Plugin for IP-Address to Interface Punting

This plugin provides per-ip address to interface punting.

When at least one rule is defined, the plugin receives all packets
which destination is one of VPP's address but which was not processed
by VPP (e.g., a TCP packet on a port that is not open, or a packet
for a protocol which is not attached).

Based on the set of configured rules, the destination address of each
packet is used to send the packet on the associated interface.

This plugin allows multiple containers to use
VPP's TCP stack (or other features provided by VPP) while still
being able to receive additional packets.

Change-Id: I3e69bb7d98183bf5163cb9ecb564cb482de252ce
Signed-off-by: Pierre Pfister <ppfister@cisco.com>

7 files changed, 872 insertions, 0 deletions

diff --git a/src/configure.ac b/src/configure.ac
index f06df6ba519..f90ff9686af 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -191,6 +191,7 @@ PLUGIN_ENABLED(memif)
 PLUGIN_ENABLED(pppoe)
 PLUGIN_ENABLED(sixrd)
 PLUGIN_ENABLED(nat)
+PLUGIN_ENABLED(stn)
 
 ###############################################################################
 # Dependency checks
diff --git a/src/plugins/Makefile.am b/src/plugins/Makefile.am
index 205bfe6d5bb..bd77c45f631 100644
--- a/src/plugins/Makefile.am
+++ b/src/plugins/Makefile.am
@@ -78,6 +78,10 @@ if ENABLE_NAT_PLUGIN
 include nat.am
 endif
 
+if ENABLE_STN_PLUGIN
+include stn.am
+endif
+
 include ../suffix-rules.mk
 
 # Remove *.la files
diff --git a/src/plugins/stn.am b/src/plugins/stn.am
new file mode 100644
index 00000000000..e2f1a179b18
--- /dev/null
+++ b/src/plugins/stn.am
@@ -0,0 +1,26 @@
+# Copyright (c) 2016 Cisco Systems, Inc.
+# 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.
+
+vppplugins_LTLIBRARIES += stn_plugin.la
+
+stn_plugin_la_SOURCES = stn/stn.c stn/stn_api.c
+
+BUILT_SOURCES +=				\
+	stn/stn.api.h		\
+	stn/stn.api.json
+
+noinst_HEADERS += stn/stn.h
+
+API_FILES += stn/stn.api
+
+# vi:syntax=automake
\ No newline at end of file
diff --git a/src/plugins/stn/stn.api b/src/plugins/stn/stn.api
new file mode 100644
index 00000000000..07d214d852a
--- /dev/null
+++ b/src/plugins/stn/stn.api
@@ -0,0 +1,61 @@
+/*
+ * 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 stn.api
+ * @brief VPP control-plane API messages for STN plugin.
+ *
+ */
+
+
+/** \brief Add/del STN rules
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param is_ip4 - 1 if address type is IPv4
+    @param ip_address - STN rule IP address
+    @param sw_if_index - Interface index
+    @param is_add - 1 if add, 0 if delete
+*/
+autoreply manual_print define stn_add_del_rule {
+  u32 client_index;
+  u32 context;
+  u8 is_ip4;
+  u8 ip_address[16];
+  u32 sw_if_index;
+  u8 is_add;
+};
+
+/** \brief Dump STN rules
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+*/
+define stn_rules_dump {
+  u32 client_index;
+  u32 context;
+};
+
+/** \brief STN response to rules request
+    @param context - sender context, to match reply w/ request
+    @param is_ip4 - 1 if address type is IPv4
+    @param ip_address - IP address
+    @param sw_if_index - Interface index
+*/
+define stn_rule_details {
+  u32 context;
+  u8 is_ip4;
+  u8 ip_address[16];
+  u32 sw_if_index;
+};
+
diff --git a/src/plugins/stn/stn.c b/src/plugins/stn/stn.c
new file mode 100644
index 00000000000..a9e6a98ebed
--- /dev/null
+++ b/src/plugins/stn/stn.c
@@ -0,0 +1,484 @@
+/*
+ * 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.
+ */
+
+#include <stn/stn.h>
+
+#include <vnet/plugin/plugin.h>
+#include <vpp/app/version.h>
+#include <vnet/ip/format.h>
+#include <vnet/ethernet/packet.h>
+#include <vnet/udp/udp.h>
+#include <vnet/tcp/tcp.h>
+
+stn_main_t stn_main;
+static vlib_node_registration_t stn_ip4_punt;
+static vlib_node_registration_t stn_ip6_punt;
+
+static u8 stn_hw_addr_local[6] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x01};
+static u8 stn_hw_addr_dst[6] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x02};
+
+static ethernet_header_t stn_ip4_ethernet_header = {};
+static ethernet_header_t stn_ip6_ethernet_header = {};
+
+typedef struct {
+  clib_bihash_kv_16_8_t kv;
+} stn_ip46_punt_trace_t;
+
+static u8 *
+format_stn_rule (u8 * s, va_list * args)
+{
+  stn_rule_t *r = va_arg (*args, stn_rule_t *);
+  stn_main_t *stn = &stn_main;
+  u32 indent = format_get_indent (s);
+  u32 node_index = ip46_address_is_ip4(&r->address)?stn_ip4_punt.index:stn_ip6_punt.index;
+  vlib_node_t *next_node = vlib_get_next_node(vlib_get_main(), node_index, r->next_node_index);
+  s = format (s, "rule_index: %d\n", r - stn->rules);
+  s = format (s, "%Uaddress: %U\n", format_white_space, indent,
+	      format_ip46_address, &r->address, IP46_TYPE_ANY);
+  s = format (s, "%Uiface: %U (%d)\n", format_white_space, indent,
+  	      format_vnet_sw_if_index_name, vnet_get_main(), r->sw_if_index,
+	      r->sw_if_index);
+  s = format (s, "%Unext_node: %s (%d)", format_white_space, indent,
+	      next_node->name, next_node->index);
+  return s;
+}
+
+static_always_inline u8 *
+format_stn_ip46_punt_trace (u8 * s, va_list * args, u8 is_ipv4)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  stn_ip46_punt_trace_t *t = va_arg (*args, stn_ip46_punt_trace_t *);
+  u32 indent = format_get_indent (s);
+
+  format (s, "dst_address: %U\n", format_ip46_address,
+	  (ip46_address_t *)&t->kv.key, IP46_TYPE_ANY);
+
+  if (t->kv.value == ~(0L))
+    {
+      s = format (s, "%Urule: none", format_white_space, indent);
+    }
+  else
+    {
+      s = format (s, "%Urule:\n%U%U", format_white_space, indent,
+		     format_white_space, indent + 2,
+		     format_stn_rule, &stn_main.rules[t->kv.value]);
+    }
+  return s;
+}
+
+static void
+stn_punt_fn (vlib_main_t * vm,
+	           vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  u32 n_left_from, *from, next_index, *to_next, n_left_to_next;
+  stn_main_t *stn = &stn_main;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+
+      /* Single loop */
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+	  u32 pi0;
+	  vlib_buffer_t *p0;
+	  u32 next0;
+
+	  pi0 = to_next[0] = from[0];
+	  from += 1;
+	  n_left_from -= 1;
+	  to_next += 1;
+	  n_left_to_next -= 1;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+
+	  ip4_header_t *ip = vlib_buffer_get_current(p0);
+	  if ((ip->ip_version_and_header_length & 0xf0) == 0x40)
+	    next0 = stn->punt_to_stn_ip4_next_index;
+	  else
+	    next0 = stn->punt_to_stn_ip6_next_index;
+
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
+					   n_left_to_next, pi0, next0);
+	}
