# HG changeset patch
# User David Demelier <markand@malikania.fr>
# Date 1445536851 -7200
# Node ID 2dbaf2fb03ef431b4779f130c6e0dd8868d6c0c7
# Parent  b9c8b179288942bfadd9aa893a5659ca56f9b272
Socket: add forgotten Sockets.*

diff -r b9c8b1792889 -r 2dbaf2fb03ef C++/modules/Socket/Sockets.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/C++/modules/Socket/Sockets.cpp	Thu Oct 22 20:00:51 2015 +0200
@@ -0,0 +1,611 @@
+/*
+ * Sockets.cpp -- portable C++ socket wrappers
+ *
+ * Copyright (c) 2013-2015 David Demelier <markand@malikania.fr>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#if defined(_WIN32)
+#  include <atomic>
+#  include <mutex>
+#endif
+
+#include <algorithm>
+#include <cstring>
+
+#include "Sockets.h"
+
+namespace net {
+
+/*
+ * Portable constants
+ * ------------------------------------------------------------------
+ */
+
+/* {{{ Constants */
+
+#if defined(_WIN32)
+
+const Handle Invalid{INVALID_SOCKET};
+const int Failure{SOCKET_ERROR};
+
+#else
+
+const Handle Invalid{-1};
+const int Failure{-1};
+
+#endif
+
+/* }}} */
+
+/*
+ * Portable functions
+ * ------------------------------------------------------------------
+ */
+
+/* {{{ Functions */
+
+#if defined(_WIN32)
+
+static std::mutex s_mutex;
+static std::atomic<bool> s_initialized{false};
+
+#endif // !_WIN32
+
+void init() noexcept
+{
+#if defined(_WIN32)
+	std::lock_guard<std::mutex> lock(s_mutex);
+
+	if (!s_initialized) {
+		s_initialized = true;
+
+		WSADATA wsa;
+		WSAStartup(MAKEWORD(2, 2), &wsa);
+
+		/*
+		 * If SOCKET_WSA_NO_INIT is not set then the user
+		 * must also call finish himself.
+		 */
+#if !defined(SOCKET_NO_AUTO_INIT)
+		atexit(finish);
+#endif
+	}
+#endif
+}
+
+void finish() noexcept
+{
+#if defined(_WIN32)
+	WSACleanup();
+#endif
+}
+
+std::string error(int errn)
+{
+#if defined(_WIN32)
+	LPSTR str = nullptr;
+	std::string errmsg = "Unknown error";
+
+	FormatMessageA(
+		FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
+		NULL,
+		errn,
+		MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+		(LPSTR)&str, 0, NULL);
+
+
+	if (str) {
+		errmsg = std::string(str);
+		LocalFree(str);
+	}
+
+	return errmsg;
+#else
+	return strerror(errn);
+#endif
+}
+
+std::string error()
+{
+#if defined(_WIN32)
+	return error(WSAGetLastError());
+#else
+	return error(errno);
+#endif
+}
+
+/* }}} */
+
+/*
+ * Error class
+ * ------------------------------------------------------------------
+ */
+
+/* {{{ Error */
+
+Error::Error(Code code, std::string function)
+	: m_code{code}
+	, m_function{std::move(function)}
+	, m_error{error()}
+{
+}
+
+Error::Error(Code code, std::string function, int n)
+	: m_code{code}
+	, m_function{std::move(function)}
+	, m_error{error(n)}
+{
+}
+
+Error::Error(Code code, std::string function, std::string error)
+	: m_code{code}
+	, m_function{std::move(function)}
+	, m_error{std::move(error)}
+{
+}
+
+/* }}} */
+
+/*
+ * Predefine addressed to be used
+ * ------------------------------------------------------------------
+ */
+
+/* {{{ Addresses */
+
+Ip::Ip(int domain) noexcept
+	: m_domain{domain}
+{
+	if (m_domain == AF_INET6) {
+		std::memset(&m_sin6, 0, sizeof (sockaddr_in6));
+	} else {
+		std::memset(&m_sin, 0, sizeof (sockaddr_in));
+	}
+}
+
+Ip::Ip(const std::string &host, int port, int domain)
+	: m_domain{domain}
+{
+	if (host == "*") {
+		if (m_domain == AF_INET6) {
+			std::memset(&m_sin6, 0, sizeof (sockaddr_in6));
+
+			m_length = sizeof (sockaddr_in6);
+			m_sin6.sin6_addr = in6addr_any;
+			m_sin6.sin6_family = AF_INET6;
+			m_sin6.sin6_port = htons(port);
+		} else {
+			std::memset(&m_sin, 0, sizeof (sockaddr_in));
+
+			m_length = sizeof (sockaddr_in);
+			m_sin.sin_addr.s_addr = INADDR_ANY;
+			m_sin.sin_family = AF_INET;
+			m_sin.sin_port = htons(port);
+		}
+	} else {
+		addrinfo hints, *res;
+
+		std::memset(&hints, 0, sizeof (addrinfo));
+		hints.ai_family = domain;
+
+		auto error = getaddrinfo(host.c_str(), std::to_string(port).c_str(), &hints, &res);
+		if (error != 0) {
+			throw Error{Error::System, "getaddrinfo", gai_strerror(error)};
+		}
+
+		if (m_domain == AF_INET6) {
+			std::memcpy(&m_sin6, res->ai_addr, res->ai_addrlen);
+		} else {
+			std::memcpy(&m_sin, res->ai_addr, res->ai_addrlen);
+		}
+
+		m_length = res->ai_addrlen;
+		freeaddrinfo(res);
+	}
+}
+
+Ip::Ip(const struct sockaddr_storage *ss, socklen_t length)
+	: m_length{length}
+{
+	if (ss->ss_family == AF_INET6) {
+		std::memcpy(&m_sin6, ss, length);
+	} else if (ss->ss_family == AF_INET) {
+		std::memcpy(&m_sin, ss, length);
+	} else {
+		throw std::invalid_argument{"invalid domain for Ip constructor"};
+	}
+}
+
+#if !defined(_WIN32)
+
+Local::Local(std::string path, bool rm)
+	: m_path{std::move(path)}
+{
+	/* Silently remove the file even if it fails */
+	if (rm) {
+		::remove(m_path.c_str());
+	}
+
+	/* Copy the path */
+	std::memset(m_sun.sun_path, 0, sizeof (m_sun.sun_path));
+	std::strncpy(m_sun.sun_path, m_path.c_str(), sizeof (m_sun.sun_path) - 1);
+
+	/* Set the parameters */
+	m_sun.sun_family = AF_UNIX;
+}
+
+Local::Local(const sockaddr_storage &ss, socklen_t length)
+{
+	if (ss.ss_family == AF_UNIX) {
+		std::memcpy(&m_sun, &ss, length);
+		m_path = reinterpret_cast<const sockaddr_un &>(m_sun).sun_path;
+	} else {
+		throw std::invalid_argument{"invalid domain for local constructor"};
+	}
+}
+
+#endif // !_WIN32
+
+/* }}} */
+
+const int FlagRead{1 << 0};
+const int FlagWrite{1 << 1};
+
+std::vector<ListenerStatus> Select::wait(const ListenerTable &table, int ms)
+{
+	timeval maxwait, *towait;
+	fd_set readset;
+	fd_set writeset;
+
+	FD_ZERO(&readset);
+	FD_ZERO(&writeset);
+
+	Handle max = 0;
+
+	for (const auto &pair : table) {
+		if (pair.second & FlagRead) {
+			FD_SET(pair.first, &readset);
+		}
+		if (pair.second & FlagWrite) {
+			FD_SET(pair.first, &writeset);
+		}
+
+		if (pair.first > max) {
+			max = pair.first;
+		}
+	}
+
+	maxwait.tv_sec = 0;
+	maxwait.tv_usec = ms * 1000;
+
+	// Set to nullptr for infinite timeout.
