ip: allow addrs from the same prefix on intf

Type: feature

Adding a prefix to an interface was not permitted if it overlapped
with another prefix on an interface which used the same FIB.

Loosen the restriction. Allow 2 or more addresses from the same
prefix on a single interface. Reference count the prefix to figure
out when a glean/connected route for the prefix needs to be added
or removed.

Added unit tests to check that the route is only removed when all
addresses in the prefix are removed from the interface.

Change-Id: I1a962ecb5e1ee65fc6d41f98a4cc097a51a55321
Signed-off-by: Matthew Smith <mgsmith@netgate.com>

1 files changed, 234 insertions, 79 deletions

diff --git a/src/vnet/ip/ip4_forward.c b/src/vnet/ip/ip4_forward.c
index 754bb21fe67..060787f9561 100644
--- a/src/vnet/ip/ip4_forward.c
+++ b/src/vnet/ip/ip4_forward.c
@@ -339,74 +339,122 @@ ip4_add_subnet_bcast_route (u32 fib_index,
 }
 
 static void
-ip4_add_interface_routes (u32 sw_if_index,
-			  ip4_main_t * im, u32 fib_index,
-			  ip_interface_address_t * a)
+ip4_add_interface_prefix_routes (ip4_main_t *im,
+				 u32 sw_if_index,
+				 u32 fib_index,
+				 ip_interface_address_t * a)
 {
   ip_lookup_main_t *lm = &im->lookup_main;
+  ip_interface_prefix_t *if_prefix;
   ip4_address_t *address = ip_interface_address_get_address (lm, a);
-  fib_prefix_t pfx = {
-    .fp_len = a->address_length,
+
+  ip_interface_prefix_key_t key = {
+    .prefix = {
+      .fp_len = a->address_length,
+      .fp_proto = FIB_PROTOCOL_IP4,
+      .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[a->address_length],
+    },
+    .sw_if_index = sw_if_index,
+  };
+
+  fib_prefix_t pfx_special = {
     .fp_proto = FIB_PROTOCOL_IP4,
-    .fp_addr.ip4 = *address,
   };
 
-  if (pfx.fp_len <= 30)
+  /* If prefix already set on interface, just increment ref count & return */
+  if_prefix = ip_get_interface_prefix (lm, &key);
+  if (if_prefix)
     {
-      /* a /30 or shorter - add a glean for the network address */
-      fib_table_entry_update_one_path (fib_index, &pfx,
-                                       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
+      if_prefix->ref_count += 1;
+      return;
+    }
+
+  /* New prefix - allocate a pool entry, initialize it, add to the hash */
+  pool_get (lm->if_prefix_pool, if_prefix);
+  if_prefix->ref_count = 1;
+  if_prefix->src_ia_index = a - lm->if_address_pool;
+  clib_memcpy (&if_prefix->key, &key, sizeof (key));
+  mhash_set (&lm->prefix_to_if_prefix_index, &key,
+	     if_prefix - lm->if_prefix_pool, 0 /* old value */);
+
+  /* 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
+                                       /* no out-label stack */
                                        NULL,
                                        FIB_ROUTE_PATH_FLAG_NONE);
 
-      /* Add the two broadcast addresses as drop */
-      fib_prefix_t net_pfx = {
-        .fp_len = 32,
-        .fp_proto = FIB_PROTOCOL_IP4,
-        .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[pfx.fp_len],
-      };
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        fib_table_entry_special_add(fib_index,
-                                    &net_pfx,
-                                    FIB_SOURCE_INTERFACE,
-                                    (FIB_ENTRY_FLAG_DROP |
-                                     FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT));
-      net_pfx.fp_addr.ip4.as_u32 |= ~im->fib_masks[pfx.fp_len];
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        ip4_add_subnet_bcast_route(fib_index, &net_pfx, sw_if_index);
-    }
-  else if (pfx.fp_len == 31)
-    {
-      u32 mask = clib_host_to_net_u32(1);
-      fib_prefix_t net_pfx = pfx;
+      /* set a drop route for the base address of the prefix */
+      pfx_special.fp_len = 32;
+      pfx_special.fp_addr.ip4.as_u32 =
+	address->as_u32 & im->fib_masks[a->address_length];
 
