Lua module for the socket99 C library.
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A Lua module that exposes the socket99 C library in Lua, making it easier to create TCP/UDP/Unix Domain client and server sockets.


Via Luarocks:

$ luarocks install luasock99


Assuming local sock99 = require 'sock99'. You can check out the tests for actual examples of using the API.


Open the socket as configured by table t, which may have the following fields:

  • host (string): the hostname to connect to, for TCP/UDP sockets.
  • port (integer): the port number to connect to, for TCP/UDP sockets.
  • path (string): the Unix Domain socket path.
  • ipv4 (string): IPv4 address, if host and path are missing.
  • ipv6 (string): IPv6 address, instead of using host.
  • server (bool): set to true to create a server socket (i.e. listen instead of connect).
  • datagram (bool): set to true for datagram socket instead of stream.
  • nonblocking (bool): set to true for a non-blocking socket.
  • backlog (integer): the size of the backlog, for server socket. TODO: add support for sockopts

It returns the file descriptor (integer) on success, or nil followed by a system-specific error message and error code on error. The file descriptor can be used with the standard POSIX calls (e.g. with luaposix: posix.unistd.close, posix.sys.socket.send, etc.).

Note that this is a raw integer, as such it cannot install a garbage collector finalizer to close itself - it must be closed explicitly.

TODO: for Lua 5.4, set a metatable with __close method.


Clone the project and install the required development dependencies:

  • luaunit (unit test runner)
  • luaposix (for tests)

If like me you prefer to keep your dependencies locally, per-project, then I recommend using my llrocks wrapper of the luarocks cli, which by default uses a local lua_modules/ tree.

$ llrocks install ...

To run tests:

$ llrocks run test/*.lua


The BSD 3-clause license for the Lua module. For the socket99 C library, see the deps/socket99/socket99.c header.