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include/asio/ip/detail/endpoint.hpp

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+//
+// ip/detail/endpoint.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// 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)
+//
+
+#ifndef ASIO_IP_DETAIL_ENDPOINT_HPP
+#define ASIO_IP_DETAIL_ENDPOINT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include <string>
+#include "asio/detail/socket_types.hpp"
+#include "asio/detail/winsock_init.hpp"
+#include "asio/error_code.hpp"
+#include "asio/ip/address.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace ip {
+namespace detail {
+
+// Helper class for implementing an IP endpoint.
+class endpoint
+{
+public:
+  // Default constructor.
+  ASIO_DECL endpoint() noexcept;
+
+  // Construct an endpoint using a family and port number.
+  ASIO_DECL endpoint(int family,
+      unsigned short port_num) noexcept;
+
+  // Construct an endpoint using an address and port number.
+  ASIO_DECL endpoint(const asio::ip::address& addr,
+      unsigned short port_num) noexcept;
+
+  // Copy constructor.
+  endpoint(const endpoint& other) noexcept
+    : data_(other.data_)
+  {
+  }
+
+  // Assign from another endpoint.
+  endpoint& operator=(const endpoint& other) noexcept
+  {
+    data_ = other.data_;
+    return *this;
+  }
+
+  // Get the underlying endpoint in the native type.
+  asio::detail::socket_addr_type* data() noexcept
+  {
+    return &data_.base[0];
+  }
+
+  // Get the underlying endpoint in the native type.
+  const asio::detail::socket_addr_type* data() const noexcept
+  {
+    return &data_.base[0];
+  }
+
+  // Get the underlying size of the endpoint in the native type.
+  std::size_t size() const noexcept
+  {
+    if (is_v4())
+      return sizeof(asio::detail::sockaddr_in4_type);
+    else
+      return sizeof(asio::detail::sockaddr_in6_type);
+  }
+
+  // Set the underlying size of the endpoint in the native type.
+  ASIO_DECL void resize(std::size_t new_size);
+
+  // Get the capacity of the endpoint in the native type.
+  std::size_t capacity() const noexcept
+  {
+    return sizeof(data_);
+  }
+
+  // Get the port associated with the endpoint.
+  ASIO_DECL unsigned short port() const noexcept;
+
+  // Set the port associated with the endpoint.
+  ASIO_DECL void port(unsigned short port_num) noexcept;
+
+  // Get the IP address associated with the endpoint.
+  ASIO_DECL asio::ip::address address() const noexcept;
+
+  // Set the IP address associated with the endpoint.
+  ASIO_DECL void address(
+      const asio::ip::address& addr) noexcept;
+
+  // Compare two endpoints for equality.
+  ASIO_DECL friend bool operator==(const endpoint& e1,
+      const endpoint& e2) noexcept;
+
+  // Compare endpoints for ordering.
+  ASIO_DECL friend bool operator<(const endpoint& e1,
+      const endpoint& e2) noexcept;
+
+  // Determine whether the endpoint is IPv4.
+  bool is_v4() const noexcept
+  {
+    return data_.base[0].sa_family == ASIO_OS_DEF(AF_INET);
+  }
+
+#if !defined(ASIO_NO_IOSTREAM)
+  // Convert to a string.
+  ASIO_DECL std::string to_string() const;
+#endif // !defined(ASIO_NO_IOSTREAM)
+
+private:
+  // The underlying IP socket address.
