Add support for IPv6

Two new configuration options are added:
     - "enable_ipv6" to enable/disable the overall use of IPv6
     - "ipv6_server" to enable/disable the use of IPv6 sockets when running
       a server (when "enable_ipv6" is enabled)

16 files changed, 475 insertions, 209 deletions

diff --git a/minetest.conf.example b/minetest.conf.example
index 4306740e9..8ec65403d 100644
--- a/minetest.conf.example
+++ b/minetest.conf.example
@@ -367,3 +367,9 @@
 
 # Float islands starts from height, 0 to disable
 #mgindev_float_islands = 500
+
+# Enable/disable IPv6
+#enable_ipv6 = true
+# Enable/disable running an IPv6 server.  An IPv6 server may be restricted
+# to IPv6 clients, depending on system configuration.
+#ipv6_server = false
diff --git a/src/client.cpp b/src/client.cpp
index 5f53e14f7..c82d9b050 100644
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -271,7 +271,8 @@ Client::Client(
 		IWritableItemDefManager *itemdef,
 		IWritableNodeDefManager *nodedef,
 		ISoundManager *sound,
-		MtEventManager *event
+		MtEventManager *event,
+		bool ipv6
 ):
 	m_tsrc(tsrc),
 	m_shsrc(shsrc),
@@ -287,7 +288,7 @@ Client::Client(
 		device->getSceneManager(),
 		tsrc, this, device
 	),
-	m_con(PROTOCOL_ID, 512, CONNECTION_TIMEOUT, this),
+	m_con(PROTOCOL_ID, 512, CONNECTION_TIMEOUT, ipv6, this),
 	m_device(device),
 	m_server_ser_ver(SER_FMT_VER_INVALID),
 	m_playeritem(0),
diff --git a/src/client.h b/src/client.h
index 1d231a5a3..0b69abf56 100644
--- a/src/client.h
+++ b/src/client.h
@@ -263,7 +263,8 @@ public:
 			IWritableItemDefManager *itemdef,
 			IWritableNodeDefManager *nodedef,
 			ISoundManager *sound,
-			MtEventManager *event
+			MtEventManager *event,
+			bool ipv6
 	);
 	
 	~Client();
diff --git a/src/connection.cpp b/src/connection.cpp
index 7bff5b113..b94df5e82 100644
--- a/src/connection.cpp
+++ b/src/connection.cpp
@@ -520,10 +520,12 @@ void Peer::reportRTT(float rtt)
 	Connection
 */
 
-Connection::Connection(u32 protocol_id, u32 max_packet_size, float timeout):
+Connection::Connection(u32 protocol_id, u32 max_packet_size, float timeout,
+		bool ipv6):
 	m_protocol_id(protocol_id),
 	m_max_packet_size(max_packet_size),
 	m_timeout(timeout),
+	m_socket(ipv6),
 	m_peer_id(0),
 	m_bc_peerhandler(NULL),
 	m_bc_receive_timeout(0),
@@ -535,10 +537,11 @@ Connection::Connection(u32 protocol_id, u32 max_packet_size, float timeout):
 }
 
 Connection::Connection(u32 protocol_id, u32 max_packet_size, float timeout,
-		PeerHandler *peerhandler):
+		bool ipv6, PeerHandler *peerhandler):
 	m_protocol_id(protocol_id),
 	m_max_packet_size(max_packet_size),
 	m_timeout(timeout),
+	m_socket(ipv6),
 	m_peer_id(0),
 	m_bc_peerhandler(peerhandler),
 	m_bc_receive_timeout(0),
diff --git a/src/connection.h b/src/connection.h
index 486cf331f..f5cddcbf4 100644
--- a/src/connection.h
+++ b/src/connection.h
@@ -548,8 +548,8 @@ struct ConnectionCommand
 class Connection: public SimpleThread
 {
 public:
-	Connection(u32 protocol_id, u32 max_packet_size, float timeout);
-	Connection(u32 protocol_id, u32 max_packet_size, float timeout,
+	Connection(u32 protocol_id, u32 max_packet_size, float timeout, bool ipv6);
+	Connection(u32 protocol_id, u32 max_packet_size, float timeout, bool ipv6,
 			PeerHandler *peerhandler);
 	~Connection();
 	void * Thread();
diff --git a/src/constants.h b/src/constants.h
index 8246c8c21..e9d9f884a 100644
--- a/src/constants.h
+++ b/src/constants.h
@@ -36,6 +36,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 // Causes the socket class to deliberately drop random packets.
 // This disables unit testing of socket and connection.
 #define INTERNET_SIMULATOR 0
+#define INTERNET_SIMULATOR_PACKET_LOSS 10 // 10 = easy, 4 = hard
 
