Encoding and Decoding of Pcap Packets

Question

I need to convert packets to byte format and decode it . How is it possible to convert packets captured using jnetpcap library to array[bytes] and vice-versa in Java?

Answer 1

PcapPacket class has the method public int transferStateAndDataTo(byte[] buffer) which will copy the contents of the packet to the byte array.
define the byte[] with size as packet.getTotalSize()

if you are looking for the payload

//opens an offline pcap file 
Pcap pcap = Pcap.openOffline(pcapIpFile, errbuf); 

//packet object
PcapPacket packet = new PcapPacket(JMemory.POINTER); 

Payload pl = new Payload();

pcap.nextEx(packet);       // retrieves the next packet from input loop thru until eof

if(packet.hasHeader(pl))  //this will check for and retrieve the payload
    pl.data()   // this will give you the data in the payload as a byte stream 

for data in the different headers (ethernet/ip/tcp) there are other methods available with the implementation