nat: Replace port refcounts with simple bitvectors

Previously, each address maintained an array of 32-bit
reference counts for each of 65K possible ports for each
of 4 NAT protocols.  Totalling 1MB per address.  Wow.

A close read of the code shows that an "is used" check
precedes each attempted reference count increment.
That means the refcount never actually gets above 1.
That in turn means algorithmically, a bit vector is
sufficient.  And one need not be allocated for more
than the highest validated port referenced.

These changes introduce a dynamically sized bit vector
replacing the reference counts, for a maximum of 32K
if all 4 protocols use port 65535.  In fact, protocol
OTHER is never used, so at most 24K will be used, and
none of it will be "statically" allocated per address.

Type: fix
Fixes: 85bee7548bc5a360851d92807dae6d4159b68314

Change-Id: I7fd70050e7bf4871692a862231f8f38cf0158132
Signed-off-by: Jon Loeliger <jdl@netgate.com>

2 files changed, 80 insertions, 17 deletions

diff --git a/src/plugins/nat/nat44-ei/nat44_ei.c b/src/plugins/nat/nat44-ei/nat44_ei.c
index 4f2fa6112d5..8446011ec92 100644
--- a/src/plugins/nat/nat44-ei/nat44_ei.c
+++ b/src/plugins/nat/nat44-ei/nat44_ei.c
@@ -185,6 +185,69 @@ static int nat44_ei_del_static_mapping_internal (
   ip4_address_t l_addr, ip4_address_t e_addr, u16 l_port, u16 e_port,
   nat_protocol_t proto, u32 vrf_id, u32 sw_if_index, u32 flags);
 