+  union data_union
+  {
+#if defined(_FORTIFY_SOURCE)
+    asio::detail::socket_addr_type base[8];
+#else // defined(_FORTIFY_SOURCE)
+    asio::detail::socket_addr_type base[1];
+#endif // defined(_FORTIFY_SOURCE)
+    asio::detail::sockaddr_in4_type v4;
+    asio::detail::sockaddr_in6_type v6;
+  } data_;
+};
+
+} // namespace detail
+} // namespace ip
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#if defined(ASIO_HEADER_ONLY)
+# include "asio/ip/detail/impl/endpoint.ipp"
+#endif // defined(ASIO_HEADER_ONLY)
+
+#endif // ASIO_IP_DETAIL_ENDPOINT_HPP

include/asio/ip/detail/impl/endpoint.ipp

@@ -0,0 +1,195 @@
+//
+// ip/detail/impl/endpoint.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// 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)
+//
+
+#ifndef ASIO_IP_DETAIL_IMPL_ENDPOINT_IPP
+#define ASIO_IP_DETAIL_IMPL_ENDPOINT_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include <cstring>
+#if !defined(ASIO_NO_IOSTREAM)
+# include <sstream>
+#endif // !defined(ASIO_NO_IOSTREAM)
+#include "asio/detail/socket_ops.hpp"
+#include "asio/detail/throw_error.hpp"
+#include "asio/error.hpp"
+#include "asio/ip/detail/endpoint.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace ip {
+namespace detail {
+
+endpoint::endpoint() noexcept
+  : data_()
+{
+  data_.v4.sin_family = ASIO_OS_DEF(AF_INET);
+  data_.v4.sin_port = 0;
+  data_.v4.sin_addr.s_addr = ASIO_OS_DEF(INADDR_ANY);
+}
+
+endpoint::endpoint(int family, unsigned short port_num) noexcept
+  : data_()
+{
+  using namespace std; // For memcpy.
+  if (family == ASIO_OS_DEF(AF_INET))
+  {
+    data_.v4.sin_family = ASIO_OS_DEF(AF_INET);
+    data_.v4.sin_port =
+      asio::detail::socket_ops::host_to_network_short(port_num);
+    data_.v4.sin_addr.s_addr = ASIO_OS_DEF(INADDR_ANY);
+  }
+  else
+  {
+    data_.v6.sin6_family = ASIO_OS_DEF(AF_INET6);
+    data_.v6.sin6_port =
+      asio::detail::socket_ops::host_to_network_short(port_num);
+    data_.v6.sin6_flowinfo = 0;
+    data_.v6.sin6_addr.s6_addr[0] = 0; data_.v6.sin6_addr.s6_addr[1] = 0;
+    data_.v6.sin6_addr.s6_addr[2] = 0; data_.v6.sin6_addr.s6_addr[3] = 0;
+    data_.v6.sin6_addr.s6_addr[4] = 0; data_.v6.sin6_addr.s6_addr[5] = 0;
+    data_.v6.sin6_addr.s6_addr[6] = 0; data_.v6.sin6_addr.s6_addr[7] = 0;
+    data_.v6.sin6_addr.s6_addr[8] = 0; data_.v6.sin6_addr.s6_addr[9] = 0;
+    data_.v6.sin6_addr.s6_addr[10] = 0; data_.v6.sin6_addr.s6_addr[11] = 0;
+    data_.v6.sin6_addr.s6_addr[12] = 0; data_.v6.sin6_addr.s6_addr[13] = 0;
+    data_.v6.sin6_addr.s6_addr[14] = 0; data_.v6.sin6_addr.s6_addr[15] = 0;
+    data_.v6.sin6_scope_id = 0;
+  }
+}
+
+endpoint::endpoint(const asio::ip::address& addr,
+    unsigned short port_num) noexcept
+  : data_()
+{
+  using namespace std; // For memcpy.
+  if (addr.is_v4())
+  {
+    data_.v4.sin_family = ASIO_OS_DEF(AF_INET);
+    data_.v4.sin_port =
+      asio::detail::socket_ops::host_to_network_short(port_num);
+    data_.v4.sin_addr.s_addr =
+      asio::detail::socket_ops::host_to_network_long(
+        addr.to_v4().to_uint());
+  }
+  else
+  {
+    data_.v6.sin6_family = ASIO_OS_DEF(AF_INET6);
+    data_.v6.sin6_port =
+      asio::detail::socket_ops::host_to_network_short(port_num);
+    data_.v6.sin6_flowinfo = 0;
+    asio::ip::address_v6 v6_addr = addr.to_v6();
+    asio::ip::address_v6::bytes_type bytes = v6_addr.to_bytes();
+    memcpy(data_.v6.sin6_addr.s6_addr, bytes.data(), 16);
+    data_.v6.sin6_scope_id =
+      static_cast<asio::detail::u_long_type>(
+        v6_addr.scope_id());
+  }
+}
+
+void endpoint::resize(std::size_t new_size)
+{
+  if (new_size > sizeof(asio::detail::sockaddr_storage_type))
+  {
+    asio::error_code ec(asio::error::invalid_argument);
+    asio::detail::throw_error(ec);
+  }
+}
+
+unsigned short endpoint::port() const noexcept
+{
+  if (is_v4())
+  {
+    return asio::detail::socket_ops::network_to_host_short(
+        data_.v4.sin_port);
+  }
+  else
+  {
+    return asio::detail::socket_ops::network_to_host_short(
+        data_.v6.sin6_port);
+  }
+}
+
+void endpoint::port(unsigned short port_num) noexcept
+{
+  if (is_v4())
+  {
+    data_.v4.sin_port
+      = asio::detail::socket_ops::host_to_network_short(port_num);
+  }
+  else
+  {
+    data_.v6.sin6_port
+      = asio::detail::socket_ops::host_to_network_short(port_num);
+  }
+}
+
+asio::ip::address endpoint::address() const noexcept
+{
+  using namespace std; // For memcpy.
