transmission/libtransmission/peer-socket.h

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// This file Copyright © 2017-2023 Mnemosyne LLC.
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// 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.
#pragma once
#ifndef __TRANSMISSION__
#error only libtransmission should #include this header.
#endif
#include <atomic>
#include <string>
#include <string_view>
#include <utility> // for std::make_pair()
#include "transmission.h"
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#include "error.h"
#include "net.h"
#include "tr-assert.h"
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#include "tr-buffer.h"
struct UTPSocket;
struct tr_session;
class tr_peer_socket
{
public:
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using Buffer = libtransmission::Buffer;
tr_peer_socket() = default;
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tr_peer_socket(tr_session const* session, tr_address const& address, tr_port port, tr_socket_t sock);
tr_peer_socket(tr_address const& address, tr_port port, struct UTPSocket* const sock);
tr_peer_socket(tr_peer_socket&& s)
{
*this = std::move(s);
}
tr_peer_socket(tr_peer_socket const&) = delete;
tr_peer_socket& operator=(tr_peer_socket&& s)
{
close();
handle = s.handle;
address_ = s.address_;
port_ = s.port_;
type_ = s.type_;
// invalidate s.type_, s.handle so s.close() won't break anything
s.type_ = Type::None;
s.handle = {};
return *this;
}
tr_peer_socket& operator=(tr_peer_socket const&) = delete;
~tr_peer_socket()
{
close();
}
void close();
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size_t try_write(Buffer& buf, size_t max, tr_error** error) const;
size_t try_read(Buffer& buf, size_t max, tr_error** error) const;
[[nodiscard]] constexpr std::pair<tr_address, tr_port> socketAddress() const noexcept
{
return std::make_pair(address_, port_);
}
[[nodiscard]] constexpr auto const& address() const noexcept
{
return address_;
}
[[nodiscard]] constexpr auto const& port() const noexcept
{
return port_;
}
template<typename OutputIt>
OutputIt display_name(OutputIt out)
{
return address_.display_name(out, port_);
}
[[nodiscard]] std::string_view display_name(char* out, size_t outlen) const
{
return address_.display_name(out, outlen, port_);
}
[[nodiscard]] std::string display_name() const
{
return address_.display_name(port_);
}
[[nodiscard]] constexpr auto is_utp() const noexcept
{
return type_ == Type::UTP;
}
[[nodiscard]] constexpr auto is_tcp() const noexcept
{
return type_ == Type::TCP;
}
[[nodiscard]] constexpr auto is_valid() const noexcept
{
#ifdef WITH_UTP
return is_tcp() || is_utp();
#else
return is_tcp();
#endif
}
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[[nodiscard]] constexpr size_t guess_packet_overhead(size_t n_bytes) const noexcept
{
if (is_tcp())
{
// 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
// So, let's guess around 7% overhead
return n_bytes / 14U;
}
// We only guess for TCP; uTP tracks its overhead via UTP_ON_OVERHEAD_STATISTICS
return {};
}
union
{
tr_socket_t tcp;
struct UTPSocket* utp;
} handle = {};
[[nodiscard]] static bool limit_reached(tr_session* const session) noexcept;
private:
enum class Type
{
None,
TCP,
UTP
};
tr_address address_;
tr_port port_;
enum Type type_ = Type::None;
static inline std::atomic<size_t> n_open_sockets_ = {};
};
tr_peer_socket tr_netOpenPeerSocket(tr_session* session, tr_address const& addr, tr_port port, bool client_is_seed);