+always_inline void
+nat44_ei_port_get (nat44_ei_address_t *a, u8 proto, u16 port)
+{
+  nat44_ei_main_t *nm = &nat44_ei_main;
+
+#define _(N, i, n, s)                                                         \
+  case NAT_PROTOCOL_##N:                                                      \
+    a->busy_##n##_port_bitmap =                                               \
+      clib_bitmap_set (a->busy_##n##_port_bitmap, port, 1);                   \
+    break;
+
+  switch (proto)
+    {
+      foreach_nat_protocol;
+    default:
+      nat_elog_info (nm, "unknown protocol");
+    }
+
+#undef _
+}
+
+always_inline void
+nat44_ei_port_put (nat44_ei_address_t *a, u8 proto, u16 port)
+{
+  nat44_ei_main_t *nm = &nat44_ei_main;
+
+#define _(N, i, n, s)                                                         \
+  case NAT_PROTOCOL_##N:                                                      \
+    a->busy_##n##_port_bitmap =                                               \
+      clib_bitmap_set (a->busy_##n##_port_bitmap, port, 0);                   \
+    break;
+
+  switch (proto)
+    {
+      foreach_nat_protocol;
+    default:
+      nat_elog_info (nm, "unknown protocol");
+    }
+
+#undef _
+}
+
+always_inline bool
+nat44_ei_port_is_used (nat44_ei_address_t *a, u8 proto, u16 port)
+{
+  nat44_ei_main_t *nm = &nat44_ei_main;
+
+#define _(N, i, n, s)                                                         \
+  case NAT_PROTOCOL_##N:                                                      \
+    return clib_bitmap_get (a->busy_##n##_port_bitmap, port);
+
+  switch (proto)
+    {
+      foreach_nat_protocol;
+    default:
+      nat_elog_info (nm, "unknown protocol");
+    }
+
+#undef _
+
+  return 0;
+}
+
 static u8 *
 format_nat44_ei_classify_trace (u8 *s, va_list *args)
 {
@@ -1256,9 +1319,9 @@ nat44_ei_set_outside_address_and_port (nat44_ei_address_t *addresses,
 	{
 #define _(N, j, n, s)                                                         \
   case NAT_PROTOCOL_##N:                                                      \
-    if (a->busy_##n##_port_refcounts[port_host_byte_order])                   \
+    if (nat44_ei_port_is_used (a, NAT_PROTOCOL_##N, port_host_byte_order))    \
       return VNET_API_ERROR_INSTANCE_IN_USE;                                  \
-    ++a->busy_##n##_port_refcounts[port_host_byte_order];                     \
+    nat44_ei_port_get (a, NAT_PROTOCOL_##N, port_host_byte_order);            \
     a->busy_##n##_ports_per_thread[thread_index]++;                           \
     a->busy_##n##_ports++;                                                    \
     return 0;
@@ -1320,8 +1383,9 @@ nat44_ei_free_outside_address_and_port (nat44_ei_address_t *addresses,
     {
 #define _(N, i, n, s)                                                         \
   case NAT_PROTOCOL_##N:                                                      \
-    ASSERT (a->busy_##n##_port_refcounts[port_host_byte_order] >= 1);         \
-    --a->busy_##n##_port_refcounts[port_host_byte_order];                     \
+    ASSERT (                                                                  \
+      nat44_ei_port_is_used (a, NAT_PROTOCOL_##N, port_host_byte_order));     \
+    nat44_ei_port_put (a, NAT_PROTOCOL_##N, port_host_byte_order);            \
     a->busy_##n##_ports--;                                                    \
     a->busy_##n##_ports_per_thread[thread_index]--;                           \
     break;
@@ -1814,9 +1878,9 @@ nat44_ei_alloc_default_cb (nat44_ei_address_t *addresses, u32 fib_index,
 			  nat_random_port (&nm->random_seed, 0,               \
 					   port_per_thread - 1) +             \
 			  1024;                                               \
-		if (a->busy_##n##_port_refcounts[portnum])                    \
+		if (nat44_ei_port_is_used (a, NAT_PROTOCOL_##N, portnum))     \
 		  continue;                                                   \
-		--a->busy_##n##_port_refcounts[portnum];                      \
+		nat44_ei_port_get (a, NAT_PROTOCOL_##N, portnum);             \
 		a->busy_##n##_ports_per_thread[thread_index]++;               \
 		a->busy_##n##_ports++;                                        \
 		*addr = a->addr;                                              \
@@ -1894,9 +1958,9 @@ nat44_ei_alloc_range_cb (nat44_ei_address_t *addresses, u32 fib_index,
 	  {                                                                   \
 	    portnum = nat_random_port (&nm->random_seed, nm->start_port,      \
 				       nm->end_port);                         \
-	    if (a->busy_##n##_port_refcounts[portnum])                        \
+	    if (nat44_ei_port_is_used (a, NAT_PROTOCOL_##N, portnum))         \
 	      continue;                                                       \
-	    ++a->busy_##n##_port_refcounts[portnum];                          \
+	    nat44_ei_port_get (a, NAT_PROTOCOL_##N, portnum);                 \
 	    a->busy_##n##_ports++;                                            \
 	    *addr = a->addr;                                                  \
 	    *port = clib_host_to_net_u16 (portnum);                           \
@@ -1943,9 +2007,9 @@ nat44_ei_alloc_mape_cb (nat44_ei_address_t *addresses, u32 fib_index,
 				 pow2_mask (nm->psid_offset));                \
 	    j = nat_random_port (&nm->random_seed, 0, pow2_mask (m));         \
 	    portnum = A | (nm->psid << nm->psid_offset) | (j << (16 - m));    \
-	    if (a->busy_##n##_port_refcounts[portnum])                        \
+	    if (nat44_ei_port_is_used (a, NAT_PROTOCOL_##N, portnum))         \
 	      continue;                                                       \
-	    ++a->busy_##n##_port_refcounts[portnum];                          \
+	    nat44_ei_port_get (a, NAT_PROTOCOL_##N, portnum);                 \
 	    a->busy_##n##_ports++;                                            \
 	    *addr = a->addr;                                                  \
 	    *port = clib_host_to_net_u16 (portnum);                           \
@@ -2111,9 +2175,9 @@ nat44_ei_reserve_port (ip4_address_t addr, u16 port, nat_protocol_t proto)
 	{
 #define _(N, j, n, s)                                                         \
   case NAT_PROTOCOL_##N:                                                      \
-    if (a->busy_##n##_port_refcounts[port])                                   \
-      goto done;                                                              \
-    ++a->busy_##n##_port_refcounts[port];                                     \
+    if (nat44_ei_port_is_used (a, NAT_PROTOCOL_##N, port))                    \
+      continue;                                                               \
+    nat44_ei_port_get (a, NAT_PROTOCOL_##N, port);                            \
     if (port > 1024)                                                          \
       {                                                                       \
 	a->busy_##n##_ports++;                                                \
@@ -2152,7 +2216,7 @@ nat44_ei_free_port (ip4_address_t addr, u16 port, nat_protocol_t proto)
 	{
 #define _(N, j, n, s)                                                         \
   case NAT_PROTOCOL_##N:                                                      \
-    --a->busy_##n##_port_refcounts[port];                                     \
+    nat44_ei_port_put (a, NAT_PROTOCOL_##N, port);                            \
     if (port > 1024)                                                          \
       {                                                                       \
 	a->busy_##n##_ports--;                                                \
@@ -2990,8 +3054,7 @@ nat44_ei_add_address (ip4_address_t *addr, u32 vrf_id)
     }
 
 #define _(N, i, n, s)                                                         \
-  clib_memset (ap->busy_##n##_port_refcounts, 0,                              \
-	       sizeof (ap->busy_##n##_port_refcounts));                       \
+  ap->busy_##n##_port_bitmap = 0;                                             \
   ap->busy_##n##_ports = 0;                                                   \
   ap->busy_##n##_ports_per_thread = 0;                                        \
   vec_validate_init_empty (ap->busy_##n##_ports_per_thread,                   \
diff --git a/src/plugins/nat/nat44-ei/nat44_ei.h b/src/plugins/nat/nat44-ei/nat44_ei.h
index f353f48c482..c79cbfe5d57 100644
--- a/src/plugins/nat/nat44-ei/nat44_ei.h
+++ b/src/plugins/nat/nat44-ei/nat44_ei.h
@@ -74,7 +74,7 @@ typedef struct
 #define _(N, i, n, s)                                                         \
   u32 busy_##n##_ports;                                                       \
   u32 *busy_##n##_ports_per_thread;                                           \
-  u32 busy_##n##_port_refcounts[0xffff + 1];
+  uword *busy_##n##_port_bitmap;
   foreach_nat_protocol
 #undef _
 } nat44_ei_address_t;