+  if (is_v4())
+  {
+    return asio::ip::address_v4(
+        asio::detail::socket_ops::network_to_host_long(
+          data_.v4.sin_addr.s_addr));
+  }
+  else
+  {
+    asio::ip::address_v6::bytes_type bytes;
+    memcpy(bytes.data(), data_.v6.sin6_addr.s6_addr, 16);
+    return asio::ip::address_v6(bytes, data_.v6.sin6_scope_id);
+  }
+}
+
+void endpoint::address(const asio::ip::address& addr) noexcept
+{
+  endpoint tmp_endpoint(addr, port());
+  data_ = tmp_endpoint.data_;
+}
+
+bool operator==(const endpoint& e1, const endpoint& e2) noexcept
+{
+  return e1.address() == e2.address() && e1.port() == e2.port();
+}
+
+bool operator<(const endpoint& e1, const endpoint& e2) noexcept
+{
+  if (e1.address() < e2.address())
+    return true;
+  if (e1.address() != e2.address())
+    return false;
+  return e1.port() < e2.port();
+}
+
+#if !defined(ASIO_NO_IOSTREAM)
+std::string endpoint::to_string() const
+{
+  std::ostringstream tmp_os;
+  tmp_os.imbue(std::locale::classic());
+  if (is_v4())
+    tmp_os << address();
+  else
+    tmp_os << '[' << address() << ']';
+  tmp_os << ':' << port();
+
+  return tmp_os.str();
+}
+#endif // !defined(ASIO_NO_IOSTREAM)
+
+} // namespace detail
+} // namespace ip
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_IP_DETAIL_IMPL_ENDPOINT_IPP

include/asio/ip/detail/socket_option.hpp

@@ -0,0 +1,566 @@
+//
+// detail/socket_option.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// 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)
+//
+
+#ifndef ASIO_IP_DETAIL_SOCKET_OPTION_HPP
+#define ASIO_IP_DETAIL_SOCKET_OPTION_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include <cstddef>
+#include <cstring>
+#include <stdexcept>
+#include "asio/detail/socket_ops.hpp"
+#include "asio/detail/socket_types.hpp"
+#include "asio/detail/throw_exception.hpp"
+#include "asio/ip/address.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace ip {
+namespace detail {
+namespace socket_option {
+
+// Helper template for implementing multicast enable loopback options.
+template <int IPv4_Level, int IPv4_Name, int IPv6_Level, int IPv6_Name>
+class multicast_enable_loopback
+{
+public:
+#if defined(__sun) || defined(__osf__)
+  typedef unsigned char ipv4_value_type;
+  typedef unsigned char ipv6_value_type;
+#elif defined(_AIX) || defined(__hpux) || defined(__QNXNTO__)
+  typedef unsigned char ipv4_value_type;
+  typedef unsigned int ipv6_value_type;
+#else
+  typedef int ipv4_value_type;
+  typedef int ipv6_value_type;
+#endif
+
+  // Default constructor.
+  multicast_enable_loopback()
+    : ipv4_value_(0),
+      ipv6_value_(0)
+  {
+  }
+
+  // Construct with a specific option value.
+  explicit multicast_enable_loopback(bool v)
+    : ipv4_value_(v ? 1 : 0),
+      ipv6_value_(v ? 1 : 0)
+  {
+  }
+
+  // Set the value of the boolean.
