9 files changed, 719 insertions, 43 deletions

diff --git a/src/Protocol/Authenticator.cpp b/src/Protocol/Authenticator.cpp
new file mode 100644
index 000000000..e0fcc0007
--- /dev/null
+++ b/src/Protocol/Authenticator.cpp
@@ -0,0 +1,314 @@
+
+#include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules
+
+#include "Authenticator.h"
+#include "../OSSupport/BlockingTCPLink.h"
+#include "../Root.h"
+#include "../Server.h"
+#include "../ClientHandle.h"
+
+#include "inifile/iniFile.h"
+#include "json/json.h"
+
+#include "polarssl/config.h"
+#include "polarssl/net.h"
+#include "polarssl/ssl.h"
+#include "polarssl/entropy.h"
+#include "polarssl/ctr_drbg.h"
+#include "polarssl/error.h"
+#include "polarssl/certs.h"
+
+#include <sstream>
+#include <iomanip>
+
+
+
+
+
+#define DEFAULT_AUTH_SERVER "sessionserver.mojang.com"
+#define DEFAULT_AUTH_ADDRESS "/session/minecraft/hasJoined?username=%USERNAME%&serverId=%SERVERID%"
+
+
+
+
+
+cAuthenticator::cAuthenticator(void) :
+	super("cAuthenticator"),
+	m_Server(DEFAULT_AUTH_SERVER),
+	m_Address(DEFAULT_AUTH_ADDRESS),
+	m_ShouldAuthenticate(true)
+{
+}
+
+
+
+
+
+cAuthenticator::~cAuthenticator()
+{
+	Stop();
+}
+
+
+
+
+
+void cAuthenticator::ReadINI(cIniFile & IniFile)
+{
+	m_Server = IniFile.GetValueSet("Authentication", "Server", DEFAULT_AUTH_SERVER);
+	m_Address = IniFile.GetValueSet("Authentication", "Address", DEFAULT_AUTH_ADDRESS);
+	m_ShouldAuthenticate = IniFile.GetValueSetB("Authentication", "Authenticate", true);
+}
+
+
+
+
+
+void cAuthenticator::Authenticate(int a_ClientID, const AString & a_UserName, const AString & a_ServerHash)
+{
+	if (!m_ShouldAuthenticate)
+	{
+		cRoot::Get()->AuthenticateUser(a_ClientID, a_UserName, cClientHandle::GenerateOfflineUUID(a_UserName));
+		return;
+	}
+
+	cCSLock LOCK(m_CS);
+	m_Queue.push_back(cUser(a_ClientID, a_UserName, a_ServerHash));
+	m_QueueNonempty.Set();
+}
+
+
+
+
+
+void cAuthenticator::Start(cIniFile & IniFile)
+{
+	ReadINI(IniFile);
+	m_ShouldTerminate = false;
+	super::Start();
+}
+
+
+
+
+
+void cAuthenticator::Stop(void)
+{
+	m_ShouldTerminate = true;
+	m_QueueNonempty.Set();
+	Wait();
+}
+
+
+
+
+
+void cAuthenticator::Execute(void)
+{
+	for (;;)
+	{
+		cCSLock Lock(m_CS);
+		while (!m_ShouldTerminate && (m_Queue.size() == 0))
+		{
+			cCSUnlock Unlock(Lock);
+			m_QueueNonempty.Wait();
+		}
+		if (m_ShouldTerminate)
+		{
+			return;
+		}
+		ASSERT(!m_Queue.empty());
+
+		cAuthenticator::cUser & User = m_Queue.front();
+		int ClientID = User.m_ClientID;
+		AString UserName = User.m_Name;
+		AString ServerID = User.m_ServerID;
+		m_Queue.pop_front();
+		Lock.Unlock();
+
+		AString NewUserName = UserName;
+		AString UUID;
+		if (AuthWithYggdrasil(NewUserName, ServerID, UUID))
+		{
+			LOGINFO("User %s authenticated with UUID '%s'", NewUserName.c_str(), UUID.c_str());
+			cRoot::Get()->AuthenticateUser(ClientID, NewUserName, UUID);
+		}
+		else
+		{
+			cRoot::Get()->KickUser(ClientID, "Failed to authenticate account!");
+		}
+	}  // for (-ever)
+}
+
+
+
+
+
+bool cAuthenticator::AuthWithYggdrasil(AString & a_UserName, const AString & a_ServerId, AString & a_UUID)
+{
+	LOGD("Trying to auth user %s", a_UserName.c_str());
+	
+	int ret, server_fd = -1;
+	unsigned char buf[1024];
+	const char *pers = "cAuthenticator";
+
+	entropy_context entropy;
+	ctr_drbg_context ctr_drbg;
+	ssl_context ssl;
+	x509_crt cacert;
+
+	/* Initialize the RNG and the session data */
+	memset(&ssl, 0, sizeof(ssl_context));
+	x509_crt_init(&cacert);
+
+	entropy_init(&entropy);
+	if ((ret = ctr_drbg_init(&ctr_drbg, entropy_func, &entropy, (const unsigned char *)pers, strlen(pers))) != 0)
+	{
+		LOGWARNING("cAuthenticator: ctr_drbg_init returned %d", ret);
+		return false;
+	}
+
+	/* Initialize certificates */
+	// TODO: Grab the sessionserver's root CA and any intermediates and hard-code them here, instead of test_ca_list
+	ret = x509_crt_parse(&cacert, (const unsigned char *)test_ca_list, strlen(test_ca_list));
+
+	if (ret < 0)
+	{
+		LOGWARNING("cAuthenticator: x509_crt_parse returned -0x%x", -ret);
+		return false;
+	}
+
+	/* Connect */
+	if ((ret = net_connect(&server_fd, m_Server.c_str(), 443)) != 0)
+	{
+		LOGWARNING("cAuthenticator: Can't connect to %s: %d", m_Server.c_str(), ret);
+		return false;
+	}
+
+	/* Setup */
+	if ((ret = ssl_init(&ssl)) != 0)
+	{
+		LOGWARNING("cAuthenticator: ssl_init returned %d", ret);
+		return false;
+	}
+	ssl_set_endpoint(&ssl, SSL_IS_CLIENT);
+	ssl_set_authmode(&ssl, SSL_VERIFY_OPTIONAL);
+	ssl_set_ca_chain(&ssl, &cacert, NULL, "PolarSSL Server 1");
+	ssl_set_rng(&ssl, ctr_drbg_random, &ctr_drbg);
+	ssl_set_bio(&ssl, net_recv, &server_fd, net_send, &server_fd);
+
+	/* Handshake */
+	while ((ret = ssl_handshake(&ssl)) != 0)
+	{
+		if ((ret != POLARSSL_ERR_NET_WANT_READ) && (ret != POLARSSL_ERR_NET_WANT_WRITE))
+		{
+			LOGWARNING("cAuthenticator: ssl_handshake returned -0x%x", -ret);
+			return false;
+		}
+	}
+
+	/* Write the GET request */
+	AString ActualAddress = m_Address;
+	ReplaceString(ActualAddress, "%USERNAME%", a_UserName);
+	ReplaceString(ActualAddress, "%SERVERID%", a_ServerId);
+
+	AString Request;
+	Request += "GET " + ActualAddress + " HTTP/1.1\r\n";
+	Request += "Host: " + m_Server + "\r\n";
+	Request += "User-Agent: MCServer\r\n";
+	Request += "Connection: close\r\n";
+	Request += "\r\n";
+
+	ret = ssl_write(&ssl, (const unsigned char *)Request.c_str(), Request.size());
+	if (ret <= 0)
+	{
+		LOGWARNING("cAuthenticator: ssl_write returned %d", ret);
+		return false;
+	}
+
+	/* Read the HTTP response */
+	std::string Response;
+	for (;;)
+	{
+		memset(buf, 0, sizeof(buf));
+		ret = ssl_read(&ssl, buf, sizeof(buf));
+
+		if ((ret == POLARSSL_ERR_NET_WANT_READ) || (ret == POLARSSL_ERR_NET_WANT_WRITE))
+		{
+			continue;
+		}
+		if (ret == POLARSSL_ERR_SSL_PEER_CLOSE_NOTIFY)
+		{
+			break;
+		}
+		if (ret < 0)
+		{
+			LOGWARNING("cAuthenticator: ssl_read returned %d", ret);
+			break;
+		}
+		if (ret == 0)
+		{
+			LOGWARNING("cAuthenticator: EOF");
+			break;
+		}
+
+		Response.append((const char *)buf, ret);
+	} 
+
+	ssl_close_notify(&ssl);
+	x509_crt_free(&cacert);
+	net_close(server_fd);
+	ssl_free(&ssl);
+	entropy_free(&entropy);
+	memset(&ssl, 0, sizeof(ssl));
+
+	// Check the HTTP status line:
+	AString prefix("HTTP/1.1 200 OK");
+	AString HexDump;
+	if (Response.compare(0, prefix.size(), prefix))
+	{
+		LOGINFO("User \"%s\" failed to auth, bad http status line received", a_UserName.c_str());
+		LOG("Response: \n%s", CreateHexDump(HexDump, Response.data(), Response.size(), 16).c_str());
+		return false;
+	}
+
+	// Erase the HTTP headers from the response:
+	size_t idxHeadersEnd = Response.find("\r\n\r\n");
+	if (idxHeadersEnd == AString::npos)
+	{
+		LOGINFO("User \"%s\" failed to authenticate, bad http response header received", a_UserName.c_str());
+		LOG("Response: \n%s", CreateHexDump(HexDump, Response.data(), Response.size(), 16).c_str());
+		return false;
+	}
+	Response.erase(0, idxHeadersEnd + 4);
+
+	// Parse the Json response:
+	if (Response.empty())
+	{
+		return false;
+	}
+	Json::Value root;
+	Json::Reader reader;
+	if (!reader.parse(Response, root, false))
+	{
+		LOGWARNING("cAuthenticator: Cannot parse Received Data to json!");
+		return false;
+	}
+	a_UserName = root.get("name", "Unknown").asString();
+	a_UUID = root.get("id", "").asString();
+	
+	// If the UUID doesn't contain the hashes, insert them at the proper places:
+	if (a_UUID.size() == 32)
+	{
+		a_UUID.insert(8, "-");
+		a_UUID.insert(13, "-");
+		a_UUID.insert(18, "-");
+		a_UUID.insert(23, "-");
+	}
+	return true;
+}
+
+
+
+
+
diff --git a/src/Protocol/Authenticator.h b/src/Protocol/Authenticator.h
new file mode 100644
index 000000000..211f51394
--- /dev/null
+++ b/src/Protocol/Authenticator.h
@@ -0,0 +1,93 @@
+
+// cAuthenticator.h
+
+// Interfaces to the cAuthenticator class representing the thread that authenticates users against the official MC server
+// Authentication prevents "hackers" from joining with an arbitrary username (possibly impersonating the server admins)
+// For more info, see http://wiki.vg/Session#Server_operation
+// In MCS, authentication is implemented as a single thread that receives queued auth requests and dispatches them one by one.
+
+
+
+
+
+#pragma once
+#ifndef CAUTHENTICATOR_H_INCLUDED
+#define CAUTHENTICATOR_H_INCLUDED
+
+#include "../OSSupport/IsThread.h"
+
+
+
+
+
+// fwd: "cRoot.h"
+class cRoot;
+
+
+
+
+
+class cAuthenticator :
+	public cIsThread
+{
+	typedef cIsThread super;
+
+public:
+	cAuthenticator(void);
+	~cAuthenticator();
+
+	/** (Re-)read server and address from INI: */
+	void ReadINI(cIniFile & IniFile);
+
+	/** Queues a request for authenticating a user. If the auth fails, the user will be kicked */
+	void Authenticate(int a_ClientID, const AString & a_UserName, const AString & a_ServerHash);
+
+	/** Starts the authenticator thread. The thread may be started and stopped repeatedly */
+	void Start(cIniFile & IniFile);
+
+	/** Stops the authenticator thread. The thread may be started and stopped repeatedly */
+	void Stop(void);
+
+private:
+
+	class cUser
+	{
+	public:
+		int     m_ClientID;
+		AString m_Name;
+		AString m_ServerID;
+
+		cUser(int a_ClientID, const AString & a_Name, const AString & a_ServerID) :
+			m_ClientID(a_ClientID),
+			m_Name(a_Name),
+			m_ServerID(a_ServerID)
+		{
+		}
+	};
+
+	typedef std::deque<cUser> cUserList;
+
+	cCriticalSection m_CS;
+	cUserList        m_Queue;
+	cEvent           m_QueueNonempty;
+
+	AString m_Server;
+	AString m_Address;
+	bool    m_ShouldAuthenticate;
+
+	/** cIsThread override: */
+	virtual void Execute(void) override;
+
+	/** Returns true if the user authenticated okay, false on error; iLevel is the recursion deptht (bails out if too deep) */
+	bool AuthWithYggdrasil(AString & a_UserName, const AString & a_ServerId, AString & a_UUID);
+};
+
+
+
+
+
+#endif  // CAUTHENTICATOR_H_INCLUDED
+
+
+
+
diff --git a/src/Protocol/Protocol.h b/src/Protocol/Protocol.h
index 939170f0e..2fbeef0fa 100644
--- a/src/Protocol/Protocol.h
+++ b/src/Protocol/Protocol.h
@@ -83,6 +83,7 @@ public:
 	virtual void SendInventorySlot       (char a_WindowID, short a_SlotNum, const cItem & a_Item) = 0;
 	virtual void SendKeepAlive           (int a_PingID) = 0;
 	virtual void SendLogin               (const cPlayer & a_Player, const cWorld & a_World) = 0;
+	virtual void SendLoginSuccess        (void) = 0;
 	virtual void SendMapColumn           (int a_ID, int a_X, int a_Y, const Byte * a_Colors, unsigned int a_Length) = 0;
 	virtual void SendMapDecorators       (int a_ID, const cMapDecoratorList & a_Decorators) = 0;
 	virtual void SendMapInfo             (int a_ID, unsigned int a_Scale) = 0;
diff --git a/src/Protocol/Protocol125.cpp b/src/Protocol/Protocol125.cpp
index 7ae359e10..b0ace7a7a 100644
--- a/src/Protocol/Protocol125.cpp
+++ b/src/Protocol/Protocol125.cpp
@@ -595,6 +595,15 @@ void cProtocol125::SendLogin(const cPlayer & a_Player, const cWorld & a_World)
 