+	towait = (ms < 0) ? nullptr : &maxwait;
+
+	auto error = ::select(max + 1, &readset, &writeset, nullptr, towait);
+	if (error == Failure) {
+		throw Error{Error::System, "select"};
+	}
+	if (error == 0) {
+		throw Error{Error::Timeout, "select", "Timeout while listening"};
+	}
+
+	std::vector<ListenerStatus> sockets;
+
+	for (const auto &pair : table) {
+		if (FD_ISSET(pair.first, &readset)) {
+			sockets.push_back(ListenerStatus{pair.first, FlagRead});
+		}
+		if (FD_ISSET(pair.first, &writeset)) {
+			sockets.push_back(ListenerStatus{pair.first, FlagWrite});
+		}
+	}
+
+	return sockets;
+}
+
+/* --------------------------------------------------------
+ * Poll implementation
+ * -------------------------------------------------------- */
+
+#if defined(SOCKET_HAVE_POLL)
+
+#if defined(_WIN32)
+#  define poll WSAPoll
+#endif
+
+short Poll::topoll(int flags) const noexcept
+{
+	short result(0);
+
+	if (flags & FlagRead) {
+		result |= POLLIN;
+	}
+	if (flags & FlagWrite) {
+		result |= POLLOUT;
+	}
+
+	return result;
+}
+
+int Poll::toflags(short &event) const noexcept
+{
+	int flags = 0;
+
+	/*
+	 * Poll implementations mark the socket differently regarding
+	 * the disconnection of a socket.
+	 *
+	 * At least, even if POLLHUP or POLLIN is set, recv() always
+	 * return 0 so we mark the socket as readable.
+	 */
+	if ((event & POLLIN) || (event & POLLHUP)) {
+		flags |= FlagRead;
+	}
+	if (event & POLLOUT) {
+		flags |= FlagWrite;
+	}
+
+	/* Reset event for safety */
+	event = 0;
+
+	return flags;
+}
+
+void Poll::set(const ListenerTable &, Handle h, int flags, bool add)
+{
+	if (add) {
+		m_fds.push_back(pollfd{h, topoll(flags), 0});
+	} else {
+		auto it = std::find_if(m_fds.begin(), m_fds.end(), [&] (const struct pollfd &pfd) {
+			return pfd.fd == h;
+		});
+
+		it->events |= topoll(flags);
+	}
+}
+
+void Poll::unset(const ListenerTable &, Handle h, int flags, bool remove)
+{
+	auto it = std::find_if(m_fds.begin(), m_fds.end(), [&] (const struct pollfd &pfd) {
+		return pfd.fd == h;
+	});
+
+	if (remove) {
+		m_fds.erase(it);
+	} else {
+		it->events &= ~(topoll(flags));
+	}
+}
+
+std::vector<ListenerStatus> Poll::wait(const ListenerTable &, int ms)
+{
+	auto result = poll(m_fds.data(), m_fds.size(), ms);
+	if (result == 0) {
+		throw Error{Error::Timeout, "select", "Timeout while listening"};
+	}
+	if (result < 0) {
+		throw Error{Error::System, "poll"};
+	}
+
+	std::vector<ListenerStatus> sockets;
+	for (auto &fd : m_fds) {
+		if (fd.revents != 0) {
+			sockets.push_back(ListenerStatus{fd.fd, toflags(fd.revents)});
+		}
+	}
+
+	return sockets;
+}
+
+#endif // !SOCKET_HAVE_POLL
+
+/* --------------------------------------------------------
+ * Epoll implementation
+ * -------------------------------------------------------- */
+
+#if defined(SOCKET_HAVE_EPOLL)
+
+uint32_t Epoll::toepoll(int flags) const noexcept
+{
+	uint32_t events = 0;
+
+	if (flags & FlagRead) {
+		events |= EPOLLIN;
+	}
+	if (flags & FlagWrite) {
+		events |= EPOLLOUT;
+	}
+
+	return events;
+}
+
+int Epoll::toflags(uint32_t events) const noexcept
+{
+	int flags = 0;
+
+	if ((events & EPOLLIN) || (events & EPOLLHUP)) {
+		flags |= FlagRead;
+	}
+	if (events & EPOLLOUT) {
+		flags |= FlagWrite;
+	}
+
+	return flags;
+}
+
+void Epoll::update(Handle h, int op, int flags)
+{
+	struct epoll_event ev;
+
+	std::memset(&ev, 0, sizeof (struct epoll_event));
+
+	ev.events = flags;
+	ev.data.fd = h;
+
+	if (epoll_ctl(m_handle, op, h, &ev) < 0) {
+		throw Error{Error::System, "epoll_ctl"};
+	}
+}
+
+Epoll::Epoll()
+	: m_handle(epoll_create1(0))
+{
+	if (m_handle < 0) {
+		throw Error{Error::System, "epoll_create"};
+	}
+}
+
+Epoll::~Epoll()
+{
+	close(m_handle);
+}
+
+/*
+ * Add a new epoll_event or just update it.
+ */
+void Epoll::set(const ListenerTable &, Handle h, int flags, bool add)
+{
+	update(h, add ? EPOLL_CTL_ADD : EPOLL_CTL_MOD, toepoll(flags));
+
+	if (add) {
+		m_events.resize(m_events.size() + 1);
+	}
+}
+
+/*
+ * Unset is a bit complicated case because SocketListener tells us which
+ * flag to remove but to update epoll descriptor we need to pass
+ * the effective flags that we want to be applied.
+ *
+ * So we put the same flags that are currently effective and remove the
+ * requested one.
+ */
+void Epoll::unset(const ListenerTable &table, Handle sc, int flags, bool remove)
+{
+	if (remove) {
+		update(sc, EPOLL_CTL_DEL, 0);
+		m_events.resize(m_events.size() - 1);
+	} else {
+		update(sc, EPOLL_CTL_MOD, table.at(sc) & ~(toepoll(flags)));
+	}
+}
+
+std::vector<ListenerStatus> Epoll::wait(const ListenerTable &, int ms)
+{
+	int ret = epoll_wait(m_handle, m_events.data(), m_events.size(), ms);
+	std::vector<ListenerStatus> result;
+
+	if (ret == 0) {
+		throw Error{Error::Timeout, "epoll_wait"};
+	}
+	if (ret < 0) {
+		throw Error{Error::System, "epoll_wait"};
+	}
+
+	for (int i = 0; i < ret; ++i) {
+		result.push_back(ListenerStatus{m_events[i].data.fd, toflags(m_events[i].events)});
+	}
+
+	return result;
+}
+
+#endif // !SOCKET_HAVE_EPOLL
+
+/* --------------------------------------------------------
+ * Kqueue implementation
+ * -------------------------------------------------------- */
+
+#if defined(SOCKET_HAVE_KQUEUE)
+
+Kqueue::Kqueue()
+	: m_handle(kqueue())
+{
+	if (m_handle < 0) {
+		throw Error{Error::System, "kqueue"};
+	}
+}
+
+Kqueue::~Kqueue()
+{
+	close(m_handle);
+}
+
+void Kqueue::update(Handle h, int filter, int flags)
+{
+	struct kevent ev;
+
+	EV_SET(&ev, h, filter, flags, 0, 0, nullptr);
+
+	if (kevent(m_handle, &ev, 1, nullptr, 0, nullptr) < 0) {
+		throw Error{Error::System, "kevent"};
+	}
+}
+
+void Kqueue::set(const ListenerTable &, Handle h, int flags, bool add)
+{
+	if (flags & FlagRead) {
+		update(h, EVFILT_READ, EV_ADD | EV_ENABLE);
+	}
+	if (flags & FlagWrite) {
+		update(h, EVFILT_WRITE, EV_ADD | EV_ENABLE);
+	}
+
+	if (add) {
+		m_result.resize(m_result.size() + 1);
+	}
+}
+
+void Kqueue::unset(const ListenerTable &, Handle h, int flags, bool remove)
+{
+	if (flags & FlagRead) {
+		update(h, EVFILT_READ, EV_DELETE);
+	}
+	if (flags & FlagWrite) {
+		update(h, EVFILT_WRITE, EV_DELETE);
+	}
+
+	if (remove) {
+		m_result.resize(m_result.size() - 1);
+	}
+}
+
+std::vector<ListenerStatus> Kqueue::wait(const ListenerTable &table, int ms)
+{
+	std::vector<ListenerStatus> sockets;
+	timespec ts = { 0, 0 };
+	timespec *pts = (ms <= 0) ? nullptr : &ts;
+
+	ts.tv_sec = ms / 1000;
+	ts.tv_nsec = (ms % 1000) * 1000000;
+
+	int nevents = kevent(m_handle, nullptr, 0, &m_result[0], m_result.capacity(), pts);
+
+	if (nevents == 0) {
+		throw Error{Error::Timeout, "kevent"};
+	}
+	if (nevents < 0) {
+		throw Error{Error::System, "kevent"};
+	}
+
+	for (int i = 0; i < nevents; ++i) {
+		sockets.push_back(ListenerStatus{m_result[i].ident, m_result[i].filter == EVFILT_READ ? FlagRead : FlagWrite});
+	}
+
+	return sockets;
+}
+
+#endif // !SOCKET_HAVE_KQUEUE
+
+} // !net
diff -r b9c8b1792889 -r 2dbaf2fb03ef C++/modules/Socket/Sockets.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/C++/modules/Socket/Sockets.h	Thu Oct 22 20:00:51 2015 +0200
@@ -0,0 +1,1875 @@
+/*
+ * Sockets.h -- portable C++ socket wrappers
+ *
+ * Copyright (c) 2013-2015 David Demelier <markand@malikania.fr>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef _SOCKETS_H_
+#define _SOCKETS_H_
+
+/**
+ * @file Sockets.h
+ * @brief Portable socket abstraction
+ *
+ * User may set the following variables before compiling these files:
+ *
+ * - **SOCKET_NO_AUTO_INIT**:(bool) Set to false if you don't want Socket class to
+ * automatically calls net::init function and net::finish functions.