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+}
+
+typedef enum
+{
+  STN_IP_PUNT_DROP,
+  STN_IP_PUNT_N_NEXT,
+} stn_ip_punt_next_t;
+
+static_always_inline uword
+stn_ip46_punt_fn (vlib_main_t * vm,
+	           vlib_node_runtime_t * node, vlib_frame_t * frame,
+		   u8 is_ipv4)
+{
+  u32 n_left_from, *from, next_index, *to_next, n_left_to_next;
+  stn_main_t *stn = &stn_main;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+
+      /* Single loop */
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+	  u32 pi0;
+	  vlib_buffer_t *p0;
+	  clib_bihash_kv_16_8_t kv;
+	  u32 next0 = STN_IP_PUNT_DROP;
+
+	  pi0 = to_next[0] = from[0];
+	  from += 1;
+	  n_left_from -= 1;
+	  to_next += 1;
+	  n_left_to_next -= 1;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+
+	  if (is_ipv4)
+	    {
+	      ip4_header_t *hdr = (ip4_header_t *) vlib_buffer_get_current(p0);
+	      ip46_address_set_ip4((ip46_address_t *)kv.key, &hdr->dst_address);
+	    }
+	  else
+	    {
+	      ip6_header_t *hdr = (ip6_header_t *) vlib_buffer_get_current(p0);
+	      kv.key[0] = hdr->dst_address.as_u64[0];
+	      kv.key[1] = hdr->dst_address.as_u64[1];
+	    }
+
+	  kv.value = ~(0L);
+	  clib_bihash_search_inline_16_8 (&stn->rule_by_address_table, &kv);
+	  if (kv.value != ~(0L))
+	    {
+	      ethernet_header_t *eth;
+	      stn_rule_t *r = &stn->rules[kv.value];
+	      vnet_buffer(p0)->sw_if_index[VLIB_TX] = r->sw_if_index;
+	      next0 = r->next_node_index;
+	      vlib_buffer_advance(p0, -sizeof(*eth));
+	      eth = (ethernet_header_t *) vlib_buffer_get_current(p0);
+	      if (is_ipv4)
+		clib_memcpy(eth, &stn_ip4_ethernet_header, sizeof(*eth));
+	      else
+		clib_memcpy(eth, &stn_ip6_ethernet_header, sizeof(*eth));
+	    }
+
+	  if (PREDICT_FALSE (p0->flags & VLIB_BUFFER_IS_TRACED))
+	    {
+	      stn_ip46_punt_trace_t *tr =
+		  vlib_add_trace (vm, node, p0, sizeof (*tr));
+	      tr->kv = kv;
+	    }
+
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
+					   n_left_to_next, pi0, next0);
+	}
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  return frame->n_vectors;
+}
+
+
+#define foreach_stn_ip_punt_error \
+ _(NONE, "no error")
+
+typedef enum {
+#define _(sym,str) STN_IP_punt_ERROR_##sym,
+  foreach_stn_ip_punt_error
+#undef _
+  STN_IP_PUNT_N_ERROR,
+} ila_error_t;
+
+static char *stn_ip_punt_error_strings[] = {
+#define _(sym,string) string,
+    foreach_stn_ip_punt_error
+#undef _
+};
+
+u8 *
+format_stn_ip6_punt_trace (u8 * s, va_list * args)
+{
+  return format_stn_ip46_punt_trace (s, args, 0);
+}
+
+static uword
+stn_ip6_punt_fn (vlib_main_t * vm,
+	           vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  return stn_ip46_punt_fn(vm, node, frame, 0);
+}
+
+/** *INDENT-OFF* */
+VLIB_REGISTER_NODE (stn_ip6_punt, static) =
+{
+  .function = stn_ip6_punt_fn,
+  .name = "stn-ip6-punt",
+  .vector_size = sizeof (u32),
+  .format_trace = format_stn_ip6_punt_trace,
+  .n_errors = STN_IP_PUNT_N_ERROR,
+  .error_strings = stn_ip_punt_error_strings,
+  .n_next_nodes = STN_IP_PUNT_N_NEXT,
+  .next_nodes =
+  {
+      [STN_IP_PUNT_DROP] = "error-drop"
