// Selects a path from the given set that does not lead back to the
// specified port.
private Path pickForwardPath(Set<Path> paths, PortNumber notToPort) {
for (Path path : paths) {
if (!path.src().port().equals(notToPort)) {
return path;
}
}
return null;
}
@Override
public void process(PacketContext context) {
// Stop processing if the packet has been handled, since we
// can't do any more to it.
if (context.isHandled()) {
return;
}
InboundPacket pkt = context.inPacket();
Ethernet ethPkt = pkt.parsed();
if (ethPkt == null) {
return;
}
// Bail if this is deemed to be a control packet.
if (isControlPacket(ethPkt)) {
return;
}
// Skip IPv6 multicast packet when IPv6 forward is disabled.
if (!ipv6Forwarding && isIpv6Multicast(ethPkt)) {
return;
}
HostId id = HostId.hostId(ethPkt.getDestinationMAC());
// Do not process link-local addresses in any way.
if (id.mac().isLinkLocal()) {
return;
}
// Do we know who this is for? If not, flood and bail.
Host dst = hostService.getHost(id);
if (dst == null) {
flood(context);
return;
}
// Are we on an edge switch that our destination is on? If so,
// simply forward out to the destination and bail.
if (pkt.receivedFrom().deviceId().equals(dst.location().deviceId())) {
if (!context.inPacket().receivedFrom().port().equals(dst.location().port())) {
installRule(context, dst.location().port());
}
return;
}
// Otherwise, get a set of paths that lead from here to the
// destination edge switch.
Set<Path> paths =
topologyService.getPaths(
topologyService.currentTopology(),
pkt.receivedFrom().deviceId(),
dst.location().deviceId());
if (paths.isEmpty()) {
// If there are no paths, flood and bail.
flood(context);
return;
}
// Otherwise, pick a path that does not lead back to where we
// came from; if no such path, flood and bail.
Path path = pickForwardPath(paths, pkt.receivedFrom().port());
if (path == null) {
log.warn(
"Doh... don't know where to go... {} -> {} received on {}",
ethPkt.getSourceMAC(),
ethPkt.getDestinationMAC(),
pkt.receivedFrom());
flood(context);
return;
}
// Otherwise forward and be done with it.
installRule(context, path.src().port());
}