 
 
+void cProtocol125::SendLoginSuccess(void)
+{
+	// Not supported in this protocol version
+}
+
+
+
+
+
 void cProtocol125::SendMapColumn(int a_ID, int a_X, int a_Y, const Byte * a_Colors, unsigned int a_Length)
 {
 	cCSLock Lock(m_CSPacket);
@@ -643,6 +652,17 @@ void cProtocol125::SendMapDecorators(int a_ID, const cMapDecoratorList & a_Decor
 
 
 
+void cProtocol125::SendMapInfo(int a_ID, unsigned int a_Scale)
+{
+	// This protocol doesn't support such message
+	UNUSED(a_ID);
+	UNUSED(a_Scale);
+}
+
+
+
+
+
 void cProtocol125::SendPickupSpawn(const cPickup & a_Pickup)
 {
 	cCSLock Lock(m_CSPacket);
@@ -685,6 +705,16 @@ void cProtocol125::SendParticleEffect(const AString & a_ParticleName, float a_Sr
 
 
 
+void cProtocol125::SendPaintingSpawn(const cPainting & a_Painting)
+{
+	// Not implemented in this protocol version
+	UNUSED(a_Painting);
+}
+
+
+
+
+
 void cProtocol125::SendPlayerListItem(const cPlayer & a_Player, bool a_IsOnline)
 {
 	cCSLock Lock(m_CSPacket);
@@ -846,6 +876,18 @@ void cProtocol125::SendExperienceOrb(const cExpOrb & a_ExpOrb)
 
 
 
+void cProtocol125::SendScoreboardObjective(const AString & a_Name, const AString & a_DisplayName, Byte a_Mode)
+{
+	// This protocol version doesn't support such message
+	UNUSED(a_Name);
+	UNUSED(a_DisplayName);
+	UNUSED(a_Mode);
+}
+
+
+
+
+
 void cProtocol125::SendSoundEffect(const AString & a_SoundName, int a_SrcX, int a_SrcY, int a_SrcZ, float a_Volume, float a_Pitch)
 {
 	// Not needed in this protocol version
diff --git a/src/Protocol/Protocol125.h b/src/Protocol/Protocol125.h
index 08d3ebbe9..16f31bd0e 100644
--- a/src/Protocol/Protocol125.h
+++ b/src/Protocol/Protocol125.h
@@ -56,19 +56,12 @@ public:
 	virtual void SendInventorySlot       (char a_WindowID, short a_SlotNum, const cItem & a_Item) override;
 	virtual void SendKeepAlive           (int a_PingID) override;
 	virtual void SendLogin               (const cPlayer & a_Player, const cWorld & a_World) override;
+	virtual void SendLoginSuccess        (void) override;
 	virtual void SendMapColumn           (int a_ID, int a_X, int a_Y, const Byte * a_Colors, unsigned int a_Length) override;
 	virtual void SendMapDecorators       (int a_ID, const cMapDecoratorList & a_Decorators) override;
-	virtual void SendMapInfo             (int a_ID, unsigned int a_Scale) override 
-	{
-		// This protocol doesn't support such message
-		UNUSED(a_ID);
-		UNUSED(a_Scale);
-	} 
+	virtual void SendMapInfo             (int a_ID, unsigned int a_Scale) override;
 	virtual void SendParticleEffect      (const AString & a_ParticleName, float a_SrcX, float a_SrcY, float a_SrcZ, float a_OffsetX, float a_OffsetY, float a_OffsetZ, float a_ParticleData, int a_ParticleAmmount) override;
-	virtual void SendPaintingSpawn       (const cPainting & a_Painting) override 
-	{
-		UNUSED(a_Painting);
-	};
+	virtual void SendPaintingSpawn       (const cPainting & a_Painting) override;
 	virtual void SendPickupSpawn         (const cPickup & a_Pickup) override;
 	virtual void SendPlayerAbilities     (void) override {}  // This protocol doesn't support such message
 	virtual void SendEntityAnimation     (const cEntity & a_Entity, char a_Animation) override;
@@ -82,12 +75,7 @@ public:
 	virtual void SendRespawn             (void) override;
 	virtual void SendExperience          (void) override;
 	virtual void SendExperienceOrb       (const cExpOrb &  a_ExpOrb) override;
-	virtual void SendScoreboardObjective (const AString & a_Name, const AString & a_DisplayName, Byte a_Mode)                            override 
-	{
-		UNUSED(a_Name);
-		UNUSED(a_DisplayName);
-		UNUSED(a_Mode);
-	} // This protocol doesn't support such message
+	virtual void SendScoreboardObjective (const AString & a_Name, const AString & a_DisplayName, Byte a_Mode) override;
 	virtual void SendScoreUpdate         (const AString & a_Objective, const AString & a_Player, cObjective::Score a_Score, Byte a_Mode) override {} // This protocol doesn't support such message
 	virtual void SendDisplayObjective    (const AString & a_Objective, cScoreboard::eDisplaySlot a_Display)                              override {} // This protocol doesn't support such message
 	virtual void SendSoundEffect         (const AString & a_SoundName, int a_SrcX, int a_SrcY, int a_SrcZ, float a_Volume, float a_Pitch) override;  // a_Src coords are Block * 8
diff --git a/src/Protocol/Protocol17x.cpp b/src/Protocol/Protocol17x.cpp
index 135518b67..ec9a9b4c5 100644
--- a/src/Protocol/Protocol17x.cpp
+++ b/src/Protocol/Protocol17x.cpp
@@ -88,8 +88,9 @@ cProtocol172::cProtocol172(cClientHandle * a_Client, const AString & a_ServerAdd
 	// Create the comm log file, if so requested:
 	if (g_ShouldLogCommIn || g_ShouldLogCommOut)
 	{
+		static int sCounter = 0;
 		cFile::CreateFolder("CommLogs");
-		AString FileName = Printf("CommLogs/%x__%s.log", (unsigned)time(NULL), a_Client->GetIPString().c_str());
+		AString FileName = Printf("CommLogs/%x_%d__%s.log", (unsigned)time(NULL), sCounter++, a_Client->GetIPString().c_str());
 		m_CommLogFile.Open(FileName, cFile::fmWrite);
 	}
 }
@@ -124,6 +125,8 @@ void cProtocol172::DataReceived(const char * a_Data, size_t a_Size)
 
 void cProtocol172::SendAttachEntity(const cEntity & a_Entity, const cEntity * a_Vehicle)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x1b);  // Attach Entity packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteInt((a_Vehicle != NULL) ? a_Vehicle->GetUniqueID() : 0);
@@ -136,6 +139,8 @@ void cProtocol172::SendAttachEntity(const cEntity & a_Entity, const cEntity * a_
 
 void cProtocol172::SendBlockAction(int a_BlockX, int a_BlockY, int a_BlockZ, char a_Byte1, char a_Byte2, BLOCKTYPE a_BlockType)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x24);  // Block Action packet
 	Pkt.WriteInt(a_BlockX);
 	Pkt.WriteShort(a_BlockY);
@@ -151,6 +156,8 @@ void cProtocol172::SendBlockAction(int a_BlockX, int a_BlockY, int a_BlockZ, cha
 
 void cProtocol172::SendBlockBreakAnim(int a_EntityID, int a_BlockX, int a_BlockY, int a_BlockZ, char a_Stage)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x25);  // Block Break Animation packet
 	Pkt.WriteVarInt(a_EntityID);
 	Pkt.WriteInt(a_BlockX);
@@ -165,6 +172,8 @@ void cProtocol172::SendBlockBreakAnim(int a_EntityID, int a_BlockX, int a_BlockY
 
 void cProtocol172::SendBlockChange(int a_BlockX, int a_BlockY, int a_BlockZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_BlockMeta)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x23);  // Block Change packet
 	Pkt.WriteInt(a_BlockX);
 	Pkt.WriteByte(a_BlockY);
@@ -179,6 +188,8 @@ void cProtocol172::SendBlockChange(int a_BlockX, int a_BlockY, int a_BlockZ, BLO
 
 void cProtocol172::SendBlockChanges(int a_ChunkX, int a_ChunkZ, const sSetBlockVector & a_Changes)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x22);  // Multi Block Change packet
 	Pkt.WriteInt(a_ChunkX);
 	Pkt.WriteInt(a_ChunkZ);
@@ -198,6 +209,8 @@ void cProtocol172::SendBlockChanges(int a_ChunkX, int a_ChunkZ, const sSetBlockV
 
 void cProtocol172::SendChat(const AString & a_Message)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x02);  // Chat Message packet
 	Pkt.WriteString(Printf("{\"text\":\"%s\"}", EscapeString(a_Message).c_str()));
 }
@@ -208,6 +221,8 @@ void cProtocol172::SendChat(const AString & a_Message)
 
 void cProtocol172::SendChat(const cCompositeChat & a_Message)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	// Compose the complete Json string to send:
 	Json::Value msg;
 	msg["text"] = "";  // The client crashes without this
@@ -280,6 +295,8 @@ void cProtocol172::SendChat(const cCompositeChat & a_Message)
 
 void cProtocol172::SendChunkData(int a_ChunkX, int a_ChunkZ, cChunkDataSerializer & a_Serializer)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	// Serialize first, before creating the Packetizer (the packetizer locks a CS)
 	// This contains the flags and bitmasks, too
 	const AString & ChunkData = a_Serializer.Serialize(cChunkDataSerializer::RELEASE_1_3_2);
@@ -296,6 +313,8 @@ void cProtocol172::SendChunkData(int a_ChunkX, int a_ChunkZ, cChunkDataSerialize
 
 void cProtocol172::SendCollectPickup(const cPickup & a_Pickup, const cPlayer & a_Player)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x0d);  // Collect Item packet
 	Pkt.WriteInt(a_Pickup.GetUniqueID());
 	Pkt.WriteInt(a_Player.GetUniqueID());
@@ -307,6 +326,8 @@ void cProtocol172::SendCollectPickup(const cPickup & a_Pickup, const cPlayer & a
 
 void cProtocol172::SendDestroyEntity(const cEntity & a_Entity)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x13);  // Destroy Entities packet
 	Pkt.WriteByte(1);
 	Pkt.WriteInt(a_Entity.GetUniqueID());
@@ -343,6 +364,8 @@ void cProtocol172::SendDisconnect(const AString & a_Reason)
 
 void cProtocol172::SendEditSign(int a_BlockX, int a_BlockY, int a_BlockZ)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x36);  // Sign Editor Open packet
 	Pkt.WriteInt(a_BlockX);
 	Pkt.WriteInt(a_BlockY);
@@ -355,6 +378,8 @@ void cProtocol172::SendEditSign(int a_BlockX, int a_BlockY, int a_BlockZ)
 
 void cProtocol172::SendEntityEffect(const cEntity & a_Entity, int a_EffectID, int a_Amplifier, short a_Duration)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x1D);  // Entity Effect packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteByte(a_EffectID);
@@ -368,6 +393,8 @@ void cProtocol172::SendEntityEffect(const cEntity & a_Entity, int a_EffectID, in
 
 void cProtocol172::SendEntityEquipment(const cEntity & a_Entity, short a_SlotNum, const cItem & a_Item)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x04);  // Entity Equipment packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteShort(a_SlotNum);
@@ -380,6 +407,8 @@ void cProtocol172::SendEntityEquipment(const cEntity & a_Entity, short a_SlotNum
 
 void cProtocol172::SendEntityHeadLook(const cEntity & a_Entity)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x19);  // Entity Head Look packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteByteAngle(a_Entity.GetHeadYaw());
@@ -391,6 +420,8 @@ void cProtocol172::SendEntityHeadLook(const cEntity & a_Entity)
 
 void cProtocol172::SendEntityLook(const cEntity & a_Entity)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x16);  // Entity Look packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteByteAngle(a_Entity.GetYaw());
@@ -403,6 +434,8 @@ void cProtocol172::SendEntityLook(const cEntity & a_Entity)
 
 void cProtocol172::SendEntityMetadata(const cEntity & a_Entity)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x1c);  // Entity Metadata packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteEntityMetadata(a_Entity);
@@ -415,6 +448,8 @@ void cProtocol172::SendEntityMetadata(const cEntity & a_Entity)
 
 void cProtocol172::SendEntityProperties(const cEntity & a_Entity)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x20);  // Entity Properties packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteEntityProperties(a_Entity);
@@ -426,6 +461,8 @@ void cProtocol172::SendEntityProperties(const cEntity & a_Entity)
 
 void cProtocol172::SendEntityRelMove(const cEntity & a_Entity, char a_RelX, char a_RelY, char a_RelZ)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x15);  // Entity Relative Move packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteByte(a_RelX);
@@ -439,6 +476,8 @@ void cProtocol172::SendEntityRelMove(const cEntity & a_Entity, char a_RelX, char
 
 void cProtocol172::SendEntityRelMoveLook(const cEntity & a_Entity, char a_RelX, char a_RelY, char a_RelZ)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x17);  // Entity Look And Relative Move packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteByte(a_RelX);
@@ -454,6 +493,8 @@ void cProtocol172::SendEntityRelMoveLook(const cEntity & a_Entity, char a_RelX,
 
 void cProtocol172::SendEntityStatus(const cEntity & a_Entity, char a_Status)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x1a);  // Entity Status packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteChar(a_Status);
@@ -465,6 +506,8 @@ void cProtocol172::SendEntityStatus(const cEntity & a_Entity, char a_Status)
 
 void cProtocol172::SendEntityVelocity(const cEntity & a_Entity)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x12);  // Entity Velocity packet
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	// 400 = 8000 / 20 ... Conversion from our speed in m/s to 8000 m/tick
@@ -479,6 +522,8 @@ void cProtocol172::SendEntityVelocity(const cEntity & a_Entity)
 
 void cProtocol172::SendExplosion(double a_BlockX, double a_BlockY, double a_BlockZ, float a_Radius, const cVector3iArray & a_BlocksAffected, const Vector3d & a_PlayerMotion)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x27);  // Explosion packet
 	Pkt.WriteFloat((float)a_BlockX);
 	Pkt.WriteFloat((float)a_BlockY);
@@ -502,6 +547,8 @@ void cProtocol172::SendExplosion(double a_BlockX, double a_BlockY, double a_Bloc
 
