Implement Happy Eyeballs for C4Network2HTTPClient

This should make masterserver requests more reliable for users with a
bad IPv6 connection.

See RFC6555

src/netpuncher/C4PuncherHash.h

@@ -76,7 +76,8 @@ namespace std {
 				auto unpack = make_tuple(v6.sin6_family, v6.sin6_port, v6.sin6_flowinfo, std::string((char*) v6.sin6_addr.s6_addr, 16), v6.sin6_scope_id);
 				return hash<decltype(unpack)>()(unpack);
 			}
-			default:
+			case C4NetIO::HostAddress::UnknownFamily:
+				assert(!"Unexpected address family");
 				return 0;
 			}
 		}

src/netpuncher/C4PuncherPacket.cpp

@@ -18,6 +18,11 @@
 #include "network/C4Network2Address.h"
 #include <sstream>
 
+void C4NetpuncherID::CompileFunc(StdCompiler *pComp) {
+	pComp->Value(mkNamingAdapt(v4, "IPv4", 0u));
+	pComp->Value(mkNamingAdapt(v6, "IPv6", 0u));
+}
+
 std::unique_ptr<C4NetpuncherPacket> C4NetpuncherPacket::Construct(const C4NetIOPacket& rpack) {
 	if (!rpack.getPData()) return nullptr;
 	try {

src/netpuncher/C4PuncherPacket.h

@@ -27,7 +27,14 @@ enum C4NetpuncherPacketType {
 	// extend this with exchanging ICE parameters, some day?
 };
 
-typedef uint32_t C4NetpuncherID_t;
+struct C4NetpuncherID {
+	typedef uint32_t value;
+
+	value v4 = 0, v6 = 0;
+
+	void CompileFunc(StdCompiler *pComp);
+	bool operator==(const C4NetpuncherID& other) const { return v4 == other.v4 && v6 == other.v6; }
+};
 
 class C4NetpuncherPacket {
 public:
@@ -38,7 +45,7 @@ public:
 	C4NetIOPacket PackTo(const C4NetIO::addr_t&) const;
 protected:
 	virtual StdBuf PackInto() const = 0;
-	typedef C4NetpuncherID_t CID;
+	typedef C4NetpuncherID::value CID;
 };
 
 template<C4NetpuncherPacketType TYPE>

src/netpuncher/main.cpp

@@ -29,7 +29,7 @@
 class C4PuncherServer : public C4NetIOUDP, private C4NetIO::CBClass
 {
 public:
-	typedef C4NetpuncherID_t CID;
+	typedef C4NetpuncherID::value CID;
 	C4PuncherServer() {
 		C4NetIOUDP::SetCallback(this);
 		rng = std::bind(std::uniform_int_distribution<CID>(1/*, max*/), std::ref(random_device));
@@ -96,7 +96,11 @@ int main(int argc, char * argv[])
 	printf("Listening on port %d...\n", iPort);
 
 	// Execute forever
-	Puncher.ExecuteUntil(-1);
+	for (;;)
+	{
+		Puncher.ExecuteUntil(-1);
+		fprintf(stderr, "ERROR: %s\n", Puncher.GetError());
+	}
 
 	return 0;
 }

src/network/C4NetIO.cpp

@@ -31,6 +31,8 @@
 
 #include <process.h>
 #include <share.h>
+#include <winsock2.h>
+#include <iphlpapi.h>
 
 typedef int socklen_t;
 int pipe(int *phandles) { return _pipe(phandles, 10, O_BINARY); }
@@ -43,6 +45,8 @@ int pipe(int *phandles) { return _pipe(phandles, 10, O_BINARY); }
 #include <arpa/inet.h>
 #include <netdb.h>
 #include <stdlib.h>
+#include <ifaddrs.h>
+#include <net/if.h>
 
 #define ioctlsocket ioctl
 #define closesocket close
@@ -50,11 +54,16 @@ int pipe(int *phandles) { return _pipe(phandles, 10, O_BINARY); }
 
 #endif
 
-
 #ifdef _MSC_VER
 #pragma warning (disable : 4355)
 #endif
 
+// These are named differently on mac.
+#if !defined(IPV6_ADD_MEMBERSHIP) && defined(IPV6_JOIN_GROUP)
+#define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
+#define IPV6_DROP_MEMBERSHIP IPV6_LEAVE_GROUP
+#endif
+
 // constants definition
 const int C4NetIO::TO_INF = -1;
 
@@ -244,6 +253,16 @@ bool C4NetIO::HostAddress::IsLoopback() const
 	return false;
 }
 
+bool C4NetIO::HostAddress::IsLocal() const
+{
+	if (gen.sa_family == AF_INET6)
+		return IN6_IS_ADDR_LINKLOCAL(&v6.sin6_addr) != 0;
+	// We don't really care about local 169.256.0.0/16 addresses here as users will either have a
+	// router doing DHCP (which will prevent usage of these addresses) or have a network that
+	// doesn't care about IP and IPv6 link-local addresses will work.
+	return false;
+}
+
 void C4NetIO::HostAddress::SetScopeId(int scopeId)
 {
 	if (gen.sa_family != AF_INET6) return;
@@ -280,11 +299,27 @@ C4NetIO::HostAddress C4NetIO::HostAddress::AsIPv6() const
 	return nrv;
 }
 
+C4NetIO::HostAddress C4NetIO::HostAddress::AsIPv4() const
+{
+	HostAddress nrv(*this);
+	if (gen.sa_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&v6.sin6_addr))
+	{
+		nrv.v4.sin_family = AF_INET;
+		memcpy((char*) &nrv.v4.sin_addr, (char*) &v6.sin6_addr.s6_addr[12], sizeof(v4.sin_addr));
+	}
+	return nrv;
+}
+
 C4NetIO::EndpointAddress C4NetIO::EndpointAddress::AsIPv6() const
 {
 	return EndpointAddress(HostAddress::AsIPv6(), GetPort());
 }
 
+C4NetIO::EndpointAddress C4NetIO::EndpointAddress::AsIPv4() const
+{
+	return EndpointAddress(HostAddress::AsIPv4(), GetPort());
+}
+
 void C4NetIO::HostAddress::SetHost(const sockaddr *addr)
 {
 	// Copy all but port number
@@ -346,7 +381,19 @@ void C4NetIO::HostAddress::SetHost(uint32_t v4addr)
 		memset(&v4.sin_zero, 0, sizeof(v4.sin_zero));
 }
 
-void C4NetIO::EndpointAddress::SetAddress(const StdStrBuf &addr)
+void C4NetIO::HostAddress::SetHost(const StdStrBuf &addr, AddressFamily family)
+{
+	addrinfo hints = addrinfo();
+	hints.ai_family = family;
+	addrinfo *addresses = nullptr;
+	if (getaddrinfo(addr.getData(), nullptr, &hints, &addresses) != 0)
+		// GAI failed
+		return;
+	SetHost(addresses->ai_addr);
+	freeaddrinfo(addresses);
+}
+
+void C4NetIO::EndpointAddress::SetAddress(const StdStrBuf &addr, AddressFamily family)
 {
 	Clear();
 
@@ -402,6 +449,7 @@ void C4NetIO::EndpointAddress::SetAddress(const StdStrBuf &addr)
 	}
 
 	addrinfo hints = addrinfo();
+	hints.ai_family = family;
 	//hints.ai_flags = AI_NUMERICHOST;
 	addrinfo *addresses = nullptr;
 	if (getaddrinfo(std::string(ab, ae).c_str(), pb != end ? std::string(pb, pe).c_str() : nullptr, &hints, &addresses) != 0)
@@ -462,6 +510,12 @@ void C4NetIO::EndpointAddress::SetPort(uint16_t port)
 	}
 }
 
