{};
readBytes(&tmp, sizeof(tmp));
*setme = ntohs(tmp);
}
void tr_peerIo::readUint32(uint32_t* setme)
{
auto tmp = uint32_t{};
readBytes(&tmp, sizeof(tmp));
*setme = ntohl(tmp);
}
void tr_peerIo::readBufferDrain(size_t byte_count)
{
auto buf = std::array<char, 4096>{};
while (byte_count > 0)
{
auto const this_pass = std::min(byte_count, std::size(buf));
readBytes(std::data(buf), this_pass);
byte_count -= this_pass;
}
}
/***
****
***/
static size_t tr_peerIoTryRead(tr_peerIo* io, size_t howmuch, tr_error** error)
{
auto n_read = size_t{ 0U };
howmuch = io->bandwidth().clamp(TR_DOWN, howmuch);
if (howmuch == 0)
{
return n_read;
}
TR_ASSERT(isSupportedSocket(io->socket));
if (io->socket.type == TR_PEER_SOCKET_TYPE_TCP)
{
tr_error* my_error = nullptr;
n_read = io->inbuf.addSocket(io->socket.handle.tcp, howmuch, &my_error);
if (io->readBufferSize() != 0)
{
canReadWrapper(io);
}
if (my_error != nullptr)
{
if (canRetryFromError(my_error->code))
{
tr_error_clear(&my_error);
}
else
{
short const what = BEV_EVENT_READING | BEV_EVENT_ERROR | (n_read == 0 ? BEV_EVENT_EOF : 0);
auto const msg = fmt::format(
"tr_peerIoTryRead err: res:{} what:{}, errno:{} ({})",
n_read,
what,
my_error->code,
my_error->message);
tr_logAddTraceIo(io, msg);
io->call_error_callback(what);
tr_error_propagate(error, &my_error);
}
}
}
#ifdef WITH_UTP
else if (io->socket.type == 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 (io->readBufferSize() == 0)
{
utp_read_drained(io->socket.handle.utp);
}
}
#endif
return n_read;
}
static size_t tr_peerIoTryWrite(tr_peerIo* io, size_t howmuch, tr_error** error)
{
auto n_written = size_t{ 0U };
auto const old_len = std::size(io->outbuf);
howmuch = std::min(howmuch, old_len);
howmuch = io->bandwidth().clamp(TR_UP, howmuch);
if (howmuch == 0)
{
return n_written;
}
if (io->socket.type == TR_PEER_SOCKET_TYPE_TCP)
{
tr_error* my_error = nullptr;
n_written = io->outbuf.toSocket(io->socket.handle.tcp, howmuch, &my_error);
if (n_written > 0)
{
didWriteWrapper(io, n_written);
}
if (my_error != nullptr)
{
if (canRetryFromError(my_error->code))
{
tr_error_clear(&my_error);
}
else
{
short constexpr What = BEV_EVENT_WRITING | BEV_EVENT_ERROR;
tr_logAddTraceIo(
io,
fmt::format(
"tr_peerIoTryWrite err: res:{}, what:{}, errno:{} ({})",
n_written,
What,
my_error->code,
my_error->message));
io->call_error_callback(What);
tr_error_propagate(error, &my_error);
}
}
}
#ifdef WITH_UTP
else if (io->socket.type == TR_PEER_SOCKET_TYPE_UTP)
{
auto iov = io->outbuf.vecs(howmuch);
errno = 0;
auto const n = utp_writev(io->socket.handle.utp, reinterpret_cast<struct utp_iovec*>(std::data(iov)), std::size(iov));
auto const error_code = errno;
if (n > 0)
{
n_written = static_cast<size_t>(n);
io->outbuf.drain(n);
didWriteWrapper(io, n);
}
else if (n < 0 && !canRetryFromError(error_code))
{
tr_error_set(error, error_code, tr_strerror(error_code));
}
}
#endif
return n_written;
}
size_t tr_peerIo::flush(tr_direction dir, size_t limit, tr_error** error)
{
TR_ASSERT(tr_isDirection(dir));
auto const bytes_used = dir == TR_DOWN ? tr_peerIoTryRead(this, limit, error) : tr_peerIoTryWrite(this, limit, error);
tr_logAddTraceIo(
this,
fmt::format("flushing peer-io, direction:{}, limit:{}, byte_used:{}", static_cast<int>(dir), limit, bytes_used));
return bytes_used;
}
size_t tr_peerIo::flushOutgoingProtocolMsgs(tr_error** error)
{
size_t byte_count = 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] : outbuf_info)
{
if (is_piece_data)
{
break;
}
byte_count += n_bytes;
}
return flush(TR_UP, byte_count, error);
}
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