please include luasocket library (or work-alike wrapper)
http://w3.impa.br/~diego/software/luasocket/ "LuaSocket is a Lua extension library that is composed by two parts: a C core that provides support for the TCP and UDP transport layers, and a set of Lua modules that add support for functionality commonly needed by applications that deal with the Internet."
VLC currently exposes only its own socket library to Lua. This makes it hard to build on externally authored libraries, which tend to use luasocket instead.
In particular, the Verse Lua library for XMPP http://code.matthewwild.co.uk/verse has a dependency on luasocket.