VPP-598: tcp stack initial commit

Change-Id: I49e5ce0aae6e4ff634024387ceaf7dbc432a0351
Signed-off-by: Dave Barach <dave@barachs.net>
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 1286 insertions, 0 deletions

diff --git a/src/vnet/session/session.c b/src/vnet/session/session.c
new file mode 100644
index 00000000000..539da613367
--- /dev/null
+++ b/src/vnet/session/session.c
@@ -0,0 +1,1286 @@
+/*
+ * 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 Session and session manager
+ */
+
+#include <vnet/session/session.h>
+#include <vlibmemory/api.h>
+#include <vnet/dpo/load_balance.h>
+#include <vnet/fib/ip4_fib.h>
+#include <vnet/session/application.h>
+
+/**
+ * Per-type vector of transport protocol virtual function tables
+ */
+static transport_proto_vft_t *tp_vfts;
+
+session_manager_main_t session_manager_main;
+
+/*
+ * Session lookup key; (src-ip, dst-ip, src-port, dst-port, session-type)
+ * Value: (owner thread index << 32 | session_index);
+ */
+static void
+stream_session_table_add_for_tc (u8 sst, transport_connection_t * tc,
+				 u64 value)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  session_kv4_t kv4;
+  session_kv6_t kv6;
+
+  switch (sst)
+    {
+    case SESSION_TYPE_IP4_UDP:
+    case SESSION_TYPE_IP4_TCP:
+      make_v4_ss_kv_from_tc (&kv4, tc);
+      kv4.value = value;
+      clib_bihash_add_del_16_8 (&smm->v4_session_hash, &kv4, 1 /* is_add */ );
+      break;
+    case SESSION_TYPE_IP6_UDP:
+    case SESSION_TYPE_IP6_TCP:
+      make_v6_ss_kv_from_tc (&kv6, tc);
+      kv6.value = value;
+      clib_bihash_add_del_48_8 (&smm->v6_session_hash, &kv6, 1 /* is_add */ );
+      break;
+    default:
+      clib_warning ("Session type not supported");
+      ASSERT (0);
+    }
+}
+
+void
+stream_session_table_add (session_manager_main_t * smm, stream_session_t * s,
+			  u64 value)
+{
+  transport_connection_t *tc;
+
+  tc = tp_vfts[s->session_type].get_connection (s->connection_index,
+						s->thread_index);
+  stream_session_table_add_for_tc (s->session_type, tc, value);
+}
+
+static void
+stream_session_half_open_table_add (u8 sst, transport_connection_t * tc,
+				    u64 value)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  session_kv4_t kv4;
+  session_kv6_t kv6;
+
+  switch (sst)
+    {
+    case SESSION_TYPE_IP4_UDP:
+    case SESSION_TYPE_IP4_TCP:
+      make_v4_ss_kv_from_tc (&kv4, tc);
+      kv4.value = value;
+      clib_bihash_add_del_16_8 (&smm->v4_half_open_hash, &kv4,
+				1 /* is_add */ );
+      break;
+    case SESSION_TYPE_IP6_UDP:
+    case SESSION_TYPE_IP6_TCP:
+      make_v6_ss_kv_from_tc (&kv6, tc);
+      kv6.value = value;
+      clib_bihash_add_del_48_8 (&smm->v6_half_open_hash, &kv6,
+				1 /* is_add */ );
+      break;
+    default:
+      clib_warning ("Session type not supported");
+      ASSERT (0);
+    }
+}
+
+static int
+stream_session_table_del_for_tc (session_manager_main_t * smm, u8 sst,
+				 transport_connection_t * tc)
+{
+  session_kv4_t kv4;
+  session_kv6_t kv6;
+
+  switch (sst)
+    {
+    case SESSION_TYPE_IP4_UDP:
+    case SESSION_TYPE_IP4_TCP:
+      make_v4_ss_kv_from_tc (&kv4, tc);
+      return clib_bihash_add_del_16_8 (&smm->v4_session_hash, &kv4,
+				       0 /* is_add */ );
+      break;
+    case SESSION_TYPE_IP6_UDP:
+    case SESSION_TYPE_IP6_TCP:
+      make_v6_ss_kv_from_tc (&kv6, tc);
+      return clib_bihash_add_del_48_8 (&smm->v6_session_hash, &kv6,
+				       0 /* is_add */ );
+      break;
+    default:
+      clib_warning ("Session type not supported");
+      ASSERT (0);
+    }
+
+  return 0;
+}
+
+static int
+stream_session_table_del (session_manager_main_t * smm, stream_session_t * s)
+{
+  transport_connection_t *ts;
+
+  ts = tp_vfts[s->session_type].get_connection (s->connection_index,
+						s->thread_index);
+  return stream_session_table_del_for_tc (smm, s->session_type, ts);
+}
+
+static void
+stream_session_half_open_table_del (session_manager_main_t * smm, u8 sst,
+				    transport_connection_t * tc)
+{
+  session_kv4_t kv4;
+  session_kv6_t kv6;
+
+  switch (sst)
+    {
+    case SESSION_TYPE_IP4_UDP:
+    case SESSION_TYPE_IP4_TCP:
+      make_v4_ss_kv_from_tc (&kv4, tc);
+      clib_bihash_add_del_16_8 (&smm->v4_half_open_hash, &kv4,
+				0 /* is_add */ );
+      break;
+    case SESSION_TYPE_IP6_UDP:
+    case SESSION_TYPE_IP6_TCP:
+      make_v6_ss_kv_from_tc (&kv6, tc);
+      clib_bihash_add_del_48_8 (&smm->v6_half_open_hash, &kv6,
+				0 /* is_add */ );
+      break;
+    default:
+      clib_warning ("Session type not supported");
+      ASSERT (0);
+    }
+}
+
+stream_session_t *
+stream_session_lookup_listener4 (ip4_address_t * lcl, u16 lcl_port, u8 proto)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  session_kv4_t kv4;
+  int rv;
+
+  make_v4_listener_kv (&kv4, lcl, lcl_port, proto);
+  rv = clib_bihash_search_inline_16_8 (&smm->v4_session_hash, &kv4);
+  if (rv == 0)
+    return pool_elt_at_index (smm->listen_sessions[proto], (u32) kv4.value);
+
+  /* Zero out the lcl ip */
+  kv4.key[0] = 0;
+  rv = clib_bihash_search_inline_16_8 (&smm->v4_session_hash, &kv4);
+  if (rv == 0)
+    return pool_elt_at_index (smm->listen_sessions[proto], kv4.value);
+
+  return 0;
+}
+
+/** Looks up a session based on the 5-tuple passed as argument.