+void C4NetIO::EndpointAddress::SetDefaultPort(uint16_t port)
+{
+	if (GetPort() == IPPORT_NONE)
+		SetPort(port);
+}
+
 uint16_t C4NetIO::EndpointAddress::GetPort() const
 {
 	switch (gen.sa_family)
@@ -546,6 +600,66 @@ void C4NetIO::EndpointAddress::CompileFunc(StdCompiler *comp)
 	}
 }
 
+std::vector<C4NetIO::HostAddress> C4NetIO::GetLocalAddresses()
+{
+	std::vector<HostAddress> result;
+
+#ifdef HAVE_WINSOCK
+	HostAddress addr;
+	const size_t BUFFER_SIZE = 16000;
+	PIP_ADAPTER_ADDRESSES addresses = nullptr;
+	for (int i = 0; i < 3; ++i)
+	{
+		addresses = (PIP_ADAPTER_ADDRESSES) realloc(addresses, BUFFER_SIZE * (i+1));
+		if (!addresses)
+			// allocation failed
+			return result;
+		ULONG bufsz = BUFFER_SIZE * (i+1);
+		DWORD rv = GetAdaptersAddresses(AF_UNSPEC,
+			GAA_FLAG_SKIP_ANYCAST|GAA_FLAG_SKIP_MULTICAST|GAA_FLAG_SKIP_DNS_SERVER|GAA_FLAG_SKIP_FRIENDLY_NAME,
+			nullptr, addresses, &bufsz);
+		if (rv == ERROR_BUFFER_OVERFLOW)
+			// too little space, try again
+			continue;
+		if (rv != NO_ERROR)
+		{
+			// Something else happened
+			free(addresses);
+			return result;
+		}
+		// All okay, add addresses
+		for (PIP_ADAPTER_ADDRESSES address = addresses; address; address = address->Next)
+		{
+			for (PIP_ADAPTER_UNICAST_ADDRESS unicast = address->FirstUnicastAddress; unicast; unicast = unicast->Next)
+			{
+				addr.SetHost(unicast->Address.lpSockaddr);
+				if (addr.IsLoopback())
+					continue;
+				result.push_back(addr);
+			}
+		}
+	}
+	free(addresses);
+#else
+	struct ifaddrs* addrs;
+	if (getifaddrs(&addrs) < 0)
+	    return result;
+	for (struct ifaddrs* ifaddr = addrs; ifaddr != nullptr; ifaddr = ifaddr->ifa_next)
+	{
+		struct sockaddr* ad = ifaddr->ifa_addr;
+		if (ad == nullptr) continue;
+
+		if ((ad->sa_family == AF_INET || ad->sa_family == AF_INET6) && (~ifaddr->ifa_flags & IFF_LOOPBACK)) // Choose only non-loopback IPv4/6 devices
+		{
+			result.emplace_back(ad);
+		}
+	}
+	freeifaddrs(addrs);
+#endif
+
+	return result;
+}
+
 // *** C4NetIO
 
 // construction / destruction
@@ -560,6 +674,17 @@ C4NetIO::~C4NetIO()
 
 }
 
+bool C4NetIO::EnableDualStack(SOCKET socket)
+{
+	int opt = 0;
+	if (setsockopt(socket, IPPROTO_IPV6, IPV6_V6ONLY, reinterpret_cast<char*>(&opt), sizeof(opt)) == SOCKET_ERROR)
+	{
+		SetError("could not enable dual-stack socket", true);
+		return false;
+	}
+	return true;
+}
+
 void C4NetIO::SetError(const char *strnError, bool fSockErr)
 {
 	fSockErr &= HaveSocketError();
@@ -1310,6 +1435,8 @@ bool C4NetIOTCP::Listen(uint16_t inListenPort)
 		SetError("socket creation failed", true);
 		return false;
 	}
+	if (!EnableDualStack(lsock))
+		return false;
 	// To be able to reuse the port after close
 #if !defined(_DEBUG) && !defined(_WIN32)
 	int reuseaddr = 1;
@@ -1682,6 +1809,9 @@ bool C4NetIOSimpleUDP::Init(uint16_t inPort)
 		return false;
 	}
 
+	if (!EnableDualStack(sock))
+		return false;
+
 	// set reuse socket option
 	if (::setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, reinterpret_cast<char *>(&fAllowReUse), sizeof fAllowReUse) == SOCKET_ERROR)
 	{
@@ -1757,9 +1887,9 @@ bool C4NetIOSimpleUDP::InitBroadcast(addr_t *pBroadcastAddr)
 	if (fMultiCast) CloseBroadcast();
 
 	// broadcast addr valid?
-	if (pBroadcastAddr->IsMulticast())
+	if (!pBroadcastAddr->IsMulticast() || pBroadcastAddr->GetFamily() != HostAddress::IPv6)
 	{
-		SetError("invalid broadcast address");
+		SetError("invalid broadcast address (only IPv6 multicast addresses are supported)");
 		return false;
 	}
 	if (pBroadcastAddr->GetPort() != iPort)
@@ -1769,8 +1899,8 @@ bool C4NetIOSimpleUDP::InitBroadcast(addr_t *pBroadcastAddr)
 	}
 
 	// set mc ttl to somewhat about "same net"
-	int iTTL = 16;
-	if (setsockopt(sock, IPPROTO_IP, IP_MULTICAST_TTL, reinterpret_cast<char*>(&iTTL), sizeof(iTTL)) == SOCKET_ERROR)
+	int TTL = 16;
+	if (setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, reinterpret_cast<char*>(&TTL), sizeof(TTL)) == SOCKET_ERROR)
 	{
 		SetError("could not set mc ttl", true);
 		return false;
@@ -1778,11 +1908,12 @@ bool C4NetIOSimpleUDP::InitBroadcast(addr_t *pBroadcastAddr)
 
 	// set up multicast group information
 	this->MCAddr = *pBroadcastAddr;
-	MCGrpInfo.imr_multiaddr = static_cast<sockaddr_in*>(&MCAddr)->sin_addr;
-	MCGrpInfo.imr_interface.s_addr = INADDR_ANY;
+	MCGrpInfo.ipv6mr_multiaddr = static_cast<sockaddr_in6>(MCAddr).sin6_addr;
+	// TODO: do multicast on all interfaces?
+	MCGrpInfo.ipv6mr_interface = 0; // default interface
 
 	// join multicast group
-	if (setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
+	if (setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP,
 	               reinterpret_cast<const char *>(&MCGrpInfo), sizeof(MCGrpInfo)) == SOCKET_ERROR)
 	{
 		SetError("could not join multicast group"); // to do: more error information
@@ -1844,10 +1975,10 @@ bool C4NetIOSimpleUDP::CloseBroadcast()
 	if (!fMultiCast) return true;
 
 	// leave multicast group
-	if (setsockopt(sock, IPPROTO_IP, IP_DROP_MEMBERSHIP,
+	if (setsockopt(sock, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
 	               reinterpret_cast<const char *>(&MCGrpInfo), sizeof(MCGrpInfo)) == SOCKET_ERROR)
 	{
-		SetError("could not join multicast group"); // to do: more error information
+		SetError("could not leave multicast group"); // to do: more error information
 		return false;
 	}
 
@@ -2049,10 +2180,10 @@ enum C4NetIOSimpleUDP::WaitResult C4NetIOSimpleUDP::WaitForSocket(int iTimeout)
 bool C4NetIOSimpleUDP::SetMCLoopback(int fLoopback)
 {
 	// enable/disable MC loopback
-	setsockopt(sock, IPPROTO_IP, IP_MULTICAST_LOOP, reinterpret_cast<char *>(&fLoopback), sizeof fLoopback);
+	setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, reinterpret_cast<char *>(&fLoopback), sizeof fLoopback);
 	// read result
 	socklen_t iSize = sizeof(fLoopback);
-	if (getsockopt(sock, IPPROTO_IP, IP_MULTICAST_LOOP, reinterpret_cast<char *>(&fLoopback), &iSize) == SOCKET_ERROR)
+	if (getsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, reinterpret_cast<char *>(&fLoopback), &iSize) == SOCKET_ERROR)
 		return false;
 	fMCLoopback = !! fLoopback;
 	return true;
@@ -2086,6 +2217,76 @@ const unsigned int C4NetIOUDP::iUDPHeaderSize = 8 + 24; // (bytes)
 
