pcap-dgram

Mock UDP socket based on pcap file data.


Example

``javascript
'use strict';

var PcapDgram = require('../dgram');
var path = require('path');

module.exports.example = function(test) {
test.expect(8);

var hello = new Buffer('Hello world!');
var remoteAddr = '192.168.207.128';
var remotePort = 137;

// Create a dgram socket using a netbios name service pcap file
var file = path.join(__dirname, 'data', 'netbios-ns-b-register-winxp.pcap');
var pdgram = new PcapDgram(file, '192.168.207.2');

// When we receive the netbios name service packet, validate it
pdgram.on('message', function(msg, rinfo) {
// assert values from inspecting pcap with tshark
test.equal(68, msg.length);
test.equal(msg.length, rinfo.size);
test.equal(remoteAddr, rinfo.address);
test.equal(remotePort, rinfo.port);

// Simulate sending a response back
pdgram.send(hello, 0, hello.length, rinfo.port, rinfo.address, function(error) {
test.equal(null, error);
});
});

// Validate the response was sent
pdgram.on('output', function(msg, port, address) {
test.equal(hello.toString(), msg.toString());
test.equal(remotePort, port);
test.equal(remoteAddr, address);
});

pdgram.on('close', function() {
test.done();
});
};
`

Limitations / TODO

* Currently only supports IPv4.
* Currently ignores all fragmented IP packets.

Class PcapDgram

The PcapDgram class implements the same API as the [dgram.Socket][] class.
Data is delivered to the 'message' event by reading data from a pcap
file. Outgoing data is redirected to the 'output' event so that it
can be validated for correctness.

$3

* pcapSource {String | Stream} If a String, pcapSource is interpreted as
the name of a pcap file to read from. Otherwise pcapSource is treated
as a stream providing pcap data.
* address {String} An IPv4 address used in the pcap file. The dgram socket
will act as that IP address. Packets sent to this address will be emitted
via the 'message' event.
* opts {Object | null} Optional parameters
* port {Number | null} The UDP port associated with the address
passed as the second argument. Packets sent to this port at the given
address wil be emitted via the 'message' event. If not provided then
the port will be automatically set to the port used on the first UDP
packet sent to the address.
* netmask {String} An IPv4 netmask to use when pretending to be the
configured address. This mainly determines if packets sent to subnet
specific broadcast addresses. For example, setting a netmask of
'255.255.255.0' will cause the socket to deliver packets addressed
like this '192.168.1.255'. Defaults to '255.255.255.255' meaning
only unicast and full broadcast will packets will be delivered.

$3

The 'output' event will fire whenever the send() fuction is called.
Instead of writing the data out to the specified remote host, the data is
provided to this event instead. This allows test code to validate that
the correct output is being produced by the code under test.

* msg {Buffer} The UDP payload to send to the remote host
* port {Number} The UDP port of the remote host
* address` {Address} The IPv4 address of the remote host

[dgram.Socket]: http://nodejs.org/api/dgram.html#dgram_class_socket