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ofp-actions: Add truncate action.

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The patch adds a new action to support packet truncation.  The new action
is formatted as 'output(port=n,max_len=m)', as output to port n, with
packet size being MIN(original_size, m).

One use case is to enable port mirroring to send smaller packets to the
destination port so that only useful packet information is mirrored/copied,
saving some performance overhead of copying entire packet payload.  Example
use case is below as well as shown in the testcases:

    - Output to port 1 with max_len 100 bytes.
    - The output packet size on port 1 will be MIN(original_packet_size, 100).
    # ovs-ofctl add-flow br0 'actions=output(port=1,max_len=100)'

    - The scope of max_len is limited to output action itself.  The following
      packet size of output:1 and output:2 will be intact.
    # ovs-ofctl add-flow br0 \
            'actions=output(port=1,max_len=100),output:1,output:2'
    - The Datapath actions shows:
    # Datapath actions: trunc(100),1,1,2

Tested-at: https://travis-ci.org/williamtu/ovs-travis/builds/140037134
Signed-off-by: William Tu <u9012063@gmail.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
This commit is contained in:
William Tu
2016-06-24 07:42:30 -07:00
committed by Pravin B Shelar
parent 4c7804f14b
commit aaca4fe0ce
27 changed files with 848 additions and 4 deletions
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3
lib/netdev-linux.c
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@@ -1172,6 +1172,9 @@ netdev_linux_send(struct netdev *netdev_, int qid OVS_UNUSED,
size_t size = dp_packet_size(pkts[i]);
ssize_t retval;
/* Truncate the packet if it is configured. */
size -= dp_packet_get_cutlen(pkts[i]);
if (!is_tap_netdev(netdev_)) {
/* Use our AF_PACKET socket to send to this device. */
struct sockaddr_ll sll;