CGN: Deterministic NAT (VPP-623)

Inside user is statically mapped to a set of outside ports. Support endpoint
dependent mapping to deal with overloading of the outside ports.

Change-Id: I8014438744597a976f8ae459283e8b91f63b7f72
Signed-off-by: Matus Fabian <matfabia@cisco.com>

1 files changed, 125 insertions, 0 deletions

diff --git a/src/plugins/snat/snat_det.c b/src/plugins/snat/snat_det.c
new file mode 100644
index 00000000..d54bca66
--- /dev/null
+++ b/src/plugins/snat/snat_det.c
@@ -0,0 +1,125 @@
+/*
+ * snat_det.c - deterministic NAT
+ *
+ * Copyright (c) 2017 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.
+ */
+/**
+ * @file
+ * @brief deterministic NAT
+ */
+
+#include <snat/snat_det.h>
+
+
+/**
+ * @brief Add/delete deterministic NAT mapping.
+ *
+ * Create bijective mapping of inside address to outside address and port range
+ * pairs, with the purpose of enabling deterministic NAT to reduce logging in
+ * CGN deployments.
+ *
+ * @param sm       SNAT main.
+ * @param in_addr  Inside network address.
+ * @param in_plen  Inside network prefix length.
+ * @param out_addr Outside network address.
+ * @param out_plen Outside network prefix length.
+ * @param is_add   If 0 delete, otherwise add.
+ */
+int
+snat_det_add_map (snat_main_t * sm, ip4_address_t * in_addr, u8 in_plen,
+		  ip4_address_t * out_addr, u8 out_plen, int is_add)
+{
+  snat_det_map_t *det_map;
+  static snat_det_session_t empty_snat_det_session = { 0 };
+  snat_interface_t *i;
+
+  pool_get (sm->det_maps, det_map);
+  memset (det_map, 0, sizeof (*det_map));
+  det_map->in_addr.as_u32 = in_addr->as_u32 & ip4_main.fib_masks[in_plen];
+  det_map->in_plen = in_plen;
+  det_map->out_addr.as_u32 = out_addr->as_u32 & ip4_main.fib_masks[out_plen];
+  det_map->out_plen = out_plen;
+  det_map->sharing_ratio = (1 << (32 - in_plen)) / (1 << (32 - out_plen));
+  det_map->ports_per_host = (65535 - 1023) / det_map->sharing_ratio;
+
+  vec_validate_init_empty (det_map->sessions,
+			   SNAT_DET_SES_PER_USER * (1 << (32 - in_plen)) - 1,
+			   empty_snat_det_session);
+
+  /* Add/del external address range to FIB */
+  /* *INDENT-OFF* */
+  pool_foreach (i, sm->interfaces,
+  ({
+    if (i->is_inside)
+      continue;
+
+    snat_add_del_addr_to_fib(out_addr, out_plen, i->sw_if_index, is_add);
+    break;
+  }));
+  /* *INDENT-ON* */
+  return 0;
+}
+
+/**
+ * @brief The 'snat-det-expire-walk' process's main loop.
+ *
+ * Check expire time for active sessions.
+ */
+static uword
+snat_det_expire_walk_fn (vlib_main_t * vm, vlib_node_runtime_t * rt,
+			 vlib_frame_t * f)
+{
+  snat_main_t *sm = &snat_main;
+  snat_det_map_t *dm;
+  snat_det_session_t *ses;
+
+  while (sm->deterministic)
+    {
+      vlib_process_wait_for_event_or_clock (vm, 10.0);
+      vlib_process_get_events (vm, NULL);
+      u32 now = (u32) vlib_time_now (vm);
+      /* *INDENT-OFF* */
+      pool_foreach (dm, sm->det_maps,
+      ({
+        vec_foreach(ses, dm->sessions)
+          {
+            /* Delete if session expired */
+            if (ses->in_port && (ses->expire < now))
+              snat_det_ses_close (dm, ses);
+          }
+      }));
+      /* *INDENT-ON* */
+    }
+
+  return 0;
+}
+
+static vlib_node_registration_t snat_det_expire_walk_node;
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (snat_det_expire_walk_node, static) = {
+    .function = snat_det_expire_walk_fn,
+    .type = VLIB_NODE_TYPE_PROCESS,
+    .name =
+    "snat-det-expire-walk",
+};
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */