Fix warpPedIntoVehicle desync right after createVehicle

Server/mods/deathmatch/logic/CGame.cpp

@@ -2389,7 +2389,14 @@ void CGame::Packet_PlayerPuresync(CPlayerPuresyncPacket& Packet)
         {
             // Allow it if he's exiting
             if (pPlayer->GetVehicleAction() != CPed::VEHICLEACTION_EXITING)
+            {
+                // Still acknowledge so the client's network-trouble watchdog doesn't trip while it catches up
+                // to the new vehicle-occupied state (e.g. just after warpPedIntoVehicle, before it starts
+                // sending vehicle puresync packets instead of these on-foot ones)
+                if ((pPlayer->GetPuresyncCount() % 4) == 0)
+                    pPlayer->Send(CReturnSyncPacket(pPlayer));
                 return;
+            }
         }
 
         // Send a returnsync packet to the player that sent it

Server/mods/deathmatch/logic/CResource.cpp

@@ -1069,6 +1069,13 @@ bool CResource::Start(std::list<CResource*>* pDependents, bool bManualStart, con
     SendNoClientCacheScripts();
     m_bClientSync = true;
 
+    // Run anything that got held back during onResourceStart because it depended on clients already knowing
+    // about elements we've just finished broadcasting above (see RunOrDeferUntilClientSynced)
+    std::vector<std::function<void()>> pendingCallbacks = std::move(m_PendingClientSyncCallbacks);
+    m_PendingClientSyncCallbacks.clear();
+    for (const auto& callback : pendingCallbacks)
+        callback();
+
     // Add us to the running resources list
     m_StartedResources.push_back(this);
 

Server/mods/deathmatch/logic/CResource.h

@@ -20,6 +20,7 @@
 #include <unzip.h>
 #include <list>
 #include <vector>
+#include <functional>
 #include <ehs/ehs.h>
 #include <time.h>
 
@@ -228,6 +229,19 @@ class CResource : public EHS
 
     bool IsClientSynced() const noexcept { return m_bClientSync; }
 
+    // Runs the callback now if our elements have already reached the clients, otherwise holds onto it and runs it
+    // right after they do (see Start()). Used for things that need to tell clients about an element created moments
+    // earlier in onResourceStart, which wouldn't make sense to the client yet (e.g. warpPedIntoVehicle on a vehicle
+    // created in the same event) - dropping it outright would leave the server and clients permanently disagreeing
+    // about that element's state instead.
+    void RunOrDeferUntilClientSynced(std::function<void()> callback)
+    {
+        if (m_bClientSync)
+            callback();
+        else
+            m_PendingClientSyncCallbacks.push_back(std::move(callback));
+    }
+
     const SString& GetName() const noexcept { return m_strResourceName; }
 
     CLuaMain*       GetVirtualMachine() { return m_pVM; }
@@ -372,6 +386,8 @@ class CResource : public EHS
     EResourceState m_eState = EResourceState::None;
     bool           m_bClientSync = false;
 
+    std::vector<std::function<void()>> m_PendingClientSyncCallbacks;
+
     unsigned short m_usNetID = -1;
     uint           m_uiScriptID = -1;
 

Server/mods/deathmatch/logic/CStaticFunctionDefinitions.cpp

@@ -4293,7 +4293,7 @@ bool CStaticFunctionDefinitions::SetPedWeaponSlot(CElement* pElement, unsigned c
     return false;
 }
 
-bool CStaticFunctionDefinitions::WarpPedIntoVehicle(CPed* pPed, CVehicle* pVehicle, unsigned int uiSeat)
+bool CStaticFunctionDefinitions::WarpPedIntoVehicle(CPed* pPed, CVehicle* pVehicle, unsigned int uiSeat, CResource* pCallingResource)
 {
     assert(pPed);
     assert(pVehicle);
@@ -4347,12 +4347,24 @@ bool CStaticFunctionDefinitions::WarpPedIntoVehicle(CPed* pPed, CVehicle* pVehic
                     if (uiSeat == 0 && g_pGame->IsWorldSpecialPropertyEnabled(WorldSpecialProperty::VEHICLE_ENGINE_AUTOSTART))
                         pVehicle->SetEngineOn(true);
 
