Can I pass LUA code to the game while it's running?

[112th_Rossi]

I'm writing a service in C# that can dynamically generate LUA code. Is there an entry point in DCS where I can inject LUA and have it execute?

 

Thanks

[FSFIan]

Yes, this is possible. I assume you want the mission scripting environment, in that case take a look at Scripts\MissionScripting.lua in your DCS: World installation directory. Have it execute a script file before all the fun stuff (require, lfs, io, etc.) gets removed from the environment to protect the user from malicious mission files. In your script file you can use LuaSocket to spin up a server that accepts lua snippets to execute.

 

Make sure that your script does not expose any fun stuff to the global mission environment (grab what you need and stuff it into file-local variables).

 

The source code of DCS: Witchcraft (link in my sig) provides an example. In Witchcraft, I have DCS connect as a client to the external program that provides the server because I didn't want to think about concurrent connections in Lua when I wrote it. For an example of a TCP server in Lua, look at the DCS-BIOS source code.

 

What does your external service do?

[112th_Rossi]

I'm looking at collecting the game state data, position of units etc and evaluating it to generate tasks then sending the lua script to the game in real time.

 

It would occasionally poll the game world and work out what tasks to assign. In a very broad sense.

 

I assume I can get information back from the dcs server? Such as enumerations of units in game and their states etc?

 

Thanks for the info.

[Durham]

Tried to do this in a script file.

 

Got the client and server communicating with the remote machine fine - sending mist.DBs.units in JSON to server and then taking messages back which I printed to screen using action.outText(string), which I then converted into lua injection.

 

One issue:

 

Using the witchcraft.lua as a template, I had above the loop:

tcpClient:settimeout(0.0001)

 

and in the loop:

local line, err = tcpClient:receive()

if err then

trigger.action.outText("Error receiving message from server!\n", 2)

else

trigger.action.outText("Message from server:"..line.."\n", 5)

end

If there was no message from the server, then the game hung for the length of the timeout. If I pinged the client with repetitive [0/enter] then no problem. I looked at multi-threading with:-

 

function receive (connection)

connection:timeout(0) -- do not block

local s, status = connection:receive(2^10)

if status == "timeout" then

coroutine.yield(connection)

end

return s, status

end

but didn't make any progress.

 

At present, my solution to this issue will be to send a 0 each cycle from the server and run a

if client:receive ~=0 then

do stuff

end

 

which seems really inefficient, but will work smoothly.

 

I got the lua injection to work with f = loadstring(string)(), which has no error handling which can be added later.

 

Do you have a solution to the stuttering on the receive() function, other than regularly sending a message from the server?

 

Many thanks

 

Durham

[FSFIan]

If there was no message from the server, then the game hung for the length of the timeout.

 

Have you tried simply setting the timeout to zero? And how are you noticing a hang of a tenth of a millisecond anyway?

 

I looked at multi-threading with:-

 

function receive (connection)

connection:timeout(0) -- do not block

local s, status = connection:receive(2^10)

if status == "timeout" then

coroutine.yield(connection)

end

return s, status

end

but didn't make any progress.

 

I can't tell why that doesn't work without looking at your complete script, but you should be aware that coroutines have nothing to do with multithreading. At any given time, at most one coroutine is executing.

[FlightControl]

Yes, but it is disabled by default in dcs to prevent other embed malicious code in their missions. On the server side however, there are more possibilities. Modify the missionscripting.lua file. Erase the sanitisation of io and os modules. And you have a lua function called os.execute.... Check here... http://www.lua.org/manual/5.1/manual.html#pdf-os.execute

[Pikey]

Yes there's an easier way. put a script on your desktop. Call it continuously using the Asset and loadfile.