+ *
+ * First it tries to find an established session, if this fails, it tries
+ * finding a listener session if this fails, it tries a lookup with a
+ * wildcarded local source (listener bound to all interfaces)
+ */
+stream_session_t *
+stream_session_lookup4 (ip4_address_t * lcl, ip4_address_t * rmt,
+			u16 lcl_port, u16 rmt_port, u8 proto,
+			u32 my_thread_index)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  session_kv4_t kv4;
+  int rv;
+
+  /* Lookup session amongst established ones */
+  make_v4_ss_kv (&kv4, lcl, rmt, lcl_port, rmt_port, proto);
+  rv = clib_bihash_search_inline_16_8 (&smm->v4_session_hash, &kv4);
+  if (rv == 0)
+    return stream_session_get_tsi (kv4.value, my_thread_index);
+
+  /* If nothing is found, check if any listener is available */
+  return stream_session_lookup_listener4 (lcl, lcl_port, proto);
+}
+
+stream_session_t *
+stream_session_lookup_listener6 (ip6_address_t * lcl, u16 lcl_port, u8 proto)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  session_kv6_t kv6;
+  int rv;
+
+  make_v6_listener_kv (&kv6, lcl, lcl_port, proto);
+  rv = clib_bihash_search_inline_48_8 (&smm->v6_session_hash, &kv6);
+  if (rv == 0)
+    return pool_elt_at_index (smm->listen_sessions[proto], kv6.value);
+
+  /* Zero out the lcl ip */
+  kv6.key[0] = kv6.key[1] = 0;
+  rv = clib_bihash_search_inline_48_8 (&smm->v6_session_hash, &kv6);
+  if (rv == 0)
+    return pool_elt_at_index (smm->listen_sessions[proto], kv6.value);
+
+  return 0;
+}
+
+/* Looks up a session based on the 5-tuple passed as argument.
+ * First it tries to find an established session, if this fails, it tries
+ * finding a listener session if this fails, it tries a lookup with a
+ * wildcarded local source (listener bound to all interfaces) */
+stream_session_t *
+stream_session_lookup6 (ip6_address_t * lcl, ip6_address_t * rmt,
+			u16 lcl_port, u16 rmt_port, u8 proto,
+			u32 my_thread_index)
+{
+  session_manager_main_t *smm = vnet_get_session_manager_main ();
+  session_kv6_t kv6;
+  int rv;
+
+  make_v6_ss_kv (&kv6, lcl, rmt, lcl_port, rmt_port, proto);
+  rv = clib_bihash_search_inline_48_8 (&smm->v6_session_hash, &kv6);
+  if (rv == 0)
+    return stream_session_get_tsi (kv6.value, my_thread_index);
+
+  /* If nothing is found, check if any listener is available */
+  return stream_session_lookup_listener6 (lcl, lcl_port, proto);
+}
+
+stream_session_t *
+stream_session_lookup_listener (ip46_address_t * lcl, u16 lcl_port, u8 proto)
+{
+  switch (proto)
+    {
+    case SESSION_TYPE_IP4_UDP:
+    case SESSION_TYPE_IP4_TCP:
+      return stream_session_lookup_listener4 (&lcl->ip4, lcl_port, proto);
+      break;
+    case SESSION_TYPE_IP6_UDP:
+    case SESSION_TYPE_IP6_TCP:
+      return stream_session_lookup_listener6 (&lcl->ip6, lcl_port, proto);
+      break;
+    }
+  return 0;
+}
+
+static u64
+stream_session_half_open_lookup (session_manager_main_t * smm,
+				 ip46_address_t * lcl, ip46_address_t * rmt,
+				 u16 lcl_port, u16 rmt_port, u8 proto)
+{
+  session_kv4_t kv4;
+  session_kv6_t kv6;
+  int rv;
+
+  switch (proto)
+    {
+    case SESSION_TYPE_IP4_UDP:
+    case SESSION_TYPE_IP4_TCP:
+      make_v4_ss_kv (&kv4, &lcl->ip4, &rmt->ip4, lcl_port, rmt_port, proto);
+      rv = clib_bihash_search_inline_16_8 (&smm->v4_half_open_hash, &kv4);
+
+      if (rv == 0)
+	return kv4.value;
+
+      return (u64) ~ 0;
+      break;
+    case SESSION_TYPE_IP6_UDP:
+    case SESSION_TYPE_IP6_TCP:
+      make_v6_ss_kv (&kv6, &lcl->ip6, &rmt->ip6, lcl_port, rmt_port, proto);
+      rv = clib_bihash_search_inline_48_8 (&smm->v6_half_open_hash, &kv6);
+
+      if (rv == 0)
+	return kv6.value;
+
+      return (u64) ~ 0;
+      break;
+    }
+  return 0;
+}
+
+transport_connection_t *
+stream_session_lookup_transport4 (session_manager_main_t * smm,
+				  ip4_address_t * lcl, ip4_address_t * rmt,
+				  u16 lcl_port, u16 rmt_port, u8 proto,
