Class VpnTunnel

java.lang.Object
com.codename1.vpn.tunnel.VpnTunnel
public abstract class VpnTunnel extends Object

The packet loop, written once for both platforms.

public class MyTunnel extends VpnTunnel {
    protected void onStart(TunnelConfiguration cfg) { }
    protected void onPacket(PacketBuffer p) { forward(p); }
    protected void onStop(TunnelStopReason r) { }
}
Where this runs

On Android, in the app's own process, inside the port's VpnService. Nowhere else: Tunnels.isSupported() is false on iOS, where a packet tunnel would have to run in a Network Extension and the translation that would give that process a virtual machine has not been written.

Write the tunnel as though it ran somewhere else anyway. Everything it needs travels in TunnelConfiguration.getData(); a static the app set happens to be there on Android and is not a thing to rely on.

What is expensive

A host process for a tunnel runs under a memory budget far below an app's, and is killed rather than warned when it exceeds it. The buffers handed to onPacket(PacketBuffer) are reused for exactly that reason, so copying every packet -- or holding one past the call -- gives back the headroom the pooling was for. See PacketBuffer.

  • Constructor Details

    • VpnTunnel

      public VpnTunnel()

  • Method Details

    • onStart

      protected abstract void onStart(TunnelConfiguration configuration)
      The tunnel is up and the platform has configured the link.

    • onPacket

      protected abstract void onPacket(PacketBuffer packet)

      One packet arrived from the device, bound for the far end.

      The buffer is REUSED once this returns; see PacketBuffer.

    • onStop

      protected abstract void onStop(TunnelStopReason reason)
      The tunnel is going down, for the given reason.

    • forward

      protected final void forward(PacketBuffer packet)

      Sends a packet back to the device.

      Safe to call with the buffer onPacket was given, which is the ordinary pass-through case and copies nothing.

    • forward

      protected final void forward(byte[] packet, int offset, int length)
      Sends bytes the tunnel produced itself.