cnat: Destination based NAT

Type: feature

Signed-off-by: Neale Ranns <nranns@cisco.com>
Change-Id: I64a99a4fbc674212944247793fd5c1fb701408cb

1 files changed, 308 insertions, 0 deletions

diff --git a/src/plugins/cnat/cnat_node_vip.c b/src/plugins/cnat/cnat_node_vip.c
new file mode 100644
index 00000000000..afabed08f1a
--- /dev/null
+++ b/src/plugins/cnat/cnat_node_vip.c
@@ -0,0 +1,308 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vlibmemory/api.h>
+#include <cnat/cnat_node.h>
+#include <cnat/cnat_translation.h>
+
+#include <vnet/dpo/load_balance.h>
+#include <vnet/dpo/load_balance_map.h>
+
+typedef struct cnat_translation_trace_t_
+{
+  cnat_session_t session;
+  cnat_translation_t tr;
+  u32 found_session;
+  u32 created_session;
+  u32 has_tr;
+} cnat_translation_trace_t;
+
+typedef enum cnat_translation_next_t_
+{
+  CNAT_TRANSLATION_NEXT_DROP,
+  CNAT_TRANSLATION_NEXT_LOOKUP,
+  CNAT_TRANSLATION_N_NEXT,
+} cnat_translation_next_t;
+
+vlib_node_registration_t cnat_vip_ip4_node;
+vlib_node_registration_t cnat_vip_ip6_node;
+
+static u8 *
+format_cnat_translation_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  cnat_translation_trace_t *t =
+    va_arg (*args, cnat_translation_trace_t *);
+
+  if (t->found_session)
+    s = format (s, "found: %U", format_cnat_session, &t->session, 1);
+  else if (t->created_session)
+    s = format (s, "created: %U\n  tr: %U",
+		format_cnat_session, &t->session, 1,
+		format_cnat_translation,
+		&t->tr, 0);
+  else if (t->has_tr)
+    s = format (s, "tr pass: %U", format_cnat_translation,
+	&t->tr, 0);
+  else
+    s = format (s, "not found");
+  return s;
+}
+
+/* CNat sub for NAT behind a fib entry (VIP or interposed real IP) */
+always_inline uword
+cnat_vip_inline (vlib_main_t * vm,
+		   vlib_node_runtime_t * node,
+		   vlib_buffer_t * b,
+		   cnat_node_ctx_t * ctx, int rv, cnat_session_t * session)
+{
+  vlib_combined_counter_main_t *cntm = &cnat_translation_counters;
+  cnat_main_t *cm = &cnat_main;
+  const cnat_translation_t *ct = NULL;
+  ip4_header_t *ip4;
+  ip_protocol_t iproto;
+  ip6_header_t *ip6;
+  udp_header_t *udp0;
+  cnat_client_t *cc;
+  u16 next0;
+  index_t cti;
+  int created_session = 0;
+  if (AF_IP4 == ctx->af)
+    {
+      ip4 = vlib_buffer_get_current (b);
+      iproto = ip4->protocol;
+      udp0 = (udp_header_t *) (ip4 + 1);
+    }
+  else
+    {
+      ip6 = vlib_buffer_get_current (b);
+      iproto = ip6->protocol;
+      udp0 = (udp_header_t *) (ip6 + 1);
+    }
+
+  cc = cnat_client_get (vnet_buffer (b)->ip.adj_index[VLIB_TX]);
+
+  if (iproto != IP_PROTOCOL_UDP && iproto != IP_PROTOCOL_TCP)
+    {
+      /* Dont translate & follow the fib programming */
+      next0 = cc->cc_parent.dpoi_next_node;
+      vnet_buffer (b)->ip.adj_index[VLIB_TX] = cc->cc_parent.dpoi_index;
+      goto trace;
+    }
+
+  ct = cnat_find_translation (cc->parent_cci,
+				clib_host_to_net_u16 (udp0->dst_port),
+				iproto);
+
+  if (!rv)
+    {
