FIB2.0: Adjacency complete pull model (VPP-487)

Change the adjacency completion model to pull not push.

A complete adjacency has a rewirte string, an incomplete one does not. the re-write string for a peer comes either from a discovery protocol (i.e. ARP/ND) or can be directly derived from the link type (i.e. GRE tunnels). Which method it is, is interface type specific.
For each packet type sent on a link to a peer there is a corresponding adjacency. For example, if there is a peer 10.0.0.1 on Eth0 and we need to send to it IPv4 and MPLS packets, there will be two adjacencies; one for the IPv4 and one for the MPLS packets. The adjacencies are thus distinguished by the packets the carry, this is known as the adjacency's 'link-type'. It is not an L3 packet type, since the adjacency can have a link type of Ethernet (for L2 over GRE).
The discovery protocols are not aware of all the link types required - only the FIB is. the FIB will create adjacencies as and when they are required, and it is thus then desirable to 'pull' from the discovery protocol the re-write required. The alternative (that we have now) is that the discovery protocol pushes (i.e. creates) adjacencies for each link type - this creates more adjacencies than we need.
To pull, FIB now requests from the interface-type to 'complete' the adjacency. The interface can then delegate to the discovery protocol (on ethernet links) or directly build the re-write (i.e on GRE).

Change-Id: I61451789ae03f26b1012d8d6524007b769b6c6ee
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 13 insertions, 14 deletions

diff --git a/vnet/vnet/ipsec/ipsec_if.c b/vnet/vnet/ipsec/ipsec_if.c
index 13901efe03e..77d5d19a82e 100644
--- a/vnet/vnet/ipsec/ipsec_if.c
+++ b/vnet/vnet/ipsec/ipsec_if.c
@@ -38,24 +38,23 @@ dummy_interface_tx (vlib_main_t * vm,
   return frame->n_vectors;
 }
 
+/* *INDENT-OFF* */
 VNET_DEVICE_CLASS (ipsec_device_class, static) =
 {
-.name = "IPSec",.format_device_name = format_ipsec_name,.format_tx_trace =
-    format_ipsec_if_output_trace,.tx_function = dummy_interface_tx,};
-
-static uword
-dummy_set_rewrite (vnet_main_t * vnm,
-		   u32 sw_if_index,
-		   u32 l3_type,
-		   void *dst_address, void *rewrite, uword max_rewrite_bytes)
-{
-  return 0;
-}
-
+  .name = "IPSec",
+  .format_device_name = format_ipsec_name,
+  .format_tx_trace = format_ipsec_if_output_trace,
+  .tx_function = dummy_interface_tx,
+};
+/* *INDENT-ON* */
+
+/* *INDENT-OFF* */
 VNET_HW_INTERFACE_CLASS (ipsec_hw_class) =
 {
-.name = "IPSec",.set_rewrite = dummy_set_rewrite,};
-
+  .name = "IPSec",
+  .build_rewrite = default_build_rewrite,
+};
+/* *INDENT-ON* */
 
 static int
 ipsec_add_del_tunnel_if_internal (vnet_main_t * vnm,