+  },
+};
+/** *INDENT-ON* */
+
+u8 *
+format_stn_ip4_punt_trace (u8 * s, va_list * args)
+{
+  return format_stn_ip46_punt_trace (s, args, 1);
+}
+
+static uword
+stn_ip4_punt_fn (vlib_main_t * vm,
+	           vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  return stn_ip46_punt_fn(vm, node, frame, 1);
+}
+
+/** *INDENT-OFF* */
+VLIB_REGISTER_NODE (stn_ip4_punt, static) =
+{
+  .function = stn_ip4_punt_fn,
+  .name = "stn-ip4-punt",
+  .vector_size = sizeof (u32),
+  .format_trace = format_stn_ip4_punt_trace,
+  .n_errors = STN_IP_PUNT_N_ERROR,
+  .error_strings = stn_ip_punt_error_strings,
+  .n_next_nodes = STN_IP_PUNT_N_NEXT,
+  .next_nodes =
+  {
+      [STN_IP_PUNT_DROP] = "error-drop",
+  },
+};
+/** *INDENT-ON* */
+
+clib_error_t *
+stn_init (vlib_main_t * vm)
+{
+  stn_main_t *stn = &stn_main;
+  stn->rules = 0;
+  clib_bihash_init_16_8(&stn->rule_by_address_table, "stn addresses",
+			1024, 1<<20);
+
+  clib_memcpy(stn_ip4_ethernet_header.dst_address, stn_hw_addr_dst, 6);
+  clib_memcpy(stn_ip4_ethernet_header.src_address, stn_hw_addr_local, 6);
+  stn_ip4_ethernet_header.type = clib_host_to_net_u16(ETHERNET_TYPE_IP4);
+
+  clib_memcpy(stn_ip6_ethernet_header.dst_address, stn_hw_addr_dst, 6);
+  clib_memcpy(stn_ip6_ethernet_header.src_address, stn_hw_addr_local, 6);
+  stn_ip6_ethernet_header.type = clib_host_to_net_u16(ETHERNET_TYPE_IP6);
+
+  u32 punt_node_index = vlib_get_node_by_name(vm, (u8 *)"error-punt")->index;
+  stn->punt_to_stn_ip4_next_index =
+      vlib_node_add_next(vm, punt_node_index, stn_ip4_punt.index);
+  stn->punt_to_stn_ip6_next_index =
+        vlib_node_add_next(vm, punt_node_index, stn_ip6_punt.index);
+
+  return stn_api_init (vm, stn);
+
+  return NULL;
+}
+
+VLIB_INIT_FUNCTION (stn_init);
+
+/* *INDENT-OFF* */
+VLIB_PLUGIN_REGISTER () = {
+    .version = VPP_BUILD_VER,
+    .description = "VPP Steals the NIC for Container integration",
+};
+/* *INDENT-ON* */
+
+int stn_rule_add_del (stn_rule_add_del_args_t *args)
+{
+  vnet_main_t *vnm = vnet_get_main();
+  vlib_main_t *vm = vlib_get_main();
+  stn_main_t *stn = &stn_main;
+
+  stn_rule_t *r = NULL;
+  clib_bihash_kv_16_8_t kv;
+  kv.key[0] = args->address.as_u64[0];
+  kv.key[1] = args->address.as_u64[1];
+
+  if (clib_bihash_search_inline_16_8 (&stn->rule_by_address_table, &kv) == 0)
+    {
+      r = &stn->rules[kv.value];
+    }
+  else if (!args->del)
+    {
+      pool_get(stn->rules, r);
+      kv.value = r - stn->rules;
+      clib_bihash_add_del_16_8(&stn->rule_by_address_table, &kv, 1);
+      r->address = args->address;
+
+      stn->n_rules++;
+      if (stn->n_rules == 1)
+	{
+	  foreach_vlib_main({
+	    this_vlib_main->os_punt_frame = stn_punt_fn;
+	  });
+	  udp_punt_unknown(vm, 0, 1);
+	  udp_punt_unknown(vm, 1, 1);
+	  tcp_punt_unknown(vm, 0, 1);
+	  tcp_punt_unknown(vm, 1, 1);
+	}
+    }
+
+  if (!args->del)
+    {
+      /* Getting output node and adding it as next */
+      u32 output_node_index =
+          vnet_tx_node_index_for_sw_interface(vnm, args->sw_if_index);
+      u32 node_index = ip46_address_is_ip4(&args->address)?
