Object stream transform that parses IP headers.
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README.md

ip-stream

IP header serialization object stream.

Build Status

Example

Reading

var IpStream = require('ip-stream');
var EtherStream = require('ether-stream');
var PcapStream = require('pcap-stream');

var pstream = new PcapStream(PCAP_FILE);
var estream = new EtherStream();
var ipstream = new IpStream();

pstream.pipe(estream).pipe(ipstream);

ipstream.on('readable', function() {
  var msg = ipstream.read();

  msg.ether.src === '12:34:56:65:43:21';  // Ethernet frame is still available

  msg.ip.src === '1.1.1.1';   // IP header data is available at .ip property
  msg.ip.dst === '2.2.2.2';
  msg.ip.protocol === 'udp';

  var payload = msg.data;     // IP packet data is available at .data property
});

// Packets that cannot be parsed as IP are emitted with 'ignored' event
ipstream.on('ignored', function(error, msg) {
  console.log('Ignored message [' + msg + '] due to [' + error + ']');
});

ipstream.read(0);

// you can also control how fragments are handled
var ipsream2 = new IpStream({fragments: 'reassemble'}); // the default
var ipsream3 = new IpStream({fragments: 'drop'});       // ignore fragments
var ipsream4 = new IpStream({fragments: 'pass'});       // passthrough frags

// When reassembling, unmatched fragments are timed-out after 30 seconds by
// default, but you can configure that:
var ipstream5 = new IpStream({fragmentTimeout: 5000});

Writing

var IpStream = require('ip-stream');
var EtherStream = require('ether-stream');
var IpHeader = require('ip-header');
var EtherFrame = require('ether-frame');

var estream = new EtherStream();
var ipstream = new IpStream();

estream.pipe(ipstream);

// define the content to write out to the buffer
var input = {
  ether: new EtherFrame({ dst: '01:23:45:54:32:10' }),
  ip: new IpHeader({ dst: '1.1.1.1', dataLength: 500 }),
  data: new Buffer(8*1024)    // adequate storage for header
};

// NOTE: packet payload is not input.data, that must be appended later

estream.write(input);
var output = ipstream.read();

// header values have been written to the buffer
out.offset === (input.ether.length * input.ip.length);
test.deepEqual(input.ether, new EtherFrame(out.data, 0));
test.deepEqual(input.ip, new IpHeader(out.data, input.ether.length));