bug 2158: Fix flooding of packets on input port, for packets received on in!=0
When you have the action OFPP_FLOOD on a flow, and the received packet is
not coming into the switch through port 0, then the packet will be flooded on
all ports, including the receiving port! This is especially bad if
you have broadcasts as packets will get replicated indefinitely (ARP req for
e.g.). This is caused by missing ntohs() that fails to convert port numbers
to their correct values. The switch works correctly for broadcast packets
received on port zero.
Example: The ReceivePacketOut() gets 0 if the input port is 0 and it works.
But will get 512 if the input port is 1 and since 512 is not our real input
port the check will fail and the packet will also be replicated on the input
port.