On Wed, Nov 28, 2018 at 5:57 PM Christoph Paasch <cpaa...@apple.com> wrote: > > There are use-cases where a host wants to use a UDP socket with a > specific 4-tuple. The way to do this is to bind() and then connect() the > socket. However, after the bind(), the socket starts receiving data even > if it does not match the intended 4-tuple. That is because after the > bind() UDP-socket will match in the lookup for all incoming UDP-traffic > that has the specific IP/port. > > This patch prevents any incoming traffic until the connect() system-call > is called whenever the app sets the UDP socket-option > UDP_WAIT_FOR_CONNECT.
Please do not add something that could mislead applications writers to think UDP stack can scale. UDP stack does not have a full hash on 4-tuples, it means that incoming traffic on a 'shared port' has to scan a list of XXX sockets to find the best match ... Also you add another cache line miss in UDP lookup to access udp_sk()->wait_for_connect. recvfrom() can be used to filter whatever frame that came before the connect()