 #define CONNECTION_TIMEOUT 30
 
diff --git a/src/debug.h b/src/debug.h
index 1b14c4e0a..31855cce7 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -34,7 +34,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #ifdef _WIN32
 	#define WIN32_LEAN_AND_MEAN
 	#ifndef _WIN32_WINNT
-		#define _WIN32_WINNT 0x0500
+		#define _WIN32_WINNT 0x0501
 	#endif
 	#include <windows.h>
 	#ifdef _MSC_VER
diff --git a/src/defaultsettings.cpp b/src/defaultsettings.cpp
index ffaa7a3c7..2802d33f5 100644
--- a/src/defaultsettings.cpp
+++ b/src/defaultsettings.cpp
@@ -251,6 +251,10 @@ void set_default_settings(Settings *settings)
 	settings->setDefault("mgindev_np_float_islands3", "0,    1,   (256, 256, 256), 6412,  2, 0.5,  1,   0.5");
 	settings->setDefault("mgindev_np_biome",          "0,    1,   (250, 250, 250), 9130,  3, 0.50, 1,   10");
 	settings->setDefault("mgindev_float_islands", "500");
+	
+	// IPv6
+	settings->setDefault("enable_ipv6", "true");
+	settings->setDefault("ipv6_server", "false");
 }
 
 void override_default_settings(Settings *settings, Settings *from)
diff --git a/src/game.cpp b/src/game.cpp
index 833117959..e4019e472 100644
--- a/src/game.cpp
+++ b/src/game.cpp
@@ -1039,12 +1039,6 @@ void the_game(
 	infostream<<"Creating client"<<std::endl;
 	
 	MapDrawControl draw_control;
-
-	Client client(device, playername.c_str(), password, draw_control,
-			tsrc, shsrc, itemdef, nodedef, sound, &eventmgr);
-	
-	// Client acts as our GameDef
-	IGameDef *gamedef = &client;
 	
 	{
 		wchar_t* text = wgettext("Resolving address...");
@@ -1054,18 +1048,39 @@ void the_game(
 	Address connect_address(0,0,0,0, port);
 	try{
 		if(address == "")
+		{
 			//connect_address.Resolve("localhost");
-			connect_address.setAddress(127,0,0,1);
+			if(g_settings->getBool("enable_ipv6") && g_settings->getBool("ipv6_server"))
+			{
+				IPv6AddressBytes addr_bytes;
+				addr_bytes.bytes[15] = 1;
+				connect_address.setAddress(&addr_bytes);
+			}
+			else
+			{
+				connect_address.setAddress(127,0,0,1);
+			}
+		}
 		else
 			connect_address.Resolve(address.c_str());
 	}
 	catch(ResolveError &e)
 	{
-		error_message = L"Couldn't resolve address";
+		error_message = L"Couldn't resolve address: " + narrow_to_wide(e.what());
 		errorstream<<wide_to_narrow(error_message)<<std::endl;
 		// Break out of client scope
 		break;
 	}
+	
+	/*
+		Create client
+	*/
+	Client client(device, playername.c_str(), password, draw_control,
+		tsrc, shsrc, itemdef, nodedef, sound, &eventmgr,
+		connect_address.isIPv6());
+	
+	// Client acts as our GameDef
+	IGameDef *gamedef = &client;
 
 	/*
 		Attempt to connect to the server
diff --git a/src/gettext.h b/src/gettext.h
index 452787de4..ca82b1f02 100644
--- a/src/gettext.h
+++ b/src/gettext.h
@@ -14,6 +14,9 @@
 
 #if defined(_WIN32)
 #define WIN32_LEAN_AND_MEAN
+#ifndef _WIN32_WINNT
+	#define _WIN32_WINNT 0x0501
+#endif
 #include <windows.h>
 #endif
 
diff --git a/src/jthread/jmutex.h b/src/jthread/jmutex.h
index 383150f3f..8efdc7bc5 100644
--- a/src/jthread/jmutex.h
+++ b/src/jthread/jmutex.h
@@ -31,7 +31,7 @@
 
 #if (defined(WIN32) || defined(_WIN32_WCE))
 	#ifndef _WIN32_WINNT
-		#define _WIN32_WINNT 0x0500
+		#define _WIN32_WINNT 0x0501
 	#endif
 	#ifndef _WIN32_WCE
 		#include <process.h>
diff --git a/src/porting.h b/src/porting.h
index bcce96ef7..12c390893 100644
--- a/src/porting.h
+++ b/src/porting.h
@@ -42,7 +42,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #ifdef _WIN32
 	#ifndef _WIN32_WINNT
-		#define _WIN32_WINNT 0x0500
+		#define _WIN32_WINNT 0x0501
 	#endif
 	#include <windows.h>
 	
