dolphin/Source/Core/Common/TraversalProto.h

// This file is public domain, in case it's useful to anyone. -comex

#pragma once
#include <array>
#include "Common/CommonTypes.h"

#define NETPLAY_CODE_SIZE 8
typedef std::array<char, NETPLAY_CODE_SIZE> TraversalHostId;
typedef u64 TraversalRequestId;

enum TraversalPacketType
{
	// [*->*]
	TraversalPacketAck = 0,
	// [c->s]
	TraversalPacketPing = 1,
	// [c->s]
	TraversalPacketHelloFromClient = 2,
	// [s->c]
	TraversalPacketHelloFromServer = 3,
	// [c->s] When connecting, first the client asks the central server...
	TraversalPacketConnectPlease = 4,
	// [s->c] ...who asks the game host to send a UDP packet to the
	// client... (an ack implies success)
	TraversalPacketPleaseSendPacket = 5,
	// [s->c] ...which the central server relays back to the client.
	TraversalPacketConnectReady = 6,
	// [s->c] Alternately, the server might not have heard of this host.
	TraversalPacketConnectFailed = 7
};

enum
{
	TraversalProtoVersion = 0
};

enum TraversalConnectFailedReason
{
	TraversalConnectFailedClientDidntRespond = 0,
	TraversalConnectFailedClientFailure,
	TraversalConnectFailedNoSuchClient
};

#pragma pack(push, 1)
struct TraversalInetAddress
{
	u8 isIPV6;
	u32 address[4];
	u16 port;
};
struct TraversalPacket
{
	u8 type;
	TraversalRequestId requestId;
	union
	{
		struct
		{
			u8 ok;
		} ack;
		struct
		{
			TraversalHostId hostId;
		} ping;
		struct
		{
			u8 protoVersion;
		} helloFromClient;
		struct
		{
			u8 ok;
			TraversalHostId yourHostId;
			TraversalInetAddress yourAddress; // currently unused
		} helloFromServer;
		struct
		{
			TraversalHostId hostId;
		} connectPlease;
		struct
		{
			TraversalInetAddress address;
		} pleaseSendPacket;
		struct
		{
			TraversalRequestId requestId;
			TraversalInetAddress address;
		} connectReady;
		struct
		{
			TraversalRequestId requestId;
			u8 reason;
		} connectFailed;
	};
};
#pragma pack(pop)