+				  u32 my_thread_index)
+{
+  session_kv4_t kv4;
+  stream_session_t *s;
+  int rv;
+
+  /* Lookup session amongst established ones */
+  make_v4_ss_kv (&kv4, lcl, rmt, lcl_port, rmt_port, proto);
+  rv = clib_bihash_search_inline_16_8 (&smm->v4_session_hash, &kv4);
+  if (rv == 0)
+    {
+      s = stream_session_get_tsi (kv4.value, my_thread_index);
+
+      return tp_vfts[s->session_type].get_connection (s->connection_index,
+						      my_thread_index);
+    }
+
+  /* If nothing is found, check if any listener is available */
+  s = stream_session_lookup_listener4 (lcl, lcl_port, proto);
+  if (s)
+    return tp_vfts[s->session_type].get_listener (s->connection_index);
+
+  /* Finally, try half-open connections */
+  rv = clib_bihash_search_inline_16_8 (&smm->v4_half_open_hash, &kv4);
+  if (rv == 0)
+    return tp_vfts[proto].get_half_open (kv4.value & 0xFFFFFFFF);
+
+  return 0;
+}
+
+transport_connection_t *
+stream_session_lookup_transport6 (session_manager_main_t * smm,
+				  ip6_address_t * lcl, ip6_address_t * rmt,
+				  u16 lcl_port, u16 rmt_port, u8 proto,
+				  u32 my_thread_index)
+{
+  stream_session_t *s;
+  session_kv6_t kv6;
+  int rv;
+
+  make_v6_ss_kv (&kv6, lcl, rmt, lcl_port, rmt_port, proto);
+  rv = clib_bihash_search_inline_48_8 (&smm->v6_session_hash, &kv6);
+  if (rv == 0)
+    {
+      s = stream_session_get_tsi (kv6.value, my_thread_index);
+
+      return tp_vfts[s->session_type].get_connection (s->connection_index,
+						      my_thread_index);
+    }
+
+  /* If nothing is found, check if any listener is available */
+  s = stream_session_lookup_listener6 (lcl, lcl_port, proto);
+  if (s)
+    return tp_vfts[s->session_type].get_listener (s->connection_index);
+
+  /* Finally, try half-open connections */
+  rv = clib_bihash_search_inline_48_8 (&smm->v6_half_open_hash, &kv6);
+  if (rv == 0)
+    return tp_vfts[s->session_type].get_half_open (kv6.value & 0xFFFFFFFF);
+
+  return 0;
+}
+
+/**
+ * Allocate vpp event queue (once) per worker thread
+ */
+void
+vpp_session_event_queue_allocate (session_manager_main_t * smm,
+				  u32 thread_index)
+{
+  api_main_t *am = &api_main;
+  void *oldheap;
+
+  if (smm->vpp_event_queues[thread_index] == 0)
+    {
+      /* Allocate event fifo in the /vpe-api shared-memory segment */
+      oldheap = svm_push_data_heap (am->vlib_rp);
+
+      smm->vpp_event_queues[thread_index] =
+	unix_shared_memory_queue_init (2048 /* nels $$$$ config */ ,
+				       sizeof (session_fifo_event_t),
+				       0 /* consumer pid */ ,
+				       0
+				       /* (do not) send signal when queue non-empty */
+	);
+
+      svm_pop_heap (oldheap);
+    }
+}
+
+void
+session_manager_get_segment_info (u32 index, u8 ** name, u32 * size)
+{
+  svm_fifo_segment_private_t *s;
+  s = svm_fifo_get_segment (index);
+  *name = s->h->segment_name;
+  *size = s->ssvm.ssvm_size;
+}
+
+always_inline int
+session_manager_add_segment_i (session_manager_main_t * smm,
+			       session_manager_t * sm,
+			       u32 segment_size, u8 * segment_name)
+{
+  svm_fifo_segment_create_args_t _ca, *ca = &_ca;
+  int rv;
+
+  memset (ca, 0, sizeof (*ca));
+
+  ca->segment_name = (char *) segment_name;
+  ca->segment_size = segment_size;
+
+  rv = svm_fifo_segment_create (ca);
+  if (rv)
+    {
+      clib_warning ("svm_fifo_segment_create ('%s', %d) failed",
+		    ca->segment_name, ca->segment_size);
+      vec_free (segment_name);
+      return -1;
+    }
+
+  vec_add1 (sm->segment_indices, ca->new_segment_index);
+
+  return 0;
+}
+
+static int
+session_manager_add_segment (session_manager_main_t * smm,
+			     session_manager_t * sm)
+{
+  u8 *segment_name;
+  svm_fifo_segment_create_args_t _ca, *ca = &_ca;
+  u32 add_segment_size;
+  u32 default_segment_size = 128 << 10;
+
+  memset (ca, 0, sizeof (*ca));
+  segment_name = format (0, "%d-%d%c", getpid (),
+			 smm->unique_segment_name_counter++, 0);
