A basic HTTP server built in JXA for macOS

http-server.jxa.js

#!/usr/bin/env osascript -l JavaScript

ObjC.bindFunction('malloc', ['void*', ['int']]);
ObjC.bindFunction('memset', ['void*', ['void*', 'int', 'int']]);

ObjC.bindFunction('listen', ['int', ['int', 'int']]);
ObjC.bindFunction('socket', ['int', ['int', 'int', 'int']]);
ObjC.bindFunction('accept', ['int', ['int', 'void*', 'void*']]);
ObjC.bindFunction('bind', ['int', ['int', 'void*', 'int']]);

ObjC.bindFunction('htons', ['int', ['int']]);

ObjC.bindFunction('read', ['int', ['int', 'void*', 'int']]);
ObjC.bindFunction('write', ['int', ['int', 'void*', 'int']]);
ObjC.bindFunction('close', ['int', ['int']]);

function run(_) {
  const LISTEN_PORT = 4444; // incoming port number
  const REQUEST_BUF = 1024; // request buffer size

  // --------------------------- Configure Socket --------------------------- //

  // Create file descriptor from socket.
  const listen_fd = $.socket(2, 1, 0);

  // Convert port number to ordered byte representation for 𝚜𝚘𝚌𝚔𝚊𝚍𝚍𝚛_𝚒𝚗 𝚜𝚝𝚛𝚞𝚌𝚝.
  const port_byte_rep = (() => {
    const buf = new ArrayBuffer(4);
    const uint32_rep = new Uint32Array(buf);
    uint32_rep[0] = $.htons(LISTEN_PORT);
    const uint8_rep = new Uint8Array(buf);
    return [...uint8_rep];
  })();

  // Create 𝚜𝚘𝚌𝚔𝚊𝚍𝚍𝚛_𝚒𝚗 𝚜𝚝𝚛𝚞𝚌𝚝 where:
  //   servaddr.sin_family = AF_INET
  //   servaddr.sin_addr.s_addr = htonl(INADDR_ANY)
  const sockaddr_bytes = [0, 2, ...port_byte_rep, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
  const $sockaddr = $.malloc(sockaddr_bytes.length);
  $.memset($sockaddr, 0, sockaddr_bytes.length);
  for (let i = 0; i < sockaddr_bytes.length; i++) {
    $sockaddr[i] = sockaddr_bytes[i];
  }

  // Bind socket address to file descriptor.
  $.bind(listen_fd, $sockaddr, sockaddr_bytes.length);

  // Begin listening for incoming connections.
  $.listen(listen_fd, 10);

  // Await/accept incoming connection.
  const connection_fd = $.accept(listen_fd, null, null);

  // ----------------------------- Read Request ----------------------------- //

  // Read request from incoming connection.
  const buf_read = $.malloc(REQUEST_BUF);
  $.memset(buf_read, 0, REQUEST_BUF);
  $.read(connection_fd, buf_read, REQUEST_BUF);

  // Convert the incoming buffered byte array to a JS String.
  const request_string = (() => {
    let buf = '';
    for (let i = 0; i < REQUEST_BUF; i++) {
      if (buf_read[i] == 0) break;
      buf = buf.concat(String.fromCharCode(buf_read[i]));
    }
    return buf;
  })();

  // ---------------------------- Handle Request ---------------------------- //

  console.log(request_string);

  // ---------------------------- Write Response ---------------------------- //

  // Prepare response with headers and body.
  const response_code = 200;
  const response_disp = 'OK';
  const response_body = 'ok';
  const response_string = [
    `HTTP/1.1 ${response_code} ${response_disp}`,
    'Content-Type: text/plain',
    'Connection: close',
    `Content-Length: ${response_body.length}`,
    '',
    response_body,
  ].join('\r\n');

  // Write response to UTF-8 character buffer.
  const buf_write = $.malloc(response_string.length);
  $.memset(buf_write, 0, response_string.length);
  for (let i = 0; i < response_string.length; i++) {
    buf_write[i] = response_string.charCodeAt(i);
  }

  // Write buffered response to connection.
  $.write(connection_fd, buf_write, response_string.length);

  // Close the connection.
  $.close(connection_fd);

  return 0;
}