transmission/libtransmission/net.h

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// This file Copyright © 2006-2023 Transmission authors and contributors.
// This file is licensed under the MIT (SPDX: MIT) license,
// A copy of this license can be found in licenses/ .
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#pragma once
#ifndef __TRANSMISSION__
#error only libtransmission should #include this header.
#endif
#include <algorithm> // for std::copy_n
#include <array>
#include <cstddef> // size_t
#include <functional>
#include <optional>
#include <string>
#include <string_view>
#include <utility> // std::pair
#ifdef _WIN32
#include <ws2tcpip.h>
#else
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#include <arpa/inet.h>
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#include <cerrno>
#include <sys/socket.h>
#include <netinet/in.h>
#endif
#ifdef _WIN32
using tr_socket_t = SOCKET;
#define TR_BAD_SOCKET INVALID_SOCKET
#undef EADDRINUSE
#define EADDRINUSE WSAEADDRINUSE
#undef ECONNREFUSED
#define ECONNREFUSED WSAECONNREFUSED
#undef ECONNRESET
#define ECONNRESET WSAECONNRESET
#undef EHOSTUNREACH
#define EHOSTUNREACH WSAEHOSTUNREACH
#undef EINPROGRESS
#define EINPROGRESS WSAEINPROGRESS
#undef ENOTCONN
#define ENOTCONN WSAENOTCONN
#undef EWOULDBLOCK
#define EWOULDBLOCK WSAEWOULDBLOCK
#undef EAFNOSUPPORT
#define EAFNOSUPPORT WSAEAFNOSUPPORT
#undef ENETUNREACH
#define ENETUNREACH WSAENETUNREACH
#define sockerrno WSAGetLastError()
#else
/** @brief Platform-specific socket descriptor type. */
using tr_socket_t = int;
/** @brief Platform-specific invalid socket descriptor constant. */
#define TR_BAD_SOCKET (-1)
#define sockerrno errno
#endif
#include "libtransmission/tr-assert.h"
#include "libtransmission/utils.h"
/**
* Literally just a port number.
*
* Exists so that you never have to wonder what byte order a port variable is in.
*/
class tr_port
{
public:
tr_port() noexcept = default;
[[nodiscard]] constexpr static tr_port from_host(uint16_t hport) noexcept
{
return tr_port{ hport };
}
[[nodiscard]] static tr_port from_network(uint16_t nport) noexcept
{
return tr_port{ ntohs(nport) };
}
[[nodiscard]] constexpr uint16_t host() const noexcept
{
return hport_;
}
[[nodiscard]] uint16_t network() const noexcept
{
return htons(hport_);
}
constexpr void set_host(uint16_t hport) noexcept
{
hport_ = hport;
}
void set_network(uint16_t nport) noexcept
{
hport_ = ntohs(nport);
}
[[nodiscard]] static std::pair<tr_port, std::byte const*> from_compact(std::byte const* compact) noexcept;
[[nodiscard]] constexpr auto operator<(tr_port const& that) const noexcept
{
return hport_ < that.hport_;
}
[[nodiscard]] constexpr auto operator==(tr_port const& that) const noexcept
{
return hport_ == that.hport_;
}
// Can be removed once we use C++20
[[nodiscard]] constexpr auto operator!=(tr_port const& that) const noexcept
{
return hport_ != that.hport_;
}
[[nodiscard]] constexpr auto empty() const noexcept
{
return hport_ == 0;
}
constexpr void clear() noexcept
{
hport_ = 0;
}
static auto constexpr CompactPortBytes = 2U;
private:
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explicit constexpr tr_port(uint16_t hport) noexcept
: hport_{ hport }
{
}
uint16_t hport_ = 0;
};
enum tr_address_type : uint8_t
