added the test code that AJ wrote
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README.md
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README.md
@ -132,8 +132,116 @@ the binary output comes out as:
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00000000
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```
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In order to figure out where the dnspacket code is going wrong,
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We will have to write our own test code to see if the dns code
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is doing what it's supposed to be doing.
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Looking at the code below:
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```javascript
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// parses through the flags
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// val can be 1 or 0
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// (val & 0x8000) >> 15 does the following
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// val = 0000 0000 0000 0001
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// & 1001 0000 0000 0000
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// _______________________
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// 0000 0000 0000 0000
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// same if val were 0
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// but if val were 0x8000
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// then
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// (val & 0x8000) >> 15 does the following
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// val = 1001 0000 0000 0001
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// & 1001 0000 0000 0000
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// _______________________
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// 1001 0000 0000 0000
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// >>15= 0000 0000 0000 0001
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function parseFlags(val, packet) {
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packet.header.qr = (val & 0x8000) >> 15;
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packet.header.opcode = (val & 0x7800) >> 11;
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packet.header.aa = (val & 0x400) >> 10;
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packet.header.tc = (val & 0x200) >> 9;
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packet.header.rd = (val & 0x100) >> 8;
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packet.header.ra = (val & 0x80) >> 7;
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packet.header.res1 = (val & 0x40) >> 6;
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packet.header.res2 = (val & 0x20) >> 5;
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packet.header.res3 = (val & 0x10) >> 4;
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packet.header.rcode = (val & 0xF);
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}
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```
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One effective way to check is to create a dns packet, pass it to
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a custom packer and parser function and compare the input and output:
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```javascript
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'use strict';
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// order one http://www.binarytides.com/dns-query-code-in-c-with-linux-sockets/
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// order two http://www.zytrax.com/books/dns/ch15/
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function parse(i) {
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var header = {
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// first byte appears to be reverse
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qr: (i & 0x8000) >> 15
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, opcode: (i & 0x7800) >> 11
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, aa: (i & 0x400) >> 10
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, tc: (i & 0x200) >> 9
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, rd: (i & 0x100) >> 8
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// second byte appears to be second byte, but also in reverse
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, ra: (i & 0x80) >> 7
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, res1: (i & 0x40) >> 6 // z
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, res2: (i & 0x20) >> 5 // ad
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, res3: (i & 0x10) >> 4 // cd
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, rcode: (i & 0x1F)
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};
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return header;
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}
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function pack(header) {
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var val = 0;
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val += (header.qr << 15) & 0x8000;
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val += (header.opcode << 11) & 0x7800;
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val += (header.aa << 10) & 0x400;
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val += (header.tc << 9) & 0x200;
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val += (header.rd << 8) & 0x100;
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val += (header.ra << 7) & 0x80;
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val += (header.res1 << 6) & 0x40;
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val += (header.res2 << 5) & 0x20;
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val += (header.res3 << 4) & 0x10;
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val += header.rcode & 0x1F;
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return val;
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}
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var start = {
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qr: 1
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, opcode: 12
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, aa: 0
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, tc: 0
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, rd: 1
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, ra: 0
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, res1: 0
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, res2: 0
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, res3: 0
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, rcode: 0
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};
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var i = pack(start);
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var obj = parse(i);
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console.log(i);
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console.log(start);
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console.log(obj);
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// does a recursive check to see if start and obj are equal
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require('assert').deepEqual(start, obj);
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```
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What are the possible problems?
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How to print out hex values of the DNS message in node.js?
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@ -150,4 +258,5 @@ socket.on('message', function (message, rinfo) {
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DNS sec: security
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puts a signature on a DNS packet and imprints a signature so that the sender of the packet is confirmed
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puts a signature on a DNS packet and imprints a signature so that the sender of
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the packet is confirmed
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@ -4,6 +4,94 @@
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// This test code is meant to take a binary sample from the crash of listen.js
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// example and parse through it to spot where the error occurs.
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/*************** ********** Functions *******************/
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/**************************************************************/
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// Number generator function: this function should be able to generate
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// and output all the the binary combinations of a 8 bits and returns a buffer.
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// ex '00000000' - '11111111'
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function cycleThroughHex(){
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// Fill the array from 0 - 65535, so the 65535 case will
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// have to be hardcoded
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var current_val = 0;
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var end_val = 65536;
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var i = 0;
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var array_size = 65536;
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var arr = new Uint16Array(array_size);
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// var buf = new Buffer.alloc(array_size);
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while (current_val <= end_val){
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console.log(arr[i]);
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arr[i] = current_val;val += header.rcode & 0val += header.rcode & 0xF;xF;
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current_val++;
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}
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var buf = Buffer.from(arr.buffer);
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// console.log(buf);
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// console.log(buf.length);
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// console.log(buf[buf.length]);
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// for (var i = 0; i < buf.length; i++){
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// console.log(buf[i]);
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// }
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// return buf;
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// this is printing out 10,000 for some reason?
