fib: Source Address Selection

Type: feature

Use the FIB to provide SAS (in so far as it is today)
 - Use the glean adjacency as the record of the connected prefixes
 = there's a glean per-{interface, protocol, connected-prefix}
 - Keep the glean up to date with whatever the recieve host prefix is
(since it can change)

Signed-off-by: Neale Ranns <neale.ranns@cisco.com>
Change-Id: I0f3dd1edb1f3fc965af1c7c586709028eb9cdeac

1 files changed, 49 insertions, 89 deletions

diff --git a/src/vnet/ip/ip4_forward.c b/src/vnet/ip/ip4_forward.c
index 919718035a1..5903ef892ca 100644
--- a/src/vnet/ip/ip4_forward.c
+++ b/src/vnet/ip/ip4_forward.c
@@ -380,28 +380,28 @@ ip4_add_interface_prefix_routes (ip4_main_t *im,
   mhash_set (&lm->prefix_to_if_prefix_index, &key,
 	     if_prefix - lm->if_prefix_pool, 0 /* old value */);
 
+  pfx_special.fp_len = a->address_length;
+  pfx_special.fp_addr.ip4.as_u32 = address->as_u32;
+
+  /* set the glean route for the prefix */
+  fib_table_entry_update_one_path (fib_index, &pfx_special,
+                                   FIB_SOURCE_INTERFACE,
+                                   (FIB_ENTRY_FLAG_CONNECTED |
+                                    FIB_ENTRY_FLAG_ATTACHED),
+                                   DPO_PROTO_IP4,
+                                   /* No next-hop address */
+                                   NULL,
+                                   sw_if_index,
+                                   /* invalid FIB index */
+                                   ~0,
+                                   1,
+                                   /* no out-label stack */
+                                   NULL,
+                                   FIB_ROUTE_PATH_FLAG_NONE);
+
   /* length <= 30 - add glean, drop first address, maybe drop bcast address */
   if (a->address_length <= 30)
     {
-      pfx_special.fp_len = a->address_length;
-      pfx_special.fp_addr.ip4.as_u32 = address->as_u32;
-
-      /* set the glean route for the prefix */
-      fib_table_entry_update_one_path (fib_index, &pfx_special,
-				       FIB_SOURCE_INTERFACE,
-				       (FIB_ENTRY_FLAG_CONNECTED |
-					FIB_ENTRY_FLAG_ATTACHED),
-				       DPO_PROTO_IP4,
-				       /* No next-hop address */
-				       NULL,
-				       sw_if_index,
-                                       /* invalid FIB index */
-                                       ~0,
-                                       1,
-                                       /* no out-label stack */
-                                       NULL,
-                                       FIB_ROUTE_PATH_FLAG_NONE);
-
       /* set a drop route for the base address of the prefix */
       pfx_special.fp_len = 32;
       pfx_special.fp_addr.ip4.as_u32 =
@@ -528,90 +528,52 @@ ip4_del_interface_prefix_routes (ip4_main_t * im,
   if_prefix->ref_count -= 1;
 
   /*
-   * Routes need to be adjusted if:
-   * - deleting last intf addr in prefix
-   * - deleting intf addr used as default source address in glean adjacency
+   * Routes need to be adjusted if deleting last intf addr in prefix
    *
    * We're done now otherwise
    */
-  if ((if_prefix->ref_count > 0) &&
-      !pool_is_free_index (lm->if_address_pool, if_prefix->src_ia_index))
+  if (if_prefix->ref_count > 0)
     return;
 
   /* length <= 30, delete glean route, first address, last address */
   if (address_length <= 30)
     {
+      /* Less work to do in FIB if we remove the covered /32s first */
 
-      /* remove glean route for prefix */
-      pfx_special.fp_addr.ip4 = *address;
-      pfx_special.fp_len = address_length;
-      fib_table_entry_delete (fib_index, &pfx_special, FIB_SOURCE_INTERFACE);
-
-      /* if no more intf addresses in prefix, remove other special routes */
-      if (!if_prefix->ref_count)
-	{
-	  /* first address in prefix */
-	  pfx_special.fp_addr.ip4.as_u32 =
-	    address->as_u32 & im->fib_masks[address_length];
-	  pfx_special.fp_len = 32;
+      /* first address in prefix */
+      pfx_special.fp_addr.ip4.as_u32 =
+        address->as_u32 & im->fib_masks[address_length];
+      pfx_special.fp_len = 32;
 
