transmission/libtransmission/peer-socket.cc

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// This file Copyright © 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.
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#include <algorithm> // std::min
#include <cerrno>
#include <fmt/core.h>
#include <libutp/utp.h>
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#include "libtransmission/error.h"
#include "libtransmission/log.h"
#include "libtransmission/peer-socket.h"
#include "libtransmission/net.h"
#include "libtransmission/session.h"
#define tr_logAddErrorIo(io, msg) tr_logAddError(msg, (io)->display_name())
#define tr_logAddWarnIo(io, msg) tr_logAddWarn(msg, (io)->display_name())
#define tr_logAddDebugIo(io, msg) tr_logAddDebug(msg, (io)->display_name())
#define tr_logAddTraceIo(io, msg) tr_logAddTrace(msg, (io)->display_name())
tr_peer_socket::tr_peer_socket(tr_session const* session, tr_socket_address const& socket_address, tr_socket_t sock)
: handle{ sock }
, socket_address_{ socket_address }
, type_{ Type::TCP }
{
TR_ASSERT(sock != TR_BAD_SOCKET);
++n_open_sockets_;
session->setSocketTOS(sock, address().type);
if (auto const& algo = session->peerCongestionAlgorithm(); !std::empty(algo))
{
tr_netSetCongestionControl(sock, algo.c_str());
}
tr_logAddTraceIo(this, fmt::format("socket (tcp) is {}", handle.tcp));
}
tr_peer_socket::tr_peer_socket(tr_socket_address const& socket_address, struct UTPSocket* const sock)
: socket_address_{ socket_address }
, type_{ Type::UTP }
{
TR_ASSERT(sock != nullptr);
++n_open_sockets_;
handle.utp = sock;
tr_logAddTraceIo(this, fmt::format("socket (µTP) is {}", fmt::ptr(handle.utp)));
}
void tr_peer_socket::close()
{
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if (is_tcp() && (handle.tcp != TR_BAD_SOCKET))
{
--n_open_sockets_;
tr_net_close_socket(handle.tcp);
}
#ifdef WITH_UTP
else if (is_utp())
{
--n_open_sockets_;
utp_set_userdata(handle.utp, nullptr);
utp_close(handle.utp);
}
#endif
type_ = Type::None;
handle = {};
}
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size_t tr_peer_socket::try_write(OutBuf& buf, size_t max, tr_error* error) const
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{
if (max == size_t{})
{
return {};
}
if (is_tcp())
{
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return buf.to_socket(handle.tcp, max, error);
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}
#ifdef WITH_UTP
if (is_utp())
{
errno = 0;
// NB: utp_write() does not modify its 2nd arg, but a wart in
// libutp's public API requires it to be non-const anyway :shrug:
auto const n_written = utp_write(handle.utp, const_cast<std::byte*>(std::data(buf)), std::min(std::size(buf), max));
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auto const error_code = errno;
if (n_written > 0)
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{
buf.drain(n_written);
return static_cast<size_t>(n_written);
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}
if (error != nullptr && n_written < 0 && error_code != 0)
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{
error->set_from_errno(error_code);
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}
}
#endif
return {};
}
size_t tr_peer_socket::try_read(InBuf& buf, size_t max, [[maybe_unused]] bool buf_is_empty, tr_error* error) const
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{
if (max == size_t{})
{
return {};
}
if (is_tcp())
{
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return buf.add_socket(handle.tcp, max, error);
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}
#ifdef WITH_UTP
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// utp_read_drained() notifies libutp that this read buffer is empty.
// It opens up the congestion window by sending an ACK (soonish) if
// one was not going to be sent.
if (is_utp() && buf_is_empty)
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{
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utp_read_drained(handle.utp);
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}
#endif
return {};
}
bool tr_peer_socket::limit_reached(tr_session const* const session) noexcept
{
return n_open_sockets_.load() >= session->peerLimit();
}