From db0c83d433d80898b86983e7b6c2199b3483626e Mon Sep 17 00:00:00 2001
From: Learath <learath2@gmail.com>
Date: Sat, 21 Sep 2024 15:46:11 +0200
Subject: [PATCH] Ban compromised old versions

---
 src/engine/server/server.cpp | 19 +++++++++++++++++++
 src/engine/server/server.h   |  1 +
 src/engine/shared/protocol.h |  2 ++
 3 files changed, 22 insertions(+)

diff --git a/src/engine/server/server.cpp b/src/engine/server/server.cpp
index 44a2f99b3..4b2c1edcd 100644
--- a/src/engine/server/server.cpp
+++ b/src/engine/server/server.cpp
@@ -1434,6 +1434,11 @@ bool CServer::CheckReservedSlotAuth(int ClientId, const char *pPassword)
 	return false;
 }
 
+void CServer::DropOldClient(int ClientId)
+{
+	m_NetServer.Drop(ClientId, "This version of the client is compromised. Do not click the update button. ddnet.org/olddomain");
+}
+
 void CServer::ProcessClientPacket(CNetChunk *pPacket)
 {
 	int ClientId = pPacket->m_ClientId;
@@ -1495,6 +1500,13 @@ void CServer::ProcessClientPacket(CNetChunk *pPacket)
 				{
 					return;
 				}
+
+				if(DDNetVersion < VERSION_DDNET_NEW_DOMAIN)
+				{
+					DropOldClient(ClientId);
+					return;
+				}
+
 				m_aClients[ClientId].m_ConnectionId = *pConnectionId;
 				m_aClients[ClientId].m_DDNetVersion = DDNetVersion;
 				str_copy(m_aClients[ClientId].m_aDDNetVersionStr, pDDNetVersionStr);
@@ -1512,6 +1524,13 @@ void CServer::ProcessClientPacket(CNetChunk *pPacket)
 				{
 					return;
 				}
+
+				if(!m_aClients[ClientId].m_GotDDNetVersionPacket)
+				{
+					DropOldClient(ClientId);
+					return;
+				}
+
 				if(str_comp(pVersion, GameServer()->NetVersion()) != 0 && str_comp(pVersion, "0.7 802f1be60a05665f") != 0)
 				{
 					// wrong version
diff --git a/src/engine/server/server.h b/src/engine/server/server.h
index 7a54efe36..994051079 100644
--- a/src/engine/server/server.h
+++ b/src/engine/server/server.h
@@ -337,6 +337,7 @@ public:
 	void UpdateClientRconCommands();
 
 	bool CheckReservedSlotAuth(int ClientId, const char *pPassword);
+	void DropOldClient(int ClientId);
 	void ProcessClientPacket(CNetChunk *pPacket);
 
 	class CCache
diff --git a/src/engine/shared/protocol.h b/src/engine/shared/protocol.h
index e0f807b10..e5309b0b8 100644
--- a/src/engine/shared/protocol.h
+++ b/src/engine/shared/protocol.h
@@ -126,6 +126,8 @@ enum
 	VERSION_DDNET_MULTI_LASER = 16040,
 	VERSION_DDNET_ENTITY_NETOBJS = 16200,
 	VERSION_DDNET_REDIRECT = 17020,
+
+	VERSION_DDNET_NEW_DOMAIN = 16040,
 };
 
 typedef std::bitset<MAX_CLIENTS> CClientMask;