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//

//

// Copyright (c) 2026 Steve Gerbino

// Copyright (c) 2026 Steve Gerbino

//

//

// Distributed under the Boost Software License, Version 1.0. (See accompanying

// Distributed under the Boost Software License, Version 1.0. (See accompanying

// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//

//

// Official repository: https://github.com/cppalliance/corosio

// Official repository: https://github.com/cppalliance/corosio

//

//

/** @file native_socket_option.hpp

/** @file native_socket_option.hpp

    Inline socket option types using platform-specific constants.

    Inline socket option types using platform-specific constants.

    All methods are `constexpr` or trivially inlined, giving zero

    All methods are `constexpr` or trivially inlined, giving zero

    overhead compared to hand-written `setsockopt` calls.

    overhead compared to hand-written `setsockopt` calls.

    This header includes platform socket headers

    This header includes platform socket headers

    (`<sys/socket.h>`, `<netinet/tcp.h>`, etc.).

    (`<sys/socket.h>`, `<netinet/tcp.h>`, etc.).

    For a version that avoids platform includes, use

    For a version that avoids platform includes, use

    `<boost/corosio/socket_option.hpp>`

    `<boost/corosio/socket_option.hpp>`

    (`boost::corosio::socket_option`).

    (`boost::corosio::socket_option`).

    Both variants satisfy the same option-type interface and work

    Both variants satisfy the same option-type interface and work

    interchangeably with `tcp_socket::set_option` /

    interchangeably with `tcp_socket::set_option` /

    `tcp_socket::get_option` and the corresponding acceptor methods.

    `tcp_socket::get_option` and the corresponding acceptor methods.

    @see boost::corosio::socket_option

    @see boost::corosio::socket_option

*/

*/

#ifndef BOOST_COROSIO_NATIVE_NATIVE_SOCKET_OPTION_HPP

#ifndef BOOST_COROSIO_NATIVE_NATIVE_SOCKET_OPTION_HPP

#define BOOST_COROSIO_NATIVE_NATIVE_SOCKET_OPTION_HPP

#define BOOST_COROSIO_NATIVE_NATIVE_SOCKET_OPTION_HPP

#ifdef _WIN32

#ifdef _WIN32

#include <winsock2.h>

#include <winsock2.h>

#include <ws2tcpip.h>

#include <ws2tcpip.h>

#else

#else

#include <netinet/in.h>

#include <netinet/in.h>

#include <netinet/tcp.h>

#include <netinet/tcp.h>

#include <sys/socket.h>

#include <sys/socket.h>

#endif

#endif

// Some older systems define only the legacy names

#ifndef IPV6_JOIN_GROUP

#define IPV6_JOIN_GROUP IPV6_ADD_MEMBERSHIP

#endif

#ifndef IPV6_LEAVE_GROUP

#define IPV6_LEAVE_GROUP IPV6_DROP_MEMBERSHIP

#endif

#include <boost/corosio/ipv4_address.hpp>

#include <boost/corosio/ipv6_address.hpp>

#include <cstddef>

#include <cstddef>

#include <cstring>

namespace boost::corosio::native_socket_option {

namespace boost::corosio::native_socket_option {

/** A socket option with a boolean value.

/** A socket option with a boolean value.

    Models socket options whose underlying representation is an `int`

    Models socket options whose underlying representation is an `int`

    where 0 means disabled and non-zero means enabled. The option's

    where 0 means disabled and non-zero means enabled. The option's

    protocol level and name are encoded as template parameters.

    protocol level and name are encoded as template parameters.

    This is the native (inline) variant that includes platform

    This is the native (inline) variant that includes platform

    headers. For a type-erased version that avoids platform

    headers. For a type-erased version that avoids platform

    includes, use `boost::corosio::socket_option` instead.

    includes, use `boost::corosio::socket_option` instead.

    @par Example

    @par Example

    @code

    @code

    sock.set_option( native_socket_option::no_delay( true ) );

    sock.set_option( native_socket_option::no_delay( true ) );

    auto nd = sock.get_option<native_socket_option::no_delay>();

    auto nd = sock.get_option<native_socket_option::no_delay>();

    if ( nd.value() )

    if ( nd.value() )

        // Nagle's algorithm is disabled

        // Nagle's algorithm is disabled

    @endcode

    @endcode

    @tparam Level The protocol level (e.g. `SOL_SOCKET`, `IPPROTO_TCP`).

