New NetSocket interface, BSD/Win implementation

Unified BSD and Winsock sockets into a single implementation of a
generic NetSocket interface.

This is some ground work for few network improvements:
- Reuse as much code as possible between Posix and Windows.
- Provide a single point of implementation for exotic sdks (consoles).
- Provide platform agnostic StreamPeerTCP and PacketPeerUDP in core.
- Implement connect for UDP allowing for DTLS implementation.

core/io/net_socket.cpp

@@ -0,0 +1,42 @@
+/*************************************************************************/
+/*  net_socket.cpp                                                       */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "net_socket.h"
+
+NetSocket *(*NetSocket::_create)() = NULL;
+
+NetSocket *NetSocket::create() {
+
+	if (_create)
+		return _create();
+
+	ERR_PRINT("Unable to create network socket, platform not supported");
+	return NULL;
+}

core/io/net_socket.h

@@ -0,0 +1,79 @@
+/*************************************************************************/
+/*  net_socket.h                                                         */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef NET_SOCKET_H
+#define NET_SOCKET_H
+
+#include "core/io/ip.h"
+#include "core/reference.h"
+
+class NetSocket : public Reference {
+
+protected:
+	static NetSocket *(*_create)();
+
+public:
+	static NetSocket *create();
+
+	enum PollType {
+		POLL_TYPE_IN,
+		POLL_TYPE_OUT,
+		POLL_TYPE_IN_OUT
+	};
+
+	enum Type {
+		TYPE_NONE,
+		TYPE_TCP,
+		TYPE_UDP,
+	};
+
+	virtual Error open(Type p_type, IP::Type &ip_type) = 0;
+	virtual void close() = 0;
+	virtual Error bind(IP_Address p_addr, uint16_t p_port) = 0;
+	virtual Error listen(int p_max_pending) = 0;
+	virtual Error connect_to_host(IP_Address p_addr, uint16_t p_port) = 0;
+	virtual Error poll(PollType p_type, int timeout) const = 0;
+	virtual Error recv(uint8_t *p_buffer, int p_len, int &r_read) = 0;
+	virtual Error recvfrom(uint8_t *p_buffer, int p_len, int &r_read, IP_Address &r_ip, uint16_t &r_port) = 0;
+	virtual Error send(const uint8_t *p_buffer, int p_len, int &r_sent) = 0;
+	virtual Error sendto(const uint8_t *p_buffer, int p_len, int &r_sent, IP_Address p_ip, uint16_t p_port) = 0;
+	virtual Ref<NetSocket> accept(IP_Address &r_ip, uint16_t &r_port) = 0;
+
+	virtual bool is_open() const = 0;
+	virtual int get_available_bytes() const = 0;
+
+	virtual void set_broadcasting_enabled(bool p_enabled) = 0;
+	virtual void set_blocking_enabled(bool p_enabled) = 0;
+	virtual void set_ipv6_only_enabled(bool p_enabled) = 0;
+	virtual void set_tcp_no_delay_enabled(bool p_enabled) = 0;
+	virtual void set_reuse_address_enabled(bool p_enabled) = 0;
+};
+
+#endif // NET_SOCKET_H

drivers/unix/net_socket_posix.cpp

@@ -0,0 +1,535 @@
+/*************************************************************************/
+/*  net_socket_posix.cpp                                                 */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "net_socket_posix.h"
+
+#if defined(UNIX_ENABLED)
+
+#include <errno.h>
+#include <netdb.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <unistd.h>
+#ifndef NO_FCNTL
+#ifdef __HAIKU__
+#include <fcntl.h>
+#else
+#include <sys/fcntl.h>
+#endif
+#else
+#include <sys/ioctl.h>
+#endif
+#include <netinet/in.h>
+
+#include <sys/socket.h>
+#ifdef JAVASCRIPT_ENABLED
+#include <arpa/inet.h>
+#endif
+
+#include <netinet/tcp.h>
+
+#if defined(OSX_ENABLED) || defined(IPHONE_ENABLED)
+#define MSG_NOSIGNAL SO_NOSIGPIPE
+#endif
+
+// Some custom defines to minimize ifdefs