+ *
+ * # For Listener objects
+ *
+ * Feature detection, multiple implementations may be avaible, for example,
+ * Linux has poll, select and epoll.
+ *
+ * We assume that select(2) is always available.
+ *
+ * Of course, you can set the variables yourself if you test it with your
+ * build system.
+ *
+ * - **SOCKET_HAVE_POLL**: Defined on all BSD, Linux. Also defined on Windows
+ * if _WIN32_WINNT is set to 0x0600 or greater.
+ * - **SOCKET_HAVE_KQUEUE**: Defined on all BSD and Apple.
+ * - **SOCKET_HAVE_EPOLL**: Defined on Linux only.
+ */
+
+#if defined(_WIN32)
+#  if _WIN32_WINNT >= 0x0600
+#    define SOCKET_HAVE_POLL
+#  endif
+#elif defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__APPLE__)
+#  define SOCKET_HAVE_KQUEUE
+#  define SOCKET_HAVE_POLL
+#elif defined(__linux__)
+#  define SOCKET_HAVE_EPOLL
+#  define SOCKET_HAVE_POLL
+#endif
+
+/**
+ * This sets the default backend to use depending on the system. The following
+ * table summaries.
+ *
+ * The preference priority is ordered from left to right.
+ *
+ * | System        | Backend                 |
+ * |---------------|-------------------------|
+ * | Linux         | epoll(7)                |
+ * | *BSD          | kqueue(2)               |
+ * | Windows       | poll(2), select(2)      |
+ * | Mac OS X      | kqueue(2)               |
+ */
+
+#if defined(_WIN32)
+#  if defined(SOCKET_HAVE_POLL)
+#    define SOCKET_DEFAULT_BACKEND Poll
+#  else
+#    define SOCKET_DEFAULT_BACKEND Select
+#  endif
+#elif defined(__linux__)
+#  include <sys/epoll.h>
+
+#  define SOCKET_DEFAULT_BACKEND Epoll
+#elif defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__) || defined(__APPLE__)
+#  include <sys/types.h>
+#  include <sys/event.h>
+#  include <sys/time.h>
+
+#  define SOCKET_DEFAULT_BACKEND Kqueue
+#else
+#  define SOCKET_DEFAULT_BACKEND Select
+#endif
+
+#if defined(SOCKET_HAVE_POLL) && !defined(_WIN32)
+#  include <poll.h>
+#endif
+
+#if defined(_WIN32)
+#  include <cstdlib>
+
+#  include <WinSock2.h>
+#  include <WS2tcpip.h>
+#else
+#  include <cerrno>
+
+#  include <sys/ioctl.h>
+#  include <sys/types.h>
+#  include <sys/socket.h>
+#  include <sys/un.h>
+
+#  include <arpa/inet.h>
+
+#  include <netinet/in.h>
+
+#  include <fcntl.h>
+#  include <netdb.h>
+#  include <unistd.h>
+#endif
+
+#include <chrono>
+#include <cstdlib>
+#include <cstring>
+#include <exception>
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace net {
+
+/*
+ * Portable constants
+ * ------------------------------------------------------------------
+ *
+ * These constants are needed to check functions return codes, they are rarely needed in end user code.
+ */
+
+/* {{{ Constants */
+
+/*
+ * The following constants are defined differently from Unix
+ * to Windows.
+ */
+#if defined(_WIN32)
+
+/**
+ * Socket creation failure or invalidation.
+ */
+extern const Handle Invalid;
+
+/**
+ * Socket operation failure.
+ */
+extern const int Failure;
+
+#else
+
+/**
+ * Socket creation failure or invalidation.
+ */
+extern const int Invalid;
+
+/**
+ * Socket operation failure.
+ */
+extern const int Failure;
+
+#endif
+
+/* }}} */
+
+/*
+ * Portable functions
+ * ------------------------------------------------------------------
+ *
+ * The following free functions can be used to initialize the library or to get the last system error.
+ */
+
+/* {{{ Functions */
+
+/**
+ * Initialize the socket library. Except if you defined SOCKET_NO_AUTO_INIT, you don't need to call this
+ * function manually.
+ */
+void init() noexcept;
+
+/**
+ * Close the socket library.
+ */
+void finish() noexcept;
+
+/**
+ * Get the last socket system error. The error is set from errno or from
+ * WSAGetLastError on Windows.
+ *
+ * @return a string message
+ */
+std::string error();
+
+/**
+ * Get the last system error.
+ *
+ * @param errn the error number (errno or WSAGetLastError)
+ * @return the error
+ */
+std::string error(int errn);
+
+/* }}} */
+
+/*
+ * Portables types
+ * ------------------------------------------------------------------
+ *
+ * The following types are defined differently between Unix and Windows.
+ */
+
+/* {{{ Types */
+
+#if defined(_WIN32)
+
+/**
+ * Socket type, SOCKET.
+ */
+using Handle	= SOCKET;
+
+/**
+ * Argument to pass to set.
+ */
+using ConstArg	= const char *;
+
+/**
+ * Argument to pass to get.
+ */
+using Arg	= char *;
+
+#else
+
+/**
+ * Socket type, int.
+ */
+using Handle	= int;
+
+/**
+ * Argument to pass to set.
+ */
+using ConstArg	= const void *;
+
+/**
+ * Argument to pass to get.
+ */
+using Arg	= void *;
+
+#endif
+
+/* }}} */
+
+/*
+ * Error class
+ * ------------------------------------------------------------------
+ *
+ * This is the main exception thrown on socket operations.
+ */
+
+/* {{{ Error */
+
+/**
+ * @class Error
+ * @brief Base class for sockets error
+ */
+class Error : public std::exception {
+public:
+	/**
+	 * @enum Code
+	 * @brief Which kind of error
+	 */
+	enum Code {
+		WouldBlockRead,		///!< The operation would block for reading
+		WouldBlockWrite,	///!< The operation would block for writing
+		Timeout,		///!< The action did timeout
+		System			///!< There is a system error
+	};
+
+private:
+	Code m_code;
+	std::string m_function;
+	std::string m_error;
+
+public:
+	/**
+	 * Constructor that use the last system error.