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{
TR_AF_INET,
TR_AF_INET6,
NUM_TR_AF_INET_TYPES
};
std::string_view tr_ip_protocol_to_sv(tr_address_type type);
int tr_ip_protocol_to_af(tr_address_type type);
tr_address_type tr_af_to_ip_protocol(int af);
struct tr_address
{
[[nodiscard]] static std::optional<tr_address> from_string(std::string_view address_sv);
[[nodiscard]] static std::pair<tr_address, std::byte const*> from_compact_ipv4(std::byte const* compact) noexcept;
[[nodiscard]] static std::pair<tr_address, std::byte const*> from_compact_ipv6(std::byte const* compact) noexcept;
// write the text form of the address, e.g. inet_ntop()
std::string_view display_name(char* out, size_t outlen) const;
[[nodiscard]] std::string display_name() const;
///
[[nodiscard]] constexpr auto is_ipv4() const noexcept
{
return type == TR_AF_INET;
}
[[nodiscard]] constexpr auto is_ipv6() const noexcept
{
return type == TR_AF_INET6;
}
/// bt protocol compact form
// compact addr only -- used e.g. as `yourip` value in extension protocol handshake
template<typename OutputIt>
static OutputIt to_compact_ipv4(OutputIt out, in_addr const& addr4)
{
return std::copy_n(reinterpret_cast<std::byte const*>(&addr4), sizeof(addr4), out);
}
template<typename OutputIt>
static OutputIt to_compact_ipv6(OutputIt out, in6_addr const& addr6)
{
return std::copy_n(reinterpret_cast<std::byte const*>(&addr6), sizeof(addr6), out);
}
template<typename OutputIt>
OutputIt to_compact(OutputIt out) const
{
switch (type)
{
case TR_AF_INET:
return to_compact_ipv4(out, addr.addr4);
case TR_AF_INET6:
return to_compact_ipv6(out, addr.addr6);
default:
TR_ASSERT_MSG(false, "invalid address type");
return out;
}
}
// comparisons
[[nodiscard]] int compare(tr_address const& that) const noexcept;
[[nodiscard]] bool operator==(tr_address const& that) const noexcept
{
return this->compare(that) == 0;
}
[[nodiscard]] bool operator<(tr_address const& that) const noexcept
{
return this->compare(that) < 0;
}
[[nodiscard]] bool operator<=(tr_address const& that) const noexcept
{
return this->compare(that) <= 0;
}
[[nodiscard]] bool operator>(tr_address const& that) const noexcept
{
return this->compare(that) > 0;
}
//
[[nodiscard]] bool is_global_unicast_address() const noexcept;
tr_address_type type;
union
{
struct in6_addr addr6;
struct in_addr addr4;
} addr;
static auto constexpr CompactAddrBytes = std::array{ 4U, 16U };
static_assert(std::size(CompactAddrBytes) == NUM_TR_AF_INET_TYPES);
[[nodiscard]] static auto constexpr any(tr_address_type type) noexcept
{
switch (type)
{
case TR_AF_INET:
return tr_address{ TR_AF_INET, { { { { INADDR_ANY } } } } };
case TR_AF_INET6:
return tr_address{ TR_AF_INET6, { IN6ADDR_ANY_INIT } };
default:
return tr_address{};
}
}
[[nodiscard]] constexpr auto is_valid() const noexcept
{
return type == TR_AF_INET || type == TR_AF_INET6;
}
[[nodiscard]] auto is_any() const noexcept
{
return *this == any(type);
}
};
struct tr_socket_address
{
tr_socket_address() = default;
tr_socket_address(tr_address const& address, tr_port port)
: address_{ address }
, port_{ port }
{
}
[[nodiscard]] constexpr auto const& address() const noexcept
{
return address_;
}
[[nodiscard]] constexpr auto port() const noexcept
{
return port_;
}
[[nodiscard]] static std::string display_name(tr_address const& address, tr_port port) noexcept;
