2017-01-14 00:58:52 +00:00
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=====
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2017-01-14 03:10:53 +00:00
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How to create a JSON file with information about your project:
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2017-01-14 00:58:52 +00:00
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```bash
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npm init
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2017-01-14 03:05:53 +00:00
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```
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2017-01-14 03:10:53 +00:00
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How to duplicate DNS crash:
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2017-01-14 02:04:27 +00:00
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2017-01-14 03:04:21 +00:00
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```
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2017-01-14 03:10:53 +00:00
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>> cd ~/dns_test
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>> node listen.js
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2017-01-14 03:04:21 +00:00
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```
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2017-01-14 03:10:53 +00:00
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Then in another terminal enter:
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2017-01-14 00:58:52 +00:00
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2017-01-14 03:04:21 +00:00
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```
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2017-01-14 17:08:07 +00:00
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>> dig @224.0.0.251 -p 5353 -t PTR _cloud._tcp.local
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2017-01-14 03:04:21 +00:00
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```
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2017-01-14 03:10:53 +00:00
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The listener then crashes with an output of:
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2017-01-14 03:04:21 +00:00
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```
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START DNS PACKET
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/home/daplie/dns_test/node_modules/dns-js/lib/bufferconsumer.js:52
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throw new Error('Buffer overflow')
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^
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Error: Buffer overflow
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at BufferConsumer.slice (/home/daplie/dns_test/node_modules/dns-js/lib/bufferconsumer.js:52:13)
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s at Function.DNSRecord.parse (/home/daplie/dns_test/node_modules/dns-js/lib/dnsrecord.js:237:46)
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at /home/daplie/dns_test/node_modules/dns-js/lib/dnspacket.js:164:30
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at Array.forEach (native)
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at Function.DNSPacket.parse (/home/daplie/dns_test/node_modules/dns-js/lib/dnspacket.js:159:17)
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at /home/daplie/dns_test/cloud-respond.js:86:31
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at Array.forEach (native)
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at /home/daplie/dns_test/cloud-respond.js:11:21
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at Array.forEach (native)
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at Object.module.exports.respond (/home/daplie/dns_test/cloud-respond.js:10:11)
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```
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2017-01-14 17:08:07 +00:00
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After commenting out lines 45-53 in dns_test/node_modules/dns-js/lib/bufferconsumer.js
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and rerunning the previous commands, the result is a new error:
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```
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START DNS PACKET
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buffer.js:829
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throw new RangeError('Index out of range');
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^
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RangeError: Index out of range
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at checkOffset (buffer.js:829:11)
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at Buffer.readUInt8 (buffer.js:867:5)
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at BufferConsumer.byte (/home/daplie/dns_test/node_modules/dns-js/lib/bufferconsumer.js:67:22)
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at BufferConsumer.name (/home/daplie/dns_test/node_modules/dns-js/lib/bufferconsumer.js:120:14)
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at Function.DNSRecord.parse (/home/daplie/dns_test/node_modules/dns-js/lib/dnsrecord.js:187:14)
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at /home/daplie/dns_test/node_modules/dns-js/lib/dnspacket.js:164:30
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at Array.forEach (native)
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at Function.DNSPacket.parse (/home/daplie/dns_test/node_modules/dns-js/lib/dnspacket.js:159:17)
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at /home/daplie/dns_test/cloud-respond.js:86:31
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at Array.forEach (native)
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```
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which is located in the node.js buffer module. The API is [here](https://nodejs.org/api/buffer.html).
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When can a Buffer overflow problem occur in js?
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2017-01-14 03:04:21 +00:00
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2017-01-14 17:08:07 +00:00
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What are the possible problems?
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2017-01-14 03:04:21 +00:00
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2017-01-14 17:08:07 +00:00
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How to print out hex values of the DNS message in node.js?
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2017-01-14 03:04:21 +00:00
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```javascript
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socket.on('message', function (message, rinfo) {
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console.log('Received %d bytes from %s:%d\n',
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message.length, rinfo.address, rinfo.port);
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//console.log(msg.toString('utf8'));
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console.log(message.toString('hex'));
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```
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