+  add_segment_size =
+    sm->add_segment_size ? sm->add_segment_size : default_segment_size;
+
+  return session_manager_add_segment_i (smm, sm, add_segment_size,
+					segment_name);
+}
+
+int
+session_manager_add_first_segment (session_manager_main_t * smm,
+				   session_manager_t * sm, u32 segment_size,
+				   u8 ** segment_name)
+{
+  svm_fifo_segment_create_args_t _ca, *ca = &_ca;
+  memset (ca, 0, sizeof (*ca));
+  *segment_name = format (0, "%d-%d%c", getpid (),
+			  smm->unique_segment_name_counter++, 0);
+  return session_manager_add_segment_i (smm, sm, segment_size, *segment_name);
+}
+
+void
+session_manager_del (session_manager_main_t * smm, session_manager_t * sm)
+{
+  u32 *deleted_sessions = 0;
+  u32 *deleted_thread_indices = 0;
+  int i, j;
+
+  /* Across all fifo segments used by the server */
+  for (j = 0; j < vec_len (sm->segment_indices); j++)
+    {
+      svm_fifo_segment_private_t *fifo_segment;
+      svm_fifo_t **fifos;
+      /* Vector of fifos allocated in the segment */
+      fifo_segment = svm_fifo_get_segment (sm->segment_indices[j]);
+      fifos = (svm_fifo_t **) fifo_segment->h->fifos;
+
+      /*
+       * Remove any residual sessions from the session lookup table
+       * Don't bother deleting the individual fifos, we're going to
+       * throw away the fifo segment in a minute.
+       */
+      for (i = 0; i < vec_len (fifos); i++)
+	{
+	  svm_fifo_t *fifo;
+	  u32 session_index, thread_index;
+	  stream_session_t *session;
+
+	  fifo = fifos[i];
+	  session_index = fifo->server_session_index;
+	  thread_index = fifo->server_thread_index;
+
+	  session = pool_elt_at_index (smm->sessions[thread_index],
+				       session_index);
+
+	  /* Add to the deleted_sessions vector (once!) */
+	  if (!session->is_deleted)
+	    {
+	      session->is_deleted = 1;
+	      vec_add1 (deleted_sessions,
+			session - smm->sessions[thread_index]);
+	      vec_add1 (deleted_thread_indices, thread_index);
+	    }
+	}
+
+      for (i = 0; i < vec_len (deleted_sessions); i++)
+	{
+	  stream_session_t *session;
+
+	  session =
+	    pool_elt_at_index (smm->sessions[deleted_thread_indices[i]],
+			       deleted_sessions[i]);
+
+	  /* Instead of directly removing the session call disconnect */
+	  stream_session_disconnect (session);
+
+	  /*
+	     stream_session_table_del (smm, session);
+	     pool_put(smm->sessions[deleted_thread_indices[i]], session);
+	   */
+	}
+
+      vec_reset_length (deleted_sessions);
+      vec_reset_length (deleted_thread_indices);
+
+      /* Instead of removing the segment, test when removing the session if
+       * the segment can be removed
+       */
+      /* svm_fifo_segment_delete (fifo_segment); */
+    }
+
+  vec_free (deleted_sessions);
+  vec_free (deleted_thread_indices);
+}
+
+int
+session_manager_allocate_session_fifos (session_manager_main_t * smm,
+					session_manager_t * sm,
+					svm_fifo_t ** server_rx_fifo,
+					svm_fifo_t ** server_tx_fifo,
+					u32 * fifo_segment_index,
+					u8 * added_a_segment)
+{
+  svm_fifo_segment_private_t *fifo_segment;
+  u32 fifo_size, default_fifo_size = 8192 /* TODO config */ ;
+  int i;
+
+  *added_a_segment = 0;
+
+  /* Allocate svm fifos */
+  ASSERT (vec_len (sm->segment_indices));
+
+again:
+  for (i = 0; i < vec_len (sm->segment_indices); i++)
+    {
+      *fifo_segment_index = sm->segment_indices[i];
+      fifo_segment = svm_fifo_get_segment (*fifo_segment_index);
+
+      fifo_size = sm->rx_fifo_size;
+      fifo_size = (fifo_size == 0) ? default_fifo_size : fifo_size;
+      *server_rx_fifo = svm_fifo_segment_alloc_fifo (fifo_segment, fifo_size);
+
+      fifo_size = sm->tx_fifo_size;
+      fifo_size = (fifo_size == 0) ? default_fifo_size : fifo_size;
+      *server_tx_fifo = svm_fifo_segment_alloc_fifo (fifo_segment, fifo_size);
+
+      if (*server_rx_fifo == 0)
+	{