 #pragma pack (push, 1)
 
+// We need to adapt C4NetIO::addr_t to put it in our UDP packages.
+// Previously, the sockaddr_in struct was just put in directly. This is
+// horribly non-portable though, especially as the value of AF_INET6 differs
+// between platforms.
+struct C4NetIOUDP::BinAddr
+{
+	BinAddr() : type(0) {}
+	BinAddr(const C4NetIO::addr_t& addr)
+	{
+		switch (addr.GetFamily())
+		{
+		case C4NetIO::HostAddress::IPv4:
+		{
+			type = 1;
+			auto addr4 = static_cast<const sockaddr_in*>(&addr); 
+			static_assert(sizeof(v4) == sizeof(addr4->sin_addr), "unexpected IPv4 address size");
+			memcpy(&v4, &addr4->sin_addr, sizeof(v4));
+			break;
+		}
+		case C4NetIO::HostAddress::IPv6:
+		{
+			type = 2;
+			auto addr6 = static_cast<const sockaddr_in6*>(&addr); 
+			static_assert(sizeof(v6) == sizeof(addr6->sin6_addr), "unexpected IPv6 address size");
+			memcpy(&v6, &addr6->sin6_addr, sizeof(v6));
+			break;
+		}
+		default:
+			assert(!"Unexpected address family");
+		}
+		port = addr.GetPort();
+	}
+
+	operator C4NetIO::addr_t() const
+	{
+		C4NetIO::addr_t result;
+		switch (type)
+		{
+		case 1:
+		{
+			sockaddr_in addr4 = sockaddr_in();
+			addr4.sin_family = AF_INET;
+			memcpy(&addr4.sin_addr, &v4, sizeof(v4));
+			result.SetAddress(reinterpret_cast<sockaddr*>(&addr4));
+			break;
+		}
+		case 2:
+		{
+			sockaddr_in6 addr6 = sockaddr_in6();
+			addr6.sin6_family = AF_INET6;
+			memcpy(&addr6.sin6_addr, &v6, sizeof(v6));
+			result.SetAddress(reinterpret_cast<sockaddr*>(&addr6));
+			break;
+		}
+		default:
+			assert(!"Invalid address type");
+		}
+		result.SetPort(port);
+		return result;
+	}
+
+	uint16_t port;
+	uint8_t type;
+	union
+	{
+		uint8_t v4[4];
+		uint8_t v6[16];
+	};
+};
+
 // packet structures
 struct C4NetIOUDP::PacketHdr
 {
@@ -2096,20 +2297,20 @@ struct C4NetIOUDP::PacketHdr
 struct C4NetIOUDP::ConnPacket : public PacketHdr
 {
 	uint32_t ProtocolVer;
-	C4NetIO::addr_t Addr;
-	C4NetIO::addr_t MCAddr;
+	BinAddr Addr;
+	BinAddr MCAddr;
 };
 
 struct C4NetIOUDP::ConnOKPacket : public PacketHdr
 {
 	enum { MCM_NoMC, MCM_MC, MCM_MCOK } MCMode;
-	C4NetIO::addr_t Addr;
+	BinAddr Addr;
 };
 
 struct C4NetIOUDP::AddAddrPacket : public PacketHdr
 {
-	C4NetIO::addr_t Addr;
-	C4NetIO::addr_t NewAddr;
+	BinAddr Addr;
+	BinAddr NewAddr;
 };
 
 struct C4NetIOUDP::DataPacketHdr : public PacketHdr
@@ -2126,7 +2327,7 @@ struct C4NetIOUDP::CheckPacketHdr : public PacketHdr
 
 struct C4NetIOUDP::ClosePacket : public PacketHdr
 {
-	C4NetIO::addr_t Addr;
+	BinAddr Addr;
 };
 
 
@@ -2214,13 +2415,40 @@ bool C4NetIOUDP::InitBroadcast(addr_t *pBroadcastAddr)
 			SetError("broadcast address is not valid");
 			return false;
 		}
-		// set up adress
-		MCAddr.SetAddress(addr_t::AnyIPv4, iPort);
-		// search for a free one
+		// Set up address as unicast-prefix-based IPv6 multicast address (RFC 3306).
+		sockaddr_in6 saddrgen = sockaddr_in6();
+		saddrgen.sin6_family = AF_INET6;
+		uint8_t *addrgen = saddrgen.sin6_addr.s6_addr;
+		// ff3e ("global multicast based on network prefix") : 64 (length of network prefix)
+		static const uint8_t mcast_prefix[4] = { 0xff, 0x3e, 0, 64};
+		memcpy(addrgen, mcast_prefix, sizeof(mcast_prefix));
+		addrgen += sizeof(mcast_prefix);
+		// 64 bit network prefix
+		addr_t prefixAddr;
+		for (auto& addr : GetLocalAddresses())
+			if (addr.GetFamily() == HostAddress::IPv6 && !addr.IsLocal())
+			{
+				prefixAddr.SetAddress(addr);
+				break;
+			}
+		if (prefixAddr.IsNull())
+		{
+			SetError("no IPv6 unicast address available");
+			return false;
+		}
+		static const size_t network_prefix_size = 8;
+		memcpy(addrgen, &static_cast<sockaddr_in6*>(&prefixAddr)->sin6_addr, network_prefix_size);
+		addrgen += network_prefix_size;
+		// 32 bit group id: search for a free one
 		for (int iRetries = 1000; iRetries; iRetries--)
 		{
+			uint32_t rnd = UnsyncedRandom();
+			memcpy(addrgen, &rnd, sizeof(rnd));
+			// "high-order bit of the Group ID will be the same value as the T flag"
+			addrgen[0] |= 0x80;
 			// create new - random - address
-			MCAddr.SetAddress(C4NetIO::HostAddress(0x000000ef | (UnsyncedRandom(0x1000000) << 8)));
+			MCAddr.SetAddress((sockaddr*) &saddrgen);
+			MCAddr.SetPort(iPort);
 			// init broadcast
 			if (!C4NetIOSimpleUDP::InitBroadcast(&MCAddr))
 				return false;
@@ -2977,14 +3205,16 @@ void C4NetIOUDP::Peer::OnRecv(const C4NetIOPacket &rPacket) // (mt-safe)
 		iLastPacketAsked = iLastMCPacketAsked = 0;
 		// Activate Multicast?
 		if (!pParent->fMultiCast)
-			if (!pPkt->MCAddr.IsNull())
+		{
+			addr_t MCAddr = pPkt->MCAddr;
+			if (!MCAddr.IsNull())
 			{
-				addr_t MCAddr = pPkt->MCAddr;
 				// Init Broadcast (with delayed loopback test)
 				pParent->fDelayedLoopbackTest = true;
 				if (!pParent->InitBroadcast(&MCAddr))
 					pParent->fDelayedLoopbackTest = false;
 			}
+		}
 		// build ConnOk Packet
 		ConnOKPacket nPack;
 
@@ -3158,7 +3388,7 @@ bool C4NetIOUDP::Peer::DoConn(bool fMC) // (mt-safe)
 	if (pParent->fMultiCast)
 		Pkt.MCAddr = pParent->C4NetIOSimpleUDP::getMCAddr();
 	else
-		Pkt.MCAddr.Clear();
+		Pkt.MCAddr = C4NetIO::addr_t();
 	return SendDirect(C4NetIOPacket(&Pkt, sizeof(Pkt), false, addr));
 }
 
