neon

A networking library for Gleam on the Erlang target. Provides TCP, UDP, and SSL/TLS sockets with a builder-style API, support for both active and passive modes, IPv4 and IPv6, and START-TLS upgrades. Built on Erlang's gen_tcp, gen_udp, and ssl modules.

gleam add neon@1

TCP

import neon/net
import neon/tcp

pub fn main() {
  let assert Ok(loopback) = net.ipv4_address(127, 0, 0, 1)
  let assert Ok(port) = net.port(0)
  let assert Ok(listener) = tcp.listen(port, loopback)
  let assert Ok(port) = tcp.port(listener)

  let address = net.ip_address(loopback)
  let assert Ok(socket) =
    tcp.new(address, port)
    |> tcp.connect

  let assert Ok(timeout) = net.timeout(5000)
  let assert Ok(server) = tcp.accept(listener, timeout)
  let assert Ok(Nil) = tcp.send(server, <<"hello world":utf8>>)

  let assert Ok(msg) = tcp.receive(socket, 11, timeout)
  let assert <<"hello world":utf8>> = msg
}

SSL/TLS

import neon/net
import neon/ssl

pub fn main() {
  let assert Ok(Nil) = ssl.start()

  // Connect to a TLS server with certificate verification
  let assert Ok(port) = net.port(443)
  let assert Ok(socket) =
    ssl.new("gleam.run", port)
    |> ssl.connect

  let assert Ok(Nil) =
    ssl.send(socket, <<"GET / HTTP/1.0\r\nHost: gleam.run\r\n\r\n":utf8>>)

  let assert Ok(timeout) = net.timeout(5000)
  let assert Ok(response) = ssl.receive(socket, 0, timeout)
}

UDP

import neon/net
import neon/udp

pub fn main() {
  let assert Ok(loopback) = net.ipv4_address(127, 0, 0, 1)
  let address = net.ip_address(loopback)

  // Open two sockets on OS-assigned ports
  let assert Ok(port) = net.port(0)
  let assert Ok(socket_a) =
    udp.new(port)
    |> udp.ip_address(loopback)
    |> udp.open
  let assert Ok(socket_b) =
    udp.new(port)
    |> udp.ip_address(loopback)
    |> udp.open

  // Connect socket_a to socket_b's address
  let assert Ok(port_b) = udp.port(socket_b)
  let assert Ok(Nil) = udp.connect(socket_a, address, port_b)

  // Send from A, receive on B
  let assert Ok(Nil) = udp.send(socket_a, <<"hello":utf8>>)
  let assert Ok(timeout) = net.timeout(5000)
  let assert Ok(msg) = udp.receive(socket_b, 0, timeout)
  let assert <<"hello":utf8>> = msg.payload
}

Further documentation can be found at https://hexdocs.pm/neon.

Development

gleam run   # Run the project
gleam test  # Run the tests