+	  /* This would be very odd, but handle it... */
+	  if (*server_tx_fifo != 0)
+	    {
+	      svm_fifo_segment_free_fifo (fifo_segment, *server_tx_fifo);
+	      *server_tx_fifo = 0;
+	    }
+	  continue;
+	}
+      if (*server_tx_fifo == 0)
+	{
+	  if (*server_rx_fifo != 0)
+	    {
+	      svm_fifo_segment_free_fifo (fifo_segment, *server_rx_fifo);
+	      *server_rx_fifo = 0;
+	    }
+	  continue;
+	}
+      break;
+    }
+
+  /* See if we're supposed to create another segment */
+  if (*server_rx_fifo == 0)
+    {
+      if (sm->add_segment)
+	{
+	  if (*added_a_segment)
+	    {
+	      clib_warning ("added a segment, still cant allocate a fifo");
+	      return SESSION_ERROR_NEW_SEG_NO_SPACE;
+	    }
+
+	  if (session_manager_add_segment (smm, sm))
+	    return VNET_API_ERROR_URI_FIFO_CREATE_FAILED;
+
+	  *added_a_segment = 1;
+	  goto again;
+	}
+      else
+	return SESSION_ERROR_NO_SPACE;
+    }
+  return 0;
+}
+
+int
+stream_session_create_i (session_manager_main_t * smm, application_t * app,
+			 transport_connection_t * tc,
+			 stream_session_t ** ret_s)
+{
+  int rv;
+  svm_fifo_t *server_rx_fifo = 0, *server_tx_fifo = 0;
+  u32 fifo_segment_index;
+  u32 pool_index, seg_size;
+  stream_session_t *s;
+  u64 value;
+  u32 thread_index = tc->thread_index;
+  session_manager_t *sm;
+  u8 segment_added;
+  u8 *seg_name;
+
+  sm = session_manager_get (app->session_manager_index);
+
+  /* Check the API queue */
+  if (app->mode == APP_SERVER && application_api_queue_is_full (app))
+    return SESSION_ERROR_API_QUEUE_FULL;
+
+  if ((rv = session_manager_allocate_session_fifos (smm, sm, &server_rx_fifo,
+						    &server_tx_fifo,
+						    &fifo_segment_index,
+						    &segment_added)))
+    return rv;
+
+  if (segment_added && app->mode == APP_SERVER)
+    {
+      /* Send an API message to the external server, to map new segment */
+      ASSERT (app->cb_fns.add_segment_callback);
+
+      session_manager_get_segment_info (fifo_segment_index, &seg_name,
+					&seg_size);
+      if (app->cb_fns.add_segment_callback (app->api_client_index, seg_name,
+					    seg_size))
+	return VNET_API_ERROR_URI_FIFO_CREATE_FAILED;
+    }
+
+  /* Create the session */
+  pool_get (smm->sessions[thread_index], s);
+  memset (s, 0, sizeof (*s));
+
+  /* Initialize backpointers */
+  pool_index = s - smm->sessions[thread_index];
+  server_rx_fifo->server_session_index = pool_index;
+  server_rx_fifo->server_thread_index = thread_index;
+
+  server_tx_fifo->server_session_index = pool_index;
+  server_tx_fifo->server_thread_index = thread_index;
+
+  s->server_rx_fifo = server_rx_fifo;
+  s->server_tx_fifo = server_tx_fifo;
+
+  /* Initialize state machine, such as it is... */
+  s->session_type = app->session_type;
+  s->session_state = SESSION_STATE_CONNECTING;
+  s->app_index = application_get_index (app);
+  s->server_segment_index = fifo_segment_index;
+  s->thread_index = thread_index;
+  s->session_index = pool_index;
+
+  /* Attach transport to session */
+  s->connection_index = tc->c_index;
+
+  /* Attach session to transport */
+  tc->s_index = s->session_index;
+
+  /* Add to the main lookup table */
+  value = (((u64) thread_index) << 32) | (u64) s->session_index;
+  stream_session_table_add_for_tc (app->session_type, tc, value);
+
+  *ret_s = s;
+
+  return 0;
+}
+
+/*
+ * Enqueue data for delivery to session peer. Does not notify peer of enqueue
+ * event but on request can queue notification events for later delivery by
+ * calling stream_server_flush_enqueue_events().
+ *
+ * @param tc Transport connection which is to be enqueued data
+ * @param data Data to be enqueued
+ * @param len Length of data to be enqueued
+ * @param queue_event Flag to indicate if peer is to be notified or if event
+ *                    is to be queued. The former is useful when more data is
+ *                    enqueued and only one event is to be generated.