@@ -3693,50 +3923,3 @@ void C4NetIOMan::EnlargeIO(int iBy)
 	delete[] ppNetIO;
 	ppNetIO = ppnNetIO;
 }
-
-// *** helpers
-
-bool ResolveAddress(const char *szAddress, C4NetIO::addr_t *paddr, uint16_t iPort)
-{
-	assert(szAddress && paddr);
-	// port?
-	StdStrBuf Buf;
-	const char *pColon = strchr(szAddress, ':');
-	if (pColon)
-	{
-		// get port
-		iPort = atoi(pColon + 1);
-		// copy address
-		Buf.CopyUntil(szAddress, ':');
-		szAddress = Buf.getData();
-	}
-	// set up address
-	sockaddr_in raddr; ZeroMem(&raddr, sizeof raddr);
-	raddr.sin_family = AF_INET;
-	raddr.sin_port = htons(iPort);
-	// no plain IP address?
-	if ((raddr.sin_addr.s_addr = inet_addr(szAddress)) == INADDR_NONE)
-	{
-#ifdef HAVE_WINSOCK
-		if (!AcquireWinSock()) return false;
-#endif
-		// resolve
-		hostent *pHost;
-		if (!(pHost = gethostbyname(szAddress)))
-#ifdef HAVE_WINSOCK
-			{ ReleaseWinSock(); return false; }
-		ReleaseWinSock();
-#else
-			return false;
-#endif
-		// correct type?
-		if (pHost->h_addrtype != AF_INET || pHost->h_length != sizeof(in_addr))
-			return false;
-		// get address
-		raddr.sin_addr = *reinterpret_cast<in_addr *>(pHost->h_addr_list[0]);
-	}
-	// ok
-	paddr->SetAddress(reinterpret_cast<sockaddr*>(&raddr));
-	paddr->SetPort(iPort);
-	return true;
-}

src/network/C4NetIO.h

@@ -92,6 +92,7 @@ public:
 		HostAddress(SpecialAddress addr) { SetHost(addr); }
 		explicit HostAddress(uint32_t addr) { SetHost(addr); }
 		HostAddress(const StdStrBuf &addr) { SetHost(addr); }
+		HostAddress(const sockaddr *addr) { SetHost(addr); }
 
 		AddressFamily GetFamily() const;
 		
@@ -102,15 +103,17 @@ public:
 		void SetHost(const sockaddr *addr);
 		void SetHost(const HostAddress &host);
 		void SetHost(SpecialAddress host);
-		void SetHost(const StdStrBuf &host);
+		void SetHost(const StdStrBuf &host, AddressFamily family = UnknownFamily);
 		void SetHost(uint32_t host);
 
 		C4NetIO::HostAddress AsIPv6() const; // convert an IPv4 address to an IPv6-mapped IPv4 address
+		C4NetIO::HostAddress AsIPv4() const; // try to convert an IPv6-mapped IPv4 address to an IPv4 address (returns unchanged address if not possible)
 
 		// General categories
 		bool IsNull() const;
 		bool IsMulticast() const;
 		bool IsLoopback() const;
+		bool IsLocal() const;
 //		bool IsBroadcast() const;
 
 		StdStrBuf ToString(int flags = 0) const;
@@ -146,12 +149,14 @@ public:
 		void SetAddress(const EndpointAddress &other);
 		void SetAddress(HostAddress::SpecialAddress addr, uint16_t port = IPPORT_NONE);
 		void SetAddress(const HostAddress &host, uint16_t port = IPPORT_NONE);
-		void SetAddress(const StdStrBuf &addr);
+		void SetAddress(const StdStrBuf &addr, AddressFamily family = UnknownFamily);
 
 		HostAddress GetHost() const { return *this; }	// HostAddress copy ctor slices off port information
 		EndpointAddress AsIPv6() const; // convert an IPv4 address to an IPv6-mapped IPv4 address
+		EndpointAddress AsIPv4() const; // try to convert an IPv6-mapped IPv4 address to an IPv4 address (returns unchanged address if not possible)
 		
 		void SetPort(uint16_t port);
+		void SetDefaultPort(uint16_t port); // set a port only if there is none
 		uint16_t GetPort() const;
 
 		bool IsNull() const;
@@ -192,8 +197,8 @@ public:
 
 		// conversions
 		operator sockaddr() const { return gen; }
-/*		operator sockaddr_in() const { assert(gen.sa_family == AF_INET); return v4; }
-		operator sockaddr_in6() const { assert(gen.sa_family == AF_INET6); return v6; }*/
+		operator sockaddr_in() const { assert(gen.sa_family == AF_INET); return v4; }
+		operator sockaddr_in6() const { assert(gen.sa_family == AF_INET6); return v6; }
 
 		// StdCompiler
 		void CompileFunc(StdCompiler *comp);
@@ -205,6 +210,8 @@ public:
 	};
 	typedef EndpointAddress addr_t;
 
+	static std::vector<HostAddress> GetLocalAddresses();
+
 	// callback class
 	class CBClass
 	{
@@ -266,6 +273,9 @@ public:
 protected:
 //	virtual SOCKET CreateSocket() = 0;
 
+	// Makes IPv4 connections from an IPv6 socket work.
+	bool EnableDualStack(SOCKET socket);
+
 	// *** errors
 protected:
 	StdCopyStrBuf Error;
@@ -532,7 +542,7 @@ private:
 #endif
 
 	// multicast
-	addr_t MCAddr; ip_mreq MCGrpInfo;
+	addr_t MCAddr; ipv6_mreq MCGrpInfo;
 	bool fMCLoopback;
 
 	// multibind
@@ -616,6 +626,7 @@ protected:
 	};
 
 	// packet structures
+	struct BinAddr;
 	struct PacketHdr; struct TestPacket; struct ConnPacket; struct ConnOKPacket; struct AddAddrPacket;
 	struct DataPacketHdr; struct CheckPacketHdr; struct ClosePacket;
 
@@ -943,26 +954,9 @@ private:
 	void EnlargeIO(int iBy);
 };
 
-// helpers
-// there seems to be no standard way to get these numbers, so let's do it the dirty way...
-inline uint8_t &in_addr_b(in_addr &addr, int i)
-{
-	assert(0 <= i && i < 4);
-	return *(reinterpret_cast<uint8_t *>(&addr.s_addr) + i);
-}
-
-inline void CompileFunc(in_addr &ip, StdCompiler *pComp)
-{
-	pComp->Value(in_addr_b(ip, 0)); pComp->Separator(StdCompiler::SEP_PART);
-	pComp->Value(in_addr_b(ip, 1)); pComp->Separator(StdCompiler::SEP_PART);
-	pComp->Value(in_addr_b(ip, 2)); pComp->Separator(StdCompiler::SEP_PART);
-	pComp->Value(in_addr_b(ip, 3));
-}
-
 #ifdef HAVE_WINSOCK
 bool AcquireWinSock();
 void ReleaseWinSock();
 #endif
-bool ResolveAddress(const char *szAddress, C4NetIO::addr_t *paddr, uint16_t iPort);
 
 #endif

src/network/C4Network2.cpp

@@ -148,7 +148,7 @@ C4Network2::C4Network2()
 		fPausedForVote(false),
 		iLastOwnVoting(0),
 		fStreaming(false),
-		NetpuncherGameID(0)
+		NetpuncherGameID(C4NetpuncherID())
 {
 