@@ -153,6 +153,9 @@ bool threadSetPriority(threadid_t tid, int prio);
 	Overflow can occur at any value higher than 10000000.
 */
 #ifdef _WIN32 // Windows
+#ifndef _WIN32_WINNT
+	#define _WIN32_WINNT 0x0501
+#endif
 	#include <windows.h>
 	
 	inline u32 getTimeS()
diff --git a/src/server.cpp b/src/server.cpp
index 7963aeaae..fea4349f1 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -639,7 +639,8 @@ Server::Server(
 	m_simple_singleplayer_mode(simple_singleplayer_mode),
 	m_async_fatal_error(""),
 	m_env(NULL),
-	m_con(PROTOCOL_ID, 512, CONNECTION_TIMEOUT, this),
+	m_con(PROTOCOL_ID, 512, CONNECTION_TIMEOUT,
+	      g_settings->getBool("enable_ipv6") && g_settings->getBool("ipv6_server"), this),
 	m_banmanager(path_world+DIR_DELIM+"ipban.txt"),
 	m_rollback(NULL),
 	m_rollback_sink_enabled(true),
diff --git a/src/socket.cpp b/src/socket.cpp
index 9e289baa2..c1517ccb9 100644
--- a/src/socket.cpp
+++ b/src/socket.cpp
@@ -20,7 +20,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "socket.h"
 
 #ifdef _WIN32
-	#define WIN32_LEAN_AND_MEAN
+	#ifndef WIN32_LEAN_AND_MEAN
+		#define WIN32_LEAN_AND_MEAN
+	#endif
 	// Without this some of the network functions are not found on mingw
 	#ifndef _WIN32_WINNT
 		#define _WIN32_WINNT 0x0501
@@ -46,27 +48,30 @@ typedef int socket_t;
 
 #include "constants.h"
 #include "debug.h"
+#include "settings.h"
+#include "main.h" // for g_settings
 #include <stdio.h>
 #include <iostream>
 #include <stdlib.h>
+#include <string.h>
 #include <errno.h>
+#include <sstream>
 #include "util/string.h"
 #include "util/numeric.h"
 
+// Set to true to enable verbose debug output
 bool socket_enable_debug_output = false;
-#define DP socket_enable_debug_output
-// This is prepended to everything printed here
-#define DPS ""
 
 bool g_sockets_initialized = false;
 
+// Initialize sockets
 void sockets_init()
 {
 #ifdef _WIN32
+	// Windows needs sockets to be initialized before use
 	WSADATA WsaData;
 	if(WSAStartup( MAKEWORD(2,2), &WsaData ) != NO_ERROR)
 		throw SocketException("WSAStartup failed");
-#else
 #endif
 	g_sockets_initialized = true;
 }
@@ -74,34 +79,57 @@ void sockets_init()
 void sockets_cleanup()
 {
 #ifdef _WIN32
+	// On Windows, cleanup sockets after use
 	WSACleanup();
 #endif
 }
 
+/*
+	Address
+*/
+
 Address::Address()
 {
-	m_address = 0;
+	m_addr_family = 0;
+	memset(&m_address, 0, sizeof m_address);
 	m_port = 0;
 }
 
-Address::Address(unsigned int address, unsigned short port)
+Address::Address(u32 address, u16 port)
 {
-	m_address = address;
-	m_port = port;
+	setAddress(address);
+	setPort(port);
 }
 
-Address::Address(unsigned int a, unsigned int b,
-		unsigned int c, unsigned int d,
-		unsigned short port)
+Address::Address(u8 a, u8 b, u8 c, u8 d, u16 port)
 {
-	m_address = (a<<24) | (b<<16) | ( c<<8) | d;
-	m_port = port;
+	setAddress(a, b, c, d);
+	setPort(port);
 }
 
+Address::Address(const IPv6AddressBytes * ipv6_bytes, u16 port)
+{
+	setAddress(ipv6_bytes);
+	setPort(port);
+}
+
+// Equality (address family, address and port must be equal)
 bool Address::operator==(Address &address)
 {
-	return (m_address == address.m_address
-			&& m_port == address.m_port);
+	if(address.m_addr_family != m_addr_family || address.m_port != m_port)
+		return false;
+	else if(m_addr_family == AF_INET)
+	{
+		return m_address.ipv4.sin_addr.s_addr ==
+		       address.m_address.ipv4.sin_addr.s_addr;
+	}
+	else if(m_addr_family == AF_INET6)
+	{
+		return memcmp(m_address.ipv6.sin6_addr.s6_addr,
+		              address.m_address.ipv6.sin6_addr.s6_addr, 16) == 0;
+	}
+	else
+		return false;
 }
 
 bool Address::operator!=(Address &address)
@@ -111,105 +139,183 @@ bool Address::operator!=(Address &address)
 
