Re: Raw socket patches for LuaSocket
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- Subject: Re: Raw socket patches for LuaSocket
- From: Sean Conner <sean@...>
- Date: Tue, 4 Jun 2013 10:10:29 -0400
It was thus said that the Great greatwolf once stated:
> Diego Nehab-3 wrote
> > I don't remember seeing a full patch, but I blieve it would
> > be easy to create a module in the flavour of the unix domain
> > socket support that ships with LuaSocket as a sample.
>
> It looks like raw socket support has been requested a few times around the
> internet already. But checking the repo here
> <https://github.com/diegonehab/luasocket/tree/unstable> shows no
> indication that this feature has ever been incorporated.
>
> Is there any hope of adding this in soon so we don't have to hack together
> our own ad-hoc solution to this?
Hmmm ... I know my own socket module [1] supports IPv4, IPv6 and Unix
sockets. I don't have code for HTTP, FTP or what have you, but I wanted a
decent low level implementation of sockets under Lua. The :read() and
:write() functions on sockets don't work the same as they do for files
though (they should have been named :recvfrom() and :sendto()).
I also have support for select, which uses epoll() (if on Linux), poll()
(for the rest of the Unix universe) or select() (if you *really really*
want it) with the same API (the implementation is picked at compile time).
Here's a sample daytime server (I use this at work [2][3]) to get a feel
for how this works:
syslog = require "org.conman.syslog"
errno = require "org.conman.errno"
net = require "org.conman.net"
syslog.open('daytime','local1')
local addr = net.address('0.0.0.0',40960,'udp')
local sock = net.socket(addr.family,'udp')
sock.reuseaddr = true
sock:bind(addr)
local function daytime()
local remaddr,data,err = sock:read()
if err ~= 0 then
syslog('err',"sock:read() = %s",errno[err])
return daytime()
end
syslog('notice',"request=%s",tostring(remaddr))
sock:write(remaddr,tostring(os.time())
return daytime()
end
Change the address, and this can run over IPv6:
local addr = net.address('fc00::dead:beef',40960,'udp')
or even a Unix socket:
local addr = net.address('/tmp/daytime','udp')
without chaning the rest of the code (it just all works). The client is
just as simple:
syslog = require "org.conman.syslog"
net = require "org.conman.net"
local server = net.address('192.168.1.10',40960,'udp')
local socket = net.socket(server.family,'udp')
socket:write(server,'just-to-trigger-a-response')
local remaddr,data,err = socket:read(5.3) -- timeout in 5.3 seconds
if err ~= 0 then
syslog('err',"%s not responding, abort!",tostring(server))
return false
end
return true,tonumber(data)
-spc (If there's interest, I can provide an example that uses select ... )
[1] https://github.com/spc476/lua-conmanorg/blob/master/src/net.c
[2] My job is to test the backend server components, which require the
servers to be in sync, time wise. I have this running on each of
the test servers so when the test code runs, it can check the time
of the servers to ensure they're in-sync.
[3] "org.conman.syslog" is my syslog interface, and "org.conman.errno"
is pretty much a wrapper for strerror().
>
>
> --
> View this message in context: http://lua.2524044.n2.nabble.com/Raw-socket-patches-for-LuaSocket-tp7628258p7649717.html
> Sent from the Lua-l mailing list archive at Nabble.com.