+#define SOCK_EMPTY -1
+#define SOCK_BUF(x) x
+#define SOCK_CBUF(x) x
+#define SOCK_IOCTL ioctl
+#define SOCK_POLL ::poll
+#define SOCK_CLOSE ::close
+
+/* Windows */
+#elif defined(WINDOWS_ENABLED)
+#include <winsock2.h>
+#include <ws2tcpip.h>
+// Some custom defines to minimize ifdefs
+#define SOCK_EMPTY INVALID_SOCKET
+#define SOCK_BUF(x) (char *)(x)
+#define SOCK_CBUF(x) (const char *)(x)
+#define SOCK_IOCTL ioctlsocket
+#define SOCK_POLL WSAPoll
+#define SOCK_CLOSE closesocket
+
+// Windows doesn't have this flag
+#ifndef MSG_NOSIGNAL
+#define MSG_NOSIGNAL 0
+#endif
+
+#endif
+
+static size_t _set_addr_storage(struct sockaddr_storage *p_addr, const IP_Address &p_ip, uint16_t p_port, IP::Type p_ip_type) {
+
+	memset(p_addr, 0, sizeof(struct sockaddr_storage));
+	if (p_ip_type == IP::TYPE_IPV6 || p_ip_type == IP::TYPE_ANY) { // IPv6 socket
+
+		// IPv6 only socket with IPv4 address
+		ERR_FAIL_COND_V(!p_ip.is_wildcard() && p_ip_type == IP::TYPE_IPV6 && p_ip.is_ipv4(), 0);
+
+		struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)p_addr;
+		addr6->sin6_family = AF_INET6;
+		addr6->sin6_port = htons(p_port);
+		if (p_ip.is_valid()) {
+			copymem(&addr6->sin6_addr.s6_addr, p_ip.get_ipv6(), 16);
+		} else {
+			addr6->sin6_addr = in6addr_any;
+		}
+		return sizeof(sockaddr_in6);
+	} else { // IPv4 socket
+
+		// IPv4 socket with IPv6 address
+		ERR_FAIL_COND_V(!p_ip.is_ipv4(), 0);
+
+		struct sockaddr_in *addr4 = (struct sockaddr_in *)p_addr;
+		addr4->sin_family = AF_INET;
+		addr4->sin_port = htons(p_port); // short, network byte order
+
+		if (p_ip.is_valid()) {
+			copymem(&addr4->sin_addr.s_addr, p_ip.get_ipv4(), 4);
+		} else {
+			addr4->sin_addr.s_addr = INADDR_ANY;
+		}
+
+		copymem(&addr4->sin_addr.s_addr, p_ip.get_ipv4(), 16);
+		return sizeof(sockaddr_in);
+	}
+}
+
+static void _set_ip_port(IP_Address &r_ip, uint16_t &r_port, struct sockaddr_storage *p_addr) {
+
+	if (p_addr->ss_family == AF_INET) {
+
+		struct sockaddr_in *addr4 = (struct sockaddr_in *)p_addr;
+		r_ip.set_ipv4((uint8_t *)&(addr4->sin_addr.s_addr));
+
+		r_port = ntohs(addr4->sin_port);
+
+	} else if (p_addr->ss_family == AF_INET6) {
+
+		struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)p_addr;
+		r_ip.set_ipv6(addr6->sin6_addr.s6_addr);
+
+		r_port = ntohs(addr6->sin6_port);
+	};
+}
+
+NetSocket *NetSocketPosix::_create_func() {
+	return memnew(NetSocketPosix);
+}
+
+void NetSocketPosix::make_default() {
+	_create = _create_func;
+}
+
+NetSocketPosix::NetSocketPosix() {
+	_sock = SOCK_EMPTY;
+	_ip_type = IP::TYPE_NONE;
+	_is_stream = false;
+}
+
+NetSocketPosix::~NetSocketPosix() {
+	close();
+}
+
+NetSocketPosix::NetError NetSocketPosix::_get_socket_error() {
+#if defined(WINDOWS_ENABLED)
+	int err = WSAGetLastError();
+
+	if (err == WSAEISCONN)
+		return ERR_NET_IS_CONNECTED;
+	if (err == WSAEINPROGRESS || errno == WSAEALREADY)
+		return ERR_NET_IN_PROGRESS;
+	if (err == WSAEWOULDBLOCK)
+		return ERR_NET_WOULD_BLOCK;
+	return ERR_NET_OTHER;
+#else
+	if (errno == EISCONN)
+		return ERR_NET_IS_CONNECTED;
+	if (errno == EINPROGRESS || errno == EALREADY)
+		return ERR_NET_IN_PROGRESS;
+	if (errno == EAGAIN || errno == EWOULDBLOCK)
+		return ERR_NET_WOULD_BLOCK;
+	return ERR_NET_OTHER;
+#endif
+}
+
+bool NetSocketPosix::_can_use_ip(const IP_Address p_ip, const bool p_for_bind) const {
+
+	if (p_for_bind && !(p_ip.is_valid() || p_ip.is_wildcard())) {
+		return false;
+	} else if (!p_for_bind && !p_ip.is_valid()) {
+		return false;
+	}
+	// Check if socket support this IP type.
