node/test/parallel/test-dgram-oob-buffer.js

'use strict';
// Some operating systems report errors when an UDP message is sent to an
// unreachable host. This error can be reported by sendto() and even by
// recvfrom(). Node should not propagate this error to the user.

const common = require('../common');
const dgram = require('dgram');

const socket = dgram.createSocket('udp4');
const buf = Buffer.from([1, 2, 3, 4]);
const portGetter = dgram.createSocket('udp4')
  .bind(0, 'localhost', common.mustCall(() => {
    const { address, port } = portGetter.address();
    portGetter.close(common.mustCall(() => {
      socket.send(buf, 0, 0, port, address, common.mustNotCall());
      socket.send(buf, 0, 4, port, address, common.mustNotCall());
      socket.send(buf, 1, 3, port, address, common.mustNotCall());
      socket.send(buf, 3, 1, port, address, common.mustNotCall());
      // Since length of zero means nothing, don't error despite OOB.
      socket.send(buf, 4, 0, port, address, common.mustNotCall());

      socket.close();
    }));
  }));