/**
* Return a route error in case a route was found to be invalid as the current hop cannot find a
* way to forward the message to the destination or any other hops in the forward part of the
* route. In that case a negative route response is forwarded to the orginal source of the
* message. Now of course we do not have any way to guarantee that the NACK message will be
* received by the sender, but the best we can do is to try :-)
*
* <p>we send a query ID to NACKROUTE_QUERYID to indicate this is a bad Route
*
* @param src original source of the message
* @param dest original destination of the message
*/
protected void generateNACKRoute(PeerID src, PeerID dest, Vector origHops) {
// As long as the group is partially initialized, do not bother
// trying to send NACKS. We can't: it just causes NPEs.
if (resolver == null) {
return;
}
if (LOG.isEnabledFor(Level.DEBUG)) {
LOG.debug("generate NACK Route response " + src);
}
// check first, if we are not already in process of looking for a
// route to the destination peer of the NACK. We should not try to
// send a NACK to that destination at that point as this will block
// our incoming processing thread while it is looking for a route to
// that destination. If there a no pending route requests to that
// destination then we can go ahead an attempt to send the NACK. At
// the maximum we should have only one thread block while looking for
// a specific destination. When we find a route to the destination,
// the next NACK processing will be sent.
if (router.isPendingRouteQuery(router.pid2addr(src))) {
if (LOG.isEnabledFor(Level.DEBUG)) {
LOG.debug("drop NACK due to pending route discovery " + src);
}
return;
}
// Generate a route response
RouteAdvertisement route =
(RouteAdvertisement)
AdvertisementFactory.newAdvertisement(RouteAdvertisement.getAdvertisementType());
AccessPointAdvertisement ap =
(AccessPointAdvertisement)
AdvertisementFactory.newAdvertisement(AccessPointAdvertisement.getAdvertisementType());
ap.setPeerID(dest);
route.setDest(ap);
route.setHops(origHops);
// set the the route of the peer that
// detected the bad route
RouteAdvertisement routeSrc =
(RouteAdvertisement)
AdvertisementFactory.newAdvertisement(RouteAdvertisement.getAdvertisementType());
AccessPointAdvertisement apSrc =
(AccessPointAdvertisement)
AdvertisementFactory.newAdvertisement(AccessPointAdvertisement.getAdvertisementType());
apSrc.setPeerID((PeerID) localPeerId);
routeSrc.setDest(apSrc);
RouteResponse routeResponse = new RouteResponse();
routeResponse.setDestRoute(route);
routeResponse.setSrcRoute(routeSrc);
if (routeResponse == null) {
if (LOG.isEnabledFor(Level.DEBUG)) {
LOG.debug("error creating route NACKresponse");
}
return;
}
ResolverResponse res =
new ResolverResponse(
routerSName,
credentialDoc,
NACKROUTE_QUERYID, // mean NACKRoute
routeResponse.toString());
// send the NACK response back to the originator
resolver.sendResponse(src.toString(), res);
}