    @tparam Level The protocol level (e.g. `SOL_SOCKET`, `IPPROTO_TCP`).

    @tparam Name The option name (e.g. `TCP_NODELAY`, `SO_KEEPALIVE`).

    @tparam Name The option name (e.g. `TCP_NODELAY`, `SO_KEEPALIVE`).

*/

*/

template<int Level, int Name>

template<int Level, int Name>

class boolean

class boolean

{

{

    int value_ = 0;

    int value_ = 0;

public:

public:

    /// Construct with default value (disabled).

    /// Construct with default value (disabled).

    boolean() = default;

    boolean() = default;

    /** Construct with an explicit value.

    /** Construct with an explicit value.

        @param v `true` to enable the option, `false` to disable.

        @param v `true` to enable the option, `false` to disable.

    */

    */

    explicit boolean(bool v) noexcept : value_(v ? 1 : 0) {}

    explicit boolean(bool v) noexcept : value_(v ? 1 : 0) {}

    /// Assign a new value.

    /// Assign a new value.

    boolean& operator=(bool v) noexcept

    boolean& operator=(bool v) noexcept

    {

    {

        value_ = v ? 1 : 0;

        value_ = v ? 1 : 0;

        return *this;

        return *this;

    }

    }

    /// Return the option value.

    /// Return the option value.

    bool value() const noexcept

    bool value() const noexcept

    {

    {

        return value_ != 0;

        return value_ != 0;

    }

    }

    /// Return the option value.

    /// Return the option value.

    explicit operator bool() const noexcept

    explicit operator bool() const noexcept

    {

    {

        return value_ != 0;

        return value_ != 0;

    }

    }

    /// Return the negated option value.

    /// Return the negated option value.

    bool operator!() const noexcept

    bool operator!() const noexcept

    {

    {

        return value_ == 0;

        return value_ == 0;

    }

    }

    /// Return the protocol level for `setsockopt`/`getsockopt`.

    /// Return the protocol level for `setsockopt`/`getsockopt`.

    {

    {

    }

    }

    /// Return the option name for `setsockopt`/`getsockopt`.

    /// Return the option name for `setsockopt`/`getsockopt`.

    {

    {

    }

    }

    /// Return a pointer to the underlying storage.

    /// Return a pointer to the underlying storage.

    void* data() noexcept

    void* data() noexcept

    {

    {

        return &value_;

        return &value_;

    }

    }

    /// Return a pointer to the underlying storage.

    /// Return a pointer to the underlying storage.

    void const* data() const noexcept

    void const* data() const noexcept

    {

    {

        return &value_;

        return &value_;

    }

    }

    /// Return the size of the underlying storage.

    /// Return the size of the underlying storage.

    std::size_t size() const noexcept

    std::size_t size() const noexcept

    {

    {

        return sizeof(value_);

        return sizeof(value_);

    }

    }

    /** Normalize after `getsockopt` returns fewer bytes than expected.

    /** Normalize after `getsockopt` returns fewer bytes than expected.

        Windows Vista+ may write only 1 byte for boolean options.

        Windows Vista+ may write only 1 byte for boolean options.

        @param s The number of bytes actually written by `getsockopt`.

        @param s The number of bytes actually written by `getsockopt`.

    */

    */

    void resize(std::size_t s) noexcept

    void resize(std::size_t s) noexcept

    {

    {

        if (s == sizeof(char))

        if (s == sizeof(char))

            value_ = *reinterpret_cast<unsigned char*>(&value_) ? 1 : 0;

            value_ = *reinterpret_cast<unsigned char*>(&value_) ? 1 : 0;

    }

    }

};

};

/** A socket option with an integer value.

/** A socket option with an integer value.

    Models socket options whose underlying representation is a

    Models socket options whose underlying representation is a

    plain `int`. The option's protocol level and name are encoded

    plain `int`. The option's protocol level and name are encoded

    as template parameters.

    as template parameters.