+	 *
+	 * @param code which kind of error
+	 * @param function the function name
+	 */
+	Error(Code code, std::string function);
+
+	/**
+	 * Constructor that use the system error set by the user.
+	 *
+	 * @param code which kind of error
+	 * @param function the function name
+	 * @param error the error
+	 */
+	Error(Code code, std::string function, int error);
+
+	/**
+	 * Constructor that set the error specified by the user.
+	 *
+	 * @param code which kind of error
+	 * @param function the function name
+	 * @param error the error
+	 */
+	Error(Code code, std::string function, std::string error);
+
+	/**
+	 * Get which function has triggered the error.
+	 *
+	 * @return the function name (e.g connect)
+	 */
+	inline const std::string &function() const noexcept
+	{
+		return m_function;
+	}
+
+	/**
+	 * The error code.
+	 *
+	 * @return the code
+	 */
+	inline Code code() const noexcept
+	{
+		return m_code;
+	}
+
+	/**
+	 * Get the error (only the error content).
+	 *
+	 * @return the error
+	 */
+	const char *what() const noexcept
+	{
+		return m_error.c_str();
+	}
+};
+
+/* }}} */
+
+/*
+ * Base Socket class
+ * ------------------------------------------------------------------
+ *
+ * This base class has operations that are common to all types of sockets but you usually instanciate
+ * a SocketTcp or SocketUdp
+ */
+
+/* {{{ Socket */
+
+/**
+ * @class Socket
+ * @brief Base socket class for socket operations
+ */
+template <typename Address, typename Type>
+class Socket {
+private:
+	Type m_type;
+
+protected:
+	/**
+	 * The native handle.
+	 */
+	Handle m_handle{Invalid};
+
+public:
+	/**
+	 * This tries to create a socket.
+	 */
+	inline Socket() noexcept
+		: Socket{Address::domain(), Type::type(), 0}
+	{
+	}
+
+	/**
+	 * Construct a socket with an already created descriptor.
+	 *
+	 * @param handle the native descriptor
+	 */
+	explicit inline Socket(Handle handle) noexcept
+		: m_handle{handle}
+	{
+	}
+
+	/**
+	 * Create a socket handle.
+	 *
+	 * @param domain the domain AF_*
+	 * @param type the type SOCK_*
+	 * @param protocol the protocol
+	 * @throw Error on failures
+	 */
+	Socket(int domain, int type, int protocol)
+	{
+#if !defined(SOCKET_NO_AUTO_INIT)
+		init();
+#endif
+		m_handle = ::socket(domain, type, protocol);
+
+		if (m_handle == Invalid) {
+			throw Error{Error::System, "socket"};
+		}
+	}
+
+	/**
+	 * Copy constructor deleted.
+	 */
+	Socket(const Socket &) = delete;
+
+	/**
+	 * Transfer ownership from other to this.
+	 *
+	 * @param other the other socket
+	 */
+	inline Socket(Socket &&other) noexcept
+		: m_handle{other.m_handle}
+	{
+		/* Invalidate other */
+		other.m_handle = -1;
+	}
+
+	/**
+	 * Default destructor.
+	 */
+	virtual ~Socket()
+	{
+		close();
+	}
+
+	/**
+	 * Set an option for the socket.
+	 *
+	 * @param level the setting level
+	 * @param name the name
+	 * @param arg the value
+	 * @throw Error on error
+	 */
+	template <typename Argument>
+	inline void set(int level, int name, const Argument &arg)
+	{
+#if defined(_WIN32)
+		if (setsockopt(m_handle, level, name, (ConstArg)&arg, sizeof (arg)) == Error)
+#else
+		if (setsockopt(m_handle, level, name, (ConstArg)&arg, sizeof (arg)) < 0)
+#endif
+			throw Error{Error::System, "set"};
+	}
+
+	/**
+	 * Get an option for the socket.
+	 *
+	 * @param level the setting level
+	 * @param name the name
+	 * @throw Error on error
+	 */
+	template <typename Argument>
+	inline Argument get(int level, int name)
+	{
+		Argument desired, result{};
+		socklen_t size = sizeof (result);
+
+#if defined(_WIN32)
+		if (getsockopt(m_handle, level, name, (Arg)&desired, &size) == Error)
+#else
+		if (getsockopt(m_handle, level, name, (Arg)&desired, &size) < 0)
+#endif
+			throw Error{Error::System, "get"};
+
+		std::memcpy(&result, &desired, size);
+
+		return result;
+	}
+
+	/**
+	 * Get the native handle.
+	 *
+	 * @return the handle
+	 * @warning Not portable
+	 */
+	inline Handle handle() const noexcept
+	{
+		return m_handle;
+	}
+
+	/**
+	 * Set the blocking mode, if set to false, the socket will be marked
+	 * **non-blocking**.
+	 *
+	 * @param block set to false to mark **non-blocking**
+	 * @throw Error on any error
+	 */
+	void setBlockMode(bool block)
+	{
+#if defined(O_NONBLOCK) && !defined(_WIN32)
+		int flags;
+
+		if ((flags = fcntl(m_handle, F_GETFL, 0)) == -1) {
+			flags = 0;
+		}
+
+		if (block) {
+			flags &= ~(O_NONBLOCK);
+		} else {
+			flags |= O_NONBLOCK;
+		}
+
+		if (fcntl(m_handle, F_SETFL, flags) == Failure) {
+			throw Error{Error::System, "setBlockMode"};
+		}
+#else
+		unsigned long flags = (block) ? 0 : 1;
+
+		if (ioctlsocket(m_handle, FIONBIO, &flags) == Failure) {
+			throw Error{Error::System, "setBlockMode"};
+		}
+#endif
+	}
+
+	/**
+	 * Bind using a native address.
+	 *
+	 * @param addr the address
+	 * @param size the size
+	 */
+	inline void bind(const sockaddr *addr, socklen_t size)
+	{
+		if (::bind(m_handle, addr, size) == Failure) {
+			throw Error{Error::System, "bind"};
+		}
+	}
+
+	/**
+	 * Overload that takes an address.
+	 *
+	 * @param address the address
+	 * @throw Error on errors
+	 */
+	inline void bind(const Address &address)
+	{
+		bind(address.address(), address.length());
+	}
+
+	/**
+	 * Listen for pending connection.
+	 *
+	 * @param max the maximum number
+	 */
+	inline void listen(int max = 128)
+	{
+		if (::listen(this->m_handle, max) == Failure) {
+			throw Error{Error::System, "listen"};
+		}
+	}
+
+	/**
+	 * Connect to an address.
+	 *
+	 * @param address the address
+	 * @throw Error on errors
+	 */
+	inline void connect(const Address &address)
+	{
+		m_type.connect(*this, address);
+	}
+
+	/**
+	 * Accept a pending connection.
+	 *
+	 * @param info the client address
+	 * @return the new socket
+	 * @throw Error on errors
+	 */
+	inline Socket<Address, Type> accept(Address &info)
+	{
+		return m_type.accept(*this, info);
+	}
+
+	/**
+	 * Overloaded function without information.
+	 *
+	 * @return the new socket
+	 * @throw Error on errors
+	 */
+	inline Socket<Address, Type> accept()
+	{
+		Address dummy;
+
+		return accept(dummy);
+	}
+
+	/**
+	 * Get the local name. This is a wrapper of getsockname().
+	 *
+	 * @return the address
+	 * @throw Error on failures
+	 */
+	Address address() const
+	{
+		// TODO: to reimplement
+		return {};
+	}
+
+	/**
+	 * Receive some data.
+	 *
+	 * @param data the destination buffer
+	 * @param length the buffer length
+	 * @throw Error on error
+	 */
+	inline unsigned recv(void *data, unsigned length)
+	{
+		return m_type.recv(*this, data, length);
+	}
+
+	/**
+	 * Overloaded function.
+	 *
+	 * @param count the number of bytes to receive
+	 * @return the string
+	 * @throw Error on error
+	 */
+	inline std::string recv(unsigned count)
+	{
+		std::string result;
+
+		result.resize(count);
+		auto n = recv(const_cast<char *>(result.data()), count);
+		result.resize(n);
+
+		return result;
+	}
+
+	/**
+	 * Send some data.