+  multicast_enable_loopback& operator=(bool v)
+  {
+    ipv4_value_ = v ? 1 : 0;
+    ipv6_value_ = v ? 1 : 0;
+    return *this;
+  }
+
+  // Get the current value of the boolean.
+  bool value() const
+  {
+    return !!ipv4_value_;
+  }
+
+  // Convert to bool.
+  operator bool() const
+  {
+    return !!ipv4_value_;
+  }
+
+  // Test for false.
+  bool operator!() const
+  {
+    return !ipv4_value_;
+  }
+
+  // Get the level of the socket option.
+  template <typename Protocol>
+  int level(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Level;
+    return IPv4_Level;
+  }
+
+  // Get the name of the socket option.
+  template <typename Protocol>
+  int name(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Name;
+    return IPv4_Name;
+  }
+
+  // Get the address of the boolean data.
+  template <typename Protocol>
+  void* data(const Protocol& protocol)
+  {
+    if (protocol.family() == PF_INET6)
+      return &ipv6_value_;
+    return &ipv4_value_;
+  }
+
+  // Get the address of the boolean data.
+  template <typename Protocol>
+  const void* data(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return &ipv6_value_;
+    return &ipv4_value_;
+  }
+
+  // Get the size of the boolean data.
+  template <typename Protocol>
+  std::size_t size(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return sizeof(ipv6_value_);
+    return sizeof(ipv4_value_);
+  }
+
+  // Set the size of the boolean data.
+  template <typename Protocol>
+  void resize(const Protocol& protocol, std::size_t s)
+  {
+    if (protocol.family() == PF_INET6)
+    {
+      if (s != sizeof(ipv6_value_))
+      {
+        std::length_error ex("multicast_enable_loopback socket option resize");
+        asio::detail::throw_exception(ex);
+      }
+      ipv4_value_ = ipv6_value_ ? 1 : 0;
+    }
+    else
+    {
+      if (s != sizeof(ipv4_value_))
+      {
+        std::length_error ex("multicast_enable_loopback socket option resize");
+        asio::detail::throw_exception(ex);
+      }
+      ipv6_value_ = ipv4_value_ ? 1 : 0;
+    }
+  }
+
+private:
+  ipv4_value_type ipv4_value_;
+  ipv6_value_type ipv6_value_;
+};
+
+// Helper template for implementing unicast hops options.
+template <int IPv4_Level, int IPv4_Name, int IPv6_Level, int IPv6_Name>
+class unicast_hops
+{
+public:
+  // Default constructor.
+  unicast_hops()
+    : value_(0)
+  {
+  }
+
+  // Construct with a specific option value.
+  explicit unicast_hops(int v)
+    : value_(v)
+  {
+  }
+
+  // Set the value of the option.
+  unicast_hops& operator=(int v)
+  {
+    value_ = v;
+    return *this;
+  }
+
+  // Get the current value of the option.
+  int value() const
+  {
+    return value_;
+  }
+
+  // Get the level of the socket option.
+  template <typename Protocol>
+  int level(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Level;
+    return IPv4_Level;
+  }
+
+  // Get the name of the socket option.
+  template <typename Protocol>
+  int name(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Name;
+    return IPv4_Name;
+  }
+
+  // Get the address of the data.
+  template <typename Protocol>
+  int* data(const Protocol&)
+  {
+    return &value_;
+  }
+
+  // Get the address of the data.
+  template <typename Protocol>
+  const int* data(const Protocol&) const
+  {
+    return &value_;
+  }
+
+  // Get the size of the data.
+  template <typename Protocol>
+  std::size_t size(const Protocol&) const
+  {
+    return sizeof(value_);
+  }
+
+  // Set the size of the data.
+  template <typename Protocol>
+  void resize(const Protocol&, std::size_t s)
+  {
+    if (s != sizeof(value_))
+    {
+      std::length_error ex("unicast hops socket option resize");
+      asio::detail::throw_exception(ex);
+    }
+#if defined(__hpux)
+    if (value_ < 0)
+      value_ = value_ & 0xFF;
+#endif
+  }
+
+private:
+  int value_;
+};
+
+// Helper template for implementing multicast hops options.