    This is the native (inline) variant that includes platform

    This is the native (inline) variant that includes platform

    headers. For a type-erased version that avoids platform

    headers. For a type-erased version that avoids platform

    includes, use `boost::corosio::socket_option` instead.

    includes, use `boost::corosio::socket_option` instead.

    @par Example

    @par Example

    @code

    @code

    sock.set_option( native_socket_option::receive_buffer_size( 65536 ) );

    sock.set_option( native_socket_option::receive_buffer_size( 65536 ) );

    auto opt = sock.get_option<native_socket_option::receive_buffer_size>();

    auto opt = sock.get_option<native_socket_option::receive_buffer_size>();

    int sz = opt.value();

    int sz = opt.value();

    @endcode

    @endcode

    @tparam Level The protocol level (e.g. `SOL_SOCKET`).

    @tparam Level The protocol level (e.g. `SOL_SOCKET`).

    @tparam Name The option name (e.g. `SO_RCVBUF`).

    @tparam Name The option name (e.g. `SO_RCVBUF`).

*/

*/

template<int Level, int Name>

template<int Level, int Name>

class integer

class integer

{

{

    int value_ = 0;

    int value_ = 0;

public:

public:

    /// Construct with default value (zero).

    /// Construct with default value (zero).

    integer() = default;

    integer() = default;

    /** Construct with an explicit value.

    /** Construct with an explicit value.

        @param v The option value.

        @param v The option value.

    */

    */

    explicit integer(int v) noexcept : value_(v) {}

    explicit integer(int v) noexcept : value_(v) {}

    /// Assign a new value.

    /// Assign a new value.

    integer& operator=(int v) noexcept

    integer& operator=(int v) noexcept

    {

    {

        value_ = v;

        value_ = v;

        return *this;

        return *this;

    }

    }

    /// Return the option value.

    /// Return the option value.

    int value() const noexcept

    int value() const noexcept

    {

    {

        return value_;

        return value_;

    }

    }

    /// Return the protocol level for `setsockopt`/`getsockopt`.

    /// Return the protocol level for `setsockopt`/`getsockopt`.

    {

    {

    }

    }

    /// Return the option name for `setsockopt`/`getsockopt`.

    /// Return the option name for `setsockopt`/`getsockopt`.

    {

    {

    }

    }

    /// Return a pointer to the underlying storage.

    /// Return a pointer to the underlying storage.

    void* data() noexcept

    void* data() noexcept

    {

    {

        return &value_;

        return &value_;

    }

    }

    /// Return a pointer to the underlying storage.

    /// Return a pointer to the underlying storage.

    void const* data() const noexcept

    void const* data() const noexcept

    {

    {

        return &value_;

        return &value_;

    }

    }

    /// Return the size of the underlying storage.

    /// Return the size of the underlying storage.

    std::size_t size() const noexcept

    std::size_t size() const noexcept

    {

    {

        return sizeof(value_);

        return sizeof(value_);

    }

    }

    /** Normalize after `getsockopt` returns fewer bytes than expected.

    /** Normalize after `getsockopt` returns fewer bytes than expected.

        @param s The number of bytes actually written by `getsockopt`.

        @param s The number of bytes actually written by `getsockopt`.

    */

    */

    void resize(std::size_t s) noexcept

    void resize(std::size_t s) noexcept

    {

    {

        if (s == sizeof(char))

        if (s == sizeof(char))

            value_ =

            value_ =

                static_cast<int>(*reinterpret_cast<unsigned char*>(&value_));

                static_cast<int>(*reinterpret_cast<unsigned char*>(&value_));

    }

    }

};

};

/** The SO_LINGER socket option (native variant).

/** The SO_LINGER socket option (native variant).

    Controls behavior when closing a socket with unsent data.

    Controls behavior when closing a socket with unsent data.

    When enabled, `close()` blocks until pending data is sent

    When enabled, `close()` blocks until pending data is sent

    or the timeout expires.

    or the timeout expires.

    This variant stores the platform's `struct linger` directly,

    This variant stores the platform's `struct linger` directly,

    avoiding the opaque-storage indirection of the type-erased

    avoiding the opaque-storage indirection of the type-erased

    version.

    version.