+          stn_ip4_punt.index : stn_ip6_punt.index;
+
+      r->sw_if_index = args->sw_if_index;
+      r->next_node_index =
+	  vlib_node_add_next(vm, node_index, output_node_index);
+
+      /* enabling forwarding on the output node (might not be done since
+       * it is unnumbered) */
+      vnet_feature_enable_disable("ip4-unicast", "ip4-lookup", args->sw_if_index,
+				  1, 0, 0);
+      vnet_feature_enable_disable("ip6-unicast", "ip6-lookup", args->sw_if_index,
+				  1, 0, 0);
+      vnet_feature_enable_disable("ip4-unicast", "ip4-drop", args->sw_if_index,
+				  0, 0, 0);
+      vnet_feature_enable_disable("ip6-unicast", "ip6-drop", args->sw_if_index,
+				  0, 0, 0);
+    }
+  else if (r)
+    {
+      clib_bihash_add_del_16_8(&stn->rule_by_address_table, &kv, 0);
+      pool_put(stn->rules, r);
+
+      stn->n_rules--;
+      if (stn->n_rules == 0)
+	{
+	  foreach_vlib_main({
+	    this_vlib_main->os_punt_frame = NULL;
+	  });
+	}
+    }
+  else
+    {
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
+
+  return 0;
+}
+
+static clib_error_t *
+show_stn_rules_fn (vlib_main_t * vm,
+		      unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+  stn_main_t *stn = &stn_main;
+  u8 *s = 0;
+  stn_rule_t *rule;
+  pool_foreach(rule, stn->rules, {
+      s = format (s, "- %U\n", format_stn_rule, rule);
+  });
+
+  vlib_cli_output(vm, "%v", s);
+
+  vec_free(s);
+  return NULL;
+}
+
+VLIB_CLI_COMMAND (show_stn_rules_command, static) =
+{
+  .path = "show stn rules",
+  .short_help = "",
+  .function = show_stn_rules_fn,
+};
+
+static clib_error_t *
+stn_rule_fn (vlib_main_t * vm,
+		      unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  clib_error_t *error = 0;
+  stn_rule_add_del_args_t args = {};
+  u8 got_addr = 0;
+  u8 got_iface = 0;
+  int ret;
+
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "address %U", unformat_ip46_address,
+		    &args.address, IP46_TYPE_ANY))
+	got_addr = 1;
+      else if (unformat
+	       (line_input, "interface %U", unformat_vnet_sw_interface,
+		vnet_get_main(), &args.sw_if_index))
+	got_iface = 1;
+      else if (unformat (line_input, "del"))
+	args.del = 1;
+      else
+	{
+	  error = clib_error_return (0, "parse error: '%U'",
+				     format_unformat_error, line_input);
+	  goto done;
+	}
+    }
+
+  if (!got_addr)
+    {
+      error = clib_error_return (0, "Missing address");
+      goto done;
+    }
+
+  if (!got_iface)
+    {
+      error = clib_error_return (0, "Missing interface");
+      goto done;
+    }
+
+  if ((ret = stn_rule_add_del (&args)))
+    {
+      error = clib_error_return (0, "stn_rule_add_del returned error %d", ret);
+      goto done;
+    }
+
+done:
+  unformat_free (line_input);
+  return error;
+}
+
+VLIB_CLI_COMMAND (stn_rule_command, static) =
+{
+  .path = "stn rule",
+  .short_help = "address <addr> interface <iface> [del]",
+  .function = stn_rule_fn,
+};
diff --git a/src/plugins/stn/stn.h b/src/plugins/stn/stn.h
new file mode 100644
index 00000000000..a6f0a0a5998
--- /dev/null
+++ b/src/plugins/stn/stn.h
@@ -0,0 +1,65 @@
+/*
+ * 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.
+ */
+
+#ifndef SRC_PLUGINS_STN_STN_H_
+#define SRC_PLUGINS_STN_STN_H_
+
+#include <vlib/vlib.h>
+#include <vnet/ip/ip4.h>
+#include <vnet/ip/ip6.h>
+#include <vppinfra/bihash_16_8.h>
+
+typedef struct {
+  ip46_address_t address;
+  u32 next_node_index;
+  u32 sw_if_index;
+} stn_rule_t;
+
+typedef struct {
+  /* pool of stn rules */
+  stn_rule_t *rules;
+
+  /* number of rules */
+  u32 n_rules;
+
+  /* hash table used to retrieve the rule from the ip address */
+  clib_bihash_16_8_t rule_by_address_table;
+
+  u32 punt_to_stn_ip4_next_index;
+  u32 punt_to_stn_ip6_next_index;
+
+  u16 msg_id_base;
+} stn_main_t;
+
+typedef struct {
+  /** Destination address of intercepted packets */
+  ip46_address_t address;
+  /** TX interface to send packets to */
+  u32 sw_if_index;
+  /** Whether to delete the rule */
+  u8 del;
+} stn_rule_add_del_args_t;
+
+/**
+ * Add or delete an stn rule.
+ */
+int stn_rule_add_del (stn_rule_add_del_args_t *args);
+
+extern stn_main_t stn_main;
+
+clib_error_t *
+stn_api_init (vlib_main_t * vm, stn_main_t * sm);
+
+#endif /* SRC_PLUGINS_STN_STN_H_ */
diff --git a/src/plugins/stn/stn_api.c b/src/plugins/stn/stn_api.c
new file mode 100644
index 00000000000..02ea29b6443
--- /dev/null
+++ b/src/plugins/stn/stn_api.c
@@ -0,0 +1,231 @@
+/*
+ * 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.
+ */
+
+#include <vlibapi/api.h>
+#include <vlibmemory/api.h>
+
+#include <plugins/stn/stn.h>
+#include <vnet/ip/format.h>
+
+#include <vppinfra/byte_order.h>
+
+/* define message IDs */
+#define vl_msg_id(n,h) n,
+typedef enum
+{
+#include <stn/stn.api.h>
+  /* We'll want to know how many messages IDs we need... */
+  VL_MSG_FIRST_AVAILABLE,
+} vl_msg_id_t;
+#undef vl_msg_id
+
+/* define message structures */
+#define vl_typedefs
+#include <stn/stn.api.h>
+#undef vl_typedefs
+
+/* define generated endian-swappers */
+#define vl_endianfun
+#include <stn/stn.api.h>
+#undef vl_endianfun
+
+/* instantiate all the print functions we know about */
+#define vl_print(handle, ...) vlib_cli_output (handle, __VA_ARGS__)
+#define vl_printfun
+#include <stn/stn.api.h>
+#undef vl_printfun
+
+/* Get the API version number */
+#define vl_api_version(n,v) static u32 api_version=(v);
+#include <nat/nat_all_api_h.h>
+#undef vl_api_version
+
+#define REPLY_MSG_ID_BASE stn_main.msg_id_base
+#include <vlibapi/api_helper_macros.h>
+
+/* Macro to finish up custom dump fns */
+#define FINISH                                  \
+    vec_add1 (s, 0);                            \
+    vl_print (handle, (char *)s);               \
+    vec_free (s);                               \
+    return handle;
+
+/**
+ * @brief API message custom-dump function
+ * @param mp vl_api_stn_add_del_rule_t * mp the api message
+ * @param handle void * print function handle
+ * @returns u8 * output string
+ */
+static void *vl_api_stn_add_del_rule_t_print
+  (vl_api_stn_add_del_rule_t * mp, void *handle)
+{
+  u8 *s;
+
+  s = format (0, "SCRIPT: stn_add_del_rule ");
+  if (mp->is_ip4)
+    s = format (s, "address %U ", format_ip4_address, mp->ip_address);
+  else
+    s = format (s, "address %U ", format_ip6_address, mp->ip_address);
+  s = format (s, "sw_if_index %d is_add %d", mp->sw_if_index, mp->is_add);
+
+  FINISH;
+}
+
+static void
+vl_api_stn_add_del_rule_t_handler (vl_api_stn_add_del_rule_t * mp)
+{
+  stn_rule_add_del_args_t args;
+  vl_api_stn_add_del_rule_reply_t *rmp;
+  int rv = 0;
+
+  if (mp->is_ip4)
+    {
+      ip4_address_t a;
+      memcpy(&a, mp->ip_address, sizeof(a));
+      ip46_address_set_ip4(&args.address, &a);
+    }
+  else
+    memcpy(&args.address.ip6, mp->ip_address, sizeof(ip6_address_t));
+
+  args.sw_if_index = clib_net_to_host_u32(mp->sw_if_index);
+  args.del = !mp->is_add;
+
+  rv = stn_rule_add_del(&args);
+
+  REPLY_MACRO (VL_API_STN_ADD_DEL_RULE_REPLY);
+}
+
+static void
+send_stn_rule (stn_rule_t *r, unix_shared_memory_queue_t *q, u32 context)
+{
+  vl_api_stn_rule_details_t *rmp;
+
+  rmp =
+      vl_msg_api_alloc (sizeof (*rmp));
+  memset (rmp, 0, sizeof (*rmp));
+  rmp->_vl_msg_id =
+      clib_host_to_net_u32 (VL_API_STN_RULES_DUMP + stn_main.msg_id_base);
+
+  if (ip46_address_is_ip4(&r->address))
+    {
+      clib_memcpy(rmp->ip_address, &r->address.ip4, sizeof(ip4_address_t));
+      rmp->is_ip4 = 1;
+    }
+  else
+    {
+      clib_memcpy(rmp->ip_address, &r->address.ip6, sizeof(ip6_address_t));
+    }
+
+  rmp->context = context;
+  rmp->sw_if_index = clib_host_to_net_u32(r->sw_if_index);
+
+  vl_msg_api_send_shmem (q, (u8 *) & rmp);
+}
+
+static void
+vl_api_stn_rules_dump_t_handler (vl_api_stn_rules_dump_t *mp)
+{
+  unix_shared_memory_queue_t *q;
+  stn_main_t *stn = &stn_main;
+  stn_rule_t *r;
+
+  q = vl_api_client_index_to_input_queue (mp->client_index);
+  if (q == 0)
+    return;
+
+  /* *INDENT-OFF* */
+  pool_foreach (r, stn->rules,
+		({
+
+    send_stn_rule (r, q, mp->context);
+  }));
+  /* *INDENT-ON* */
+}
+
+
+/* List of message types that this plugin understands */
+#define foreach_stn_plugin_api_msg			\
+_(STN_ADD_DEL_RULE, stn_add_del_rule)	\
+_(STN_RULES_DUMP, stn_rules_dump)
+
+/**
+ * @brief Set up the API message handling tables
+ * @param vm vlib_main_t * vlib main data structure pointer
+ * @returns 0 to indicate all is well
+ */
+static clib_error_t *
+stn_plugin_api_hookup (vlib_main_t * vm)
+{
+  stn_main_t *stn = &stn_main;
+#define _(N,n)                                                  \
+    vl_msg_api_set_handlers((VL_API_##N + stn->msg_id_base),     \
+                           #n,					\
+                           vl_api_##n##_t_handler,              \
+                           vl_noop_handler,                     \
+                           vl_api_##n##_t_endian,               \
+                           vl_api_##n##_t_print,                \
+                           sizeof(vl_api_##n##_t), 1);
+  foreach_stn_plugin_api_msg;
+#undef _
+
+  return 0;
+}
+
+#define vl_msg_name_crc_list
+#include <stn/stn.api.h>
+#undef vl_msg_name_crc_list
+
+static void
+setup_message_id_table (stn_main_t * stn, api_main_t * am)
+{
+#define _(id,n,crc) \
+  vl_msg_api_add_msg_name_crc (am, #n "_" #crc, id + stn->msg_id_base);
+  foreach_vl_msg_name_crc_stn;
+#undef _
+}
+
+static void
+plugin_custom_dump_configure (stn_main_t * stn)
+{
+#define _(n,f) api_main.msg_print_handlers \
+  [VL_API_##n + stn->msg_id_base]                \
+    = (void *) vl_api_##f##_t_print;
+  foreach_stn_plugin_api_msg;
+#undef _
+}
+
+clib_error_t *
+stn_api_init (vlib_main_t * vm, stn_main_t * sm)
+{
+  u8 *name;
+  clib_error_t *error = 0;
+
+  name = format (0, "stn_%08x%c", api_version, 0);
+
+  /* Ask for a correctly-sized block of API message decode slots */
+  sm->msg_id_base =
+    vl_msg_api_get_msg_ids ((char *) name, VL_MSG_FIRST_AVAILABLE);
+
+  error = stn_plugin_api_hookup (vm);
+
+  /* Add our API messages to the global name_crc hash table */
+  setup_message_id_table (sm, &api_main);
+
+  plugin_custom_dump_configure (sm);
+
+  vec_free (name);
+
+  return error;
+}