Hello guys, I wanted to ask you: do you have buffer management functionality to duplicate a packet?
I have seen that the function OvsOutputBeforeSetAction CLONES instead of duplicating the packet. Did you know that, when cloning a packet, both the old and the cloned packet reference the same data (buffer)? So that setting bytes, say, in the ipv4 header of the cloned NET_BUFFER actually modifies the original NET_BUFFER as well? Also, we are not allowed to set data in the original packet. We must create a clone / duplicate for this. For tunneling (i.e. adding headroom) cloning is ok, because the clone writes bytes to the "unused" area of the buffer, or allocates a new MDL for the headroom (which is removed at Complete). The procedure for setting data within the buffer using cloning is a bit more complicated: You must allocate a new MDL, copy the 'modified' data into its buffer, and chain it to the cloned NET_BUFFER (replacing the old MDL). And at Complete, you must free your MDL and put the old MDL back. A simpler method would be to duplicate the buffer, instead of cloning it. Here the architecture of a cloned NET_BUFFER_LIST is presented: http://msdn.microsoft.com/en-us/library/windows/hardware/ff544929(v=vs.85).aspx Samuel Ghinet _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