-                    // Tell all the players
-                    CBitStream BitStream;
-                    BitStream.pBitStream->Write(pVehicle->GetID());
-                    BitStream.pBitStream->Write(static_cast<unsigned char>(uiSeat));
-                    BitStream.pBitStream->Write(pPed->GenerateSyncTimeContext());
-                    m_pPlayerManager->BroadcastOnlyJoined(CElementRPCPacket(pPed, WARP_PED_INTO_VEHICLE, *BitStream.pBitStream));
+                    // Tell all the players. If the calling resource's elements haven't reached the clients yet
+                    // (e.g. called from onResourceStart on a vehicle created in the same event), hold off until
+                    // they have instead of just dropping it - the vehicle itself isn't synced to clients yet
+                    // either, and an RPC referencing an unknown element there would leave the server and clients
+                    // permanently disagreeing about whether this ped is in a vehicle.
+                    auto sendWarpRpc = [pPed, pVehicle, uiSeat]()
+                    {
+                        CBitStream BitStream;
+                        BitStream.pBitStream->Write(pVehicle->GetID());
+                        BitStream.pBitStream->Write(static_cast<unsigned char>(uiSeat));
+                        BitStream.pBitStream->Write(pPed->GenerateSyncTimeContext());
+                        m_pPlayerManager->BroadcastOnlyJoined(CElementRPCPacket(pPed, WARP_PED_INTO_VEHICLE, *BitStream.pBitStream));
+                    };
+
+                    if (pCallingResource)
+                        pCallingResource->RunOrDeferUntilClientSynced(sendWarpRpc);
+                    else
+                        sendWarpRpc();
 
                     // Call the player->vehicle event
                     CLuaArguments PlayerVehicleArguments;

Server/mods/deathmatch/logic/CStaticFunctionDefinitions.h

@@ -213,7 +213,7 @@ class CStaticFunctionDefinitions
     static bool SetPedGravity(CElement* pElement, float fGravity);
     static bool SetPedChoking(CElement* pElement, bool bChoking);
     static bool SetPedWeaponSlot(CElement* pElement, unsigned char ucWeaponSlot);
-    static bool WarpPedIntoVehicle(CPed* pPed, CVehicle* pVehicle, unsigned int uiSeat = 0);
+    static bool WarpPedIntoVehicle(CPed* pPed, CVehicle* pVehicle, unsigned int uiSeat = 0, CResource* pCallingResource = nullptr);
     static bool RemovePedFromVehicle(CElement* pElement);
     static bool SetPedDoingGangDriveby(CElement* pElement, bool bGangDriveby);
     static bool SetPedAnimation(CElement* pElement, const SString& blockName, const SString& animName, int iTime, int iBlend, bool bLoop, bool bUpdatePosition,

Server/mods/deathmatch/logic/luadefs/CLuaPedDefs.cpp

@@ -1360,7 +1360,10 @@ int CLuaPedDefs::WarpPedIntoVehicle(lua_State* luaVM)
     {
         LogWarningIfPlayerHasNotJoinedYet(luaVM, pPed);
 
-        if (CStaticFunctionDefinitions::WarpPedIntoVehicle(pPed, pVehicle, uiSeat))
+        CLuaMain*  pLuaMain = g_pGame->GetLuaManager()->GetVirtualMachine(luaVM);
+        CResource* pResource = pLuaMain ? pLuaMain->GetResource() : nullptr;
+
+        if (CStaticFunctionDefinitions::WarpPedIntoVehicle(pPed, pVehicle, uiSeat, pResource))
         {
             lua_pushboolean(luaVM, true);
             return 1;
@@ -1394,7 +1397,10 @@ int CLuaPedDefs::OOP_WarpPedIntoVehicle(lua_State* luaVM)
         {
             LogWarningIfPlayerHasNotJoinedYet(luaVM, pPed);
 
-            if (CStaticFunctionDefinitions::WarpPedIntoVehicle(pPed, pVehicle, uiSeat))
+            CLuaMain*  pLuaMain = g_pGame->GetLuaManager()->GetVirtualMachine(luaVM);
+            CResource* pResource = pLuaMain ? pLuaMain->GetResource() : nullptr;
+
+            if (CStaticFunctionDefinitions::WarpPedIntoVehicle(pPed, pVehicle, uiSeat, pResource))
             {
                 lua_pushboolean(luaVM, true);
                 return 1;