simplest-http-server.ex

defmodule HTTPServer do
  def receive_http_request(socket) do
    {:ok, data} = :gen_tcp.recv(socket, 0)
    case data do
      "\r\n" ->
        IO.puts("Message received")
      _ ->
        receive_http_request(socket)
    end
  end

  def send_http_response(client_socket) do
    response_text = "hello world"
    send_http_line(client_socket, "HTTP/1.1 200 OK")
    send_http_line(client_socket, "Server: Dummy Elixir script")
    send_http_line(client_socket, "Content-Type: text/plain; charset=us-ascii")
    send_http_line(client_socket, "Content-Length: #{String.length(response_text) + 1}")
    send_http_line(client_socket, "Connection: close")
    send_http_line(client_socket, "\r")
    send_http_line(client_socket, response_text)
  end

  defp send_http_line(client_socket, line) do
    :ok = :gen_tcp.send(client_socket, line <> "\n")
  end
end

{:ok, server_socket} = :gen_tcp.listen(3128, [:binary, packet: :line, active: false, reuseaddr: true])
{:ok, client_socket} = :gen_tcp.accept(server_socket)
IO.puts("Client connected")
HTTPServer.receive_http_request(client_socket)
HTTPServer.send_http_response(client_socket)