 void cProtocol172::SendGameMode(eGameMode a_GameMode)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x2b);  // Change Game State packet
 	Pkt.WriteByte(3);  // Reason: Change game mode
 	Pkt.WriteFloat((float)a_GameMode);
@@ -513,6 +560,8 @@ void cProtocol172::SendGameMode(eGameMode a_GameMode)
 
 void cProtocol172::SendHealth(void)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x06);  // Update Health packet
 	cPlayer * Player = m_Client->GetPlayer();
 	Pkt.WriteFloat((float)Player->GetHealth());
@@ -526,6 +575,8 @@ void cProtocol172::SendHealth(void)
 
 void cProtocol172::SendInventorySlot(char a_WindowID, short a_SlotNum, const cItem & a_Item)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x2f);  // Set Slot packet
 	Pkt.WriteChar(a_WindowID);
 	Pkt.WriteShort(a_SlotNum);
@@ -538,6 +589,13 @@ void cProtocol172::SendInventorySlot(char a_WindowID, short a_SlotNum, const cIt
 
 void cProtocol172::SendKeepAlive(int a_PingID)
 {
+	// Drop the packet if the protocol is not in the Game state yet (caused a client crash):
+	if (m_State != 3)
+	{
+		LOGWARNING("Trying to send a KeepAlive packet to a player who's not yet fully logged in (%d). The protocol class prevented the packet.", m_State);
+		return;
+	}
+	
 	cPacketizer Pkt(*this, 0x00);  // Keep Alive packet
 	Pkt.WriteInt(a_PingID);
 }
@@ -575,8 +633,25 @@ void cProtocol172::SendLogin(const cPlayer & a_Player, const cWorld & a_World)
 
 
 
+void cProtocol172::SendLoginSuccess(void)
+{
+	ASSERT(m_State == 2);  // State: login?
+	
+	cPacketizer Pkt(*this, 0x02);  // Login success packet
+	Pkt.WriteString(m_Client->GetUUID());
+	Pkt.WriteString(m_Client->GetUsername());
+
+	m_State = 3;  // State = Game
+}
+
+
+
+
+
 void cProtocol172::SendPaintingSpawn(const cPainting & a_Painting)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x10);  // Spawn Painting packet
 	Pkt.WriteVarInt(a_Painting.GetUniqueID());
 	Pkt.WriteString(a_Painting.GetName().c_str());
@@ -592,6 +667,8 @@ void cProtocol172::SendPaintingSpawn(const cPainting & a_Painting)
 
 void cProtocol172::SendMapColumn(int a_ID, int a_X, int a_Y, const Byte * a_Colors, unsigned int a_Length)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x34);
 	Pkt.WriteVarInt(a_ID);
 	Pkt.WriteShort (3 + a_Length);
@@ -612,6 +689,8 @@ void cProtocol172::SendMapColumn(int a_ID, int a_X, int a_Y, const Byte * a_Colo
 
 void cProtocol172::SendMapDecorators(int a_ID, const cMapDecoratorList & a_Decorators)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x34);
 	Pkt.WriteVarInt(a_ID);
 	Pkt.WriteShort (1 + (3 * a_Decorators.size()));
@@ -632,6 +711,8 @@ void cProtocol172::SendMapDecorators(int a_ID, const cMapDecoratorList & a_Decor
 
 void cProtocol172::SendMapInfo(int a_ID, unsigned int a_Scale)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x34);
 	Pkt.WriteVarInt(a_ID);
 	Pkt.WriteShort (2);
@@ -647,6 +728,8 @@ void cProtocol172::SendMapInfo(int a_ID, unsigned int a_Scale)
 
 void cProtocol172::SendPickupSpawn(const cPickup & a_Pickup)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	{
 		cPacketizer Pkt(*this, 0x0e);  // Spawn Object packet
 		Pkt.WriteVarInt(a_Pickup.GetUniqueID());
@@ -673,6 +756,8 @@ void cProtocol172::SendPickupSpawn(const cPickup & a_Pickup)
 
 void cProtocol172::SendPlayerAbilities(void)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x39);  // Player Abilities packet
 	Byte Flags = 0;
 	cPlayer * Player = m_Client->GetPlayer();
@@ -700,6 +785,8 @@ void cProtocol172::SendPlayerAbilities(void)
 
 void cProtocol172::SendEntityAnimation(const cEntity & a_Entity, char a_Animation)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x0b);  // Animation packet
 	Pkt.WriteVarInt(a_Entity.GetUniqueID());
 	Pkt.WriteChar(a_Animation);
@@ -711,6 +798,8 @@ void cProtocol172::SendEntityAnimation(const cEntity & a_Entity, char a_Animatio
 
 void cProtocol172::SendParticleEffect(const AString & a_ParticleName, float a_SrcX, float a_SrcY, float a_SrcZ, float a_OffsetX, float a_OffsetY, float a_OffsetZ, float a_ParticleData, int a_ParticleAmmount)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x2A);
 	Pkt.WriteString(a_ParticleName);
 	Pkt.WriteFloat(a_SrcX);
@@ -729,6 +818,8 @@ void cProtocol172::SendParticleEffect(const AString & a_ParticleName, float a_Sr
 
 void cProtocol172::SendPlayerListItem(const cPlayer & a_Player, bool a_IsOnline)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x38);  // Playerlist Item packet
 	Pkt.WriteString(a_Player.GetName());
 	Pkt.WriteBool(a_IsOnline);
@@ -741,6 +832,8 @@ void cProtocol172::SendPlayerListItem(const cPlayer & a_Player, bool a_IsOnline)
 
 void cProtocol172::SendPlayerMaxSpeed(void)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x20);  // Entity Properties
 	cPlayer * Player = m_Client->GetPlayer();
 	Pkt.WriteInt(Player->GetUniqueID());
@@ -768,6 +861,8 @@ void cProtocol172::SendPlayerMaxSpeed(void)
 
 void cProtocol172::SendPlayerMoveLook(void)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x08);  // Player Position And Look packet
 	cPlayer * Player = m_Client->GetPlayer();
 	Pkt.WriteDouble(Player->GetPosX());
@@ -798,10 +893,12 @@ void cProtocol172::SendPlayerPosition(void)
 
 void cProtocol172::SendPlayerSpawn(const cPlayer & a_Player)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	// Called to spawn another player for the client
 	cPacketizer Pkt(*this, 0x0c);  // Spawn Player packet
 	Pkt.WriteVarInt(a_Player.GetUniqueID());
-	Pkt.WriteString(Printf("%d", a_Player.GetUniqueID()));  // TODO: Proper UUID
+	Pkt.WriteString(a_Player.GetClientHandle()->GetUUID());
 	Pkt.WriteString(a_Player.GetName());
 	Pkt.WriteFPInt(a_Player.GetPosX());
 	Pkt.WriteFPInt(a_Player.GetPosY());
@@ -821,6 +918,8 @@ void cProtocol172::SendPlayerSpawn(const cPlayer & a_Player)
 
 void cProtocol172::SendPluginMessage(const AString & a_Channel, const AString & a_Message)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x3f);
 	Pkt.WriteString(a_Channel);
 	Pkt.WriteShort((short)a_Message.size());
@@ -833,7 +932,9 @@ void cProtocol172::SendPluginMessage(const AString & a_Channel, const AString &
 