[[nodiscard]] auto display_name() const noexcept
{
return display_name(address_, port_);
}
[[nodiscard]] auto is_valid() const noexcept
{
return address_.is_valid();
}
[[nodiscard]] bool is_valid_for_peers() const noexcept;
[[nodiscard]] int compare(tr_socket_address const& that) const noexcept
{
if (auto const val = tr_compare_3way(address_, that.address_); val != 0)
{
return val;
}
return tr_compare_3way(port_, that.port_);
}
// --- compact addr + port -- very common format used for peer exchange, dht, tracker announce responses
[[nodiscard]] static std::pair<tr_socket_address, std::byte const*> from_compact_ipv4(std::byte const* compact) noexcept
{
auto socket_address = tr_socket_address{};
std::tie(socket_address.address_, compact) = tr_address::from_compact_ipv4(compact);
std::tie(socket_address.port_, compact) = tr_port::from_compact(compact);
return { socket_address, compact };
}
[[nodiscard]] static std::pair<tr_socket_address, std::byte const*> from_compact_ipv6(std::byte const* compact) noexcept
{
auto socket_address = tr_socket_address{};
std::tie(socket_address.address_, compact) = tr_address::from_compact_ipv6(compact);
std::tie(socket_address.port_, compact) = tr_port::from_compact(compact);
return { socket_address, compact };
}
template<typename OutputIt>
static OutputIt to_compact(OutputIt out, tr_address const& addr, tr_port const port)
{
out = addr.to_compact(out);
auto const nport = port.network();
return std::copy_n(reinterpret_cast<std::byte const*>(&nport), sizeof(nport), out);
}
template<typename OutputIt>
OutputIt to_compact(OutputIt out) const
{
return to_compact(out, address_, port_);
}
// --- compact sockaddr helpers
template<typename OutputIt>
static OutputIt to_compact(OutputIt out, sockaddr const* saddr)
{
if (auto socket_address = from_sockaddr(saddr); socket_address)
{
return socket_address->to_compact(out);
}
return out;
}
template<typename OutputIt>
static OutputIt to_compact(OutputIt out, sockaddr_storage const* ss)
{
return to_compact(out, reinterpret_cast<sockaddr const*>(ss));
}
// --- sockaddr helpers
[[nodiscard]] static std::optional<tr_socket_address> from_sockaddr(sockaddr const*);
[[nodiscard]] static std::pair<sockaddr_storage, socklen_t> to_sockaddr(tr_address const& addr, tr_port port) noexcept;
[[nodiscard]] std::pair<sockaddr_storage, socklen_t> to_sockaddr() const noexcept
{
return to_sockaddr(address_, port_);
}
// --- Comparisons
[[nodiscard]] auto operator<(tr_socket_address const& that) const noexcept
{
return compare(that) < 0;
}
[[nodiscard]] auto operator==(tr_socket_address const& that) const noexcept
{
return compare(that) == 0;
}
tr_address address_;
tr_port port_;
static auto constexpr CompactSockAddrBytes = std::array{ tr_address::CompactAddrBytes[0] + tr_port::CompactPortBytes,
tr_address::CompactAddrBytes[1] + tr_port::CompactPortBytes };
static_assert(std::size(CompactSockAddrBytes) == NUM_TR_AF_INET_TYPES);
};
template<>
class std::hash<tr_socket_address>
{
public:
std::size_t operator()(tr_socket_address const& socket_address) const noexcept
{
auto const& [addr, port] = socket_address;
return hash_combine(ip_hash(addr), PortHasher(port.host()));
}
private:
// https://stackoverflow.com/a/27952689/11390656
