dns-suite.js/howto.md

mDNS howto Documentation
=====

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

```bash
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](https://nodejs.org/api/buffer.html).

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 

```javascript
function pad(str, len, ch) {

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

  return str;
}
```
the binary output comes out as:

```
11100001
10001000
00000001
00100000
00000000
00000001
00000000
00000000
00000000
00000000
00000000
00000001
00000110
01011111
01100011
01101100
01101111
01110101
01100100
00000100
01011111
01110100
01100011
01110000
00000101
01101100
01101111
01100011
01100001
01101100
00000000
00000000
00001100
00000000
00000001
00000000
00000000
00101001
00010000
00000000
00000000
00000000
00000000
00000000
00000000
00000000
```


What are the possible problems?


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

```javascript
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'));
```

###Objective