    @par Example

    @par Example

    @code

    @code

    sock.set_option( native_socket_option::linger( true, 5 ) );

    sock.set_option( native_socket_option::linger( true, 5 ) );

    auto opt = sock.get_option<native_socket_option::linger>();

    auto opt = sock.get_option<native_socket_option::linger>();

    if ( opt.enabled() )

    if ( opt.enabled() )

        std::cout << "linger timeout: " << opt.timeout() << "s\n";

        std::cout << "linger timeout: " << opt.timeout() << "s\n";

    @endcode

    @endcode

*/

*/

class linger

class linger

{

{

    struct ::linger value_{};

    struct ::linger value_{};

public:

public:

    /// Construct with default values (disabled, zero timeout).

    /// Construct with default values (disabled, zero timeout).

    /** Construct with explicit values.

    /** Construct with explicit values.

        @param enabled `true` to enable linger behavior on close.

        @param enabled `true` to enable linger behavior on close.

        @param timeout The linger timeout in seconds.

        @param timeout The linger timeout in seconds.

    */

    */

    /// Return whether linger is enabled.

    /// Return whether linger is enabled.

    {

    {

    }

    }

    /// Set whether linger is enabled.

    /// Set whether linger is enabled.

    {

    {

    /// Return the linger timeout in seconds.

    /// Return the linger timeout in seconds.

    {

    {

    }

    }

    /// Set the linger timeout in seconds.

    /// Set the linger timeout in seconds.

    {

    {

    /// Return the protocol level for `setsockopt`/`getsockopt`.

    /// Return the protocol level for `setsockopt`/`getsockopt`.

    {

    {

    }

    }

    /// Return the option name for `setsockopt`/`getsockopt`.

    /// Return the option name for `setsockopt`/`getsockopt`.

    {

    {

    }

    }

    /// Return a pointer to the underlying storage.

    /// Return a pointer to the underlying storage.

    {

    {

    }

    }

    /// Return a pointer to the underlying storage.

    /// Return a pointer to the underlying storage.

    void const* data() const noexcept

    void const* data() const noexcept

    {

    {

        return &value_;

        return &value_;

    }

    }

    /// Return the size of the underlying storage.

    /// Return the size of the underlying storage.

    {

    {

    }

    }

    /** Normalize after `getsockopt`.

    /** Normalize after `getsockopt`.

        No-op — `struct linger` is always returned at full size.

        No-op — `struct linger` is always returned at full size.

        @param s The number of bytes actually written by `getsockopt`.

        @param s The number of bytes actually written by `getsockopt`.

    */

    */

    void resize(std::size_t) noexcept {}

    void resize(std::size_t) noexcept {}

};

};

/// Disable Nagle's algorithm (TCP_NODELAY).

/// Disable Nagle's algorithm (TCP_NODELAY).

using no_delay = boolean<IPPROTO_TCP, TCP_NODELAY>;

using no_delay = boolean<IPPROTO_TCP, TCP_NODELAY>;

/// Enable periodic keepalive probes (SO_KEEPALIVE).

/// Enable periodic keepalive probes (SO_KEEPALIVE).

using keep_alive = boolean<SOL_SOCKET, SO_KEEPALIVE>;

using keep_alive = boolean<SOL_SOCKET, SO_KEEPALIVE>;

/// Restrict an IPv6 socket to IPv6 only (IPV6_V6ONLY).

/// Restrict an IPv6 socket to IPv6 only (IPV6_V6ONLY).

using v6_only = boolean<IPPROTO_IPV6, IPV6_V6ONLY>;

using v6_only = boolean<IPPROTO_IPV6, IPV6_V6ONLY>;

/// Allow local address reuse (SO_REUSEADDR).

/// Allow local address reuse (SO_REUSEADDR).

using reuse_address = boolean<SOL_SOCKET, SO_REUSEADDR>;

using reuse_address = boolean<SOL_SOCKET, SO_REUSEADDR>;

/// Allow sending to broadcast addresses (SO_BROADCAST).

using broadcast = boolean<SOL_SOCKET, SO_BROADCAST>;

/// Set the receive buffer size (SO_RCVBUF).

/// Set the receive buffer size (SO_RCVBUF).

using receive_buffer_size = integer<SOL_SOCKET, SO_RCVBUF>;

using receive_buffer_size = integer<SOL_SOCKET, SO_RCVBUF>;

/// Set the send buffer size (SO_SNDBUF).

/// Set the send buffer size (SO_SNDBUF).

using send_buffer_size = integer<SOL_SOCKET, SO_SNDBUF>;

using send_buffer_size = integer<SOL_SOCKET, SO_SNDBUF>;

#ifdef SO_REUSEPORT

#ifdef SO_REUSEPORT

/// Allow multiple sockets to bind to the same port (SO_REUSEPORT).

/// Allow multiple sockets to bind to the same port (SO_REUSEPORT).

using reuse_port = boolean<SOL_SOCKET, SO_REUSEPORT>;

using reuse_port = boolean<SOL_SOCKET, SO_REUSEPORT>;

#endif

#endif

/// Enable loopback of outgoing multicast on IPv4 (IP_MULTICAST_LOOP).

using multicast_loop_v4 = boolean<IPPROTO_IP, IP_MULTICAST_LOOP>;

/// Enable loopback of outgoing multicast on IPv6 (IPV6_MULTICAST_LOOP).

using multicast_loop_v6 = boolean<IPPROTO_IPV6, IPV6_MULTICAST_LOOP>;

/// Set the multicast TTL for IPv4 (IP_MULTICAST_TTL).

using multicast_hops_v4 = integer<IPPROTO_IP, IP_MULTICAST_TTL>;

/// Set the multicast hop limit for IPv6 (IPV6_MULTICAST_HOPS).

using multicast_hops_v6 = integer<IPPROTO_IPV6, IPV6_MULTICAST_HOPS>;

/// Set the outgoing interface for IPv6 multicast (IPV6_MULTICAST_IF).

using multicast_interface_v6 = integer<IPPROTO_IPV6, IPV6_MULTICAST_IF>;

/** Join an IPv4 multicast group (IP_ADD_MEMBERSHIP).

    @par Example

    @code

    sock.set_option( native_socket_option::join_group_v4(

        ipv4_address( "239.255.0.1" ) ) );

    @endcode

*/

class join_group_v4

{

    struct ip_mreq value_{};

public:

    /// Construct with default values.

    /** Construct with a group and optional interface address.

        @param group The multicast group address to join.

        @param iface The local interface to use (default: any).

    */

        ipv4_address group, ipv4_address iface = ipv4_address()) noexcept

    /// Return the protocol level for `setsockopt`/`getsockopt`.

    {

    }

    /// Return the option name for `setsockopt`/`getsockopt`.

    {

    }

    /// Return a pointer to the underlying storage.

    {

    }

    /// Return a pointer to the underlying storage.

    void const* data() const noexcept

    {

        return &value_;

    }

    /// Return the size of the underlying storage.

    {

    }

    /// No-op resize.

    void resize(std::size_t) noexcept {}

};

/** Leave an IPv4 multicast group (IP_DROP_MEMBERSHIP).

    @par Example

    @code

    sock.set_option( native_socket_option::leave_group_v4(

        ipv4_address( "239.255.0.1" ) ) );

    @endcode

*/

class leave_group_v4

{

    struct ip_mreq value_{};

public:

    /// Construct with default values.

    /** Construct with a group and optional interface address.

        @param group The multicast group address to leave.

        @param iface The local interface (default: any).

    */

        ipv4_address group, ipv4_address iface = ipv4_address()) noexcept

    /// Return the protocol level for `setsockopt`/`getsockopt`.

    {

    }

    /// Return the option name for `setsockopt`/`getsockopt`.

    {

    }

    /// Return a pointer to the underlying storage.

    {

    }

    /// Return a pointer to the underlying storage.

    void const* data() const noexcept

    {

        return &value_;

    }

    /// Return the size of the underlying storage.

    {

    }

    /// No-op resize.

    void resize(std::size_t) noexcept {}

};

/** Join an IPv6 multicast group (IPV6_JOIN_GROUP).

    @par Example

    @code

    sock.set_option( native_socket_option::join_group_v6(

        ipv6_address( "ff02::1" ), 0 ) );

    @endcode

*/

class join_group_v6

{

    struct ipv6_mreq value_{};

public:

    /// Construct with default values.

    /** Construct with a group and optional interface index.

        @param group The multicast group address to join.

        @param if_index The interface index (0 = kernel chooses).

    */