 }
@@ -169,7 +169,7 @@ bool C4Network2::InitHost(bool fLobby)
 	fChasing = false;
 	fAllowJoin = false;
 	iNextClientID = C4ClientIDStart;
-	NetpuncherGameID = 0;
+	NetpuncherGameID = C4NetpuncherID();
 	NetpuncherAddr = ::Config.Network.PuncherAddress;
 	// initialize client list
 	Clients.Init(&Game.Clients, true);
@@ -310,9 +310,25 @@ C4Network2::InitResult C4Network2::InitClient(const class C4Network2Address *pAd
 	for (int i = 0; i < iAddrCount; i++)
 		if (!pAddrs[i].isIPNull())
 		{
+			auto addr = pAddrs[i].getAddr();
+			std::vector<C4NetIO::addr_t> addrs;
+			if (addr.IsLocal())
+			{
+				// Local IPv6 addresses need a scope id.
+				for (auto& id : Clients.GetLocal()->getInterfaceIDs())
+				{
+					addr.SetScopeId(id);
+					addrs.push_back(addr);
+				}
+			}
+			else
+				addrs.push_back(addr);
 			// connection
-			if (!NetIO.Connect(pAddrs[i].getAddr(), pAddrs[i].getProtocol(), HostCore, szPassword))
-				continue;
+			int cnt = 0;
+			for (auto& a : addrs)
+				if (NetIO.Connect(a, pAddrs[i].getProtocol(), HostCore, szPassword))
+					cnt++;
+			if (cnt == 0) continue;
 			// format for message
 			if (strAddresses.getLength())
 				strAddresses.Append(", ");
@@ -673,7 +689,7 @@ void C4Network2::Clear()
 	delete pVoteDialog; pVoteDialog = nullptr;
 	fPausedForVote = false;
 	iLastOwnVoting = 0;
-	NetpuncherGameID = 0;
+	NetpuncherGameID = C4NetpuncherID();
 	Votes.Clear();
 	// don't clear fPasswordNeeded here, it's needed by InitClient
 }
@@ -891,7 +907,7 @@ void C4Network2::HandleLobbyPacket(char cStatus, const C4PacketBase *pBasePkt, C
 	if (pLobby) pLobby->HandlePacket(cStatus, pBasePkt, pClient);
 }
 
-bool C4Network2::HandlePuncherPacket(C4NetpuncherPacket::uptr pkt)
+bool C4Network2::HandlePuncherPacket(C4NetpuncherPacket::uptr pkt, C4NetIO::HostAddress::AddressFamily family)
 {
 	// TODO: is this all thread-safe?
 	assert(pkt);
@@ -912,26 +928,48 @@ bool C4Network2::HandlePuncherPacket(C4NetpuncherPacket::uptr pkt)
 		case PID_Puncher_AssID:
 			if (isHost())
 			{
-				NetpuncherGameID = GETPKT(AssID)->GetID();
+				getNetpuncherGameID(family) = GETPKT(AssID)->GetID();
 				InvalidateReference();
 			}
 			else
 			{
 				// While we don't need the ID as a client, this nicely serves as the signal that we can start using the netpuncher
-				if (Status.getState() == GS_Init && getNetpuncherGameID())
-					NetIO.SendPuncherPacket(C4NetpuncherPacketSReq(getNetpuncherGameID()));
+				if (Status.getState() == GS_Init && getNetpuncherGameID(family))
+					NetIO.SendPuncherPacket(C4NetpuncherPacketSReq(getNetpuncherGameID(family)), family);
 			}
 			return true;
 		default: return false;
 	}
 }
 
+C4NetpuncherID::value& C4Network2::getNetpuncherGameID(C4NetIO::HostAddress::AddressFamily family)
+{
+    switch (family)
+    {
+    case C4NetIO::HostAddress::IPv4: return NetpuncherGameID.v4;
+    case C4NetIO::HostAddress::IPv6: return NetpuncherGameID.v6;
+    case C4NetIO::HostAddress::UnknownFamily: assert(!"Unexpected address family");
+    }
+    // We need to return a valid reference to satisfy the compiler, even though the code here is unreachable.
+    return NetpuncherGameID.v4;
+}
+
 void C4Network2::InitPuncher()
 {
 	// We have an internet connection, so let's punch the puncher server here in order to open an udp port
 	C4NetIO::addr_t PuncherAddr;
-	if (ResolveAddress(getNetpuncherAddr().getData(), &PuncherAddr, C4NetStdPortPuncher))
-		NetIO.InitPuncher(PuncherAddr);
+	PuncherAddr.SetAddress(getNetpuncherAddr(), C4NetIO::HostAddress::IPv4);
+	if (!PuncherAddr.IsNull())
+	{
+	    PuncherAddr.SetDefaultPort(C4NetStdPortPuncher);
+	    NetIO.InitPuncher(PuncherAddr);
+	}
+	PuncherAddr.SetAddress(getNetpuncherAddr(), C4NetIO::HostAddress::IPv6);
+	if (!PuncherAddr.IsNull())
+	{
+	    PuncherAddr.SetDefaultPort(C4NetStdPortPuncher);
+	    NetIO.InitPuncher(PuncherAddr);
+	}
 }
 
 void C4Network2::OnGameSynchronized()
@@ -1198,9 +1236,6 @@ bool C4Network2::CheckConn(const C4ClientCore &CCore, C4Network2IOConnection *pC
 	// check core
 	if (CCore.getDiffLevel(pClient->getCore()) > C4ClientCoreDL_IDMatch)
 		{ *szReply = "wrong client core"; return false; }
-	// check address
-	if (pClient->isConnected() && pClient->getMsgConn()->getPeerAddr() != pConn->getPeerAddr())
-		{ *szReply = "wrong address"; return false; }
 	// accept
 	return true;
 }

src/network/C4Network2.h

@@ -194,7 +194,7 @@ protected:
 	unsigned int iCurrentStreamAmount, iCurrentStreamPosition;
 
 	// puncher
-	C4NetpuncherID_t NetpuncherGameID;
+	C4NetpuncherID NetpuncherGameID;
 	StdCopyStrBuf NetpuncherAddr;
 
 public:
@@ -257,7 +257,7 @@ public:
 	void OnDisconn(C4Network2IOConnection *pConn);
 	void HandlePacket(char cStatus, const C4PacketBase *pBasePkt, C4Network2IOConnection *pConn);
 	void HandleLobbyPacket(char cStatus, const C4PacketBase *pBasePkt, C4Network2IOConnection *pConn);
-	bool HandlePuncherPacket(C4NetpuncherPacket::uptr);
+	bool HandlePuncherPacket(C4NetpuncherPacket::uptr, C4NetIO::HostAddress::AddressFamily family);
 
 	// runtime join stuff
 	void OnGameSynchronized();
@@ -303,7 +303,8 @@ public:
 	bool StopStreaming();
 
 	// netpuncher
-	C4NetpuncherID_t getNetpuncherGameID() const { return NetpuncherGameID; }
+	C4NetpuncherID::value& getNetpuncherGameID(C4NetIO::HostAddress::AddressFamily family);
+	C4NetpuncherID getNetpuncherGameID() const { return NetpuncherGameID; };
 	StdStrBuf getNetpuncherAddr() const { return NetpuncherAddr; }
 
 protected:

src/network/C4Network2Client.cpp

@@ -25,16 +25,6 @@
 #include "game/C4Game.h"
 #include "player/C4PlayerList.h"
 
-#ifdef _WIN32
-#include <winsock2.h>
-#include <iphlpapi.h>
-#else
-#include <arpa/inet.h>
-#include <netdb.h>
-#include <ifaddrs.h>
-#include <net/if.h>
-#endif
-
 // *** C4Network2Client
 
 C4Network2Client::C4Network2Client(C4Client *pClient)
@@ -147,10 +137,22 @@ bool C4Network2Client::DoConnectAttempt(C4Network2IO *pIO)
 		{ iNextConnAttempt = time(nullptr) + 10; return true; }
 	// save attempt
 	AddrAttempts[iBestAddress]++; iNextConnAttempt = time(nullptr) + C4NetClientConnectInterval;
-	// log
-	LogSilentF("Network: connecting client %s on %s...", getName(), Addr[iBestAddress].toString().getData());
-	// connect
-	return pIO->Connect(Addr[iBestAddress].getAddr(), Addr[iBestAddress].getProtocol(), pClient->getCore());
+	auto addr = Addr[iBestAddress].getAddr();
+	std::set<int> interfaceIDs;
+	if (addr.IsLocal())
+	    interfaceIDs = Network.Clients.GetLocal()->getInterfaceIDs();
+	else
+	    interfaceIDs = {0};
+	for (auto id : interfaceIDs)
+	{
+	    addr.SetScopeId(id);
+	    // log
+	    LogSilentF("Network: connecting client %s on %s...", getName(), addr.ToString().getData());
+	    // connect
+	    if (pIO->Connect(addr, Addr[iBestAddress].getProtocol(), pClient->getCore()))
+		return true;
+	}
+	return false;
 }
 
 bool C4Network2Client::hasAddr(const C4Network2Address &addr) const
@@ -187,80 +189,24 @@ bool C4Network2Client::AddAddr(const C4Network2Address &addr, bool fAnnounce)
 
 void C4Network2Client::AddLocalAddrs(int16_t iPortTCP, int16_t iPortUDP)
 {
-	// set up address struct
 	C4NetIO::addr_t addr;
 