 void cProtocol172::SendRemoveEntityEffect(const cEntity & a_Entity, int a_EffectID)
 {
-	cPacketizer Pkt(*this, 0x1E);
+	ASSERT(m_State == 3);  // In game mode?
+	
+	cPacketizer Pkt(*this, 0x1e);
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteByte(a_EffectID);
 }
@@ -858,7 +959,9 @@ void cProtocol172::SendRespawn(void)
 
 void cProtocol172::SendExperience (void)
 {
-	cPacketizer Pkt(*this, 0x1F); //Experience Packet
+	ASSERT(m_State == 3);  // In game mode?
+	
+	cPacketizer Pkt(*this, 0x1f);  // Experience Packet
 	cPlayer * Player = m_Client->GetPlayer();
 	Pkt.WriteFloat(Player->GetXpPercentage());
 	Pkt.WriteShort(Player->GetXpLevel());
@@ -871,6 +974,8 @@ void cProtocol172::SendExperience (void)
 
 void cProtocol172::SendExperienceOrb(const cExpOrb & a_ExpOrb)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x11);	
 	Pkt.WriteVarInt(a_ExpOrb.GetUniqueID());
 	Pkt.WriteInt((int) a_ExpOrb.GetPosX());
@@ -885,7 +990,9 @@ void cProtocol172::SendExperienceOrb(const cExpOrb & a_ExpOrb)
 
 void cProtocol172::SendScoreboardObjective(const AString & a_Name, const AString & a_DisplayName, Byte a_Mode)
 {
-	cPacketizer Pkt(*this, 0x3B);
+	ASSERT(m_State == 3);  // In game mode?
+	
+	cPacketizer Pkt(*this, 0x3b);
 	Pkt.WriteString(a_Name);
 	Pkt.WriteString(a_DisplayName);
 	Pkt.WriteByte(a_Mode);
@@ -897,7 +1004,9 @@ void cProtocol172::SendScoreboardObjective(const AString & a_Name, const AString
 
 void cProtocol172::SendScoreUpdate(const AString & a_Objective, const AString & a_Player, cObjective::Score a_Score, Byte a_Mode)
 {
-	cPacketizer Pkt(*this, 0x3C);
+	ASSERT(m_State == 3);  // In game mode?
+	
+	cPacketizer Pkt(*this, 0x3c);
 	Pkt.WriteString(a_Player);
 	Pkt.WriteByte(a_Mode);
 
@@ -914,7 +1023,9 @@ void cProtocol172::SendScoreUpdate(const AString & a_Objective, const AString &
 
 void cProtocol172::SendDisplayObjective(const AString & a_Objective, cScoreboard::eDisplaySlot a_Display)
 {
-	cPacketizer Pkt(*this, 0x3D);
+	ASSERT(m_State == 3);  // In game mode?
+	
+	cPacketizer Pkt(*this, 0x3d);
 	Pkt.WriteByte((int) a_Display);
 	Pkt.WriteString(a_Objective);
 }
@@ -925,6 +1036,8 @@ void cProtocol172::SendDisplayObjective(const AString & a_Objective, cScoreboard
 
 void cProtocol172::SendSoundEffect(const AString & a_SoundName, int a_SrcX, int a_SrcY, int a_SrcZ, float a_Volume, float a_Pitch)  // a_Src coords are Block * 8
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x29);  // Sound Effect packet
 	Pkt.WriteString(a_SoundName);
 	Pkt.WriteInt(a_SrcX);
@@ -940,6 +1053,8 @@ void cProtocol172::SendSoundEffect(const AString & a_SoundName, int a_SrcX, int
 
 void cProtocol172::SendSoundParticleEffect(int a_EffectID, int a_SrcX, int a_SrcY, int a_SrcZ, int a_Data)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x28);  // Effect packet
 	Pkt.WriteInt(a_EffectID);
 	Pkt.WriteInt(a_SrcX);
@@ -955,6 +1070,8 @@ void cProtocol172::SendSoundParticleEffect(int a_EffectID, int a_SrcX, int a_Src
 
 void cProtocol172::SendSpawnFallingBlock(const cFallingBlock & a_FallingBlock)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x0e);  // Spawn Object packet
 	Pkt.WriteVarInt(a_FallingBlock.GetUniqueID());
 	Pkt.WriteByte(70);  // Falling block
@@ -975,6 +1092,8 @@ void cProtocol172::SendSpawnFallingBlock(const cFallingBlock & a_FallingBlock)
 
 void cProtocol172::SendSpawnMob(const cMonster & a_Mob)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x0f);  // Spawn Mob packet
 	Pkt.WriteVarInt(a_Mob.GetUniqueID());
 	Pkt.WriteByte((Byte)a_Mob.GetMobType());
@@ -997,6 +1116,8 @@ void cProtocol172::SendSpawnMob(const cMonster & a_Mob)
 
 void cProtocol172::SendSpawnObject(const cEntity & a_Entity, char a_ObjectType, int a_ObjectData, Byte a_Yaw, Byte a_Pitch)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0xe);  // Spawn Object packet
 	Pkt.WriteVarInt(a_Entity.GetUniqueID());
 	Pkt.WriteByte(a_ObjectType);
@@ -1020,6 +1141,8 @@ void cProtocol172::SendSpawnObject(const cEntity & a_Entity, char a_ObjectType,
 
 void cProtocol172::SendSpawnVehicle(const cEntity & a_Vehicle, char a_VehicleType, char a_VehicleSubType)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0xe);  // Spawn Object packet
 	Pkt.WriteVarInt(a_Vehicle.GetUniqueID());
 	Pkt.WriteByte(a_VehicleType);
@@ -1043,6 +1166,8 @@ void cProtocol172::SendSpawnVehicle(const cEntity & a_Vehicle, char a_VehicleTyp
 
 void cProtocol172::SendTabCompletionResults(const AStringVector & a_Results)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x3a);  // Tab-Complete packet
 	Pkt.WriteVarInt(a_Results.size());
 
@@ -1058,6 +1183,8 @@ void cProtocol172::SendTabCompletionResults(const AStringVector & a_Results)
 
 void cProtocol172::SendTeleportEntity(const cEntity & a_Entity)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x18);
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteFPInt(a_Entity.GetPosX());
@@ -1073,6 +1200,8 @@ void cProtocol172::SendTeleportEntity(const cEntity & a_Entity)
 
 void cProtocol172::SendThunderbolt(int a_BlockX, int a_BlockY, int a_BlockZ)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x2c);  // Spawn Global Entity packet
 	Pkt.WriteVarInt(0);  // EntityID = 0, always
 	Pkt.WriteByte(1);  // Type = Thunderbolt
@@ -1087,6 +1216,8 @@ void cProtocol172::SendThunderbolt(int a_BlockX, int a_BlockY, int a_BlockZ)
 
 void cProtocol172::SendTimeUpdate(Int64 a_WorldAge, Int64 a_TimeOfDay)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x03);
 	Pkt.WriteInt64(a_WorldAge);
 	Pkt.WriteInt64(a_TimeOfDay);
@@ -1098,6 +1229,8 @@ void cProtocol172::SendTimeUpdate(Int64 a_WorldAge, Int64 a_TimeOfDay)
 