 void Address::Resolve(const char *name)
 {
-	struct addrinfo *resolved;
-	int e = getaddrinfo(name, NULL, NULL, &resolved);
+	struct addrinfo *resolved, hints;
+	memset(&hints, 0, sizeof(hints));
+	
+	// Setup hints
+	hints.ai_socktype = 0;
+	hints.ai_protocol = 0;
+	hints.ai_flags    = 0;
+	if(g_settings->getBool("enable_ipv6"))
+	{
+		// AF_UNSPEC allows both IPv6 and IPv4 addresses to be returned
+		hints.ai_family = AF_UNSPEC;
+	}
+	else
+	{
+		hints.ai_family = AF_INET;
+	}
+	
+	// Do getaddrinfo()
+	int e = getaddrinfo(name, NULL, &hints, &resolved);
 	if(e != 0)
+		throw ResolveError(gai_strerror(e));
+
+	// Copy data
+	if(resolved->ai_family == AF_INET)
+	{
+		struct sockaddr_in *t = (struct sockaddr_in *) resolved->ai_addr;
+		m_addr_family = AF_INET;
+		m_address.ipv4 = *t;
+	}
+	else if(resolved->ai_family == AF_INET6)
+	{
+		struct sockaddr_in6 *t = (struct sockaddr_in6 *) resolved->ai_addr;
+		m_addr_family = AF_INET6;
+		m_address.ipv6 = *t;
+	}
+	else
+	{
+		freeaddrinfo(resolved);
 		throw ResolveError("");
-	/*
-		FIXME: This is an ugly hack; change the whole class
-		to store the address as sockaddr
-	*/
-	struct sockaddr_in *t = (struct sockaddr_in*)resolved->ai_addr;
-	m_address = ntohl(t->sin_addr.s_addr);
+	}
 	freeaddrinfo(resolved);
 }
 
+// IP address -> textual representation
 std::string Address::serializeString() const
 {
-	unsigned int a, b, c, d;
-	a = (m_address & 0xFF000000)>>24;
-	b = (m_address & 0x00FF0000)>>16;
-	c = (m_address & 0x0000FF00)>>8;
-	d = (m_address & 0x000000FF);
-	return itos(a)+"."+itos(b)+"."+itos(c)+"."+itos(d);
+	if(m_addr_family == AF_INET)
+	{
+		u8 a, b, c, d, addr;
+		addr = ntohl(m_address.ipv4.sin_addr.s_addr);
+		a = (addr & 0xFF000000) >> 24;
+		b = (addr & 0x00FF0000) >> 16;
+		c = (addr & 0x0000FF00) >> 8;
+		d = (addr & 0x000000FF);
+		return itos(a) + "." + itos(b) + "." + itos(c) + "." + itos(d);
+	}
+	else if(m_addr_family == AF_INET6)
+	{
+		std::ostringstream os;
+		for(int i = 0; i < 16; i += 2)
+		{
+			u16 section =
+				(m_address.ipv6.sin6_addr.s6_addr[i] << 8) |
+				(m_address.ipv6.sin6_addr.s6_addr[i + 1]);
+			os << std::hex << section;
+			if(i < 14)
+				os << ":";
+		}
+		return os.str();
+	}
+	else
+		return std::string("");
+}
+
+struct sockaddr_in Address::getAddress() const
+{
+	return m_address.ipv4; // NOTE: NO PORT INCLUDED, use getPort()
 }
 
-unsigned int Address::getAddress() const
+struct sockaddr_in6 Address::getAddress6() const
 {
-	return m_address;
+	return m_address.ipv6; // NOTE: NO PORT INCLUDED, use getPort()
 }
 
-unsigned short Address::getPort() const
+u16 Address::getPort() const
 {
 	return m_port;
 }
 
-void Address::setAddress(unsigned int address)
+int Address::getFamily() const
 {
-	m_address = address;
+	return m_addr_family;
 }
 
-void Address::setAddress(unsigned int a, unsigned int b,
-		unsigned int c, unsigned int d)
+bool Address::isIPv6() const
 {
-	m_address = (a<<24) | (b<<16) | ( c<<8) | d;
+	return m_addr_family == AF_INET6;
 }
 
-void Address::setPort(unsigned short port)
+void Address::setAddress(u32 address)
 {
-	m_port = port;
+	m_addr_family = AF_INET;
+	m_address.ipv4.sin_family = AF_INET;
+	m_address.ipv4.sin_addr.s_addr = htonl(address);
 }
 
-void Address::print(std::ostream *s) const
+void Address::setAddress(u8 a, u8 b, u8 c, u8 d)
+{
+	m_addr_family = AF_INET;
+	m_address.ipv4.sin_family = AF_INET;
+	u32 addr = htonl((a << 24) | (b << 16) | (c << 8) | d);
+	m_address.ipv4.sin_addr.s_addr = addr;
+}
+
+void Address::setAddress(const IPv6AddressBytes * ipv6_bytes)
 {
-	(*s)<<((m_address>>24)&0xff)<<"."
-			<<((m_address>>16)&0xff)<<"."
-			<<((m_address>>8)&0xff)<<"."
-			<<((m_address>>0)&0xff)<<":"
-			<<m_port;
+	m_addr_family = AF_INET6;
+	m_address.ipv6.sin6_family = AF_INET6;
+	if(ipv6_bytes)
+		memcpy(m_address.ipv6.sin6_addr.s6_addr, ipv6_bytes->bytes, 16);
+	else
+		memset(m_address.ipv6.sin6_addr.s6_addr, 0, 16);
 }
 