+	IP::Type type = p_ip.is_ipv4() ? IP::TYPE_IPV4 : IP::TYPE_IPV6;
+	if (_ip_type != IP::TYPE_ANY && !p_ip.is_wildcard() && _ip_type != type) {
+		return false;
+	}
+	return true;
+}
+
+void NetSocketPosix::_set_socket(SOCKET_TYPE p_sock, IP::Type p_ip_type, bool p_is_stream) {
+	_sock = p_sock;
+	_ip_type = p_ip_type;
+	_is_stream = p_is_stream;
+}
+
+Error NetSocketPosix::open(Type p_sock_type, IP::Type &ip_type) {
+	ERR_FAIL_COND_V(is_open(), ERR_ALREADY_IN_USE);
+	ERR_FAIL_COND_V(ip_type > IP::TYPE_ANY || ip_type < IP::TYPE_NONE, ERR_INVALID_PARAMETER);
+
+#if defined(__OpenBSD__)
+	// OpenBSD does not support dual stacking, fallback to IPv4 only.
+	if (ip_type == IP::TYPE_ANY)
+		ip_type = IP::TYPE_IPV4;
+#endif
+
+	int family = ip_type == IP::TYPE_IPV4 ? AF_INET : AF_INET6;
+	int protocol = p_sock_type == TYPE_TCP ? IPPROTO_TCP : IPPROTO_UDP;
+	int type = p_sock_type == TYPE_TCP ? SOCK_STREAM : SOCK_DGRAM;
+	_sock = socket(family, type, protocol);
+
+	if (_sock == SOCK_EMPTY && ip_type == IP::TYPE_ANY) {
+		// Careful here, changing the referenced parameter so the caller knows that we are using an IPv4 socket
+		// in place of a dual stack one, and further calls to _set_sock_addr will work as expected.
+		ip_type = IP::TYPE_IPV4;
+		family = AF_INET;
+		_sock = socket(family, type, protocol);
+	}
+
+	ERR_FAIL_COND_V(_sock == SOCK_EMPTY, FAILED);
+	_ip_type = ip_type;
+
+	if (family == AF_INET6) {
+		// Select IPv4 over IPv6 mapping
+		set_ipv6_only_enabled(ip_type != IP::TYPE_ANY);
+	}
+
+	if (protocol == IPPROTO_UDP && ip_type != IP::TYPE_IPV6) {
+		// Enable broadcasting for UDP sockets if it's not IPv6 only (IPv6 has no broadcast option).