+	 *
+	 * @param data the data buffer
+	 * @param length the buffer length
+	 * @throw Error on error
+	 */
+	inline unsigned send(const void *data, unsigned length)
+	{
+		return m_type.send(*this, data, length);
+	}
+
+	/**
+	 * Overloaded function.
+	 *
+	 * @param data the string to send
+	 * @return the number of bytes sent
+	 * @throw Error on error
+	 */
+	inline unsigned send(const std::string &data)
+	{
+		return send(data.c_str(), data.size());
+	}
+
+	/**
+	 * Send data to an end point.
+	 *
+	 * @param data the buffer
+	 * @param length the buffer length
+	 * @param address the client address
+	 * @return the number of bytes sent
+	 * @throw Error on error
+	 */
+	inline unsigned sendto(const void *data, unsigned length, const Address &address)
+	{
+		return m_type.sendto(*this, data, length, address);
+	}
+
+	/**
+	 * Overloaded function.
+	 *
+	 * @param data the data
+	 * @param address the address
+	 * @return the number of bytes sent
+	 * @throw Error on error
+	 */
+	inline unsigned sendto(const std::string &data, const Address &address)
+	{
+		return sendto(data.c_str(), data.length(), address);
+	}
+
+	/**
+	 * Receive data from an end point.
+	 *
+	 * @param data the destination buffer
+	 * @param length the buffer length
+	 * @param info the client information
+	 * @return the number of bytes received
+	 * @throw Error on error
+	 */
+	unsigned recvfrom(void *data, unsigned length, Address &info)
+	{
+		return m_type.recvfrom(*this, data, length, info);
+	}
+
+	/**
+	 * Overloaded function.
+	 *
+	 * @param count the maximum number of bytes to receive
+	 * @param info the client information
+	 * @return the string
+	 * @throw Error on error
+	 */
+	inline std::string recvfrom(unsigned count, Address &info)
+	{
+		std::string result;
+
+		result.resize(count);
+		auto n = recvfrom(const_cast<char *>(result.data()), count, info);
+		result.resize(n);
+
+		return result;
+	}
+
+	/**
+	 * Overloaded function.
+	 *
+	 * @param count the number of bytes to read
+	 * @return the string
+	 * @throw Error on errors
+	 */
+	inline std::string recvfrom(unsigned count)
+	{
+		Address dummy;
+
+		return recvfrom(count, dummy);
+	}
+
+	/**
+	 * Close the socket.
+	 *
+	 * Automatically called from the destructor.
+	 */
+	virtual void close()
+	{
+		if (m_handle != Invalid) {
+#if defined(_WIN32)
+			::closesocket(m_handle);
+#else
+			::close(m_handle);
+#endif
+			m_handle = Invalid;
+		}
+	}
+
+	/**
+	 * Assignment operator forbidden.
+	 *
+	 * @return *this
+	 */
+	Socket &operator=(const Socket &) = delete;
+
+	/**
+	 * Transfer ownership from other to this. The other socket is left
+	 * invalid and will not be closed.
+	 *
+	 * @param other the other socket
+	 * @return this
+	 */
+	Socket &operator=(Socket &&other) noexcept
+	{
+		m_handle = other.m_handle;
+
+		/* Invalidate other */
+		other.m_handle = Invalid;
+
+		return *this;
+	}
+};
+
+/**
+ * Compare two sockets.
+ *
+ * @param s1 the first socket
+ * @param s2 the second socket
+ * @return true if they equals
+ */
+template <typename Address, typename Type>
+bool operator==(const Socket<Address, Type> &s1, const Socket<Address, Type> &s2)
+{
+	return s1.handle() == s2.handle();
+}
+
+/**
+ * Compare two sockets.
+ *
+ * @param s1 the first socket
+ * @param s2 the second socket
+ * @return true if they are different
+ */
+template <typename Address, typename Type>
+bool operator!=(const Socket<Address, Type> &s1, const Socket<Address, Type> &s2)
+{
+	return s1.handle() != s2.handle();
+}
+
+/**
+ * Compare two sockets.
+ *
+ * @param s1 the first socket
+ * @param s2 the second socket
+ * @return true if s1 < s2
+ */
+template <typename Address, typename Type>
+bool operator<(const Socket<Address, Type> &s1, const Socket<Address, Type> &s2)
+{
+	return s1.handle() < s2.handle();
+}
+
+/**
+ * Compare two sockets.
+ *
+ * @param s1 the first socket
+ * @param s2 the second socket
+ * @return true if s1 > s2
+ */
+template <typename Address, typename Type>
+bool operator>(const Socket<Address, Type> &s1, const Socket<Address, Type> &s2)
+{
+	return s1.handle() > s2.handle();
+}
+
+/**
+ * Compare two sockets.
+ *
+ * @param s1 the first socket
+ * @param s2 the second socket
+ * @return true if s1 <= s2
+ */
+template <typename Address, typename Type>
+bool operator<=(const Socket<Address, Type> &s1, const Socket<Address, Type> &s2)
+{
+	return s1.handle() <= s2.handle();
+}
+
+/**
+ * Compare two sockets.
+ *
+ * @param s1 the first socket
+ * @param s2 the second socket
+ * @return true if s1 >= s2
+ */
+template <typename Address, typename Type>
+bool operator>=(const Socket<Address, Type> &s1, const Socket<Address, Type> &s2)
+{
+	return s1.handle() >= s2.handle();
+}
+
+/* }}} */
+
+/*
+ * Predefine addressed to be used
+ * ------------------------------------------------------------------
+ *
+ * - Ipv6
+ * - Ipv4
+ * - Local
+ */
+
+/* {{{ Addresses */
+
+/**
+ * @class Ip
+ * @brief Base class for IPv6 and IPv4, don't use it directly
+ */
+class Ip {
+private:
+	friend class Ipv6;
+	friend class Ipv4;
+
+	union {
+		sockaddr_in m_sin;
+		sockaddr_in6 m_sin6;
+	};
+
+	socklen_t m_length{0};
+	int m_domain{AF_INET};
+
+	Ip(int domain) noexcept;
+
+	Ip(const std::string &host, int port, int domain);
+
+	Ip(const struct sockaddr_storage *ss, socklen_t length);
+
+public:
+	/**
+	 * Return the underlying address, either sockaddr_in6 or sockaddr_in.
+	 *
+	 * @return the address
+	 */
+	inline const sockaddr *address() const noexcept
+	{
+		if (m_domain == AF_INET6) {
+			return reinterpret_cast<const sockaddr *>(&m_sin6);
+		}
+
+		return reinterpret_cast<const sockaddr *>(&m_sin);
+	}
+
+	/**
+	 * Return the underlying address length.
+	 *
+	 * @return the length
+	 */
+	inline socklen_t length() const noexcept
+	{
+		return m_length;
+	}
+};
+
+/**
+ * @class Ipv6
+ * @brief Use IPv6 address
+ */
+class Ipv6 : public Ip {
+public:
+	/**
+	 * Get the domain AF_INET6.
+	 *
+	 * @return AF_INET6
+	 */
+	static inline int domain() noexcept
+	{
+		return AF_INET6;
+	}
+
+	/**
+	 * Construct an empty address.
+	 */
+	inline Ipv6() noexcept
+		: Ip{AF_INET6}
+	{
+	}
+
+	/**
+	 * Construct an address on a specific host.
+	 *
+	 * @param host the host ("*" for any)
+	 * @param port the port
+	 * @throw Error on errors
+	 */
+	inline Ipv6(const std::string &host, int port)
+		: Ip{host, port, AF_INET6}
+	{
+	}
+
+	/**
+	 * Construct an address from a storage.