 void cProtocol172::SendUnloadChunk(int a_ChunkX, int a_ChunkZ)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x21);  // Chunk Data packet
 	Pkt.WriteInt(a_ChunkX);
 	Pkt.WriteInt(a_ChunkZ);
@@ -1112,6 +1245,8 @@ void cProtocol172::SendUnloadChunk(int a_ChunkX, int a_ChunkZ)
 
 void cProtocol172::SendUpdateBlockEntity(cBlockEntity & a_BlockEntity)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x35);  // Update tile entity packet
 	Pkt.WriteInt(a_BlockEntity.GetPosX());
 	Pkt.WriteShort(a_BlockEntity.GetPosY());
@@ -1137,6 +1272,8 @@ void cProtocol172::SendUpdateBlockEntity(cBlockEntity & a_BlockEntity)
 
 void cProtocol172::SendUpdateSign(int a_BlockX, int a_BlockY, int a_BlockZ, const AString & a_Line1, const AString & a_Line2, const AString & a_Line3, const AString & a_Line4)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x33);
 	Pkt.WriteInt(a_BlockX);
 	Pkt.WriteShort((short)a_BlockY);
@@ -1154,6 +1291,8 @@ void cProtocol172::SendUpdateSign(int a_BlockX, int a_BlockY, int a_BlockZ, cons
 
 void cProtocol172::SendUseBed(const cEntity & a_Entity, int a_BlockX, int a_BlockY, int a_BlockZ)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x0a);
 	Pkt.WriteInt(a_Entity.GetUniqueID());
 	Pkt.WriteInt(a_BlockX);
@@ -1167,6 +1306,8 @@ void cProtocol172::SendUseBed(const cEntity & a_Entity, int a_BlockX, int a_Bloc
 
 void cProtocol172::SendWeather(eWeather a_Weather)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	{
 		cPacketizer Pkt(*this, 0x2b);  // Change Game State packet
 		Pkt.WriteByte((a_Weather == wSunny) ? 1 : 2);  // End rain / begin rain
@@ -1182,6 +1323,8 @@ void cProtocol172::SendWeather(eWeather a_Weather)
 
 void cProtocol172::SendWholeInventory(const cWindow & a_Window)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x30);  // Window Items packet
 	Pkt.WriteChar(a_Window.GetWindowID());
 	Pkt.WriteShort(a_Window.GetNumSlots());
@@ -1199,6 +1342,8 @@ void cProtocol172::SendWholeInventory(const cWindow & a_Window)
 
 void cProtocol172::SendWindowClose(const cWindow & a_Window)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x2e);
 	Pkt.WriteChar(a_Window.GetWindowID());
 }
@@ -1209,6 +1354,8 @@ void cProtocol172::SendWindowClose(const cWindow & a_Window)
 
 void cProtocol172::SendWindowOpen(const cWindow & a_Window)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	if (a_Window.GetWindowType() < 0)
 	{
 		// Do not send this packet for player inventory windows
@@ -1233,6 +1380,8 @@ void cProtocol172::SendWindowOpen(const cWindow & a_Window)
 
 void cProtocol172::SendWindowProperty(const cWindow & a_Window, short a_Property, short a_Value)
 {
+	ASSERT(m_State == 3);  // In game mode?
+	
 	cPacketizer Pkt(*this, 0x31);  // Window Property packet
 	Pkt.WriteChar(a_Window.GetWindowID());
 	Pkt.WriteShort(a_Property);
@@ -1563,15 +1712,6 @@ void cProtocol172::HandlePacketLoginEncryptionResponse(cByteBuffer & a_ByteBuffe
 	}
 	
 	StartEncryption(DecryptedKey);
-
-	// Send login success:
-	{
-		cPacketizer Pkt(*this, 0x02);  // Login success packet
-		Pkt.WriteString(Printf("%d", m_Client->GetUniqueID()));  // TODO: proper UUID
-		Pkt.WriteString(m_Client->GetUsername());
-	}
-
-	m_State = 3;  // State = Game
 	m_Client->HandleLogin(4, m_Client->GetUsername());
 }
 
@@ -1605,14 +1745,6 @@ void cProtocol172::HandlePacketLoginStart(cByteBuffer & a_ByteBuffer)
 		return;
 	}
 	
-	// Send login success:
-	{
-		cPacketizer Pkt(*this, 0x02);  // Login success packet
-		Pkt.WriteString(Printf("%d", m_Client->GetUniqueID()));  // TODO: proper UUID
-		Pkt.WriteString(Username);
-	}
-
-	m_State = 3;  // State = Game
 	m_Client->HandleLogin(4, Username);
 }
 
@@ -2766,3 +2898,64 @@ void cProtocol172::cPacketizer::WriteEntityProperties(const cEntity & a_Entity)
 
 
 
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// cProtocol176:
+
+cProtocol176::cProtocol176(cClientHandle * a_Client, const AString &a_ServerAddress, UInt16 a_ServerPort, UInt32 a_State) :
+	super(a_Client, a_ServerAddress, a_ServerPort, a_State)
+{
+}
+
+
+
+
+
+void cProtocol176::SendPlayerSpawn(const cPlayer & a_Player)
+{
+	// Called to spawn another player for the client
+	cPacketizer Pkt(*this, 0x0c);  // Spawn Player packet
+	Pkt.WriteVarInt(a_Player.GetUniqueID());
+	Pkt.WriteString(a_Player.GetClientHandle()->GetUUID());
+	Pkt.WriteString(a_Player.GetName());
+	Pkt.WriteVarInt(0);  // We have no data to send here
+	Pkt.WriteFPInt(a_Player.GetPosX());
+	Pkt.WriteFPInt(a_Player.GetPosY());
+	Pkt.WriteFPInt(a_Player.GetPosZ());
+	Pkt.WriteByteAngle(a_Player.GetYaw());
+	Pkt.WriteByteAngle(a_Player.GetPitch());
+	short ItemType = a_Player.GetEquippedItem().IsEmpty() ? 0 : a_Player.GetEquippedItem().m_ItemType;
+	Pkt.WriteShort(ItemType);
+	Pkt.WriteByte((3 << 5) | 6);  // Metadata: float + index 6
+	Pkt.WriteFloat((float)a_Player.GetHealth());
+	Pkt.WriteByte(0x7f);  // Metadata: end
+}
+
+
+
+
+
+void cProtocol176::HandlePacketStatusRequest(cByteBuffer & a_ByteBuffer)
+{
+	// Send the response:
+	AString Response = "{\"version\":{\"name\":\"1.7.6\",\"protocol\":5},\"players\":{";
+	AppendPrintf(Response, "\"max\":%u,\"online\":%u,\"sample\":[]},",
+		cRoot::Get()->GetServer()->GetMaxPlayers(),
+		cRoot::Get()->GetServer()->GetNumPlayers()
+	);
+	AppendPrintf(Response, "\"description\":{\"text\":\"%s\"},",
+		cRoot::Get()->GetServer()->GetDescription().c_str()
+	);
+	AppendPrintf(Response, "\"favicon\":\"data:image/png;base64,%s\"",
+		cRoot::Get()->GetServer()->GetFaviconData().c_str()
+	);
+	Response.append("}");
+	
+	cPacketizer Pkt(*this, 0x00);  // Response packet
+	Pkt.WriteString(Response);
+}
+
+
+
+
+
diff --git a/src/Protocol/Protocol17x.h b/src/Protocol/Protocol17x.h
index 91186b270..5cafc4722 100644
--- a/src/Protocol/Protocol17x.h
+++ b/src/Protocol/Protocol17x.h
@@ -87,6 +87,7 @@ public:
 	virtual void SendInventorySlot       (char a_WindowID, short a_SlotNum, const cItem & a_Item) override;
 	virtual void SendKeepAlive           (int a_PingID) override;
 	virtual void SendLogin               (const cPlayer & a_Player, const cWorld & a_World) override;
+	virtual void SendLoginSuccess        (void) override;
 	virtual void SendMapColumn           (int a_ID, int a_X, int a_Y, const Byte * a_Colors, unsigned int a_Length) override;
 	virtual void SendMapDecorators       (int a_ID, const cMapDecoratorList & a_Decorators) override;
 	virtual void SendMapInfo             (int a_ID, unsigned int a_Scale) override;
@@ -252,7 +253,7 @@ protected:
 	
