nat: nat44-ed pool address allocation improvement

This patch improves algorithm responsible for choosing nat pool address
during dynamic session creation.

Patch synchronizes nat pool address attributes with vpp interfaces doing
so gives nat option to determine correct nat pool address  when creating
dynamic session.

Improvements:
    * match dst address subnet and src fib with nat pool address
    * for output-feature also fallback match of tx_sw_if_index with nat
      pool address

Type: improvement

Change-Id: I594638bc76fc1153f582add376838b4b72ff573a
Signed-off-by: Filip Varga <fivarga@cisco.com>

1 files changed, 146 insertions, 7 deletions

diff --git a/src/plugins/nat/nat44-ed/nat44_ed.c b/src/plugins/nat/nat44-ed/nat44_ed.c
index 56c5ab2e32f..7907d8ffa6b 100644
--- a/src/plugins/nat/nat44-ed/nat44_ed.c
+++ b/src/plugins/nat/nat44-ed/nat44_ed.c
@@ -309,6 +309,112 @@ is_snat_address_used_in_static_mapping (snat_main_t *sm, ip4_address_t addr)
   return 0;
 }
 
+static ip_interface_address_t *
+nat44_ed_get_ip_interface_address (u32 sw_if_index, ip4_address_t addr)
+{
+  snat_main_t *sm = &snat_main;
+
+  ip_lookup_main_t *lm = &sm->ip4_main->lookup_main;
+  ip_interface_address_t *ia;
+  ip4_address_t *ip4a;
+
+  foreach_ip_interface_address (
+    lm, ia, sw_if_index, 1, ({
+      ip4a = ip_interface_address_get_address (lm, ia);
+      nat_log_debug ("sw_if_idx: %u addr: %U ? %U", sw_if_index,
+		     format_ip4_address, ip4a, format_ip4_address, &addr);
+      if (ip4a->as_u32 == addr.as_u32)
+	{
+	  return ia;
+	}
+    }));
+  return NULL;
+}
+
+static int
+nat44_ed_resolve_nat_addr_len (snat_address_t *ap,
+			       snat_interface_t *interfaces)
+{
+  ip_interface_address_t *ia;
+  snat_interface_t *i;
+  u32 fib_index;
+
+  pool_foreach (i, interfaces)
+    {
+      if (!nat44_ed_is_interface_outside (i))
+	{
+	  continue;
+	}
+
+      fib_index = ip4_fib_table_get_index_for_sw_if_index (i->sw_if_index);
+      if (fib_index != ap->fib_index)
+	{
+	  continue;
+	}
+
+      if ((ia = nat44_ed_get_ip_interface_address (i->sw_if_index, ap->addr)))
+	{
+	  ap->addr_len = ia->address_length;
+	  ap->sw_if_index = i->sw_if_index;
+	  ap->net.as_u32 = (ap->addr.as_u32 >> (32 - ap->addr_len))
+			   << (32 - ap->addr_len);
+
+	  nat_log_debug ("pool addr %U binds to -> sw_if_idx: %u net: %U/%u",
+			 format_ip4_address, &ap->addr, ap->sw_if_index,
+			 format_ip4_address, &ap->net, ap->addr_len);
+	  return 0;
+	}
+    }
+  return 1;
+}
+
+static void
+nat44_ed_update_outside_if_addresses (snat_address_t *ap)
+{
+  snat_main_t *sm = &snat_main;
+
+  if (!nat44_ed_resolve_nat_addr_len (ap, sm->interfaces))
+    {
+      return;
+    }
+
+  if (!nat44_ed_resolve_nat_addr_len (ap, sm->output_feature_interfaces))
+    {
+      return;
+    }
+}
+
+static void
+nat44_ed_bind_if_addr_to_nat_addr (u32 sw_if_index)
+{
+  snat_main_t *sm = &snat_main;
+  ip_interface_address_t *ia;
+  snat_address_t *ap;
+
+  u32 fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index);
+
+  vec_foreach (ap, sm->addresses)
+    {
+      if (fib_index != ap->fib_index)
+	{
+	  continue;
+	}
+
+      if ((ia = nat44_ed_get_ip_interface_address (sw_if_index, ap->addr)))
+	{
+	  ap->addr_len = ia->address_length;
+	  ap->sw_if_index = sw_if_index;
+	  ap->net.as_u32 = (ap->addr.as_u32 >> (32 - ap->addr_len))
+			   << (32 - ap->addr_len);
+
+	  nat_log_debug ("pool addr %U binds to -> sw_if_idx: %u net: %U/%u",
+			 format_ip4_address, &ap->addr, ap->sw_if_index,
+			 format_ip4_address, &ap->net, ap->addr_len);
+	  return;
+	}
+    }
+}
+
 static void
 nat44_ed_add_del_addr_to_fib (ip4_address_t *addr, u8 p_len, u32 sw_if_index,
 			      int is_add)
@@ -424,6 +530,7 @@ nat44_ed_add_address (ip4_address_t *addr, u32 vrf_id, u8 twice_nat)
       vec_add2 (sm->addresses, ap, 1);
     }
 