+	 *
+	 * @param ss the storage
+	 * @param length the length
+	 */
+	inline Ipv6(const struct sockaddr_storage *ss, socklen_t length)
+		: Ip{ss, length}
+	{
+	}
+};
+
+/**
+ * @class Ipv4
+ * @brief Use IPv4 address
+ */
+class Ipv4 : public Ip {
+public:
+	/**
+	 * Get the domain AF_INET.
+	 *
+	 * @return AF_INET
+	 */
+	static inline int domain() noexcept
+	{
+		return AF_INET;
+	}
+
+	/**
+	 * Construct an empty address.
+	 */
+	inline Ipv4() noexcept
+		: Ip{AF_INET}
+	{
+	}
+
+	/**
+	 * Construct an address on a specific host.
+	 *
+	 * @param host the host ("*" for any)
+	 * @param port the port
+	 * @throw Error on errors
+	 */
+	inline Ipv4(const std::string &host, int port)
+		: Ip{host, port, AF_INET}
+	{
+	}
+
+	/**
+	 * Construct an address from a storage.
+	 *
+	 * @param ss the storage
+	 * @param length the length
+	 */
+	inline Ipv4(const struct sockaddr_storage *ss, socklen_t length)
+		: Ip{ss, length}
+	{
+	}
+};
+
+#if !defined(_WIN32)
+
+/**
+ * @class Local
+ * @brief unix family sockets
+ *
+ * Create an address to a specific path. Only available on Unix.
+ */
+class Local {
+private:
+	sockaddr_un m_sun;
+	std::string m_path;
+
+public:
+	/**
+	 * Get the domain AF_LOCAL.
+	 *
+	 * @return AF_LOCAL
+	 */
+	static inline int domain() noexcept
+	{
+		return AF_LOCAL;
+	}
+
+	/**
+	 * Default constructor.
+	 */
+	Local() = default;
+
+	/**
+	 * Construct an address to a path.
+	 *
+	 * @param path the path
+	 * @param rm remove the file before (default: false)
+	 */
+	Local(std::string path, bool rm = false);
+
+	/**
+	 * Construct an unix address from a storage address.
+	 *
+	 * @param ss the storage
+	 * @param length the length
+	 */
+	Local(const sockaddr_storage &ss, socklen_t length);
+
+	/**
+	 * Get the sockaddr_un.
+	 *
+	 * @return the address
+	 */
+	inline const sockaddr *address() const noexcept
+	{
+		return reinterpret_cast<const sockaddr *>(&m_sun);
+	}
+
+	/**
+	 * Get the address length.
+	 *
+	 * @return the length
+	 */
+	inline socklen_t length() const noexcept
+	{
+#if defined(SOCKET_HAVE_SUN_LEN)
+		return SUN_LEN(&m_sun);
+#else
+		return sizeof (m_sun);
+#endif
+	}
+};
+
+#endif // !_WIN32
+
+/* }}} */
+
+/*
+ * Predefined types
+ * ------------------------------------------------------------------
+ *
+ * - Tcp, for standard stream connections
+ * - Udp, for standard datagram connection
+ */
+
+/* {{{ Types */
+
+/* {{{ Tcp */
+
+/**
+ * @class Tcp
+ * @brief Clear TCP implementation.
+ */
+class Tcp {
+public:
+	/**
+	 * Socket type.
+	 *
+	 * @return SOCK_STREAM
+	 */
+	static inline int type() noexcept
+	{
+		return SOCK_STREAM;
+	}
+
+	/**
+	 * Accept a clear client. Wrapper of accept(2).
+	 *
+	 * @param sc the socket
+	 * @param address the address destination
+	 * @return the socket
+	 * @throw Error on errors
+	 */
+	template <typename Address>
+	Socket<Address, Tcp> accept(Socket<Address, Tcp> &sc, Address &address)
+	{
+		Handle handle;
+		sockaddr_storage storage;
+		socklen_t addrlen = sizeof (sockaddr_storage);
+
+		handle = ::accept(sc.handle(), reinterpret_cast<sockaddr *>(&storage), &addrlen);
+
+		if (handle == Invalid) {
+#if defined(_WIN32)
+			int error = WSAGetLastError();
+
+			if (error == WSAEWOULDBLOCK) {
+				throw Error{Error::WouldBlockRead, "accept", error};
+			}
+
+			throw Error{Error::System, "accept", error};
+#else
+			if (errno == EAGAIN || errno == EWOULDBLOCK) {
+				throw Error{Error::WouldBlockRead, "accept"};
+			}
+
+			throw Error{Error::System, "accept"};
+#endif
+		}
+
+		address = Address{&storage, addrlen};
+
+		return Socket<Address, Tcp>{handle};
+	}
+
+	/**
+	 * Connect to the end point. Wrapper for connect(2).
+	 *
+	 * @param sc the socket
+	 * @param address the address
+	 * @throw Error on errors
+	 */
+	template <typename Address>
+	void connect(Socket<Address, Tcp> &sc, const Address &address)
+	{
+		if (::connect(sc.handle(), address.address(), address.length()) == Failure) {
+			/*
+			 * Determine if the error comes from a non-blocking connect that cannot be
+			 * accomplished yet.
+			 */
+#if defined(_WIN32)
+			int error = WSAGetLastError();
+
+			if (error == WSAEWOULDBLOCK) {
+				throw Error{Error::WouldBlockWrite, "connect", error};
+			}
+
+			throw Error{Error::System, "connect", error};
+#else
+			if (errno == EINPROGRESS) {
+				throw Error{Error::WouldBlockWrite, "connect"};
+			}
+
+			throw Error{Error::System, "connect"};
+		}
+#endif
+	}
+
+	/**
+	 * Receive data. Wrapper of recv(2).
+	 *
+	 * @param sc the socket
+	 * @param data the destination
+	 * @param length the destination length
+	 * @return the number of bytes read
+	 * @throw Error on errors
+	 */
+	template <typename Address>
+	unsigned recv(Socket<Address, Tcp> &sc, void *data, unsigned length)
+	{
+		int nbread;
+
+		nbread = ::recv(sc.handle(), (Arg)data, length, 0);
+		if (nbread == Failure) {
+#if defined(_WIN32)
+			int error = WSAGetLastError();
+
+			if (error == WSAEWOULDBLOCK) {
+				throw Error{Error::WouldBlockRead, "recv", error};
+			}
+
+			throw Error{Error::System, "recv", error};
+#else
+			if (errno == EAGAIN || errno == EWOULDBLOCK) {
+				throw Error{Error::WouldBlockRead, "recv"};
+			}
+
+			throw Error{Error::System, "recv"};
+#endif
+		}
+
+		return static_cast<unsigned>(nbread);
+	}
+
+	/**
+	 * Send some data. Wrapper for send(2).
+	 *
+	 * @param sc the socket
+	 * @param data the buffer to send
+	 * @param length the buffer length
+	 * @return the number of bytes sent
+	 * @throw Error on errors
+	 */
+	template <typename Address>
+	unsigned send(Socket<Address, Tcp> &sc, const void *data, unsigned length)
+	{
+		int nbsent;
+
+		nbsent = ::send(sc.handle(), (ConstArg)data, length, 0);
+		if (nbsent == Failure) {
+#if defined(_WIN32)
+			int error = WSAGetLastError();
+
+			if (error == WSAEWOULDBLOCK) {
+				throw Error{Error::WouldBlockWrite, "send", error};
+			}
+
+			throw Error{Error::System, "send", error};
+#else
+			if (errno == EAGAIN || errno == EWOULDBLOCK) {
+				throw Error{Error::WouldBlockWrite, "send"};
+			}
+
+			throw Error{Error::System, "send"};
+#endif
+		}
+
+		return static_cast<unsigned>(nbsent);
+	}
+};
+
+/* }}} */
+
+/* {{{ Udp */
+
+/**
+ * @class Udp
+ * @brief Clear UDP type.
+ *
+ * This class is the basic implementation of UDP sockets.
+ */
+class Udp {
+public:
+	/**
+	 * Socket type.
+	 *
+	 * @return SOCK_DGRAM
+	 */
+	static inline int type() noexcept
+	{
+		return SOCK_DGRAM;
+	}
+
+	/**
+	 * Receive data from an end point.