+template <int IPv4_Level, int IPv4_Name, int IPv6_Level, int IPv6_Name>
+class multicast_hops
+{
+public:
+#if defined(ASIO_WINDOWS) && defined(UNDER_CE)
+  typedef int ipv4_value_type;
+#else
+  typedef unsigned char ipv4_value_type;
+#endif
+  typedef int ipv6_value_type;
+
+  // Default constructor.
+  multicast_hops()
+    : ipv4_value_(0),
+      ipv6_value_(0)
+  {
+  }
+
+  // Construct with a specific option value.
+  explicit multicast_hops(int v)
+  {
+    if (v < 0 || v > 255)
+    {
+      std::out_of_range ex("multicast hops value out of range");
+      asio::detail::throw_exception(ex);
+    }
+    ipv4_value_ = (ipv4_value_type)v;
+    ipv6_value_ = v;
+  }
+
+  // Set the value of the option.
+  multicast_hops& operator=(int v)
+  {
+    if (v < 0 || v > 255)
+    {
+      std::out_of_range ex("multicast hops value out of range");
+      asio::detail::throw_exception(ex);
+    }
+    ipv4_value_ = (ipv4_value_type)v;
+    ipv6_value_ = v;
+    return *this;
+  }
+
+  // Get the current value of the option.
+  int value() const
+  {
+    return ipv6_value_;
+  }
+
+  // Get the level of the socket option.
+  template <typename Protocol>
+  int level(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Level;
+    return IPv4_Level;
+  }
+
+  // Get the name of the socket option.
+  template <typename Protocol>
+  int name(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Name;
+    return IPv4_Name;
+  }
+
+  // Get the address of the data.
+  template <typename Protocol>
+  void* data(const Protocol& protocol)
+  {
+    if (protocol.family() == PF_INET6)
+      return &ipv6_value_;
+    return &ipv4_value_;
+  }
+
+  // Get the address of the data.
+  template <typename Protocol>
+  const void* data(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return &ipv6_value_;
+    return &ipv4_value_;
+  }
+
+  // Get the size of the data.
+  template <typename Protocol>
+  std::size_t size(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return sizeof(ipv6_value_);
+    return sizeof(ipv4_value_);
+  }
+
+  // Set the size of the data.
+  template <typename Protocol>
+  void resize(const Protocol& protocol, std::size_t s)
+  {
+    if (protocol.family() == PF_INET6)
+    {
+      if (s != sizeof(ipv6_value_))
+      {
+        std::length_error ex("multicast hops socket option resize");
+        asio::detail::throw_exception(ex);
+      }
+      if (ipv6_value_ < 0)
+        ipv4_value_ = 0;
+      else if (ipv6_value_ > 255)
+        ipv4_value_ = 255;
+      else
+        ipv4_value_ = (ipv4_value_type)ipv6_value_;
+    }
+    else
+    {
+      if (s != sizeof(ipv4_value_))
+      {
+        std::length_error ex("multicast hops socket option resize");
+        asio::detail::throw_exception(ex);
+      }
+      ipv6_value_ = ipv4_value_;
+    }
+  }
+
+private:
+  ipv4_value_type ipv4_value_;
+  ipv6_value_type ipv6_value_;
+};
+
+// Helper template for implementing ip_mreq-based options.
+template <int IPv4_Level, int IPv4_Name, int IPv6_Level, int IPv6_Name>
+class multicast_request
+{
+public:
+  // Default constructor.
+  multicast_request()
+    : ipv4_value_(), // Zero-initialisation gives the "any" address.
+      ipv6_value_() // Zero-initialisation gives the "any" address.
+  {
+  }
+
+  // Construct with multicast address only.
+  explicit multicast_request(const address& multicast_address)
+    : ipv4_value_(), // Zero-initialisation gives the "any" address.
+      ipv6_value_() // Zero-initialisation gives the "any" address.
+  {
+    if (multicast_address.is_v6())
+    {
+      using namespace std; // For memcpy.
+      address_v6 ipv6_address = multicast_address.to_v6();
+      address_v6::bytes_type bytes = ipv6_address.to_bytes();
+      memcpy(ipv6_value_.ipv6mr_multiaddr.s6_addr, bytes.data(), 16);
+      ipv6_value_.ipv6mr_interface = ipv6_address.scope_id();
+    }
+    else
+    {
+      ipv4_value_.imr_multiaddr.s_addr =
+        asio::detail::socket_ops::host_to_network_long(
+            multicast_address.to_v4().to_uint());
+      ipv4_value_.imr_interface.s_addr =
+        asio::detail::socket_ops::host_to_network_long(
+            address_v4::any().to_uint());
+    }
+  }
+
+  // Construct with multicast address and IPv4 address specifying an interface.
