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mDNS howto Documentation

How to create a JSON file with information about your project:

npm init

How to duplicate DNS crash:

>> cd ~/dns_test
>> node listen.jss

Then in another terminal enter:

>> dig @224.0.0.251 -p 5353 -t PTR _cloud._tcp.local

The listener then crashes with an output of:

START DNS PACKET
/home/daplie/dns_test/node_modules/dns-js/lib/bufferconsumer.js:52
      throw new Error('Buffer overflow')
      ^

Error: Buffer overflow
    at BufferConsumer.slice (/home/daplie/dns_test/node_modules/dns-js/lib/bufferconsumer.js:52:13)
  s  at Function.DNSRecord.parse (/home/daplie/dns_test/node_modules/dns-js/lib/dnsrecord.js:237:46)
    at /home/daplie/dns_test/node_modules/dns-js/lib/dnspacket.js:164:30
    at Array.forEach (native)
    at Function.DNSPacket.parse (/home/daplie/dns_test/node_modules/dns-js/lib/dnspacket.js:159:17)
    at /home/daplie/dns_test/cloud-respond.js:86:31
    at Array.forEach (native)
    at /home/daplie/dns_test/cloud-respond.js:11:21
    at Array.forEach (native)
    at Object.module.exports.respond (/home/daplie/dns_test/cloud-respond.js:10:11)

After commenting out lines 45-53 in dns_test/node_modules/dns-js/lib/bufferconsumer.js and rerunning the previous commands, the result is a new error:

START DNS PACKET
buffer.js:829
    throw new RangeError('Index out of range');
    ^

RangeError: Index out of range
    at checkOffset (buffer.js:829:11)
    at Buffer.readUInt8 (buffer.js:867:5)
    at BufferConsumer.byte (/home/daplie/dns_test/node_modules/dns-js/lib/bufferconsumer.js:67:22)
    at BufferConsumer.name (/home/daplie/dns_test/node_modules/dns-js/lib/bufferconsumer.js:120:14)
    at Function.DNSRecord.parse (/home/daplie/dns_test/node_modules/dns-js/lib/dnsrecord.js:187:14)
    at /home/daplie/dns_test/node_modules/dns-js/lib/dnspacket.js:164:30
    at Array.forEach (native)
    at Function.DNSPacket.parse (/home/daplie/dns_test/node_modules/dns-js/lib/dnspacket.js:159:17)
    at /home/daplie/dns_test/cloud-respond.js:86:31
    at Array.forEach (native)

which is located in the node.js buffer module. The API is here.

However, the error we are working with will most likely be dealt with by parsing through the binary and putting it in a format that is acceptable to a custom buffer, since the current buffer.js does doesn't seem to do the trick.

Using

function pad(str, len, ch) {

  while (str.length < len) {
    str = ch + str;
  }

  return str;
}

the binary output comes out as:

What are the possible problems?

How to print out hex values of the DNS message in node.js?

socket.on('message', function (message, rinfo) {
  console.log('Received %d bytes from %s:%d\n',
    message.length, rinfo.address, rinfo.port);
  //console.log(msg.toString('utf8'));

  console.log(message.toString('hex'));

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mDNS howto Documentation

Objective

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