+		set_broadcasting_enabled(true);
+	}
+
+	_is_stream = p_sock_type == TYPE_TCP;
+	return OK;
+}
+
+void NetSocketPosix::close() {
+
+	if (_sock != SOCK_EMPTY)
+		SOCK_CLOSE(_sock);
+
+	_sock = SOCK_EMPTY;
+	_ip_type = IP::TYPE_NONE;
+	_is_stream = false;
+}
+
+Error NetSocketPosix::bind(IP_Address p_addr, uint16_t p_port) {
+
+	ERR_FAIL_COND_V(!is_open(), ERR_UNCONFIGURED);
+	ERR_FAIL_COND_V(!_can_use_ip(p_addr, true), ERR_INVALID_PARAMETER);
+
+	sockaddr_storage addr;
+	size_t addr_size = _set_addr_storage(&addr, p_addr, p_port, _ip_type);
+
+	if (::bind(_sock, (struct sockaddr *)&addr, addr_size) == SOCK_EMPTY) {
+		close();
+		ERR_FAIL_V(ERR_UNAVAILABLE);
+	}
+
+	return OK;
+}
+
+Error NetSocketPosix::listen(int p_max_pending) {
+	ERR_FAIL_COND_V(!is_open(), ERR_UNCONFIGURED);
+
+	if (::listen(_sock, p_max_pending) == SOCK_EMPTY) {
+
+		close();
+		ERR_FAIL_V(FAILED);
+	};
+
+	return OK;
+}
+
+Error NetSocketPosix::connect_to_host(IP_Address p_host, uint16_t p_port) {
+
+	ERR_FAIL_COND_V(!is_open(), ERR_UNCONFIGURED);
+	ERR_FAIL_COND_V(!_can_use_ip(p_host, false), ERR_INVALID_PARAMETER);
+
+	struct sockaddr_storage addr;
+	size_t addr_size = _set_addr_storage(&addr, p_host, p_port, _ip_type);
+
+	if (::connect(_sock, (struct sockaddr *)&addr, addr_size) == SOCK_EMPTY) {
+
+		NetError err = _get_socket_error();
+
+		switch (err) {
+			// We are already connected
+			case ERR_NET_IS_CONNECTED:
+				return OK;
+			// Still waiting to connect, try again in a while
+			case ERR_NET_WOULD_BLOCK:
+			case ERR_NET_IN_PROGRESS:
+				return ERR_BUSY;
+			default:
+				ERR_PRINT("Connection to remote host failed!");
+				close();
+				return FAILED;
+		}
+	}
+
+	return OK;
+}
+
+Error NetSocketPosix::poll(PollType p_type, int timeout) const {
+
+	ERR_FAIL_COND_V(!is_open(), ERR_UNCONFIGURED);
+
+	struct pollfd pfd;
+	pfd.fd = _sock;
+	pfd.events = POLLIN;
+	pfd.revents = 0;
+
+	switch (p_type) {
+		case POLL_TYPE_IN:
+			pfd.events = POLLIN;
+			break;
+		case POLL_TYPE_OUT:
+			pfd.events = POLLOUT;
+			break;
+		case POLL_TYPE_IN_OUT:
+			pfd.events = POLLOUT || POLLIN;
+	}
+
+	int ret = SOCK_POLL(&pfd, 1, timeout);
+
+	ERR_FAIL_COND_V(ret < 0, FAILED);
+
+	if (ret == 0)
+		return ERR_BUSY;
+
+	return OK;
+}
+
+Error NetSocketPosix::recv(uint8_t *p_buffer, int p_len, int &r_read) {
+	ERR_FAIL_COND_V(!is_open(), ERR_UNCONFIGURED);
+
+	r_read = ::recv(_sock, SOCK_BUF(p_buffer), p_len, 0);
+
+	if (r_read < 0) {
+		NetError err = _get_socket_error();
+		if (err == ERR_NET_WOULD_BLOCK)
+			return ERR_BUSY;
+
+		return FAILED;
+	}
+
+	return OK;
+}
+
+Error NetSocketPosix::recvfrom(uint8_t *p_buffer, int p_len, int &r_read, IP_Address &r_ip, uint16_t &r_port) {
+	ERR_FAIL_COND_V(!is_open(), ERR_UNCONFIGURED);
+
+	struct sockaddr_storage from;
+	socklen_t len = sizeof(struct sockaddr_storage);
+	memset(&from, 0, len);
+
+	r_read = ::recvfrom(_sock, SOCK_BUF(p_buffer), p_len, 0, (struct sockaddr *)&from, &len);
+
+	if (r_read < 0) {
+		NetError err = _get_socket_error();
+		if (err == ERR_NET_WOULD_BLOCK)
+			return ERR_BUSY;
+
+		return FAILED;
+	}
+
+	if (from.ss_family == AF_INET) {
+		struct sockaddr_in *sin_from = (struct sockaddr_in *)&from;
+		r_ip.set_ipv4((uint8_t *)&sin_from->sin_addr);
+		r_port = ntohs(sin_from->sin_port);
+	} else if (from.ss_family == AF_INET6) {
+		struct sockaddr_in6 *s6_from = (struct sockaddr_in6 *)&from;
+		r_ip.set_ipv6((uint8_t *)&s6_from->sin6_addr);
+		r_port = ntohs(s6_from->sin6_port);
+	} else {
+		// Unsupported socket family, should never happen.
