From 546aace3dd120b17b0bbc7f6534a16fa2b3e86d4 Mon Sep 17 00:00:00 2001
From: Yaroslav Tretyakov <zsilencergame@gmail.com>
Date: Tue, 7 Feb 2017 05:04:41 -0700
Subject: [PATCH] Fix invalid desync checks

#5185
---
 src/openrct2/network/network.cpp | 10 +++++++++-
 src/openrct2/network/network.h   |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/openrct2/network/network.cpp b/src/openrct2/network/network.cpp
index ba227e0f7b..0f7cdd44ae 100644
--- a/src/openrct2/network/network.cpp
+++ b/src/openrct2/network/network.cpp
@@ -472,7 +472,6 @@ void Network::UpdateClient()
 			}
 			Close();
 		}
-		ProcessGameCommandQueue();
 
 		// Check synchronisation
 		if (!_desynchronised && !CheckSRAND(gCurrentTicks, gScenarioSrand0)) {
@@ -484,6 +483,8 @@ void Network::UpdateClient()
 				Close();
 			}
 		}
+
+		ProcessGameCommandQueue();
 		break;
 	}
 	}
@@ -562,6 +563,11 @@ bool Network::CheckSRAND(uint32 tick, uint32 srand0)
 		return true;
 	}
 
+	if (game_commands_processed_this_tick != 0) {
+		// SRAND/sprite hash is only updated once at beginning of tick so it is invalid otherwise
+		return true;
+	}
+
 	if (tick == server_srand0_tick) {
 		server_srand0_tick = 0;
 		// Check that the server and client sprite hashes match
@@ -1231,6 +1237,7 @@ void Network::ProcessGameCommandQueue()
 		sint32 command = gc.esi;
 		money32 cost = game_do_command_p(command, (sint32*)&gc.eax, (sint32*)&gc.ebx, (sint32*)&gc.ecx, (sint32*)&gc.edx, (sint32*)&gc.esi, (sint32*)&gc.edi, (sint32*)&gc.ebp);
 		if (cost != MONEY32_UNDEFINED) {
+			game_commands_processed_this_tick++;
 			NetworkPlayer* player = GetPlayerByID(gc.playerid);
 			if (player) {
 				player->LastAction = NetworkActions::FindCommand(command);
@@ -1778,6 +1785,7 @@ void Network::Client_Handle_TICK(NetworkConnection& connection, NetworkPacket& p
 			}
 		}
 	}
+	game_commands_processed_this_tick = 0;
 }
 
 void Network::Client_Handle_PLAYERLIST(NetworkConnection& connection, NetworkPacket& packet)
diff --git a/src/openrct2/network/network.h b/src/openrct2/network/network.h
index 8d7ded8bf1..2af7c1eca7 100644
--- a/src/openrct2/network/network.h
+++ b/src/openrct2/network/network.h
@@ -213,6 +213,7 @@ private:
 	uint8 default_group = 0;
 	SDL_RWops *_chatLogStream = nullptr;
 	std::string _chatLogPath;
+	uint32 game_commands_processed_this_tick = 0;
 
 	void UpdateServer();
 	void UpdateClient();