-	// get local address(es)
-#ifdef HAVE_WINSOCK
-	const size_t BUFFER_SIZE = 16000;
-	PIP_ADAPTER_ADDRESSES addresses = nullptr;
-	for (int i = 0; i < 3; ++i)
+	for (auto& ha : C4NetIO::GetLocalAddresses())
 	{
-		addresses = (PIP_ADAPTER_ADDRESSES) realloc(addresses, BUFFER_SIZE * (i+1));
-		if (!addresses)
-			// allocation failed
-			return;
-		ULONG bufsz = BUFFER_SIZE * (i+1);
-		DWORD rv = GetAdaptersAddresses(AF_UNSPEC,
-			GAA_FLAG_SKIP_ANYCAST|GAA_FLAG_SKIP_MULTICAST|GAA_FLAG_SKIP_DNS_SERVER|GAA_FLAG_SKIP_FRIENDLY_NAME,
-			nullptr, addresses, &bufsz);
-		if (rv == ERROR_BUFFER_OVERFLOW)
-			// too little space, try again
-			continue;
-		if (rv != NO_ERROR)
+		addr.SetAddress(ha);
+		if (iPortTCP)
 		{
-			// Something else happened
-			free(addresses);
-			return;
+			addr.SetPort(iPortTCP);
+			AddAddr(C4Network2Address(addr, P_TCP), false);
 		}
-		// All okay, add addresses
-		for (PIP_ADAPTER_ADDRESSES address = addresses; address; address = address->Next)
+		if (iPortUDP)
 		{
-			for (PIP_ADAPTER_UNICAST_ADDRESS unicast = address->FirstUnicastAddress; unicast; unicast = unicast->Next)
-			{
-				addr.SetHost(unicast->Address.lpSockaddr);
-				if (addr.IsLoopback())
-					continue;
-				if (iPortTCP)
-				{
-					addr.SetPort(iPortTCP);
-					AddAddr(C4Network2Address(addr, P_TCP), false);
-				}
-				if (iPortUDP)
-				{
-					addr.SetPort(iPortUDP);
-					AddAddr(C4Network2Address(addr, P_UDP), false);
-				}
-			}
+			addr.SetPort(iPortUDP);
+			AddAddr(C4Network2Address(addr, P_UDP), false);
 		}
+		if (addr.GetScopeId())
+			InterfaceIDs.insert(addr.GetScopeId());
 	}
-	free(addresses);
-#else
-	struct ifaddrs* addrs;
-	if (getifaddrs(&addrs) < 0)
-	    return;
-	for (struct ifaddrs* ifaddr = addrs; ifaddr != nullptr; ifaddr = ifaddr->ifa_next)
-	{
-		struct sockaddr* ad = ifaddr->ifa_addr;
-		if (ad == nullptr) continue;
-
-		if ((ad->sa_family == AF_INET || ad->sa_family == AF_INET6) && (~ifaddr->ifa_flags & IFF_LOOPBACK)) // Choose only non-loopback IPv4/6 devices
-		{
-			addr.SetHost(ad);
-			if (iPortTCP >= 0)
-			{
-				addr.SetPort(iPortTCP);
-				AddAddr(C4Network2Address(addr, P_TCP), false);
-			}
-			if (iPortUDP >= 0)
-			{
-				addr.SetPort(iPortUDP);
-				AddAddr(C4Network2Address(addr, P_UDP), false);
-			}
-		}
-	}
-	freeifaddrs(addrs);
-#endif
 }
 
 void C4Network2Client::SendAddresses(C4Network2IOConnection *pConn)

src/network/C4Network2Client.h

@@ -57,6 +57,9 @@ protected:
 	int32_t AddrAttempts[C4ClientMaxAddr];
 	int32_t iAddrCnt;
 
+	// interface ids
+	std::set<int> InterfaceIDs;
+
 	// status
 	C4Network2ClientStatus eStatus;
 
@@ -88,6 +91,8 @@ public:
 	int32_t     getAddrCnt()    const { return iAddrCnt; }
 	const C4Network2Address &getAddr(int32_t i) const { return Addr[i]; }
 
+	const std::set<int> &getInterfaceIDs() const { return InterfaceIDs; }
+
 	C4Network2ClientStatus getStatus() const { return eStatus; }
 	bool        hasJoinData()   const { return getStatus() != NCS_Joining; }
 	bool        isChasing()     const { return getStatus() == NCS_Chasing; }

src/network/C4Network2Discover.cpp

@@ -17,6 +17,17 @@
 #include "network/C4Network2Discover.h"
 
 // *** C4Network2IODiscover
+//
+// Quick multicast discovery guide by Luchs:
+//
+// All engines in network mode join a multicast group (defined by C4NetDiscoveryAddress).
+//
+// Engines searching for a game ("client") send a single byte c = 3 to that multicast group. This
+// happens while on the network list on each refresh.
+//
+// Engines hosting a game (when going into the lobby) send a byte c = 4 plus their reference server
+// port to the multicast group. Additionally, they listen for the c = 3 bytes and will reply with
+// another multicast answer.
 
 struct C4Network2IODiscoverReply
 {
@@ -53,7 +64,7 @@ bool C4Network2IODiscover::Init(uint16_t iPort)
 bool C4Network2IODiscover::Announce()
 {
 	// Announce our presence
-	C4Network2IODiscoverReply Reply = { 4, htons(iRefServerPort) };
+	C4Network2IODiscoverReply Reply = { 4, iRefServerPort };
 	return Send(C4NetIOPacket(&Reply, sizeof(Reply), false, DiscoveryAddr));
 }
 

src/network/C4Network2Discover.h

@@ -20,7 +20,7 @@
 
 const int C4NetMaxDiscover = 64;
 
-const C4NetIO::HostAddress C4NetDiscoveryAddress = C4NetIO::HostAddress(0xef000000); // 239.0.0.0
+const C4NetIO::HostAddress C4NetDiscoveryAddress = C4NetIO::HostAddress(StdStrBuf("ff02::1"));
 
 class C4Network2IODiscover : public C4NetIOSimpleUDP, private C4NetIO::CBClass
 {

src/network/C4Network2IO.cpp

@@ -460,28 +460,49 @@ bool C4Network2IO::InitPuncher(C4NetIO::addr_t nPuncherAddr)
 	if (!pNetIO_UDP)
 		return false;
 	// save address
-	PuncherAddr = nPuncherAddr;
+	switch (nPuncherAddr.GetFamily())
+	{
+	case C4NetIO::HostAddress::IPv4:
+	    PuncherAddrIPv4 = nPuncherAddr;
+	    break;
+	case C4NetIO::HostAddress::IPv6:
+	    PuncherAddrIPv6 = nPuncherAddr;
+	    break;
+	case C4NetIO::HostAddress::UnknownFamily:
+	    assert(!"Unexpected address family");
+	}
 	// let's punch
-	return pNetIO_UDP->Connect(PuncherAddr);
+	return pNetIO_UDP->Connect(nPuncherAddr);
 }
 
-void C4Network2IO::Punch(const C4NetIO::addr_t &punchee_addr) {
+void C4Network2IO::Punch(const C4NetIO::addr_t &punchee_addr)
+{
 	if (!pNetIO_UDP)
 		return;
 	C4PacketPing PktPeng;
 	dynamic_cast<C4NetIOUDP*>(pNetIO_UDP)->SendDirect(MkC4NetIOPacket(PID_Pong, PktPeng, punchee_addr));
 }
 