+		ERR_FAIL_V(FAILED);
+	}
+
+	return OK;
+}
+
+Error NetSocketPosix::send(const uint8_t *p_buffer, int p_len, int &r_sent) {
+	ERR_FAIL_COND_V(!is_open(), ERR_UNCONFIGURED);
+
+	int flags = 0;
+	if (_is_stream)
+		flags = MSG_NOSIGNAL;
+	r_sent = ::send(_sock, SOCK_CBUF(p_buffer), p_len, flags);
+
+	if (r_sent < 0) {
+		NetError err = _get_socket_error();
+		if (err == ERR_NET_WOULD_BLOCK)
+			return ERR_BUSY;
+
+		return FAILED;
+	}
+
+	return OK;
+}
+
+Error NetSocketPosix::sendto(const uint8_t *p_buffer, int p_len, int &r_sent, IP_Address p_ip, uint16_t p_port) {
+	ERR_FAIL_COND_V(!is_open(), ERR_UNCONFIGURED);
+
+	struct sockaddr_storage addr;
+	size_t addr_size = _set_addr_storage(&addr, p_ip, p_port, _ip_type);
+	r_sent = ::sendto(_sock, SOCK_CBUF(p_buffer), p_len, 0, (struct sockaddr *)&addr, addr_size);
+
+	if (r_sent < 0) {
+		NetError err = _get_socket_error();
+		if (err == ERR_NET_WOULD_BLOCK)
+			return ERR_BUSY;
+
+		return FAILED;
+	}
+
+	return OK;
+}
+
+void NetSocketPosix::set_broadcasting_enabled(bool p_enabled) {
+	ERR_FAIL_COND(!is_open());
+	// IPv6 has no broadcast support.
+	ERR_FAIL_COND(_ip_type == IP::TYPE_IPV6);
+
+	int par = p_enabled ? 1 : 0;
+	if (setsockopt(_sock, SOL_SOCKET, SO_BROADCAST, SOCK_CBUF(&par), sizeof(int)) != 0) {
+		WARN_PRINT("Unable to change broadcast setting");
+	}
+}
+
+void NetSocketPosix::set_blocking_enabled(bool p_enabled) {
+	ERR_FAIL_COND(!is_open());
+
+	int ret = 0;
+#if defined(WINDOWS_ENABLED) || defined(NO_FCNTL)
+	unsigned long par = p_enabled ? 0 : 1;
+	ret = SOCK_IOCTL(_sock, FIONBIO, &par);
+#else
+	int opts = fcntl(_sock, F_GETFL);
+	if (p_enabled)
+		ret = fcntl(_sock, F_SETFL, opts & ~O_NONBLOCK);
+	else
+		ret = fcntl(_sock, F_SETFL, opts | O_NONBLOCK);
+#endif
+
+	if (ret != 0)
+		WARN_PRINT("Unable to change non-block mode");
+}
+
+void NetSocketPosix::set_ipv6_only_enabled(bool p_enabled) {
+	ERR_FAIL_COND(!is_open());
+	// This option is only avaiable in IPv6 sockets.
+	ERR_FAIL_COND(_ip_type == IP::TYPE_IPV4);
+
+	int par = p_enabled ? 1 : 0;
+	if (setsockopt(_sock, IPPROTO_IPV6, IPV6_V6ONLY, SOCK_CBUF(&par), sizeof(int)) != 0) {
+		WARN_PRINT("Unable to change IPv4 address mapping over IPv6 option");
+	}
+}
+
+void NetSocketPosix::set_tcp_no_delay_enabled(bool p_enabled) {
+	ERR_FAIL_COND(!is_open());
+	ERR_FAIL_COND(_ip_type != TYPE_TCP);
+
+	int par = p_enabled ? 1 : 0;
+	if (setsockopt(_sock, IPPROTO_TCP, TCP_NODELAY, SOCK_CBUF(&par), sizeof(int)) < 0) {
+		ERR_PRINT("Unable to set TCP no delay option");
+	}
+}
+
+void NetSocketPosix::set_reuse_address_enabled(bool p_enabled) {
+	ERR_FAIL_COND(!is_open());
+
+	int par = p_enabled ? 1 : 0;
+	if (setsockopt(_sock, SOL_SOCKET, SO_REUSEADDR, SOCK_CBUF(&par), sizeof(int)) < 0) {
+		WARN_PRINT("Unable to set socket REUSEADDR option!");
+	}
+}
+
+void NetSocketPosix::set_reuse_port_enabled(bool p_enabled) {
+// Windows does not have this option, as it is always ON when setting REUSEADDR.