-void Address::print() const
+void Address::setPort(u16 port)
 {
-	print(&dstream);
+	m_port = port;
+}
+
+void Address::print(std::ostream *s) const
+{
+	if(m_addr_family == AF_INET6)
+	{
+		(*s) << "[" << serializeString() << "]:" << m_port;
+	}
+	else
+	{
+		(*s) << serializeString() << ":" << m_port;
+	}
 }
 
-UDPSocket::UDPSocket()
+/*
+	UDPSocket
+*/
+
+UDPSocket::UDPSocket(bool ipv6)
 {
 	if(g_sockets_initialized == false)
 		throw SocketException("Sockets not initialized");
-	
-    m_handle = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
-	
-	if(DP)
-	dstream<<DPS<<"UDPSocket("<<(int)m_handle<<")::UDPSocket()"<<std::endl;
-	
-    if(m_handle <= 0)
-    {
-		throw SocketException("Failed to create socket");
-    }
 
-/*#ifdef _WIN32
-	DWORD nonblocking = 0;
-	if(ioctlsocket(m_handle, FIONBIO, &nonblocking) != 0)
+	// Use IPv6 if specified
+	m_addr_family = ipv6 ? AF_INET6 : AF_INET;
+	m_handle = socket(m_addr_family, SOCK_DGRAM, IPPROTO_UDP);
+	
+	if(socket_enable_debug_output)
 	{
-		throw SocketException("Failed set non-blocking mode");
+		dstream << "UDPSocket(" << (int) m_handle
+		        << ")::UDPSocket(): ipv6 = "
+		        << (ipv6 ? "true" : "false")
+		        << std::endl;
 	}
-#else
-	int nonblocking = 0;
-	if(fcntl(m_handle, F_SETFL, O_NONBLOCK, nonblocking) == -1)
+
+	if(m_handle <= 0)
 	{
-		throw SocketException("Failed set non-blocking mode");
+		throw SocketException("Failed to create socket");
 	}
-#endif*/
 
 	setTimeoutMs(0);
 }
 
 UDPSocket::~UDPSocket()
 {
-	if(DP)
-	dstream<<DPS<<"UDPSocket("<<(int)m_handle<<")::~UDPSocket()"<<std::endl;
+	if(socket_enable_debug_output)
+	{
+		dstream << "UDPSocket( " << (int) m_handle << ")::~UDPSocket()"
+		        << std::endl;
+	}
 
 #ifdef _WIN32
 	closesocket(m_handle);
@@ -218,111 +324,175 @@ UDPSocket::~UDPSocket()
 #endif
 }
 
-void UDPSocket::Bind(unsigned short port)
+void UDPSocket::Bind(u16 port)
 {
-	if(DP)
-	dstream<<DPS<<"UDPSocket("<<(int)m_handle
-			<<")::Bind(): port="<<port<<std::endl;
-
-    sockaddr_in address;
-    address.sin_family = AF_INET;
-    address.sin_addr.s_addr = INADDR_ANY;
-    address.sin_port = htons(port);
-
-    if(bind(m_handle, (const sockaddr*)&address, sizeof(sockaddr_in)) < 0)
-    {
-#ifndef DISABLE_ERRNO
-		dstream<<(int)m_handle<<": Bind failed: "<<strerror(errno)<<std::endl;
-#endif
-		throw SocketException("Failed to bind socket");
-    }
+	if(socket_enable_debug_output)
+	{
+		dstream << "UDPSocket(" << (int) m_handle << ")::Bind(): "
+		        << "port=" << port << std::endl;
+	}
+
+	if(m_addr_family == AF_INET6)
+	{
+		struct sockaddr_in6 address;
+		address.sin6_family = AF_INET6;
+		address.sin6_addr   = in6addr_any;
+		address.sin6_port   = htons(port);
+
+		if(bind(m_handle, (const struct sockaddr *) &address,
+		        sizeof(struct sockaddr_in6)) < 0)
+		{
+			dstream << (int) m_handle << ": Bind failed: "
+			        << strerror(errno) << std::endl;
+			throw SocketException("Failed to bind socket");
+		}
+	}
+	else
+	{
+		struct sockaddr_in address;
+		address.sin_family      = AF_INET;
+		address.sin_addr.s_addr = INADDR_ANY;
+		address.sin_port        = htons(port);
+
+		if(bind(m_handle, (const struct sockaddr *) &address,
+		        sizeof(struct sockaddr_in)) < 0)
+		{
+			dstream << (int) m_handle << ": Bind failed: "
+			        << strerror(errno) << std::endl;
+			throw SocketException("Failed to bind socket");
+		}
+	}
 }
 