-void C4Network2IO::SendPuncherPacket(const C4NetpuncherPacket& p) {
-	if (!pNetIO_UDP || PuncherAddr.IsNull()) return;
-	pNetIO_UDP->Send(p.PackTo(PuncherAddr));
+void C4Network2IO::SendPuncherPacket(const C4NetpuncherPacket& p, C4NetIO::HostAddress::AddressFamily family)
+{
+	if (!pNetIO_UDP) return;
+	if (family == C4NetIO::HostAddress::IPv4 && !PuncherAddrIPv4.IsNull())
+		pNetIO_UDP->Send(p.PackTo(PuncherAddrIPv4));
+	else if (family == C4NetIO::HostAddress::IPv6 && !PuncherAddrIPv6.IsNull())
+		pNetIO_UDP->Send(p.PackTo(PuncherAddrIPv6));
+}
+
+bool C4Network2IO::IsPuncherAddr(const C4NetIO::addr_t& addr) const
+{
+	return (!PuncherAddrIPv4.IsNull() && PuncherAddrIPv4 == addr)
+	    || (!PuncherAddrIPv6.IsNull() && PuncherAddrIPv6 == addr);
 }
 
 // C4NetIO interface
 bool C4Network2IO::OnConn(const C4NetIO::addr_t &PeerAddr, const C4NetIO::addr_t &ConnectAddr, const C4NetIO::addr_t *pOwnAddr, C4NetIO *pNetIO)
 {
 	// puncher answer?
-	if (pNetIO == pNetIO_UDP && !PuncherAddr.IsNull() && PuncherAddr == ConnectAddr)
+	if (pNetIO == pNetIO_UDP && IsPuncherAddr(ConnectAddr))
 	{
 		// got an address?
 		if (pOwnAddr)
@@ -537,9 +558,12 @@ bool C4Network2IO::OnConn(const C4NetIO::addr_t &PeerAddr, const C4NetIO::addr_t
 void C4Network2IO::OnDisconn(const C4NetIO::addr_t &addr, C4NetIO *pNetIO, const char *szReason)
 {
 	// punch?
-	if (pNetIO == pNetIO_UDP && !PuncherAddr.IsNull() && PuncherAddr == addr)
+	if (pNetIO == pNetIO_UDP && IsPuncherAddr(addr))
 	{
-		PuncherAddr.Clear();
+		if (PuncherAddrIPv4 == addr)
+			PuncherAddrIPv4.Clear();
+		else
+			PuncherAddrIPv6.Clear();
 		return;
 	}
 #if(C4NET2IO_DUMP_LEVEL > 1)
@@ -579,7 +603,7 @@ void C4Network2IO::OnPacket(const class C4NetIOPacket &rPacket, C4NetIO *pNetIO)
 	           C4TimeMilliseconds::Now().AsString().getData(),
 	           rPacket.getStatus(), getNetIOName(pNetIO));
 #endif
-	if (pNetIO == pNetIO_UDP && !PuncherAddr.IsNull() && PuncherAddr == rPacket.getAddr())
+	if (pNetIO == pNetIO_UDP && IsPuncherAddr(rPacket.getAddr()))
 	{
 		HandlePuncherPacket(rPacket);
 		return;
@@ -1141,7 +1165,7 @@ void C4Network2IO::HandleFwdReq(const C4PacketFwd &rFwd, C4Network2IOConnection
 void C4Network2IO::HandlePuncherPacket(const C4NetIOPacket& rPacket)
 {
 	auto pkt = C4NetpuncherPacket::Construct(rPacket);
-	if (pkt && ::Network.HandlePuncherPacket(move(pkt)));
+	if (pkt && ::Network.HandlePuncherPacket(move(pkt), rPacket.getAddr().GetFamily()));
 	else
 	{
 		assert(pNetIO_UDP);
@@ -1268,15 +1292,23 @@ void C4Network2IO::SendConnPackets()
 
 void C4Network2IO::OnPuncherConnect(C4NetIO::addr_t addr)
 {
-	// Sanity check
-	if (addr.GetFamily() != C4NetIO::HostAddress::IPv4)
-		return;
-	Application.InteractiveThread.ThreadLogS("Adding address from puncher: %s", addr.ToString().getData());
+	// NAT punching is only relevant for IPv4, so convert here to show a proper address.
+	auto maybe_v4 = addr.AsIPv4();
+	Application.InteractiveThread.ThreadLogS("Adding address from puncher: %s", maybe_v4.ToString().getData());
 	// Add for local client
 	C4Network2Client *pLocal = ::Network.Clients.GetLocal();
 	if (pLocal)
-		pLocal->AddAddr(C4Network2Address(addr, P_UDP), true);
+	{
+		pLocal->AddAddr(C4Network2Address(maybe_v4, P_UDP), true);
+		// If the outside port matches the inside port, there is no port translation and the
+		// TCP address will probably work as well.
+		if (addr.GetPort() == Config.Network.PortUDP && Config.Network.PortTCP > 0)
+		{
+			maybe_v4.SetPort(Config.Network.PortTCP);
+			pLocal->AddAddr(C4Network2Address(maybe_v4, P_TCP), true);
+		}
 		// Do not ::Network.InvalidateReference(); yet, we're expecting an ID from the netpuncher
+	}
 }
 
 // *** C4Network2IOConnection

src/network/C4Network2IO.h

@@ -97,7 +97,8 @@ protected:
 	iUDPIRate, iUDPORate, iUDPBCRate;
 
 	// punching
-	C4NetIO::addr_t PuncherAddr;
+	C4NetIO::addr_t PuncherAddrIPv4, PuncherAddrIPv6;
+	bool IsPuncherAddr(const C4NetIO::addr_t& addr) const;
 
 public:
 
@@ -137,7 +138,7 @@ public:
 
 	// punch
 	bool InitPuncher(C4NetIO::addr_t PuncherAddr); // by main thread
-	void SendPuncherPacket(const C4NetpuncherPacket&);
+	void SendPuncherPacket(const C4NetpuncherPacket&, C4NetIO::HostAddress::AddressFamily family);
 	void Punch(const C4NetIO::addr_t&); // sends a ping packet
 
 	// stuff

src/network/C4Network2IRC.cpp

@@ -318,8 +318,10 @@ bool C4Network2IRCClient::Connect(const char *szServer, const char *szNick, cons
 	if (!Init())
 		return false;
 	// Resolve address
-	if (!ResolveAddress(szServer, &ServerAddr, 6666))
+	ServerAddr.SetAddress(StdStrBuf(szServer));
+	if (ServerAddr.IsNull())
 		{ SetError("Could no resolve server address!"); return false; }
+	ServerAddr.SetDefaultPort(6666);
 	// Set connection data
 	Nick = szNick; RealName = szRealName;
 	Password = szPassword; AutoJoin = szAutoJoin;

src/network/C4Network2Reference.cpp

@@ -30,7 +30,7 @@
 C4Network2Reference::C4Network2Reference()
 		: Icon(0), GameMode(), Time(0), Frame(0), StartTime(0), LeaguePerformance(0),
 		JoinAllowed(true), ObservingAllowed(true), PasswordNeeded(false), OfficialServer(false),
-		IsEditor(false), iAddrCnt(0), NetpuncherGameID(0)
+		IsEditor(false), iAddrCnt(0), NetpuncherGameID(C4NetpuncherID())
 {
 
