AcraNetwork 0.5

Classes and utilities to support Flight Test Instrumentation Ethernet networks

AcraNetwork

A collection of classes that can be used to decom network or PCM based FTI traffic

Summary

• iNetX : Class for packing and unpacking iNetX objects

• IENA : Class for packing and unpacking IENA objects

• SimpleEthernet : A simplified set of classes for Ethernet, IP and UDP packets. These are not fully featured is sufficient for the network systems used in the KAM500 networks

• Pcap : Class and helper methods for reading pcap files

• McastSocket : Class to bind to ports to capture multicast packets

Install

Install using the standard setuptools install method

python setup.py install

or clone this repository to your local directory

git clone https://github.com/diarmuidcwc/AcraNetwork.git

Classes

iNetx

This will create an iNetx object. Once you have an iNetX object you can then either * assign values to the various fields and then convert(pack) the object into a buffer that is suitable for transmission or writing to a file or * convert (unpack) a buffer containing an iNetX packet

Methods

pack()

This method will take an iNetX object and return a string buffer containing the binary representation of the iNetX packet This method is typically run if you want to write an iNetX packet to a file or to transmit over the network

unpack(buffer)

This method will convert a binary buffer into an iNetX object. This is typically used to convert some data read from a pcap file or captured from the network into the iNetX object.

setPacketTime(utctimeinseconds,timeinmicroseconds)

This method will accept two arguments, utctimeinseconds and nanoseconds and assign the time to the iNetX object

IENA

This will create an IENA object. Once you have an IENA object you can then either * assign values to the various fields and then convert(pack) the object into a buffer that is suitable for transmission or writing to a file or * convert (unpack) a buffer containing an IENA packet

Methods

pack()

This method will take an IENA object and return a string buffer containing the binary representation of the IENA packet. This method is typically run if you want to write an IENA packet to a file or to transmit over the network

unpack(buffer)

This method will convert a binary buffer into an IENA object. This is typically used to convert some data read from a pcap file or captured from the network into the IENA object.

setPacketTime(utctimeinseconds,timeinnanoseconds)

This method will accept two arguments, utctimeinseconds and microseconds and assign the time to the IENA object

Ethernet / IP / UDP

Each of these classes will create the corresponding object. Once you create this object you can then either * assign values to the various fields and then convert(pack) the object into a buffer that is suitable for transmission or writing to a file or * convert (unpack) a buffer containing the packet

Methods

pack()

This method will take the object and return a string buffer containing the binary representation of the packet. This method is typically run if you want to write a packet to a file or to transmit over the network

unpack(buffer)

This method will convert a binary buffer into an object. This is typically used to convert some data read from a pcap file or captured from the network into the IENA object.

Pcap

This class will allow you to read and write to a Pcap file. Due to the potentially large size of pcap files, the complete file is not read or written in one operation but in pieces. This keeps the memory usage to a minimum

Methods

init()

To create a new pcap object you need to supply a filename and a flag to indicate if you want to read or write to this file. eg

pcap_for_reading = pcap.Pcap("input.pcap")                      # Create a new Pcap object based on reading from the file
pcap_for_writing = pcap.Pcap("output.pcap",forreading=False)    # Create a new Pcap object that will be writting to a file

readGlobalHeader()

When reading a pcap file this should be the first method called. This method will populate the fields in the Pcap object as described in the Pcap Wiki

readAPacket()

This method is called when reading a pcap file. It can be called repeatedly until the end of the file is reached and the method raises an IOError exception This method will return a PcapRecord object which will contain one pcap record, containing the header and payload

writeGlobalHeader()

When creating a new pcap file, this method should be called first. It will write a valid global header to the file. When creating a new Pcap object the defaults used in the object will generate a standard pcap file that will support Ethernet packets

writeARecord(pcaprecord)

Write out one pcap record to the file. The argument is required to be a PcapRecord object

close()

Close the pcap file

Usage

Here are two brief examples on how to create and read a pcap file. Further examples can be viewed in the examples directory or in the unittest folder

To read in a pcap file with multiple ethernet packets all containing an iNetX packet wrapped in UDP

import sys
sys.path.append("..")

import AcraNetwork.iNetX as inetx
import AcraNetwork.SimpleEthernet as SimpleEthernet
import AcraNetwork.Pcap as pcap

import struct
mypcap = pcap.Pcap("inetx_test.pcap")       # Read the pcap file
mypcap.readGlobalHeader()
while True:
    # Loop through the pcap file reading one packet at a time
    try:
        mypcaprecord = mypcap.readAPacket()
    except IOError:
        # End of file reached
        break

    ethpacket = SimpleEthernet.Ethernet()   # Create an Ethernet object
    ethpacket.unpack(mypcaprecord.packet)   # Unpack the pcap record into the eth object
    ippacket =  SimpleEthernet.IP()         # Create an IP packet
    ippacket.unpack(ethpacket.payload)      # Unpack the ethernet payload into the IP packet
    udppacket = SimpleEthernet.UDP()        # Create a UDP packet
    udppacket.unpack(ippacket.payload)      # Unpack the IP payload into the UDP packet
    inetxpacket = inetx.iNetX()             # Create an iNetx object
    inetxpacket.unpack(udppacket.payload)   # Unpack the UDP payload into this iNetX object
    print "INETX: StreamID ={:08X} Sequence = {:8d} PTP Seconds = {}".format(inetxpacket.streamid,inetxpacket.sequence,inetxpacket.ptptimeseconds)

To Make a Distribution

python setup.py sdist bdist_wininst upload