+ * @return Number of bytes enqueued or a negative value if enqueueing failed.
+ */
+int
+stream_session_enqueue_data (transport_connection_t * tc, u8 * data, u16 len,
+			     u8 queue_event)
+{
+  stream_session_t *s;
+  int enqueued;
+
+  s = stream_session_get (tc->s_index, tc->thread_index);
+
+  /* Make sure there's enough space left. We might've filled the pipes */
+  if (PREDICT_FALSE (len > svm_fifo_max_enqueue (s->server_rx_fifo)))
+    return -1;
+
+  enqueued = svm_fifo_enqueue_nowait (s->server_rx_fifo, s->pid, len, data);
+
+  if (queue_event)
+    {
+      /* Queue RX event on this fifo. Eventually these will need to be flushed
+       * by calling stream_server_flush_enqueue_events () */
+      session_manager_main_t *smm = vnet_get_session_manager_main ();
+      u32 thread_index = s->thread_index;
+      u32 my_enqueue_epoch = smm->current_enqueue_epoch[thread_index];
+
+      if (s->enqueue_epoch != my_enqueue_epoch)
+	{
+	  s->enqueue_epoch = my_enqueue_epoch;
+	  vec_add1 (smm->session_indices_to_enqueue_by_thread[thread_index],
+		    s - smm->sessions[thread_index]);
+	}
+    }
+
+  return enqueued;
+}
+
+/** Check if we have space in rx fifo to push more bytes */
+u8
+stream_session_no_space (transport_connection_t * tc, u32 thread_index,
+			 u16 data_len)
+{
+  stream_session_t *s = stream_session_get (tc->c_index, thread_index);
+
+  if (PREDICT_FALSE (s->session_state != SESSION_STATE_READY))
+    return 1;
+
+  if (data_len > svm_fifo_max_enqueue (s->server_rx_fifo))
+    return 1;
+
+  return 0;
+}
+
+u32
+stream_session_peek_bytes (transport_connection_t * tc, u8 * buffer,
+			   u32 offset, u32 max_bytes)
+{
+  stream_session_t *s = stream_session_get (tc->s_index, tc->thread_index);
+  return svm_fifo_peek (s->server_tx_fifo, s->pid, offset, max_bytes, buffer);
+}
+
+u32
+stream_session_dequeue_drop (transport_connection_t * tc, u32 max_bytes)
+{
+  stream_session_t *s = stream_session_get (tc->s_index, tc->thread_index);
+  return svm_fifo_dequeue_drop (s->server_tx_fifo, s->pid, max_bytes);
+}
+
+/**
+ * Notify session peer that new data has been enqueued.
+ *
+ * @param s Stream session for which the event is to be generated.
+ * @param block Flag to indicate if call should block if event queue is full.
+ *
+ * @return 0 on succes or negative number if failed to send notification.
+ */
+static int
+stream_session_enqueue_notify (stream_session_t * s, u8 block)
+{
+  application_t *app;
+  session_fifo_event_t evt;
+  unix_shared_memory_queue_t *q;
+  static u32 serial_number;
+
+  if (PREDICT_FALSE (s->session_state == SESSION_STATE_CLOSED))
+    return 0;
+
+  /* Get session's server */
+  app = application_get (s->app_index);
+
+  /* Fabricate event */
+  evt.fifo = s->server_rx_fifo;
+  evt.event_type = FIFO_EVENT_SERVER_RX;
+  evt.event_id = serial_number++;
+  evt.enqueue_length = svm_fifo_max_dequeue (s->server_rx_fifo);
+
+  /* Add event to server's event queue */
+  q = app->event_queue;
+
+  /* Based on request block (or not) for lack of space */
+  if (block || PREDICT_TRUE (q->cursize < q->maxsize))
+    unix_shared_memory_queue_add (app->event_queue, (u8 *) & evt,
+				  0 /* do wait for mutex */ );
+  else
+    return -1;
+
+  if (1)
+    {
+      ELOG_TYPE_DECLARE (e) =
+      {
+      .format = "evt-enqueue: id %d length %d",.format_args = "i4i4",};
+      struct
+      {
+	u32 data[2];
+      } *ed;
+      ed = ELOG_DATA (&vlib_global_main.elog_main, e);
+      ed->data[0] = evt.event_id;
+      ed->data[1] = evt.enqueue_length;
+    }
+
+  return 0;
+}
+
+/**
+ * Flushes queue of sessions that are to be notified of new data
+ * enqueued events.
+ *
+ * @param thread_index Thread index for which the flush is to be performed.
+ * @return 0 on success or a positive number indicating the number of
+ *         failures due to API queue being full.