 }
@@ -127,7 +127,7 @@ void C4Network2Reference::CompileFunc(StdCompiler *pComp)
 	pComp->Value(mkNamingAdapt(Game.sEngineName,      "Game",             "None"));
 	pComp->Value(mkNamingAdapt(mkArrayAdaptDM(Game.iVer,0),"Version"    ));
 	pComp->Value(mkNamingAdapt(OfficialServer,  "OfficialServer", false));
-	pComp->Value(mkNamingAdapt(NetpuncherGameID,  "NetpuncherID", 0, false, false));
+	pComp->Value(mkNamingAdapt(NetpuncherGameID,  "NetpuncherID", C4NetpuncherID(), false, false));
 	pComp->Value(mkNamingAdapt(NetpuncherAddr,  "NetpuncherAddr", "", false, false));
 
 	pComp->Value(Parameters);
@@ -407,7 +407,7 @@ bool C4Network2HTTPClient::Decompress(StdBuf *pData)
 bool C4Network2HTTPClient::OnConn(const C4NetIO::addr_t &AddrPeer, const C4NetIO::addr_t &AddrConnect, const C4NetIO::addr_t *pOwnAddr, C4NetIO *pNetIO)
 {
 	// Make sure we're actually waiting for this connection
-	if (AddrConnect != ServerAddr)
+	if (fConnected || (AddrConnect != ServerAddr && AddrConnect != ServerAddrFallback))
 		return false;
 	// Save pack peer address
 	PeerAddr = AddrPeer;
@@ -445,10 +445,19 @@ void C4Network2HTTPClient::OnPacket(const class C4NetIOPacket &rPacket, C4NetIO
 bool C4Network2HTTPClient::Execute(int iMaxTime)
 {
 	// Check timeout
-	if (fBusy && time(nullptr) > iRequestTimeout)
+	if (fBusy)
 	{
-		Cancel("Request timeout");
-		return true;
+		if (C4TimeMilliseconds::Now() > HappyEyeballsTimeout)
+		{
+			HappyEyeballsTimeout = C4TimeMilliseconds::PositiveInfinity;
+			Application.InteractiveThread.ThreadLogS("HTTP: Starting fallback connection to %s (%s)", Server.getData(), ServerAddrFallback.ToString().getData());
+			Connect(ServerAddrFallback);
+		}
+		if (time(nullptr) > iRequestTimeout)
+		{
+			Cancel("Request timeout");
+			return true;
+		}
 	}
 	// Execute normally
 	return C4NetIOTCP::Execute(iMaxTime);
@@ -462,7 +471,9 @@ C4TimeMilliseconds C4Network2HTTPClient::GetNextTick(C4TimeMilliseconds tNow)
 
 	C4TimeMilliseconds tHTTPClientTick = tNow + 1000 * std::max<time_t>(iRequestTimeout - time(nullptr), 0);
 
-	return std::max(tNetIOTCPTick, tHTTPClientTick);
+	C4TimeMilliseconds HappyEyeballsTick = tNow + std::max(HappyEyeballsTimeout - C4TimeMilliseconds::Now(), 0);
+
+	return std::min({tNetIOTCPTick, tHTTPClientTick, HappyEyeballsTick});
 }
 
 bool C4Network2HTTPClient::Query(const StdBuf &Data, bool fBinary)
@@ -512,6 +523,11 @@ bool C4Network2HTTPClient::Query(const StdBuf &Data, bool fBinary)
 	// Start connecting
 	if (!Connect(ServerAddr))
 		return false;
+	// Also try the fallback address after some time (if there is one)
+	if (!ServerAddrFallback.IsNull())
+		HappyEyeballsTimeout = C4TimeMilliseconds::Now() + C4Network2HTTPHappyEyeballsTimeout;
+	else
+		HappyEyeballsTimeout = C4TimeMilliseconds::PositiveInfinity;
 	// Okay, request will be performed when connection is complete
 	fBusy = true;
 	iDataOffset = 0;
@@ -529,7 +545,7 @@ void C4Network2HTTPClient::ResetRequestTimeout()
 void C4Network2HTTPClient::Cancel(const char *szReason)
 {
 	// Close connection - and connection attempt
-	Close(ServerAddr); Close(PeerAddr);
+	Close(ServerAddr); Close(ServerAddrFallback); Close(PeerAddr);
 	// Reset flags
 	fBusy = fSuccess = fConnected = fBinary = false;
 	iDownloadedSize = iTotalSize = iDataOffset = 0;
@@ -566,14 +582,23 @@ bool C4Network2HTTPClient::SetServer(const char *szServerAddress)
 		SetError(FormatString("Could not resolve server address %s!", Server.getData()).getData());
 		return false;
 	}
-	if (ServerAddr.GetPort() == C4NetIO::EndpointAddress::IPPORT_NONE)
+	ServerAddr.SetDefaultPort(GetDefaultPort());
+	if (ServerAddr.GetFamily() == C4NetIO::HostAddress::IPv6)
 	{
-		ServerAddr.SetPort(GetDefaultPort());
+		// Try to find a fallback IPv4 address for Happy Eyeballs.
+		ServerAddrFallback.SetAddress(Server, C4NetIO::HostAddress::IPv4);
+		ServerAddrFallback.SetDefaultPort(GetDefaultPort());
 	}
+	else
+		ServerAddrFallback.Clear();
 	// Remove port
-	const char *pColon = strchr(Server.getData(), ':');
-	if (pColon)
-		Server.SetLength(pColon - Server.getData());
+	const char *firstColon = strchr(Server.getData(), ':');
+	const char *lastColon = strrchr(Server.getData(), ':');
+	if (firstColon)
+		// hostname/IPv4 address    or IPv6 address with port (e.g. [::1]:1234)
+		if (firstColon == lastColon || (Server[0] == '[' && *(lastColon - 1) == ']'))
+			Server.SetLength(lastColon - Server.getData());
+		
 	// Done
 	ResetError();
 	return true;

src/network/C4Network2Reference.h

@@ -24,6 +24,7 @@
 #include "lib/C4InputValidation.h"
 
 const int C4Network2HTTPQueryTimeout = 10; // (s)
+const uint32_t C4Network2HTTPHappyEyeballsTimeout = 300; // (ms)
 
 // Session data
 class C4Network2Reference
@@ -51,7 +52,7 @@ private:
 	bool PasswordNeeded;
 	bool OfficialServer;
 	bool IsEditor;
-	C4NetpuncherID_t NetpuncherGameID;
+	C4NetpuncherID NetpuncherGameID;
 	StdCopyStrBuf NetpuncherAddr;
 
 	// Engine information
@@ -79,7 +80,7 @@ public:
 	int32_t getStartTime() const { return StartTime; }
 	StdStrBuf getGameGoalString() const;
 	bool isEditor() const { return IsEditor; }
-	C4NetpuncherID_t getNetpuncherGameID() const { return NetpuncherGameID; }
+	C4NetpuncherID getNetpuncherGameID() const { return NetpuncherGameID; }
 	StdStrBuf getNetpuncherAddr() const { return NetpuncherAddr; }
 
 	void SetSourceAddress(const C4NetIO::EndpointAddress &ip);
@@ -129,7 +130,7 @@ public:
 private:
 
 	// Address information
-	C4NetIO::addr_t ServerAddr, PeerAddr;
+	C4NetIO::addr_t ServerAddr, ServerAddrFallback, PeerAddr;
 	StdCopyStrBuf Server, RequestPath;
 
 	bool fBinary;
@@ -137,6 +138,7 @@ private:
 	size_t iDataOffset;
 	StdCopyBuf Request;
 	time_t iRequestTimeout;
+	C4TimeMilliseconds HappyEyeballsTimeout;
 
 	// Response header data
 	size_t iDownloadedSize, iTotalSize;

src/script/C4AulDebug.cpp

@@ -158,7 +158,8 @@ bool C4AulDebug::SetAllowed(const char *szHost)
 	// No host?
 	if (!szHost || !*szHost) return true;
 	// Resolve the address
-	return ResolveAddress(szHost, &AllowedAddr, 0);
+	AllowedAddr.SetAddress(StdStrBuf(szHost));
+	return !AllowedAddr.IsNull();
 }
 
 bool C4AulDebug::Init(uint16_t iPort)