+  ap->addr_len = ~0;
   ap->fib_index = ~0;
   ap->addr = *addr;
 
@@ -433,12 +540,13 @@ nat44_ed_add_address (ip4_address_t *addr, u32 vrf_id, u8 twice_nat)
 	FIB_PROTOCOL_IP4, vrf_id, sm->fib_src_low);
     }
 
-    if (!twice_nat)
-  {
-    // if we don't have enabled interface we don't add address
-    // to fib
-    nat44_ed_add_del_addr_to_fib_foreach_out_if (addr, 1);
-  }
+  if (!twice_nat)
+    {
+      // if we don't have enabled interface we don't add address
+      // to fib
+      nat44_ed_add_del_addr_to_fib_foreach_out_if (addr, 1);
+      nat44_ed_update_outside_if_addresses (ap);
+    }
   return 0;
 }
 
@@ -1641,6 +1749,8 @@ nat44_ed_add_interface (u32 sw_if_index, u8 is_inside)
 
       nat44_ed_add_del_addr_to_fib_foreach_addr (sw_if_index, 1);
       nat44_ed_add_del_addr_to_fib_foreach_addr_only_sm (sw_if_index, 1);
+
+      nat44_ed_bind_if_addr_to_nat_addr (sw_if_index);
     }
   else
     {
@@ -1850,6 +1960,8 @@ nat44_ed_add_output_interface (u32 sw_if_index)
   nat44_ed_add_del_addr_to_fib_foreach_addr (sw_if_index, 1);
   nat44_ed_add_del_addr_to_fib_foreach_addr_only_sm (sw_if_index, 1);
 
+  nat44_ed_bind_if_addr_to_nat_addr (sw_if_index);
+
   return 0;
 }
 
@@ -3244,7 +3356,7 @@ nat44_ed_add_del_interface_address_cb (ip4_main_t *im, uword opaque,
 {
   snat_main_t *sm = &snat_main;
   snat_static_map_resolve_t *rp;
-  snat_address_t *addresses = sm->addresses;
+  snat_address_t *ap, *addresses = sm->addresses;
   u8 twice_nat = 0;
   int rv, i;
 
@@ -3259,6 +3371,33 @@ nat44_ed_add_del_interface_address_cb (ip4_main_t *im, uword opaque,
       if (!is_sw_if_index_reg_for_auto_resolve (
 	    sm->auto_add_sw_if_indices_twice_nat, sw_if_index))
 	{
+	  // interface resolve
+	  u32 fib_index =
+	    ip4_fib_table_get_index_for_sw_if_index (sw_if_index);
+	  vec_foreach (ap, sm->addresses)
+	    {
+	      if ((fib_index == ap->fib_index) &&
+		  (address->as_u32 == ap->addr.as_u32))
+		{
+		  if (!is_delete)
+		    {
+		      ap->addr_len = address_length;
+		      ap->sw_if_index = sw_if_index;
+		      ap->net.as_u32 = (ap->addr.as_u32 >> (32 - ap->addr_len))
+				       << (32 - ap->addr_len);
+
+		      nat_log_debug (
+			"pool addr %U binds to -> sw_if_idx: %u net: %U/%u",
+			format_ip4_address, &ap->addr, ap->sw_if_index,
+			format_ip4_address, &ap->net, ap->addr_len);
+		    }
+		  else
+		    {
+		      ap->addr_len = ~0;
+		    }
+		  break;
+		}
+	    }
 	  return;
 	}
       else