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}
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// message packer:
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// message parser:
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function hasError(output, int, flag){
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var hasError = 0;
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if (output > 0x0001 || output < 0x0000){
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console.log("There was an error with" + flag + " at index ", i , ". Output: " + output);
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hasError = 1;
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}
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return hasError;
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}
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function main (){
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// var val1 = '00000000';
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// var val2 = '11111111';
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// var val3 = '10101010';
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// var val4 = '01010101';
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var output = 0;
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var buf = cycleThroughHex();
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var val = 0;
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for (var i = 0; i < buf.length; i++){
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val = buf[i];
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output = (val & 0x8000) >> 15; // test for qr
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hasError(output, i, 'qr')
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output = (val & 0x400) >> 10; // test for aa
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hasError(output, i, 'aa');
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output = (val & 0x200) >> 9; // test for tc
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hasError(output,i, 'tc');
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output = (val & 0x100) >> 8; // test for rd
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hasError(output, i , 'rd');
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output = (val & 0x80) >> 7; // test for ra
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hasError(output, i, 'ra');
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}
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console.log("test successful");
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}
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// ex: pad('11111', 8, '0')
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function pad(str, len, ch) {
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@ -25,21 +113,6 @@ function bin2hex(str){
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return hex;
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}
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// ex: hex2ascii('A92F')
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function hex2ascii(str){
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var hex = str.toString();
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var ascii = '';
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for (var n = 0; n < hex.length; n+=2) {
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ascii += String.fromCharCode(parseInt(hex.substr(n,2), 16));
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}
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return ascii;
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}
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function binaryAgent(str) {
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var binString = '';
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@ -50,22 +123,90 @@ str.split(' ').map(function(bin) {
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return binString;
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}
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var str = binaryAgent('01000001 01110010 01100101 01101110 00100111 01110100');
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console.log(str);
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// binary Agent test
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// var str = binaryAgent('01000001 01110010 01100101 01101110 00100111 01110100');
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// console.log(str);
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// cycleThroughHex();
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// var hex = (0x8000 & 0x8000) >> 15;
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// console.log(hex.toString(16));
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// main();
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'use strict';
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// order one http://www.binarytides.com/dns-query-code-in-c-with-linux-sockets/
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// order two http://www.zytrax.com/books/dns/ch15/
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function parse(i) {
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var header = {
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// first byte appears to be reverse
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qr: (i & 0x8000) >> 15
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, opcode: (i & 0x7800) >> 11
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, aa: (i & 0x400) >> 10
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, tc: (i & 0x200) >> 9
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, rd: (i & 0x100) >> 8
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// second byte appears to be second byte, but also in reverse
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, ra: (i & 0x80) >> 7
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, res1: (i & 0x40) >> 6 // z
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, res2: (i & 0x20) >> 5 // ad
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, res3: (i & 0x10) >> 4 // cd
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, rcode: (i & 0x1F)
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};
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return header;
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}
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function pack(header) {
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var val = 0;
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val += (header.qr << 15) & 0x8000;
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val += (header.opcode << 11) & 0x7800;
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val += (header.aa << 10) & 0x400;
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val += (header.tc << 9) & 0x200;
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val += (header.rd << 8) & 0x100;
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val += (header.ra << 7) & 0x80;
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val += (header.res1 << 6) & 0x40;
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val += (header.res2 << 5) & 0x20;
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val += (header.res3 << 4) & 0x10;
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val += header.rcode & 0x1F;
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return val;
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}
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var start = {
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qr: 1
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, opcode: 12
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, aa: 0
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, tc: 0
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, rd: 1
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, ra: 0
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, res1: 0
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, res2: 0
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, res3: 0
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, rcode: 0
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};
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var i = pack(start);
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var obj = parse(i);
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console.log(i);
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console.log(start);
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console.log(obj);
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// does a recursive check to see if start and obj are equal
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require('assert').deepEqual(start, obj);
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parse
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//translates to "Aren't"
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// // binary to hex convestion
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// var bin = '00001111';
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// var hex = bin2hex(bin);
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// // hex to ascii character converstion
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// console.log('binary: ' + bin + ' Hex: ' + hex);
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// var hex = '';
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// var ascii = hex2ascii(hex);
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// console.log('Hex: ' + hex + ' ascii: ' + ascii);
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