'use strict'; const common = require('../common'); const assert = require('assert'); const dgram = require('dgram'); const client = dgram.createSocket('udp4'); const buf = Buffer.alloc(256, 'x'); const offset = 20; const len = buf.length - offset; const onMessage = common.mustCall(function messageSent(err, bytes) { assert.ifError(err); assert.notStrictEqual(bytes, buf.length); assert.strictEqual(bytes, buf.length - offset); client.close(); }); client.bind(0, () => client.send(buf, offset, len, client.address().port, onMessage));