+#ifndef WINDOWS_ENABLED
+	ERR_FAIL_COND(!is_open());
+
+	int par = p_enabled ? 1 : 0;
+	if (setsockopt(_sock, SOL_SOCKET, SO_REUSEPORT, SOCK_CBUF(&par), sizeof(int)) < 0) {
+		WARN_PRINT("Unable to set socket REUSEPORT option!");
+	}
+#endif
+}
+
+bool NetSocketPosix::is_open() const {
+	return _sock != SOCK_EMPTY;
+}
+
+int NetSocketPosix::get_available_bytes() const {
+
+	ERR_FAIL_COND_V(_sock == SOCK_EMPTY, -1);
+
+	unsigned long len;
+	int ret = SOCK_IOCTL(_sock, FIONREAD, &len);
+	ERR_FAIL_COND_V(ret == -1, 0);
+	return len;
+}
+
+Ref<NetSocket> NetSocketPosix::accept(IP_Address &r_ip, uint16_t &r_port) {
+
+	Ref<NetSocket> out;
+	ERR_FAIL_COND_V(!is_open(), out);
+
+	struct sockaddr_storage their_addr;
+	socklen_t size = sizeof(their_addr);
+	SOCKET_TYPE fd = ::accept(_sock, (struct sockaddr *)&their_addr, &size);
+	ERR_FAIL_COND_V(fd == SOCK_EMPTY, out);
+
+	_set_ip_port(r_ip, r_port, &their_addr);
+
+	NetSocketPosix *ns = memnew(NetSocketPosix);
+	ns->_set_socket(fd, _ip_type, _is_stream);
+	ns->set_blocking_enabled(false);
+	return Ref<NetSocket>(ns);
+}

drivers/unix/net_socket_posix.h

@@ -0,0 +1,97 @@
+/*************************************************************************/
+/*  net_socket_posix.h                                                   */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef NET_SOCKET_UNIX_H
+#define NET_SOCKET_UNIX_H
+
+#include "core/io/net_socket.h"
+
+#if defined(WINDOWS_ENABLED)
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#define SOCKET_TYPE SOCKET
+
+#else
+#define SOCKET_TYPE int
+
+#endif
+
+class NetSocketPosix : public NetSocket {
+
+private:
+	SOCKET_TYPE _sock;
+	IP::Type _ip_type;
+	bool _is_stream;
+
+	enum NetError {
+		ERR_NET_WOULD_BLOCK,
+		ERR_NET_IS_CONNECTED,
+		ERR_NET_IN_PROGRESS,
+		ERR_NET_OTHER
+	};
+
+	NetError _get_socket_error();
+	void _set_socket(SOCKET_TYPE p_sock, IP::Type p_ip_type, bool p_is_stream);
+
+protected:
+	static NetSocket *_create_func();
+
+	bool _can_use_ip(const IP_Address p_ip, const bool p_for_bind) const;
+
+public:
+	static void make_default();
+
+	virtual Error open(Type p_sock_type, IP::Type &ip_type);
+	virtual void close();
+	virtual Error bind(IP_Address p_addr, uint16_t p_port);
+	virtual Error listen(int p_max_pending);
+	virtual Error connect_to_host(IP_Address p_addr, uint16_t p_port);
+	virtual Error poll(PollType p_type, int timeout) const;
+	virtual Error recv(uint8_t *p_buffer, int p_len, int &r_read);
+	virtual Error recvfrom(uint8_t *p_buffer, int p_len, int &r_read, IP_Address &r_ip, uint16_t &r_port);
+	virtual Error send(const uint8_t *p_buffer, int p_len, int &r_sent);
+	virtual Error sendto(const uint8_t *p_buffer, int p_len, int &r_sent, IP_Address p_ip, uint16_t p_port);
+	virtual Ref<NetSocket> accept(IP_Address &r_ip, uint16_t &r_port);
+
+	virtual bool is_open() const;
+	virtual int get_available_bytes() const;
+
+	virtual void set_broadcasting_enabled(bool p_enabled);
+	virtual void set_blocking_enabled(bool p_enabled);
+	virtual void set_ipv6_only_enabled(bool p_enabled);
+	virtual void set_tcp_no_delay_enabled(bool p_enabled);
+	virtual void set_reuse_address_enabled(bool p_enabled);
+	virtual void set_reuse_port_enabled(bool p_enabled);
+
+	NetSocketPosix();
+	~NetSocketPosix();
+};
+
+#endif