+ */
+int
+session_manager_flush_enqueue_events (u32 thread_index)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  u32 *session_indices_to_enqueue;
+  int i, errors = 0;
+
+  session_indices_to_enqueue =
+    smm->session_indices_to_enqueue_by_thread[thread_index];
+
+  for (i = 0; i < vec_len (session_indices_to_enqueue); i++)
+    {
+      stream_session_t *s0;
+
+      /* Get session */
+      s0 = stream_session_get (session_indices_to_enqueue[i], thread_index);
+      if (stream_session_enqueue_notify (s0, 0 /* don't block */ ))
+	{
+	  errors++;
+	}
+    }
+
+  vec_reset_length (session_indices_to_enqueue);
+
+  smm->session_indices_to_enqueue_by_thread[thread_index] =
+    session_indices_to_enqueue;
+
+  /* Increment enqueue epoch for next round */
+  smm->current_enqueue_epoch[thread_index]++;
+
+  return errors;
+}
+
+/*
+ * Start listening on server's ip/port pair for requested transport.
+ *
+ * Creates a 'dummy' stream session with state LISTENING to be used in session
+ * lookups, prior to establishing connection. Requests transport to build
+ * it's own specific listening connection.
+ */
+int
+stream_session_start_listen (u32 server_index, ip46_address_t * ip, u16 port)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  stream_session_t *s;
+  transport_connection_t *tc;
+  application_t *srv;
+  u32 tci;
+
+  srv = application_get (server_index);
+
+  pool_get (smm->listen_sessions[srv->session_type], s);
+  memset (s, 0, sizeof (*s));
+
+  s->session_type = srv->session_type;
+  s->session_state = SESSION_STATE_LISTENING;
+  s->session_index = s - smm->listen_sessions[srv->session_type];
+  s->app_index = srv->index;
+
+  /* Transport bind/listen  */
+  tci = tp_vfts[srv->session_type].bind (smm->vlib_main, s->session_index, ip,
+					 port);
+
+  /* Attach transport to session */
+  s->connection_index = tci;
+  tc = tp_vfts[srv->session_type].get_listener (tci);
+
+  srv->session_index = s->session_index;
+
+  /* Add to the main lookup table */
+  stream_session_table_add_for_tc (s->session_type, tc, s->session_index);
+
+  return 0;
+}
+
+void
+stream_session_stop_listen (u32 server_index)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  stream_session_t *listener;
+  transport_connection_t *tc;
+  application_t *srv;
+
+  srv = application_get (server_index);
+  listener = pool_elt_at_index (smm->listen_sessions[srv->session_type],
+				srv->session_index);
+
+  tc = tp_vfts[srv->session_type].get_listener (listener->connection_index);
+  stream_session_table_del_for_tc (smm, listener->session_type, tc);
+
+  tp_vfts[srv->session_type].unbind (smm->vlib_main,
+				     listener->connection_index);
+  pool_put (smm->listen_sessions[srv->session_type], listener);
+}
+
+int
+connect_server_add_segment_cb (application_t * ss, char *segment_name,
+			       u32 segment_size)
+{
+  /* Does exactly nothing, but die */
+  ASSERT (0);
+  return 0;
+}
+
+void
+connects_session_manager_init (session_manager_main_t * smm, u8 session_type)
+{
+  session_manager_t *sm;
+  u32 connect_fifo_size = 8 << 10;	/* Config? */
+  u32 default_segment_size = 1 << 20;
+
+  pool_get (smm->session_managers, sm);
+  memset (sm, 0, sizeof (*sm));
+
+  sm->add_segment_size = default_segment_size;
+  sm->rx_fifo_size = connect_fifo_size;
+  sm->tx_fifo_size = connect_fifo_size;
+  sm->add_segment = 1;
+
+  session_manager_add_segment (smm, sm);
+  smm->connect_manager_index[session_type] = sm - smm->session_managers;
+}
+
+void
+stream_session_connect_notify (transport_connection_t * tc, u8 sst,
+			       u8 is_fail)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  application_t *app;
+  stream_session_t *new_s = 0;
+  u64 value;
+
+  value = stream_session_half_open_lookup (smm, &tc->lcl_ip, &tc->rmt_ip,
+					   tc->lcl_port, tc->rmt_port,
+					   tc->proto);
+  if (value == HALF_OPEN_LOOKUP_INVALID_VALUE)
+    {
+      clib_warning ("This can't be good!");
+      return;
+    }
+
+  app = application_get (value >> 32);
+
+  if (!is_fail)
+    {
+      /* Create new session (server segments are allocated if needed) */
+      if (stream_session_create_i (smm, app, tc, &new_s))
+	return;
+
+      app->session_index = stream_session_get_index (new_s);
+      app->thread_index = new_s->thread_index;
+
+      /* Allocate vpp event queue for this thread if needed */
+      vpp_session_event_queue_allocate (smm, tc->thread_index);
+    }
+
+  /* Notify client */
+  app->cb_fns.session_connected_callback (app->api_client_index, new_s,
+					  is_fail);
+
+  /* Cleanup session lookup */
+  stream_session_half_open_table_del (smm, sst, tc);
+}
+
+void
+stream_session_accept_notify (transport_connection_t * tc)
+{
+  application_t *server;
+  stream_session_t *s;
+
+  s = stream_session_get (tc->s_index, tc->thread_index);
+  server = application_get (s->app_index);
+  server->cb_fns.session_accept_callback (s);
+}
+
+/**
+ * Notification from transport that connection is being closed.