[[nodiscard]] static constexpr std::size_t hash_combine(std::size_t const a, std::size_t const b)
{
return a ^ (b + 0x9e3779b9U + (a << 6U) + (a >> 2U));
}
[[nodiscard]] static std::size_t ip_hash(tr_address const& addr) noexcept
{
switch (addr.type)
{
case TR_AF_INET:
return IPv4Hasher(addr.addr.addr4.s_addr);
case TR_AF_INET6:
return IPv6Hasher({ reinterpret_cast<char const*>(addr.addr.addr6.s6_addr), sizeof(addr.addr.addr6.s6_addr) });
default:
TR_ASSERT_MSG(false, "Invalid type");
return {};
}
}
constexpr static std::hash<uint32_t> IPv4Hasher{};
constexpr static std::hash<std::string_view> IPv6Hasher{};
constexpr static std::hash<uint16_t> PortHasher{};
};
// --- Sockets
struct tr_session;
tr_socket_t tr_netBindTCP(tr_address const& addr, tr_port port, bool suppress_msgs);
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[[nodiscard]] std::optional<std::pair<tr_socket_address, tr_socket_t>> tr_netAccept(
tr_session* session,
tr_socket_t listening_sockfd);
void tr_netSetCongestionControl(tr_socket_t s, char const* algorithm);
void tr_net_close_socket(tr_socket_t fd);
// --- TOS / DSCP
/**
* A `toString()` / `from_string()` convenience wrapper around the TOS int value
*/
class tr_tos_t
{
public:
constexpr tr_tos_t() = default;
constexpr explicit tr_tos_t(int value)
: value_{ value }
{
}
[[nodiscard]] constexpr operator int() const noexcept
{
return value_;
}
[[nodiscard]] static std::optional<tr_tos_t> from_string(std::string_view);
[[nodiscard]] std::string toString() const;
private:
int value_ = 0x04;
// RFCs 2474, 3246, 4594 & 8622
// Service class names are defined in RFC 4594, RFC 5865, and RFC 8622.
// Not all platforms have these IPTOS_ definitions, so hardcode them here
static auto constexpr Names = std::array<std::pair<int, std::string_view>, 28>{ {
{ 0x00, "cs0" }, // IPTOS_CLASS_CS0
{ 0x04, "le" },
{ 0x20, "cs1" }, // IPTOS_CLASS_CS1
{ 0x28, "af11" }, // IPTOS_DSCP_AF11
{ 0x30, "af12" }, // IPTOS_DSCP_AF12
{ 0x38, "af13" }, // IPTOS_DSCP_AF13
{ 0x40, "cs2" }, // IPTOS_CLASS_CS2
{ 0x48, "af21" }, // IPTOS_DSCP_AF21
{ 0x50, "af22" }, // IPTOS_DSCP_AF22
{ 0x58, "af23" }, // IPTOS_DSCP_AF23
{ 0x60, "cs3" }, // IPTOS_CLASS_CS3
{ 0x68, "af31" }, // IPTOS_DSCP_AF31
{ 0x70, "af32" }, // IPTOS_DSCP_AF32
{ 0x78, "af33" }, // IPTOS_DSCP_AF33
{ 0x80, "cs4" }, // IPTOS_CLASS_CS4
{ 0x88, "af41" }, // IPTOS_DSCP_AF41
{ 0x90, "af42" }, // IPTOS_DSCP_AF42
{ 0x98, "af43" }, // IPTOS_DSCP_AF43
{ 0xa0, "cs5" }, // IPTOS_CLASS_CS5
{ 0xb8, "ef" }, // IPTOS_DSCP_EF
{ 0xc0, "cs6" }, // IPTOS_CLASS_CS6
{ 0xe0, "cs7" }, // IPTOS_CLASS_CS7
// <netinet/ip.h> lists these TOS names as deprecated,
// but keep them defined here for backward compatibility
{ 0x00, "routine" }, // IPTOS_PREC_ROUTINE
{ 0x02, "lowcost" }, // IPTOS_LOWCOST
{ 0x02, "mincost" }, // IPTOS_MINCOST
{ 0x04, "reliable" }, // IPTOS_RELIABILITY
{ 0x08, "throughput" }, // IPTOS_THROUGHPUT
{ 0x10, "lowdelay" }, // IPTOS_LOWDELAY
} };
};
// set the IPTOS_ value for the specified socket
void tr_netSetTOS(tr_socket_t sock, int tos, tr_address_type type);
/**
* @brief get a human-representable string representing the network error.
* @param err an errno on Unix/Linux and an WSAError on win32)
*/
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[[nodiscard]] std::string tr_net_strerror(int err);