+  explicit multicast_request(const address_v4& multicast_address,
+      const address_v4& network_interface = address_v4::any())
+    : ipv6_value_() // Zero-initialisation gives the "any" address.
+  {
+    ipv4_value_.imr_multiaddr.s_addr =
+      asio::detail::socket_ops::host_to_network_long(
+          multicast_address.to_uint());
+    ipv4_value_.imr_interface.s_addr =
+      asio::detail::socket_ops::host_to_network_long(
+          network_interface.to_uint());
+  }
+
+  // Construct with multicast address and IPv6 network interface index.
+  explicit multicast_request(
+      const address_v6& multicast_address,
+      unsigned long network_interface = 0)
+    : ipv4_value_() // Zero-initialisation gives the "any" address.
+  {
+    using namespace std; // For memcpy.
+    address_v6::bytes_type bytes = multicast_address.to_bytes();
+    memcpy(ipv6_value_.ipv6mr_multiaddr.s6_addr, bytes.data(), 16);
+    if (network_interface)
+      ipv6_value_.ipv6mr_interface = network_interface;
+    else
+      ipv6_value_.ipv6mr_interface = multicast_address.scope_id();
+  }
+
+  // Get the level of the socket option.
+  template <typename Protocol>
+  int level(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Level;
+    return IPv4_Level;
+  }
+
+  // Get the name of the socket option.
+  template <typename Protocol>
+  int name(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Name;
+    return IPv4_Name;
+  }
+
+  // Get the address of the option data.
+  template <typename Protocol>
+  const void* data(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return &ipv6_value_;
+    return &ipv4_value_;
+  }
+
+  // Get the size of the option data.
+  template <typename Protocol>
+  std::size_t size(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return sizeof(ipv6_value_);
+    return sizeof(ipv4_value_);
+  }
+
+private:
+  asio::detail::in4_mreq_type ipv4_value_;
+  asio::detail::in6_mreq_type ipv6_value_;
+};
+
+// Helper template for implementing options that specify a network interface.
+template <int IPv4_Level, int IPv4_Name, int IPv6_Level, int IPv6_Name>
+class network_interface
+{
+public:
+  // Default constructor.
+  network_interface()
+  {
+    ipv4_value_.s_addr =
+      asio::detail::socket_ops::host_to_network_long(
+          address_v4::any().to_uint());
+    ipv6_value_ = 0;
+  }
+
+  // Construct with IPv4 interface.
+  explicit network_interface(const address_v4& ipv4_interface)
+  {
+    ipv4_value_.s_addr =
+      asio::detail::socket_ops::host_to_network_long(
+          ipv4_interface.to_uint());
+    ipv6_value_ = 0;
+  }
+
+  // Construct with IPv6 interface.
+  explicit network_interface(unsigned int ipv6_interface)
+  {
+    ipv4_value_.s_addr =
+      asio::detail::socket_ops::host_to_network_long(
+          address_v4::any().to_uint());
+    ipv6_value_ = ipv6_interface;
+  }
+
+  // Get the level of the socket option.
+  template <typename Protocol>
+  int level(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Level;
+    return IPv4_Level;
+  }
+
+  // Get the name of the socket option.
+  template <typename Protocol>
+  int name(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return IPv6_Name;
+    return IPv4_Name;
+  }
+
+  // Get the address of the option data.
+  template <typename Protocol>
+  const void* data(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return &ipv6_value_;
+    return &ipv4_value_;
+  }
+
+  // Get the size of the option data.
+  template <typename Protocol>
+  std::size_t size(const Protocol& protocol) const
+  {
+    if (protocol.family() == PF_INET6)
+      return sizeof(ipv6_value_);
+    return sizeof(ipv4_value_);
+  }
+
+private:
+  asio::detail::in4_addr_type ipv4_value_;
+  unsigned int ipv6_value_;
+};
+
+} // namespace socket_option
+} // namespace detail
+} // namespace ip
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_IP_DETAIL_SOCKET_OPTION_HPP