 	// Packet handlers while in the Status state (m_State == 1):
 	void HandlePacketStatusPing   (cByteBuffer & a_ByteBuffer);
-	void HandlePacketStatusRequest(cByteBuffer & a_ByteBuffer);
+	virtual void HandlePacketStatusRequest(cByteBuffer & a_ByteBuffer);
 	
 	// Packet handlers while in the Login state (m_State == 2):
 	void HandlePacketLoginEncryptionResponse(cByteBuffer & a_ByteBuffer);
@@ -306,3 +307,22 @@ protected:
 
 
 
+
+/** The version 5 lengthed protocol, used by 1.7.6 through 1.7.9. */
+class cProtocol176 :
+	public cProtocol172
+{
+	typedef cProtocol172 super;
+	
+public:
+	cProtocol176(cClientHandle * a_Client, const AString & a_ServerAddress, UInt16 a_ServerPort, UInt32 a_State);
+	
+	// cProtocol172 overrides:
+	virtual void SendPlayerSpawn(const cPlayer & a_Player) override;
+	virtual void HandlePacketStatusRequest(cByteBuffer & a_ByteBuffer) override;
+
+} ;
+
+
+
+
diff --git a/src/Protocol/ProtocolRecognizer.cpp b/src/Protocol/ProtocolRecognizer.cpp
index f9a7ba92b..2ccb9f197 100644
--- a/src/Protocol/ProtocolRecognizer.cpp
+++ b/src/Protocol/ProtocolRecognizer.cpp
@@ -59,6 +59,7 @@ AString cProtocolRecognizer::GetVersionTextFromInt(int a_ProtocolVersion)
 		case PROTO_VERSION_1_6_3: return "1.6.3";
 		case PROTO_VERSION_1_6_4: return "1.6.4";
 		case PROTO_VERSION_1_7_2: return "1.7.2";
+		case PROTO_VERSION_1_7_6: return "1.7.6";
 	}
 	ASSERT(!"Unknown protocol version");
 	return Printf("Unknown protocol (%d)", a_ProtocolVersion);
@@ -396,6 +397,16 @@ void cProtocolRecognizer::SendLogin(const cPlayer & a_Player, const cWorld & a_W
 
 
 
+void cProtocolRecognizer::SendLoginSuccess(void)
+{
+	ASSERT(m_Protocol != NULL);
+	m_Protocol->SendLoginSuccess();
+}
+
+
+
+
+
 void cProtocolRecognizer::SendMapColumn(int a_ID, int a_X, int a_Y, const Byte * a_Colors, unsigned int a_Length)
 {
 	ASSERT(m_Protocol != NULL);
@@ -965,6 +976,18 @@ bool cProtocolRecognizer::TryRecognizeLengthedProtocol(UInt32 a_PacketLengthRema
 			m_Protocol = new cProtocol172(m_Client, ServerAddress, (UInt16)ServerPort, NextState);
 			return true;
 		}
+		case PROTO_VERSION_1_7_6:
+		{
+			AString ServerAddress;
+			short ServerPort;
+			UInt32 NextState;
+			m_Buffer.ReadVarUTF8String(ServerAddress);
+			m_Buffer.ReadBEShort(ServerPort);
+			m_Buffer.ReadVarInt(NextState);
+			m_Buffer.CommitRead();
+			m_Protocol = new cProtocol176(m_Client, ServerAddress, (UInt16)ServerPort, NextState);
+			return true;
+		}
 	}
 	LOGINFO("Client \"%s\" uses an unsupported protocol (lengthed, version %u)",
 		m_Client->GetIPString().c_str(), ProtocolVersion
diff --git a/src/Protocol/ProtocolRecognizer.h b/src/Protocol/ProtocolRecognizer.h
index 072d7c2d2..408109ef4 100644
--- a/src/Protocol/ProtocolRecognizer.h
+++ b/src/Protocol/ProtocolRecognizer.h
@@ -18,8 +18,8 @@
 
 
 // Adjust these if a new protocol is added or an old one is removed:
-#define MCS_CLIENT_VERSIONS "1.2.4, 1.2.5, 1.3.1, 1.3.2, 1.4.2, 1.4.4, 1.4.5, 1.4.6, 1.4.7, 1.5, 1.5.1, 1.5.2, 1.6.1, 1.6.2, 1.6.3, 1.6.4, 1.7.2, 1.7.4"
-#define MCS_PROTOCOL_VERSIONS "29, 39, 47, 49, 51, 60, 61, 73, 74, 77, 78, 4"
+#define MCS_CLIENT_VERSIONS "1.2.4, 1.2.5, 1.3.1, 1.3.2, 1.4.2, 1.4.4, 1.4.5, 1.4.6, 1.4.7, 1.5, 1.5.1, 1.5.2, 1.6.1, 1.6.2, 1.6.3, 1.6.4, 1.7.2, 1.7.4, 1.7.5, 1.7.6, 1.7.7, 1.7.8, 1.7.9"
+#define MCS_PROTOCOL_VERSIONS "29, 39, 47, 49, 51, 60, 61, 73, 74, 77, 78, 4, 5"
 
 
 
@@ -50,6 +50,7 @@ public:
 
 		// These will be kept "under" the next / latest, because the next and latest are only needed for previous protocols
 		PROTO_VERSION_1_7_2 = 4,
+		PROTO_VERSION_1_7_6 = 5,
 	} ;
 
 	cProtocolRecognizer(cClientHandle * a_Client);
@@ -90,6 +91,7 @@ public:
 	virtual void SendInventorySlot       (char a_WindowID, short a_SlotNum, const cItem & a_Item) override;
 	virtual void SendKeepAlive           (int a_PingID) override;
 	virtual void SendLogin               (const cPlayer & a_Player, const cWorld & a_World) override;
+	virtual void SendLoginSuccess        (void) override;
 	virtual void SendMapColumn           (int a_ID, int a_X, int a_Y, const Byte * a_Colors, unsigned int a_Length) override;
 	virtual void SendMapDecorators       (int a_ID, const cMapDecoratorList & a_Decorators) override;
 	virtual void SendMapInfo             (int a_ID, unsigned int a_Scale) override;