Function writeDNSPacket

test/common/dns.js:194–307

(parsed)

}

function writeDNSPacket(parsed) {
  const buffers = [];
  const kStandardResponseFlags = 0x8180;

  buffers.push(new Uint16Array([
    parsed.id,
    parsed.flags ?? kStandardResponseFlags,
    parsed.questions?.length,
    parsed.answers?.length,
    parsed.authorityAnswers?.length,
    parsed.additionalRecords?.length,
  ]));

  for (const q of parsed.questions) {
    assert(types[q.type]);
    buffers.push(writeDomainName(q.domain));
    buffers.push(new Uint16Array([
      types[q.type],
      q.cls === undefined ? classes.IN : q.cls,
    ]));
  }

  for (const rr of [].concat(parsed.answers,
                             parsed.authorityAnswers,
                             parsed.additionalRecords)) {
    if (!rr) continue;

    assert(types[rr.type]);
    buffers.push(writeDomainName(rr.domain));
    buffers.push(new Uint16Array([
      types[rr.type],
      rr.cls === undefined ? classes.IN : rr.cls,
    ]));
    buffers.push(new Int32Array([rr.ttl]));

    const rdLengthBuf = new Uint16Array(1);
    buffers.push(rdLengthBuf);

    switch (rr.type) {
      case 'A':
        rdLengthBuf[0] = 4;
        buffers.push(new Uint8Array(rr.address.split('.')));
        break;
      case 'AAAA':
        rdLengthBuf[0] = 16;
        buffers.push(writeIPv6(rr.address));
        break;
      case 'TXT': {
        const total = rr.entries.map((s) => s.length).reduce((a, b) => a + b);
        // Total length of all strings + 1 byte each for their lengths.
        rdLengthBuf[0] = rr.entries.length + total;
        for (const txt of rr.entries) {
          buffers.push(new Uint8Array([Buffer.byteLength(txt)]));
          buffers.push(Buffer.from(txt));
        }
        break;
      }
      case 'MX':