-	  if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
-	  fib_table_entry_special_remove (fib_index,
-					  &pfx_special,
-					  FIB_SOURCE_INTERFACE);
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+        fib_table_entry_special_remove (fib_index,
+                                        &pfx_special,
+                                        FIB_SOURCE_INTERFACE);
 
-	  /* prefix broadcast address */
-	  pfx_special.fp_addr.ip4.as_u32 =
-	    address->as_u32 | ~im->fib_masks[address_length];
-	  pfx_special.fp_len = 32;
+      /* prefix broadcast address */
+      pfx_special.fp_addr.ip4.as_u32 =
+        address->as_u32 | ~im->fib_masks[address_length];
+      pfx_special.fp_len = 32;
 
-	  if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
-	  fib_table_entry_special_remove (fib_index,
-					  &pfx_special,
-					  FIB_SOURCE_INTERFACE);
-	}
-      else
-	/* default source addr just got deleted, find another */
-	{
-	  ip_interface_address_t *new_src_ia = NULL;
-	  ip4_address_t *new_src_addr = NULL;
-
-	  new_src_addr =
-	    ip4_interface_address_matching_destination
-	      (im, address, sw_if_index, &new_src_ia);
-
-	  if_prefix->src_ia_index = new_src_ia - lm->if_address_pool;
-
-	  pfx_special.fp_len = address_length;
-	  pfx_special.fp_addr.ip4 = *new_src_addr;
-
-	  /* set new glean route for the prefix */
-	  fib_table_entry_update_one_path (fib_index, &pfx_special,
-					   FIB_SOURCE_INTERFACE,
-					   (FIB_ENTRY_FLAG_CONNECTED |
-					    FIB_ENTRY_FLAG_ATTACHED),
-					   DPO_PROTO_IP4,
-					   /* No next-hop address */
-					   NULL,
-					   sw_if_index,
-					   /* invalid FIB index */
-					   ~0,
-					   1,
-					   /* no out-label stack */
-					   NULL,
-					   FIB_ROUTE_PATH_FLAG_NONE);
-	  return;
-	}
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+        fib_table_entry_special_remove (fib_index,
+                                        &pfx_special,
+                                        FIB_SOURCE_INTERFACE);
     }
-  /* length == 31, delete attached route for the other address */
   else if (address_length == 31)
     {
+      /* length == 31, delete attached route for the other address */
       pfx_special.fp_addr.ip4.as_u32 =
 	address->as_u32 ^ clib_host_to_net_u32(1);
 
       fib_table_entry_delete (fib_index, &pfx_special, FIB_SOURCE_INTERFACE);
     }
 
+  /* remove glean route for prefix */
+  pfx_special.fp_addr.ip4 = *address;
+  pfx_special.fp_len = address_length;
+  fib_table_entry_delete (fib_index, &pfx_special, FIB_SOURCE_INTERFACE);
+
   mhash_unset (&lm->prefix_to_if_prefix_index, &key, 0 /* old_value */);
   pool_put (lm->if_prefix_pool, if_prefix);
 }
@@ -623,16 +585,15 @@ ip4_del_interface_routes (u32 sw_if_index,
 			  ip4_address_t * address, u32 address_length)
 {
   fib_prefix_t pfx = {
-    .fp_len = address_length,
+    .fp_len = 32,
     .fp_proto = FIB_PROTOCOL_IP4,
     .fp_addr.ip4 = *address,
   };
 
+  fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
+
   ip4_del_interface_prefix_routes (im, sw_if_index, fib_index,
 				   address, address_length);
-
-  pfx.fp_len = 32;
-  fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
 }
 
 #ifndef CLIB_MARCH_VARIANT
@@ -2540,9 +2501,8 @@ ip4_rewrite_inline_with_gso (vlib_main_t * vm,
 	       thread_index, adj_index0, 1,
 	       vlib_buffer_length_in_chain (vm, b[0]) + rw_len0);
 
-	  if (is_midchain && adj0->sub_type.midchain.fixup_func)
-	    adj0->sub_type.midchain.fixup_func
-	      (vm, adj0, b[0], adj0->sub_type.midchain.fixup_data);
+	  if (is_midchain)
+	    adj_midchain_fixup (vm, adj0, b[0]);
 
 	  if (is_mcast)
 	    /* copy bytes from the IP address into the MAC rewrite */