Lunatik
Lua API · Sockets and netlink

socket.inetModule

Internet (AF_INET) socket operations.

This module provides a higher-level abstraction over the raw socket and net modules for creating and managing INET (IPv4) sockets, including TCP and UDP.

It simplifies common socket operations like binding, connecting, sending, and receiving data.

See also

Class inet

inet.tcp TCP socket specialization.
inet.tcp:accept (flags) Accepts an incoming connection on a listening TCP socket.
inet.tcp:listen (backlog) Listens for incoming connections on a TCP socket.
inet.udp UDP socket specialization.
inet.udp:receivefrom (len, flags) Receives data from a UDP socket, along with the sender’s address.
inet.udp:sendto (msg, addr, port) Alias for inet.udp:send.
inet:__call () Metamethod to create a new socket instance when inet() or inet.tcp() or inet.udp() is called.
inet:bind (addr, port) Binds the socket to a specific address and port.
inet:close () Closes the underlying socket.
inet:connect (addr, port, flags) Connects the socket to a remote address and port.
inet:getpeername () Gets the remote address (IP and port) to which the socket is connected.
inet:getsockname () Gets the local address (IP and port) to which the socket is bound.
inet:new ([o]) Derives a specialization of the class, as inet.tcp and inet.udp are, or wraps a table in it.
inet:receive (...) Receives data from the socket; inet.udp:receivefrom also returns the sender.
inet:send (msg, addr, port) Sends data through the socket.

Class inet in detail

Base class for socket types.
inet.tcp
TCP socket specialization. Provides methods specific to TCP sockets (e.g., listen, accept). Create TCP sockets using inet.tcp().

Fields

  • type The socket type (e.g., linux.socket.sock.STREAM).
  • proto The protocol (e.g., linux.socket.ipproto.TCP).
inet.tcp:accept (flags)
Accepts an incoming connection on a listening TCP socket.

Parameters

  • flags (number) [optional] Flags for the accept operation.

Returns

    (socket) The accepted connection, as a plain socket object, or nil and "EAGAIN" when the wait ended with no connection to accept.

Raises

error on failure

See also

inet.tcp:listen (backlog)
Listens for incoming connections on a TCP socket.

Parameters

  • backlog (number) The maximum length of the queue of pending connections.

Raises

error on failure

See also

inet.udp
UDP socket specialization. Provides methods specific to UDP sockets (e.g., receivefrom, sendto). Create UDP sockets using inet.udp().

Fields

  • type The socket type (e.g., linux.socket.sock.DGRAM).
  • proto The protocol (e.g., linux.socket.ipproto.UDP).
inet.udp:receivefrom (len, flags)
Receives data from a UDP socket, along with the sender’s address. This is a wrapper around socket:receivefrom that converts the raw IP address from net.aton format to a string using net.ntoa.

Parameters

  • len (number) The maximum number of bytes to receive.
  • flags (number) [optional] Flags for the receive operation.

Returns

  1. (string) The received data, or nil when the wait ended with nothing to read.
  2. (string) The sender’s IP address, or "EAGAIN" beside that nil.
  3. (number) The sender’s port number.

Raises

error on failure

See also

inet.udp:sendto (msg, addr, port)
Alias for inet.udp:send. Sends data to a specific address and port using UDP.

Parameters

  • msg (string) The message to send.
  • addr (string) The destination IP address.
  • port (number) The destination port.

Returns

    (number|boolean) Number of bytes sent, or false when a send timeout ended the wait with nothing queued.

Raises

error on failure

See also

inet:__call ()
Metamethod to create a new socket instance when inet() or inet.tcp() or inet.udp() is called. This is the primary way to create new socket instances (e.g., local sock = inet.tcp()).

Returns

    (table) A new socket object (e.g., a TCP or UDP socket object).

See also

Usage

local tcp_socket = inet.tcp()
local udp_socket = inet.udp()
inet:bind (addr, port)
Binds the socket to a specific address and port. The address ‘*’ is treated as INADDR_ANY (0.0.0.0).

Parameters

  • addr (string) The IP address to bind to. Use ‘*’ for any address.
  • port (number) The port number to bind to.

Raises

error on failure

See also

inet:close ()
Closes the underlying socket.

See also

inet:connect (addr, port, flags)
Connects the socket to a remote address and port.

Parameters

  • addr (string) The remote IP address.
  • port (number) The remote port.
  • flags (number) [optional] Connection flags.

Returns

    (boolean) true once connected, or nil and "EINPROGRESS" when the connection it started is still in progress, "EALREADY" when an earlier connect started it.

Raises

error on failure

See also

inet:getpeername ()
Gets the remote address (IP and port) to which the socket is connected.

Returns

  1. (string) Remote IP address.
  2. (number) Remote port number.

See also

inet:getsockname ()
Gets the local address (IP and port) to which the socket is bound.

Returns

  1. (string) Local IP address.
  2. (number) Local port number.

See also

inet:new ([o])
Derives a specialization of the class, as inet.tcp and inet.udp are, or wraps a table in it. It opens no socket: calling the class does, inet.tcp().

Parameters

  • o table an initial object table. (optional)

Returns

    inet the derived class or the wrapped table.

See also

inet:receive (...)
Receives data from the socket; inet.udp:receivefrom also returns the sender.

Parameters

  • ... Varargs passed directly to the underlying socket:receive(): (len[, flags]).

Returns

    The data the underlying socket:receive() returns.

Raises

error on failure

See also

inet:send (msg, addr, port)
Sends data through the socket. If addr and port are provided (typical for UDP), the address is converted using net.aton before sending.

Parameters

  • msg (string) The message to send.
  • addr (string) [optional] The destination IP address (e.g., for UDP).
  • port (number) [optional] The destination port (e.g., for UDP).

Returns

    (number|boolean) Number of bytes sent, or false when a send timeout ended the wait with nothing queued.

Raises

error on failure

See also