+	 *
+	 * @param sc the socket
+	 * @param data the destination buffer
+	 * @param length the buffer length
+	 * @param info the client information
+	 * @return the number of bytes received
+	 * @throw Error on error
+	 */
+	template <typename Address>
+	unsigned recvfrom(Socket<Address, Udp> &sc, void *data, unsigned length, Address &info)
+	{
+		int nbread;
+
+		/* Store information */
+		sockaddr_storage address;
+		socklen_t addrlen = sizeof (struct sockaddr_storage);
+
+		nbread = ::recvfrom(sc.handle(), (Arg)data, length, 0, reinterpret_cast<sockaddr *>(&address), &addrlen);
+		info = Address{&address, addrlen};
+
+		if (nbread == Failure) {
+#if defined(_WIN32)
+			int error = WSAGetLastError();
+
+			if (error == WSAEWOULDBLOCK) {
+				throw Error{Error::WouldBlockRead, "recvfrom", error};
+			}
+
+			throw Error{Error::System, "recvfrom", error};
+#else
+			if (errno == EAGAIN || errno == EWOULDBLOCK) {
+				throw Error{Error::WouldBlockRead, "recvfrom"};
+			}
+
+			throw Error{Error::System, "recvfrom"};
+#endif
+		}
+
+		return static_cast<unsigned>(nbread);
+	}
+
+	/**
+	 * Send data to an end point.
+	 *
+	 * @param sc the socket
+	 * @param data the buffer
+	 * @param length the buffer length
+	 * @param address the client address
+	 * @return the number of bytes sent
+	 * @throw Error on error
+	 */
+	template <typename Address>
+	unsigned sendto(Socket<Address, Udp> &sc, const void *data, unsigned length, const Address &address)
+	{
+		int nbsent;
+
+		nbsent = ::sendto(sc.handle(), (ConstArg)data, length, 0, address.address(), address.length());
+		if (nbsent == Failure) {
+#if defined(_WIN32)
+			int error = WSAGetLastError();
+
+			if (error == WSAEWOULDBLOCK) {
+				throw Error{Error::WouldBlockWrite, "sendto", error};
+			}
+
+			throw Error{Error::System, "sendto", error};
+#else
+			if (errno == EAGAIN || errno == EWOULDBLOCK) {
+				throw Error{Error::WouldBlockWrite, "sendto"};
+			}
+
+			throw Error{Error::System, "sendto"};
+#endif
+		}
+
+		return static_cast<unsigned>(nbsent);
+	}
+};
+
+/* }}} */
+
+/* }}} */
+
+/*
+ * Convenient helpers
+ * ------------------------------------------------------------------
+ *
+ * - SocketTcp<Address>, for TCP sockets,
+ * - SocketUdp<Address>, for UDP sockets
+ */
+
+/* {{{ Helpers */
+
+/**
+ * Helper to create TCP sockets.
+ */
+template <typename Address>
+using SocketTcp = Socket<Address, Tcp>;
+
+/**
+ * Helper to create UDP sockets.
+ */
+template <typename Address>
+using SocketUdp = Socket<Address, Udp>;
+
+/* }}} */
+
+/*
+ * Select wrapper
+ * ------------------------------------------------------------------
+ *
+ * Wrapper for select(2) and other various implementations.
+ */
+
+/* {{{ Listener */
+
+/**
+ * @struct ListenerStatus
+ * @brief Result of polling
+ *
+ * Result of a select call, returns the first ready socket found with its
+ * flags.
+ */
+class ListenerStatus {
+public:
+	Handle socket;		//!< which socket is ready
+	int flags;		//!< the flags
+};
+
+/**
+ * Table used in the socket listener to store which sockets have been
+ * set in which directions.
+ */
+using ListenerTable = std::map<Handle, int>;
+
+/**
+ * @class Select
+ * @brief Implements select(2)
+ *
+ * This class is the fallback of any other method, it is not preferred at all for many reasons.
+ */
+class Select {
+public:
+	/**
+	 * Backend identifier
+	 */
+	inline const char *name() const noexcept
+	{
+		return "select";
+	}
+
+	/**
+	 * No-op, uses the ListenerTable directly.
+	 */
+	inline void set(const ListenerTable &, Handle, int, bool) noexcept {}
+
+	/**
+	 * No-op, uses the ListenerTable directly.
+	 */
+	inline void unset(const ListenerTable &, Handle, int, bool) noexcept {}
+
+	/**
+	 * Return the sockets
+	 */
+	std::vector<ListenerStatus> wait(const ListenerTable &table, int ms);
+};
+
+#if defined(SOCKET_HAVE_POLL)
+
+/**
+ * @class Poll
+ * @brief Implements poll(2)
+ *
+ * Poll is widely supported and is better than select(2). It is still not the
+ * best option as selecting the sockets is O(n).
+ */
+class Poll {
+private:
+	std::vector<pollfd> m_fds;
+
+	short topoll(int flags) const noexcept;
+	int toflags(short &event) const noexcept;
+
+public:
+	void set(const ListenerTable &, Handle sc, int flags, bool add);
+	void unset(const ListenerTable &, Handle sc, int flags, bool remove);
+	std::vector<ListenerStatus> wait(const ListenerTable &, int ms);
+
+	/**
+	 * Backend identifier
+	 */
+	inline const char *name() const noexcept
+	{
+		return "poll";
+	}
+};
+
+#endif
+
+#if defined(SOCKET_HAVE_EPOLL)
+
+class Epoll {
+private:
+	int m_handle;
+	std::vector<struct epoll_event> m_events;
+
+	Epoll(const Epoll &) = delete;
+	Epoll &operator=(const Epoll &) = delete;
+	Epoll(const Epoll &&) = delete;
+	Epoll &operator=(const Epoll &&) = delete;
+
+	uint32_t toepoll(int flags) const noexcept;
+	int toflags(uint32_t events) const noexcept;
+	void update(Handle sc, int op, int flags);
+
+public:
+	Epoll();
+	~Epoll();
+	void set(const ListenerTable &, Handle sc, int flags, bool add);
+	void unset(const ListenerTable &, Handle sc, int flags, bool remove);
+	std::vector<ListenerStatus> wait(const ListenerTable &table, int ms);
+
+	/**
+	 * Backend identifier
+	 */
+	inline const char *name() const noexcept
+	{
+		return "epoll";
+	}
+};
+
+#endif
+
+#if defined(SOCKET_HAVE_KQUEUE)
+
+/**
+ * @class Kqueue
+ * @brief Implements kqueue(2)
+ *
+ * This implementation is available on all BSD and Mac OS X. It is better than
+ * poll(2) because it's O(1), however it's a bit more memory consuming.
+ */
+class Kqueue {
+private:
+	std::vector<struct kevent> m_result;
+	int m_handle;
+
+	Kqueue(const Kqueue &) = delete;
+	Kqueue &operator=(const Kqueue &) = delete;
+	Kqueue(Kqueue &&) = delete;
+	Kqueue &operator=(Kqueue &&) = delete;
+
+	void update(Handle sc, int filter, int flags);
+
+public:
+	Kqueue();
+	~Kqueue();
+
+	void set(const ListenerTable &, Handle sc, int flags, bool add);
+	void unset(const ListenerTable &, Handle sc, int flags, bool remove);
+	std::vector<ListenerStatus> wait(const ListenerTable &, int ms);
+
+	/**
+	 * Backend identifier
+	 */
+	inline const char *name() const noexcept
+	{
+		return "kqueue";
+	}
+};
+
+#endif
+
+/**
+ * Mark the socket for read operation.
+ */
+extern const int FlagRead;
+
+/**
+ * Mark the socket for write operation.
+ */
+extern const int FlagWrite;
+
+/**
+ * @class Listener
+ * @brief Synchronous multiplexing
+ *
+ * Convenient wrapper around the select() system call.
+ *
+ * This class is implemented using a bridge pattern to allow different uses
+ * of listener implementation.