-      net_pfx.fp_len = 32;
-      net_pfx.fp_addr.ip4.as_u32 ^= mask;
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+	fib_table_entry_special_add (fib_index, &pfx_special,
+				     FIB_SOURCE_INTERFACE,
+				     (FIB_ENTRY_FLAG_DROP |
+				      FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT));
 
-      /* a /31 - add the other end as an attached host */
-      fib_table_entry_update_one_path (fib_index, &net_pfx,
-                                       FIB_SOURCE_INTERFACE,
-                                       (FIB_ENTRY_FLAG_ATTACHED),
-                                       DPO_PROTO_IP4,
-                                       &net_pfx.fp_addr,
-                                       sw_if_index,
-                                       // invalid FIB index
+      /* set a route for the broadcast address of the prefix */
+      pfx_special.fp_len = 32;
+      pfx_special.fp_addr.ip4.as_u32 =
+	address->as_u32 | ~im->fib_masks[a->address_length];
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+	ip4_add_subnet_bcast_route (fib_index, &pfx_special, sw_if_index);
+
+
+    }
+  /* length == 31 - add an attached route for the other address */
+  else if (a->address_length == 31)
+    {
+      pfx_special.fp_len = 32;
+      pfx_special.fp_addr.ip4.as_u32 =
+	address->as_u32 ^ clib_host_to_net_u32(1);
+
+      fib_table_entry_update_one_path (fib_index, &pfx_special,
+				       FIB_SOURCE_INTERFACE,
+				       (FIB_ENTRY_FLAG_ATTACHED),
+				       DPO_PROTO_IP4,
+				       &pfx_special.fp_addr,
+				       sw_if_index,
+                                       /* invalid FIB index */
                                        ~0,
                                        1,
                                        NULL,
                                        FIB_ROUTE_PATH_FLAG_NONE);
     }
-  pfx.fp_len = 32;
+}
+
+static void
+ip4_add_interface_routes (u32 sw_if_index,
+			  ip4_main_t * im, u32 fib_index,
+			  ip_interface_address_t * a)
+{
+  ip_lookup_main_t *lm = &im->lookup_main;
+  ip4_address_t *address = ip_interface_address_get_address (lm, a);
+  fib_prefix_t pfx = {
+    .fp_len = 32,
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_addr.ip4 = *address,
+  };
+
+  /* set special routes for the prefix if needed */
+  ip4_add_interface_prefix_routes (im, sw_if_index, fib_index, a);
 
   if (sw_if_index < vec_len (lm->classify_table_index_by_sw_if_index))
     {
@@ -443,45 +491,143 @@ ip4_add_interface_routes (u32 sw_if_index,
 }
 
 static void
-ip4_del_interface_routes (ip4_main_t * im,
-			  u32 fib_index,
-			  ip4_address_t * address, u32 address_length)
+ip4_del_interface_prefix_routes (ip4_main_t * im,
+				 u32 sw_if_index,
+				 u32 fib_index,
+				 ip4_address_t * address,
+				 u32 address_length)
 {
-  fib_prefix_t pfx = {
-    .fp_len = address_length,
+  ip_lookup_main_t *lm = &im->lookup_main;
+  ip_interface_prefix_t *if_prefix;
+
+  ip_interface_prefix_key_t key = {
+    .prefix = {
+      .fp_len = address_length,
+      .fp_proto = FIB_PROTOCOL_IP4,
+      .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[address_length],
+    },
+    .sw_if_index = sw_if_index,
+  };
+
+  fib_prefix_t pfx_special = {
+    .fp_len = 32,
     .fp_proto = FIB_PROTOCOL_IP4,
-    .fp_addr.ip4 = *address,
   };
 