 void UDPSocket::Send(const Address & destination, const void * data, int size)
 {
-	bool dumping_packet = false;
+	bool dumping_packet = false; // for INTERNET_SIMULATOR
+
 	if(INTERNET_SIMULATOR)
-		dumping_packet = (myrand()%10==0); //easy
-		//dumping_packet = (myrand()%4==0); // hard
-
-	if(DP){
-		/*dstream<<DPS<<"UDPSocket("<<(int)m_handle
-				<<")::Send(): destination=";*/
-		dstream<<DPS;
-		dstream<<(int)m_handle<<" -> ";
-		destination.print();
-		dstream<<", size="<<size<<", data=";
-		for(int i=0; i<size && i<20; i++){
-			if(i%2==0) DEBUGPRINT(" ");
-			unsigned int a = ((const unsigned char*)data)[i];
+		dumping_packet = (myrand() % INTERNET_SIMULATOR_PACKET_LOSS == 0);
+
+	if(socket_enable_debug_output)
+	{
+		// Print packet destination and size
+		dstream << (int) m_handle << " -> ";
+		destination.print(&dstream);
+		dstream << ", size=" << size;
+		
+		// Print packet contents
+		dstream << ", data=";
+		for(int i = 0; i < size && i < 20; i++)
+		{
+			if(i % 2 == 0)
+				DEBUGPRINT(" ");
+			unsigned int a = ((const unsigned char *) data)[i];
 			DEBUGPRINT("%.2X", a);
 		}
-		if(size>20)
-			dstream<<"...";
+		
+		if(size > 20)
+			dstream << "...";
+		
 		if(dumping_packet)
-			dstream<<" (DUMPED BY INTERNET_SIMULATOR)";
-		dstream<<std::endl;
-	}
-	else if(dumping_packet)
-	{
-		// Lol let's forget it
-		dstream<<"UDPSocket::Send(): "
-				"INTERNET_SIMULATOR: dumping packet."
-				<<std::endl;
+			dstream << " (DUMPED BY INTERNET_SIMULATOR)";
+		
+		dstream << std::endl;
 	}
 
 	if(dumping_packet)
+	{
+		// Lol let's forget it
+		dstream << "UDPSocket::Send(): "
+				   "INTERNET_SIMULATOR: dumping packet."
+				<< std::endl;
 		return;
+	}
 
-	sockaddr_in address;
-	address.sin_family = AF_INET;
-	address.sin_addr.s_addr = htonl(destination.getAddress());
-	address.sin_port = htons(destination.getPort());
+	if(destination.getFamily() != m_addr_family)
+		throw SendFailedException("Address family mismatch");
 
-	int sent = sendto(m_handle, (const char*)data, size,
-		0, (sockaddr*)&address, sizeof(sockaddr_in));
+	int sent;
+	if(m_addr_family == AF_INET6)
+	{
+		struct sockaddr_in6 address = destination.getAddress6();
+		address.sin6_port = htons(destination.getPort());
+		sent = sendto(m_handle, (const char *) data, size,
+			0, (struct sockaddr *) &address, sizeof(struct sockaddr_in6));
+	}
+	else
+	{
+		struct sockaddr_in address = destination.getAddress();
+		address.sin_port = htons(destination.getPort());
+		sent = sendto(m_handle, (const char *) data, size,
+			0, (struct sockaddr *) &address, sizeof(struct sockaddr_in));
+	}
 
-    if(sent != size)
-    {
+	if(sent != size)
+	{
 		throw SendFailedException("Failed to send packet");
-    }
+	}
 }
 
 int UDPSocket::Receive(Address & sender, void * data, int size)
 {
+	// Return on timeout
 	if(WaitData(m_timeout_ms) == false)
 	{
 		return -1;
 	}
 
-	sockaddr_in address;
-	socklen_t address_len = sizeof(address);
+	int received;
+	if(m_addr_family == AF_INET6)
+	{
+		struct sockaddr_in6 address;
+		socklen_t address_len = sizeof(address);
 
-	int received = recvfrom(m_handle, (char*)data,
-			size, 0, (sockaddr*)&address, &address_len);
+		received = recvfrom(m_handle, (char *) data,
+				size, 0, (struct sockaddr *) &address, &address_len);
 
-	if(received < 0)
-		return -1;
+		if(received < 0)
+			return -1;
+
+		u16 address_port = ntohs(address.sin6_port);
+		IPv6AddressBytes bytes;
+		memcpy(bytes.bytes, address.sin6_addr.s6_addr, 16);
+		sender = Address(&bytes, address_port);
+	}
+	else
+	{
+		struct sockaddr_in address;
+		socklen_t address_len = sizeof(address);
+
+		received = recvfrom(m_handle, (char *) data,
+				size, 0, (struct sockaddr *) &address, &address_len);
 
-	unsigned int address_ip = ntohl(address.sin_addr.s_addr);
-	unsigned int address_port = ntohs(address.sin_port);
+		if(received < 0)
+			return -1;
 
-	sender = Address(address_ip, address_port);
+		u32 address_ip = ntohl(address.sin_addr.s_addr);
+		u16 address_port = ntohs(address.sin_port);
+
+		sender = Address(address_ip, address_port);
+	}
 
