[2.0.49] Crash when executing commands via local RCON during tick 0

[jeff.s]

Sending RCON commands during tick 0 causes the game to crash. I have a full repro, below. This happens on 2.0.49 running on Win11 x64, but I have also experienced it with 2.0.49 running on Linux x64 as well. Here's the crash (full factorio-current.log is attached, and I can send factorio-dump-current.dmp via email or Discord if it's helpful)

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  29.361 Checksum for script __level__/control.lua: 2552759552
  29.383 Info RemoteCommandProcessor.cpp:126: Starting RCON interface at IP ADDR:({0.0.0.0:27015})
  29.383 Info RemoteCommandProcessor.cpp:245: New RCON connection from IP ADDR:({127.0.0.1:56972})
Factorio crashed. Generating symbolized stacktrace, please wait ...
...
Stack trace logging done
  30.150 Error PlayerInputSource.cpp:597: Cannot deduce player for input action.
  30.150 Error CrashHandler.cpp:643: Received 22
Logger::writeStacktrace skipped.
  30.150 Error CrashHandler.cpp:190: Map tick at moment of crash: 0
  30.181 Info CrashHandler.cpp:318: Executable CRC: 1222861164
  30.181 Error Util.cpp:95: Unexpected error occurred. If you're running the latest version of the game you can help us solve the problem by posting the contents of the log file on the Factorio forums.
Please also include the save file(s), any mods you may be using, and any steps you know of to reproduce the crash.
  33.035 Uploading log file
  33.054 Error CrashHandler.cpp:270: Heap validation: success.
  33.055 Creating crash dump.
  33.128 CrashDump success

As far as I can tell these three conditions are necessary to cause the crash:

• game.speed is very low (achieved via a scenario that changes game.speed to 0.01 during script.on_init)
• local-rcon is enabled via the hidden settings
• alongside the game, an RCON client runs that connects immediately when RCON is available and runs a command

Steps to Reproduce:

Run RCON client

To reproduce this you need something that spams RCON connection attempts then immediately runs a game command. Here is one I wrote in Go, which I dedicate into the public domain for anybody to use freely. Put these three files into some folder like `rconclient`:

rconclient/go.mod

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module factorio_rcon_crash_demo

go 1.23.4

require github.com/gorcon/rcon v1.4.1-0.20241116133332-ccafaeb72624

rconclient/go.sum

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github.com/gorcon/rcon v1.4.1-0.20241116133332-ccafaeb72624 h1:l23/ZiR7UFuC7CCIS5bzzr+PDc1jHShKy03E0Nfz394=
github.com/gorcon/rcon v1.4.1-0.20241116133332-ccafaeb72624/go.mod h1:M6v6sNmr/NET9YIf+2rq+cIjTBridoy62uzQ58WgC1I=

rconclient/main.go

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package main

import (
	"time"
	"github.com/gorcon/rcon"
)

func spamConnect() *rcon.Conn {
	for {
		conn, err := rcon.Dial("localhost:27015", "hunter2", rcon.SetDialTimeout(1*time.Millisecond))
		if err == nil {
			return conn
		}
	}
}

func main() {
	conn := spamConnect()
	defer conn.Close()
	println("Connected")
	conn.Execute("/seed")
}

You can start the client and leave it running. The important thing is to start the client before the game starts the RCON server, so the client can connect immediately when the server is available:

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cd rconclient
go run main.go

Setup game

First, download and extract the Windows standalone build, factorio-space-age_win_2.0.49.zip, which will give you a folder Factorio_2.0.49. In that folder we will create a few files, to setup config options and create a simple scenario that sets the game speed:

Factorio_2.0.49/config/config.ini

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; version=12

[path]
read-data=__PATH__executable__/../../data
write-data=__PATH__executable__/../..

[other]
check-updates=false
local-rcon-socket=0.0.0.0:27015
local-rcon-password=hunter2

Factorio_2.0.49/scenarios/crasher/info.json

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{
  "name": "crasher",
  "version": "1.0.0",
  "title": "Crasher Demo",
  "author": "jeFFeSS",
  "description": "Just need an empty scenario to make it crash",
  "factorio_version": "2.0",
  "dependencies": [
    "base"
  ]
}

Factorio_2.0.49/scenarios/crasher/control.lua

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-- if the game speed is very slow, it's possible for RCON to connect during tick 0
script.on_init(function()
  game.speed = 0.01
end)

Run Game

Open a terminal in the directory Factorio_2.0.49 and run this (make sure the RCON client, above, is already running first):

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bin\x64\factorio.exe --load-scenario crasher

The game will load, then the RCON client will connect and run the command triggering the crash.

Here is a list of the different commands I tried sending over RCON during tick 0, each one leading to a crash. The only ones I could find that don't crash are /help and /quit

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/c print('hello')
/silent-command print('hello')
/time
/version
/seed
hi

Let me know if there's anything else I can help but this should repro the crash for you.

[Rseding91]

Thanks for the report. This is now fixed for the next release.