-  if (pfx.fp_len <= 30)
+  if_prefix = ip_get_interface_prefix (lm, &key);
+  if (!if_prefix)
     {
-      fib_prefix_t net_pfx = {
-        .fp_len = 32,
-        .fp_proto = FIB_PROTOCOL_IP4,
-        .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[pfx.fp_len],
-      };
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        fib_table_entry_special_remove(fib_index,
-                                       &net_pfx,
-                                       FIB_SOURCE_INTERFACE);
-      net_pfx.fp_addr.ip4.as_u32 |= ~im->fib_masks[pfx.fp_len];
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        fib_table_entry_special_remove(fib_index,
-                                       &net_pfx,
-                                       FIB_SOURCE_INTERFACE);
-      fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
+      clib_warning ("Prefix not found while deleting %U",
+		    format_ip4_address_and_length, address, address_length);
+      return;
     }
-    else if (pfx.fp_len == 31)
+
+  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
+   *
+   * We're done now otherwise
+   */
+  if ((if_prefix->ref_count > 0) &&
+      !pool_is_free_index (lm->if_address_pool, if_prefix->src_ia_index))
+    return;
+
+  /* length <= 30, delete glean route, first address, last address */
+  if (address_length <= 30)
     {
-      u32 mask = clib_host_to_net_u32(1);
-      fib_prefix_t net_pfx = pfx;
 
-      net_pfx.fp_len = 32;
-      net_pfx.fp_addr.ip4.as_u32 ^= mask;
+      /* 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;
+
+	  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;
 
-      fib_table_entry_delete (fib_index, &net_pfx, 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);
+	}
+      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;
+	}
+    }
+  /* length == 31, delete attached route for the other address */
+  else if (address_length == 31)
+    {
+      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);
     }
 
+  mhash_unset (&lm->prefix_to_if_prefix_index, &key, 0 /* old_value */);
+  pool_put (lm->if_prefix_pool, if_prefix);
+}
+
+static void
+ip4_del_interface_routes (u32 sw_if_index,
+			  ip4_main_t * im,
+			  u32 fib_index,
+			  ip4_address_t * address, u32 address_length)
+{
+  fib_prefix_t pfx = {
+    .fp_len = address_length,
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_addr.ip4 = *address,
+  };
+
+  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);
 }
@@ -579,6 +725,13 @@ ip4_add_del_interface_address_internal (vlib_main_t * vm,
                                                       address,
                                                       address_length))
                      {
+		       /* an intf may have >1 addr from the same prefix */
+		       if ((sw_if_index == sif->sw_if_index) &&
+			   (ia->address_length == address_length) &&
+			   (x->as_u32 != address->as_u32))
+		         continue;
+
+		       /* error if the length or intf was different */
                        vnm->api_errno = VNET_API_ERROR_DUPLICATE_IF_ADDRESS;
 
                        return
@@ -610,7 +763,8 @@ ip4_add_del_interface_address_internal (vlib_main_t * vm,
   if (vnet_sw_interface_is_admin_up (vnm, sw_if_index))
     {
       if (is_del)
-	ip4_del_interface_routes (im, ip4_af.fib_index, address,
+	ip4_del_interface_routes (sw_if_index,
+				  im, ip4_af.fib_index, address,
 				  address_length);
       else
 	ip4_add_interface_routes (sw_if_index,
@@ -712,7 +866,8 @@ ip4_sw_interface_admin_up_down (vnet_main_t * vnm, u32 sw_if_index, u32 flags)
 				im, fib_index,
 				ia);
     else
-      ip4_del_interface_routes (im, fib_index,
+      ip4_del_interface_routes (sw_if_index,
+				im, fib_index,
 				a, ia->address_length);
   }));
   /* *INDENT-ON* */