-	if(DP){
-		//dstream<<DPS<<"UDPSocket("<<(int)m_handle<<")::Receive(): sender=";
-		dstream<<DPS<<(int)m_handle<<" <- ";
-		sender.print();
-		//dstream<<", received="<<received<<std::endl;
-		dstream<<", size="<<received<<", data=";
-		for(int i=0; i<received && i<20; i++){
-			if(i%2==0) DEBUGPRINT(" ");
-			unsigned int a = ((const unsigned char*)data)[i];
+	if(socket_enable_debug_output)
+	{
+		// Print packet sender and size
+		dstream << (int) m_handle << " <- ";
+		sender.print(&dstream);
+		dstream << ", size=" << received;
+		
+		// Print packet contents
+		dstream << ", data=";
+		for(int i = 0; i < received && i < 20; i++)
+		{
+			if(i % 2 == 0)
+				DEBUGPRINT(" ");
+			unsigned int a = ((const unsigned char *) data)[i];
 			DEBUGPRINT("%.2X", a);
 		}
-		if(received>20)
-			dstream<<"...";
-		dstream<<std::endl;
+		if(received > 20)
+			dstream << "...";
+		
+		dstream << std::endl;
 	}
 
 	return received;
@@ -351,42 +521,39 @@ bool UDPSocket::WaitData(int timeout_ms)
 	struct timeval tv;
 	tv.tv_sec = 0;
 	tv.tv_usec = timeout_ms * 1000;
+
 	// select()
 	result = select(m_handle+1, &readset, NULL, NULL, &tv);
 
-	if(result == 0){
-		// Timeout
-		/*dstream<<"Select timed out (timeout_ms="
-				<<timeout_ms<<")"<<std::endl;*/
+	if(result == 0)
 		return false;
-	}
-	else if(result < 0 && errno == EINTR){
+	else if(result < 0 && errno == EINTR)
 		return false;
-	}
-	else if(result < 0){
-		// Error
-#ifndef DISABLE_ERRNO
-		dstream<<(int)m_handle<<": Select failed: "<<strerror(errno)<<std::endl;
-#endif
+	else if(result < 0)
+	{
+		dstream << (int) m_handle << ": Select failed: "
+		        << strerror(errno) << std::endl;
+
 #ifdef _WIN32
 		int e = WSAGetLastError();
-		dstream<<(int)m_handle<<": WSAGetLastError()="<<e<<std::endl;
-		if(e == 10004 /*=WSAEINTR*/)
+		dstream << (int) m_handle << ": WSAGetLastError()="
+		        << e << std::endl;
+		if(e == 10004 /* = WSAEINTR */)
 		{
-			dstream<<"WARNING: Ignoring WSAEINTR."<<std::endl;
+			dstream << "WARNING: Ignoring WSAEINTR." << std::endl;
 			return false;
 		}
 #endif
+
 		throw SocketException("Select failed");
 	}
-	else if(FD_ISSET(m_handle, &readset) == false){
+	else if(FD_ISSET(m_handle, &readset) == false)
+	{
 		// No data
-		//dstream<<"Select reported no data in m_handle"<<std::endl;
 		return false;
 	}
 	
 	// There is data
-	//dstream<<"Select reported data in m_handle"<<std::endl;
 	return true;
 }
 
diff --git a/src/socket.h b/src/socket.h
index 994a07e45..ba88b0142 100644
--- a/src/socket.h
+++ b/src/socket.h
@@ -20,7 +20,24 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #ifndef SOCKET_HEADER
 #define SOCKET_HEADER
 
+#ifdef _WIN32
+	#ifndef WIN32_LEAN_AND_MEAN
+		#define WIN32_LEAN_AND_MEAN
+	#endif
+#ifndef _WIN32_WINNT
+	#define _WIN32_WINNT 0x0501
+#endif
+	#include <windows.h>
+	#include <winsock2.h>
+	#include <ws2tcpip.h>
+#else
+	#include <sys/socket.h>
+	#include <netinet/in.h>
+#endif
+
 #include <ostream>
+#include <string.h>
+#include "irrlichttypes.h"
 #include "exceptions.h"
 
 extern bool socket_enable_debug_output;
@@ -55,35 +72,48 @@ public:
 void sockets_init();
 void sockets_cleanup();
 
