Get Packet Destination IP

[ssrirama]

Hi,

I have an application that registers itself as a packet listener on the controller (by implementing SequencedPacketListener). When the SPL event() method is triggered, I want to get the destination IP address and destination port of the packet passed in (from the MessageContext object). How can I get this information?

EDIT:

I did find the PathDiagnosticService interface which has a .getPath() method. Looks like what I want. Can I use this the same way the ControllerService interface is used?  By this I mean can I simply say "protected volatile PathDiagnosticService pds;" then later invoke it's methods like "pds.findPacketModel(...)" or will that return a NullPointerException because pds wasn't instantiated?

[sepbot]

Try this:

Packet packet = Codec.decodeEthernet(context.getPacketIn().getData());
Ip ip = (Ip) packet.get(ProtocolId.IP);
IpAddress dst = ip.dstAddr();

[ssrirama]

Haven't tested it yet, but I'll post if it doesn't work.

One question about the code you supplied, why use Codec specifically to decode the packet? Wouldn't context.decodedPacket() work?

[ssrirama]

The code you've supplied causes a NullPointerException on the line:

IpAddress dst = ip.dstAddr();

Full code used in that method was:

@Override
    public boolean event(MessageContext messageContext) {
        Packet packet = messageContext.decodedPacket();
        Ip ip = (Ip) packet.get(ProtocolId.IP);
        IpAddress dst = ip.dstAddr();
        return false;
    }

[sepbot]

If the packet only goes up to layer 2, then it will not have any IP information which might be the cause of the NullPointerException. Try puttin a check like this and see if it works:

if (packet.has(ProtocolId.IP) || packet.has(ProtocolId.IPV6)) {

}

[sdnindia]

Hello ssrirama,

Did you try as suggested in earlier post?

Please let us know if your problem is solved or you are still facing the issue.

Thanks,

HP SDN Team