Add a safeguard to map command (#564)

Adds safeguard to the `map` command that prevents it from executing if the requested map is invalid or no map argument is given.

Retry of #529

Co-authored-by: cat_or_not <41955154+catornot@users.noreply.github.com>

NorthstarDLL/util/printmaps.cpp

@@ -31,6 +31,12 @@ struct MapVPKInfo
 // our current list of maps in the game
 std::vector<MapVPKInfo> vMapList;
 
+typedef void (*Host_Map_helperType)(const CCommand&, void*);
+typedef void (*Host_Changelevel_fType)(const CCommand&);
+
+Host_Map_helperType Host_Map_helper;
+Host_Changelevel_fType Host_Changelevel_f;
+
 void RefreshMapList()
 {
 	// Only update the maps list every 10 seconds max to we avoid constantly reading fs
@@ -188,10 +194,40 @@ void ConCommand_maps(const CCommand& args)
 			spdlog::info("({}) {}", PrintMapSource.at(map.source), map.name);
 }
 
+// clang-format off
+AUTOHOOK(Host_Map_f, engine.dll + 0x15B340, void, __fastcall, (const CCommand& args))
+// clang-format on
+{
+	RefreshMapList();
+
+	if (args.ArgC() > 1 &&
+		std::find_if(vMapList.begin(), vMapList.end(), [&](MapVPKInfo map) -> bool { return map.name == args.Arg(1); }) == vMapList.end())
+	{
+		spdlog::warn("Map load failed: {} not found or invalid", args.Arg(1));
+		return;
+	}
+	else if (args.ArgC() == 1)
+	{
+		spdlog::warn("Map load failed: no map name provided");
+		return;
+	}
+
+	if (*R2::g_pServerState >= R2::server_state_t::ss_active)
+		return Host_Changelevel_f(args);
+	else
+		return Host_Map_helper(args, nullptr);
+}
+
 void InitialiseMapsPrint()
 {
 	AUTOHOOK_DISPATCH()
 
 	ConCommand* mapsCommand = R2::g_pCVar->FindCommand("maps");
 	mapsCommand->m_pCommandCallback = ConCommand_maps;
 }
+
+ON_DLL_LOAD("engine.dll", Host_Map_f, (CModule module))
+{
+	Host_Map_helper = module.Offset(0x15AEF0).RCast<Host_Map_helperType>();
+	Host_Changelevel_f = module.Offset(0x15AAD0).RCast<Host_Changelevel_fType>();
+}