+class IPv6AddressBytes
+{
+public:
+	u8 bytes[16];
+	IPv6AddressBytes() { memset(bytes, 0, 16); }
+};
+
 class Address
 {
 public:
 	Address();
-	Address(unsigned int address, unsigned short port);
-	Address(unsigned int a, unsigned int b,
-			unsigned int c, unsigned int d,
-			unsigned short port);
+	Address(u32 address, u16 port);
+	Address(u8 a, u8 b, u8 c, u8 d, u16 port);
+	Address(const IPv6AddressBytes * ipv6_bytes, u16 port);
 	bool operator==(Address &address);
 	bool operator!=(Address &address);
 	void Resolve(const char *name);
-	unsigned int getAddress() const;
+	struct sockaddr_in getAddress() const;
 	unsigned short getPort() const;
-	void setAddress(unsigned int address);
-	void setAddress(unsigned int a, unsigned int b,
-			unsigned int c, unsigned int d);
+	void setAddress(u32 address);
+	void setAddress(u8 a, u8 b, u8 c, u8 d);
+	void setAddress(const IPv6AddressBytes * ipv6_bytes);
+	struct sockaddr_in6 getAddress6() const;
+	int getFamily() const;
+	bool isIPv6() const;
 	void setPort(unsigned short port);
 	void print(std::ostream *s) const;
-	void print() const;
 	std::string serializeString() const;
 private:
-	unsigned int m_address;
-	unsigned short m_port;
+	unsigned int m_addr_family;
+	union
+	{
+		struct sockaddr_in  ipv4;
+		struct sockaddr_in6 ipv6;
+	} m_address;
+	u16 m_port; // Port is separate from sockaddr structures
 };
 
 class UDPSocket
 {
 public:
-	UDPSocket();
+	UDPSocket(bool ipv6);
 	~UDPSocket();
 	void Bind(unsigned short port);
 	//void Close();
@@ -98,6 +128,7 @@ public:
 private:
 	int m_handle;
 	int m_timeout_ms;
+	int m_addr_family;
 };
 
 #endif
diff --git a/src/test.cpp b/src/test.cpp
index 5267b2768..b66f65daf 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -1293,26 +1293,56 @@ struct TestSocket: public TestBase
 	void Run()
 	{
 		const int port = 30003;
-		UDPSocket socket;
-		socket.Bind(port);
 
-		const char sendbuffer[] = "hello world!";
-		socket.Send(Address(127,0,0,1,port), sendbuffer, sizeof(sendbuffer));
+		// IPv6 socket test
+		{
+			UDPSocket socket6(true);
+			socket6.Bind(port);
 
-		sleep_ms(50);
+			const char sendbuffer[] = "hello world!";
+			IPv6AddressBytes bytes;
+			bytes.bytes[15] = 1;
+			socket6.Send(Address(&bytes, port), sendbuffer, sizeof(sendbuffer));
+
+			sleep_ms(50);
+
+			char rcvbuffer[256];
+			memset(rcvbuffer, 0, sizeof(rcvbuffer));
+			Address sender;
+			for(;;)
+			{
+				int bytes_read = socket6.Receive(sender, rcvbuffer, sizeof(rcvbuffer));
+				if(bytes_read < 0)
+					break;
+			}
+			//FIXME: This fails on some systems
+			UASSERT(strncmp(sendbuffer, rcvbuffer, sizeof(sendbuffer))==0);
+			UASSERT(memcmp(sender.getAddress6().sin6_addr.s6_addr, Address(&bytes, 0).getAddress6().sin6_addr.s6_addr, 16) == 0);
+		}
 
-		char rcvbuffer[256];
-		memset(rcvbuffer, 0, sizeof(rcvbuffer));
-		Address sender;
-		for(;;)
+		// IPv4 socket test
 		{
-			int bytes_read = socket.Receive(sender, rcvbuffer, sizeof(rcvbuffer));
-			if(bytes_read < 0)
-				break;
+			UDPSocket socket(false);
+			socket.Bind(port);
+
+			const char sendbuffer[] = "hello world!";
+			socket.Send(Address(127,0,0,1,port), sendbuffer, sizeof(sendbuffer));
+
+			sleep_ms(50);
+
+			char rcvbuffer[256];
+			memset(rcvbuffer, 0, sizeof(rcvbuffer));
+			Address sender;
+			for(;;)
+			{
+				int bytes_read = socket.Receive(sender, rcvbuffer, sizeof(rcvbuffer));
+				if(bytes_read < 0)
+					break;
+			}
+			//FIXME: This fails on some systems
+			UASSERT(strncmp(sendbuffer, rcvbuffer, sizeof(sendbuffer))==0);
+			UASSERT(sender.getAddress().sin_addr.s_addr == Address(127,0,0,1, 0).getAddress().sin_addr.s_addr);
 		}
-		//FIXME: This fails on some systems
-		UASSERT(strncmp(sendbuffer, rcvbuffer, sizeof(sendbuffer))==0);
-		UASSERT(sender.getAddress() == Address(127,0,0,1, 0).getAddress());
 	}
 };
 
@@ -1412,12 +1442,12 @@ struct TestConnection: public TestBase
 		Handler hand_client("client");
 		
 		infostream<<"** Creating server Connection"<<std::endl;
-		con::Connection server(proto_id, 512, 5.0, &hand_server);
+		con::Connection server(proto_id, 512, 5.0, false, &hand_server);
 		server.Serve(30001);
 		
 		infostream<<"** Creating client Connection"<<std::endl;
-		con::Connection client(proto_id, 512, 5.0, &hand_client);
-
+		con::Connection client(proto_id, 512, 5.0, false, &hand_client);
+		
 		UASSERT(hand_server.count == 0);
 		UASSERT(hand_client.count == 0);