+      /* session table hit */
+      cnat_timestamp_update (session->value.cs_ts_index, ctx->now);
+
+      if (NULL != ct)
+	{
+	  /* Translate & follow the translation given LB */
+	  next0 = ct->ct_lb.dpoi_next_node;
+	  vnet_buffer (b)->ip.adj_index[VLIB_TX] = session->value.cs_lbi;
+	}
+      else if (session->value.flags & CNAT_SESSION_FLAG_HAS_SNAT)
+	{
+	  /* The return needs DNAT, so we need an additionnal
+	   * lookup after translation */
+	  next0 = CNAT_TRANSLATION_NEXT_LOOKUP;
+	}
+      else
+	{
+	  /* Translate & follow the fib programming */
+	  next0 = cc->cc_parent.dpoi_next_node;
+	  vnet_buffer (b)->ip.adj_index[VLIB_TX] = cc->cc_parent.dpoi_index;
+	}
+    }
+  else
+    {
+      if (NULL == ct)
+	{
+	  /* Dont translate & Follow the fib programming */
+	  vnet_buffer (b)->ip.adj_index[VLIB_TX] = cc->cc_parent.dpoi_index;
+	  next0 = cc->cc_parent.dpoi_next_node;
+	  goto trace;
+	}
+
+      /* New flow, create the sessions */
+      const load_balance_t *lb0;
+      cnat_ep_trk_t *trk0;
+      u32 hash_c0, bucket0;
+      u32 rsession_flags = 0;
+      const dpo_id_t *dpo0;
+
+      lb0 = load_balance_get (ct->ct_lb.dpoi_index);
+      if (!lb0->lb_n_buckets)
+	{
+	  /* Dont translate & Follow the fib programming */
+	  vnet_buffer (b)->ip.adj_index[VLIB_TX] = cc->cc_parent.dpoi_index;
+	  next0 = cc->cc_parent.dpoi_next_node;
+	  goto trace;
+	}
+
+      /* session table miss */
+      hash_c0 = (AF_IP4 == ctx->af ?
+		 ip4_compute_flow_hash (ip4, lb0->lb_hash_config) :
+		 ip6_compute_flow_hash (ip6, lb0->lb_hash_config));
+      bucket0 = hash_c0 & lb0->lb_n_buckets_minus_1;
+      dpo0 = load_balance_get_fwd_bucket (lb0, bucket0);
+
+      /* add the session */
+      trk0 = &ct->ct_paths[bucket0];
+
+      ip46_address_copy (&session->value.cs_ip[VLIB_TX],
+			 &trk0->ct_ep[VLIB_TX].ce_ip.ip);
+      if (ip_address_is_zero (&trk0->ct_ep[VLIB_RX].ce_ip))
+	{
+	  if (AF_IP4 == ctx->af)
+	    ip46_address_set_ip4 (&session->value.cs_ip[VLIB_RX],
+				  &ip4->src_address);
+	  else
+	    ip46_address_set_ip6 (&session->value.cs_ip[VLIB_RX],
+				  &ip6->src_address);
+	}
+      else
+	{
+	  /* We source NAT with the translation */
+	  rsession_flags |= CNAT_SESSION_FLAG_HAS_SNAT;
+	  ip46_address_copy (&session->value.cs_ip[VLIB_RX],
+			     &trk0->ct_ep[VLIB_RX].ce_ip.ip);
+	}
+      session->value.cs_port[VLIB_TX] =
+	clib_host_to_net_u16 (trk0->ct_ep[VLIB_TX].ce_port);
+      session->value.cs_port[VLIB_RX] =
+	clib_host_to_net_u16 (trk0->ct_ep[VLIB_RX].ce_port);
+
+      session->value.flags = 0;
+      if (!session->value.cs_port[VLIB_RX])
+	{
+	  u16 sport;
+	  sport = udp0->src_port;
+	  /* Allocate a port only if asked and if we actually sNATed */
+	  if ((ct->flags & CNAT_TRANSLATION_FLAG_ALLOCATE_PORT)
+	       && (rsession_flags & CNAT_SESSION_FLAG_HAS_SNAT)) {
+	    sport = 0; /* force allocation */
+	    session->value.flags |= CNAT_SESSION_FLAG_ALLOC_PORT;
