OpenFlow-level flow-based tunneling support.

OpenFlow-level flow-based tunneling support.

Adds tun_src and tun_dst match and set capabilities via new NXM fields
NXM_NX_TUN_IPV4_SRC and NXM_NX_TUN_IPV4_DST.  This allows management of
large number of tunnels via the flow tables, without requiring the tunnels
to be pre-configured.

Flow-based tunnels can be configured with options remote_ip=flow and
local_ip=flow.  local_ip=flow requires remote_ip=flow.  When set, the
tunnel remote IP address and/or local IP address is set from the flow,
instead of the tunnel configuration.

Example:

$ ovs-vsctl add-port br0 gre -- set Interface gre ofport_request=1 type=gre options:remote_ip=flow options:key=flow
$ ovs-ofctl add-flow br0 "in_port=LOCAL actions=set_tunnel:1,set_field:192.168.0.1->tun_dst,output:1"
$ ovs-ofctl add-flow br0 "in_port=1 tun_src=192.168.0.1 tun_id=1 actions=LOCAL"

Signed-off-by: Jarno Rajahalme <jarno.rajahalme@nsn.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>