Lua Socket
More actions
LuaSockets allow a widget to use tcp/udp sockets. With luasockets you can create a client or a server connecting to a server and transfering some data.
There are many possibilties what could be done with luasockets in spring, some ideas:
- webserver that shows all files in VFS
- telnet console, that allows control of spring
- statistics webpage
- ingame widget updater
- ingame news pages
- ...
config
All LuaSocket related config is readonly for LuaWidgets. They can be only changed through unitsync.
As default, socket access is restricted, as default no connections are allowed. To allow a connection / sending a packet, the destination has to the corresponding allow rule. For example, if a lua widget wants to connect to springrts.com at port 80,
TCPAllowConnect springrts.com:80
has to be set.
Since spring 97.0 lobby.springrts.com:8200 is allowed as default.
Since Spring 98.0 all tcp connections are allowed by default (udp is still restricted).
Creating a server socket needs no config value to be set.
possible config values
| LuaSocketEnabled = 1 | Default is 1 means, all Socket functions are enabled, 0 disables access to sockets. |
| TCPAllowConnect | allow TCP-connections to the listed hosts, for example: "springrts.com:80 springfiles.com:80" which allows luasockets to connect to springrts.com at port 80 and springfiles.com at port 80. |
| UDPAllowConnect | see TCPAllowConnect |
example code
Notes / known issues / TODO
- only ipv4 is supported (could be solved by using unstable luasocket2: http://code.matthewwild.co.uk/luasocket2-hg/) or https://github.com/diegonehab/luasocket (seems to be the more official)
- dns resolving is blocking, solutions: worker thread or some lib:
- adns http://www.chiark.greenend.org.uk/~ian/adns/
- dns.c http://25thandclement.com/~william/projects/dns.c.html
- tadns http://adns.sourceforge.net/
- or a lua implementation? biggest problem would be to find the local dns-server
- most lua scripts from luasocket won't work as they are blocking! rewriting them non-blocking is required! (should be in most cases few work, as parsing stuff can be reused)
- config file should be better protected, see https://github.com/spring/spring/blob/develop/rts/System/Config/ConfigHandler.cpp#L289 + https://github.com/spring/spring/commit/948d6fb9d1c95b99b5cc7929cf3e0de0f9d6d93e maybe just locking the file is best?! see also http://springrts.com/mantis/view.php?id=2891 (private report)
- access to autohost interface / game host is denied
- If you get this error:
Error in Initialize(): [string "LuaUI/Widgets/luasocket.lua"]:65:
attempt to index upvalue 'socket' (a nil value)
you maybe need to add to system.lua: socket = socket,
documentation
links
lua sockets in spring - original thread Lua Lobby / Socket - some code pieces for connecting to spring lobby server & protocol