+	    rv = cnat_allocate_port (cm, &sport);
+	    if (rv)
+	      {
+		vlib_node_increment_counter (vm, cnat_vip_ip4_node.index,
+				            CNAT_ERROR_EXHAUSTED_PORTS, 1);
+		next0 = CNAT_TRANSLATION_NEXT_DROP;
+		goto trace;
+	      }
+	    }
+
+	  session->value.cs_port[VLIB_RX] = sport;
+	}
+      session->value.cs_lbi = dpo0->dpoi_index;
+
+      cnat_client_cnt_session (cc);
+      cnat_session_create (session, ctx, rsession_flags);
+      created_session = 1;
+
+      next0 = ct->ct_lb.dpoi_next_node;
+      vnet_buffer (b)->ip.adj_index[VLIB_TX] = session->value.cs_lbi;
+    }
+
+
+  if (AF_IP4 == ctx->af)
+    cnat_translation_ip4 (session, ip4, udp0);
+  else
+    cnat_translation_ip6 (session, ip6, udp0);
+
+  if (NULL != ct)
+    {
+      cti = ct - cnat_translation_pool;
+      vlib_increment_combined_counter (cntm, ctx->thread_index, cti, 1,
+				  vlib_buffer_length_in_chain (vm, b));
+    }
+
+trace:
+  if (PREDICT_FALSE (ctx->do_trace))
+    {
+      cnat_translation_trace_t *t;
+
+      t = vlib_add_trace (vm, node, b, sizeof (*t));
+
+      t->found_session = !rv;
+      t->created_session = created_session;
+      if (t->found_session || t->created_session)
+	clib_memcpy (&t->session, session, sizeof (t->session));
+      t->has_tr = (NULL != ct);
+      if (t->has_tr)
+	clib_memcpy (&t->tr, ct, sizeof (cnat_translation_t));
+    }
+  return next0;
+}
+
+VLIB_NODE_FN (cnat_vip_ip4_node) (vlib_main_t * vm,
+				    vlib_node_runtime_t * node,
+				    vlib_frame_t * frame)
+{
+  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
+    return cnat_node_inline (vm, node, frame, cnat_vip_inline, AF_IP4,
+			       1 /* do_trace */ );
+  return cnat_node_inline (vm, node, frame, cnat_vip_inline, AF_IP4,
+			     0 /* do_trace */ );
+}
+
+VLIB_NODE_FN (cnat_vip_ip6_node) (vlib_main_t * vm,
+				    vlib_node_runtime_t * node,
+				    vlib_frame_t * frame)
+{
+  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
+    return cnat_node_inline (vm, node, frame, cnat_vip_inline, AF_IP6,
+			       1 /* do_trace */ );
+  return cnat_node_inline (vm, node, frame, cnat_vip_inline, AF_IP6,
+			     0 /* do_trace */ );
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (cnat_vip_ip4_node) =
+{
+  .name = "ip4-cnat-tx",
+  .vector_size = sizeof (u32),
+  .format_trace = format_cnat_translation_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = 0,
+  .n_next_nodes = CNAT_TRANSLATION_N_NEXT,
+  .next_nodes =
+  {
+    [CNAT_TRANSLATION_NEXT_DROP] = "ip4-drop",
+    [CNAT_TRANSLATION_NEXT_LOOKUP] = "ip4-lookup",
+  }
+};
+VLIB_REGISTER_NODE (cnat_vip_ip6_node) =
+{
+  .name = "ip6-cnat-tx",
+  .vector_size = sizeof (u32),
+  .format_trace = format_cnat_translation_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = 0,
+  .n_next_nodes = CNAT_TRANSLATION_N_NEXT,
+  .next_nodes =
+  {
+    [CNAT_TRANSLATION_NEXT_DROP] = "ip6-drop",
+    [CNAT_TRANSLATION_NEXT_LOOKUP] = "ip6-lookup",
+  }
+};
+/* *INDENT-ON* */
+