+ *
+ * You should not reinstanciate a new SocketListener at each iteartion of your
+ * main loop as it can be extremely costly. Instead use the same listener that
+ * you can safely modify on the fly.
+ *
+ * Currently, poll, epoll, select and kqueue are available.
+ *
+ * To implement the backend, the following functions must be available:
+ *
+ * # Set
+ *
+ * @code
+ * void set(const ListenerTable &, const Handle &sc, int flags, bool add);
+ * @endcode
+ *
+ * This function, takes the socket to be added and the flags. The flags are
+ * always guaranteed to be correct and the function will never be called twice
+ * even if the user tries to set the same flag again.
+ *
+ * An optional add argument is added for backends which needs to do different
+ * operation depending if the socket was already set before or if it is the
+ * first time (e.g EPOLL_CTL_ADD vs EPOLL_CTL_MOD for epoll(7).
+ *
+ * # Unset
+ *
+ * @code
+ * void unset(const ListenerTable &, const Handle &sc, int flags, bool remove);
+ * @endcode
+ *
+ * Like set, this function is only called if the flags are actually set and will
+ * not be called multiple times.
+ *
+ * Also like set, an optional remove argument is set if the socket is being
+ * completely removed (e.g no more flags are set for this socket).
+ *
+ * # Wait
+ *
+ * @code
+ * std::vector<ListenerStatus> wait(const ListenerTable &, int ms);
+ * @encode
+ *
+ * Wait for the sockets to be ready with the specified milliseconds. Must return a list of ListenerStatus,
+ * may throw any exceptions.
+ *
+ * # Name
+ *
+ * @code
+ * inline const char *name() const noexcept
+ * @endcode
+ *
+ * Returns the backend name. Usually the class in lower case.
+ */
+template <typename Backend = SOCKET_DEFAULT_BACKEND>
+class Listener {
+public:
+
+private:
+	Backend m_backend;
+	ListenerTable m_table;
+
+public:
+	/**
+	 * Construct an empty listener.
+	 */
+	Listener() = default;
+
+	/**
+	 * Get the backend.
+	 *
+	 * @return the backend
+	 */
+	inline const Backend &backend() const noexcept
+	{
+		return m_backend;
+	}
+
+	/**
+	 * Get the non-modifiable table.
+	 *
+	 * @return the table
+	 */
+	inline const ListenerTable &table() const noexcept
+	{
+		return m_table;
+	}
+
+	/**
+	 * Overloaded function.
+	 *
+	 * @return the iterator
+	 */
+	inline ListenerTable::const_iterator begin() const noexcept
+	{
+		return m_table.begin();
+	}
+
+	/**
+	 * Overloaded function.
+	 *
+	 * @return the iterator
+	 */
+	inline ListenerTable::const_iterator cbegin() const noexcept
+	{
+		return m_table.cbegin();
+	}
+
+	/**
+	 * Overloaded function.
+	 *
+	 * @return the iterator
+	 */
+	inline ListenerTable::const_iterator end() const noexcept
+	{
+		return m_table.end();
+	}
+
+	/**
+	 * Overloaded function.
+	 *
+	 * @return the iterator
+	 */
+	inline ListenerTable::const_iterator cend() const noexcept
+	{
+		return m_table.cend();
+	}
+
+	/**
+	 * Add or update a socket to the listener.
+	 *
+	 * If the socket is already placed with the appropriate flags, the
+	 * function is a no-op.
+	 *
+	 * If incorrect flags are passed, the function does nothing.
+	 *
+	 * @param sc the socket
+	 * @param flags (may be OR'ed)
+	 * @throw SocketError if the backend failed to set
+	 */
+	void set(Handle sc, int flags)
+	{
+		/* Invalid or useless flags */
+		if (flags == 0 || flags > 0x3)
+			return;
+
+		auto it = m_table.find(sc);
+
+		/*
+		 * Do not update the table if the backend failed to add
+		 * or update.
+		 */
+		if (it == m_table.end()) {
+			m_backend.set(m_table, sc, flags, true);
+			m_table.emplace(sc, flags);
+		} else {
+			if ((flags & FlagRead) && (it->second & FlagRead)) {
+				flags &= ~(FlagRead);
+			}
+			if ((flags & FlagWrite) && (it->second & FlagWrite)) {
+				flags &= ~(FlagWrite);
+			}
+
+			/* Still need a call? */
+			if (flags != 0) {
+				m_backend.set(m_table, sc, flags, false);
+				it->second |= flags;
+			}
+		}
+	}
+
+	/**
+	 * Unset a socket from the listener, only the flags is removed
+	 * unless the two flagss are requested.
+	 *
+	 * For example, if you added a socket for both reading and writing,
+	 * unsetting the write flags will keep the socket for reading.
+	 *
+	 * @param sc the socket
+	 * @param flags the flags (may be OR'ed)
+	 * @see remove
+	 */
+	void unset(Handle sc, int flags)
+	{
+		auto it = m_table.find(sc);
+
+		/* Invalid or useless flags */
+		if (flags == 0 || flags > 0x3 || it == m_table.end())
+			return;
+
+		/*
+		 * Like set, do not update if the socket is already at the appropriate
+		 * state.
+		 */
+		if ((flags & FlagRead) && !(it->second & FlagRead)) {
+			flags &= ~(FlagRead);
+		}
+		if ((flags & FlagWrite) && !(it->second & FlagWrite)) {
+			flags &= ~(FlagWrite);
+		}
+
+		if (flags != 0) {
+			/* Determine if it's a complete removal */
+			bool removal = ((it->second) & ~(flags)) == 0;
+
+			m_backend.unset(m_table, sc, flags, removal);
+
+			if (removal) {
+				m_table.erase(it);
+			} else {
+				it->second.second &= ~(flags);
+			}
+		}
+	}
+
+	/**
+	 * Remove completely the socket from the listener.
+	 *
+	 * It is a shorthand for unset(sc, FlagRead | FlagWrite);
+	 *
+	 * @param sc the socket
+	 */
+	inline void remove(Handle sc)
+	{
+		unset(sc, FlagRead | FlagWrite);
+	}
+
+	/**
+	 * Remove all sockets.
+	 */
+	inline void clear()
+	{
+		while (!m_table.empty()) {
+			remove(m_table.begin()->second.first);
+		}
+	}
+
+	/**
+	 * Get the number of sockets in the listener.
+	 */
+	inline ListenerTable::size_type size() const noexcept
+	{
+		return m_table.size();
+	}
+
+	/**
+	 * Select a socket. Waits for a specific amount of time specified as the duration.
+	 *
+	 * @param duration the duration
+	 * @return the socket ready
+	 */
+	template <typename Rep, typename Ratio>
+	inline ListenerStatus wait(const std::chrono::duration<Rep, Ratio> &duration)
+	{
+		auto cvt = std::chrono::duration_cast<std::chrono::milliseconds>(duration);
+
+		return m_backend.wait(m_table, cvt.count())[0];
+	}
+
+	/**
+	 * Overload with milliseconds.
+	 *
+	 * @param timeout the optional timeout in milliseconds
+	 * @return the socket ready
+	 */
+	inline ListenerStatus wait(int timeout = -1)
+	{
+		return wait(std::chrono::milliseconds(timeout));
+	}
+
+	/**
+	 * Select multiple sockets.
+	 *
+	 * @param duration the duration
+	 * @return the socket ready
+	 */
+	template <typename Rep, typename Ratio>
+	inline std::vector<ListenerStatus> waitMultiple(const std::chrono::duration<Rep, Ratio> &duration)
+	{
+		auto cvt = std::chrono::duration_cast<std::chrono::milliseconds>(duration);
+
+		return m_backend.wait(m_table, cvt.count());
+	}
+
+	/**
+	 * Overload with milliseconds.
+	 *
+	 * @return the socket ready
+	 */
+	inline std::vector<ListenerStatus> waitMultiple(int timeout = -1)
+	{
+		return waitMultiple(std::chrono::milliseconds(timeout));
+	}
+};
+
+/* }}} */
+
+} // !net
+
+#endif // !_SOCKETS_H_