+ *
+ * A disconnect is sent to application but state is not removed. Once
+ * disconnect is acknowledged by application, session disconnect is called.
+ * Ultimately this leads to close being called on transport (passive close).
+ */
+void
+stream_session_disconnect_notify (transport_connection_t * tc)
+{
+  application_t *server;
+  stream_session_t *s;
+
+  s = stream_session_get (tc->s_index, tc->thread_index);
+  server = application_get (s->app_index);
+  server->cb_fns.session_disconnect_callback (s);
+}
+
+/**
+ * Cleans up session and associated app if needed.
+ */
+void
+stream_session_delete (stream_session_t * s)
+{
+  session_manager_main_t *smm = vnet_get_session_manager_main ();
+  svm_fifo_segment_private_t *fifo_segment;
+  application_t *app;
+  int rv;
+
+  /* delete from the main lookup table */
+  rv = stream_session_table_del (smm, s);
+
+  if (rv)
+    clib_warning ("hash delete error, rv %d", rv);
+
+  /* Cleanup fifo segments */
+  fifo_segment = svm_fifo_get_segment (s->server_segment_index);
+  svm_fifo_segment_free_fifo (fifo_segment, s->server_rx_fifo);
+  svm_fifo_segment_free_fifo (fifo_segment, s->server_tx_fifo);
+
+  /* Cleanup app if client */
+  app = application_get (s->app_index);
+  if (app->mode == APP_CLIENT)
+    {
+      application_del (app);
+    }
+  else if (app->mode == APP_SERVER)
+    {
+      session_manager_t *sm;
+      svm_fifo_segment_private_t *fifo_segment;
+      svm_fifo_t **fifos;
+      u32 fifo_index;
+
+      sm = session_manager_get (app->session_manager_index);
+
+      /* Delete fifo */
+      fifo_segment = svm_fifo_get_segment (s->server_segment_index);
+      fifos = (svm_fifo_t **) fifo_segment->h->fifos;
+
+      fifo_index = svm_fifo_segment_index (fifo_segment);
+
+      /* Remove segment only if it holds no fifos and not the first */
+      if (sm->segment_indices[0] != fifo_index && vec_len (fifos) == 0)
+	svm_fifo_segment_delete (fifo_segment);
+    }
+
+  pool_put (smm->sessions[s->thread_index], s);
+}
+
+/**
+ * Notification from transport that connection is being deleted
+ *
+ * This should be called only on previously fully established sessions. For
+ * instance failed connects should call stream_session_connect_notify and
+ * indicate that the connect has failed.
+ */
+void
+stream_session_delete_notify (transport_connection_t * tc)
+{
+  stream_session_t *s;
+
+  s = stream_session_get_if_valid (tc->s_index, tc->thread_index);
+  if (!s)
+    {
+      clib_warning ("Surprised!");
+      return;
+    }
+  stream_session_delete (s);
+}
+
+/**
+ * Notify application that connection has been reset.
+ */
+void
+stream_session_reset_notify (transport_connection_t * tc)
+{
+  stream_session_t *s;
+  application_t *app;
+  s = stream_session_get (tc->s_index, tc->thread_index);
+
+  app = application_get (s->app_index);
+  app->cb_fns.session_reset_callback (s);
+}
+
+/**
+ * Accept a stream session. Optionally ping the server by callback.
+ */
+int
+stream_session_accept (transport_connection_t * tc, u32 listener_index,
+		       u8 sst, u8 notify)
+{
+  session_manager_main_t *smm = &session_manager_main;
+  application_t *server;
+  stream_session_t *s, *listener;
+
+  int rv;
+
+  /* Find the server */
+  listener = pool_elt_at_index (smm->listen_sessions[sst], listener_index);
+  server = application_get (listener->app_index);
+
+  if ((rv = stream_session_create_i (smm, server, tc, &s)))
+    return rv;
+
+  /* Allocate vpp event queue for this thread if needed */
+  vpp_session_event_queue_allocate (smm, tc->thread_index);
+
+  /* Shoulder-tap the server */
+  if (notify)
+    {
+      server->cb_fns.session_accept_callback (s);
+    }
+
+  return 0;
+}
+
+void
+stream_session_open (u8 sst, ip46_address_t * addr, u16 port_host_byte_order,
+		     u32 app_index)
+{
+  transport_connection_t *tc;
+  u32 tci;
+  u64 value;
+
+  /* Ask transport to open connection */
+  tci = tp_vfts[sst].open (addr, port_host_byte_order);
+
+  /* Get transport connection */
+  tc = tp_vfts[sst].get_half_open (tci);
+
+  /* Store api_client_index and transport connection index */
+  value = (((u64) app_index) << 32) | (u64) tc->c_index;
+
+  /* Add to the half-open lookup table */
+  stream_session_half_open_table_add (sst, tc, value);
+}
+
+/**
+ * Disconnect session and propagate to transport. This should eventually
+ * result in a delete notification that allows us to cleanup session state.
+ * Called for both active/passive disconnects.
+ */
+void
+stream_session_disconnect (stream_session_t * s)
+{
+  tp_vfts[s->session_type].close (s->connection_index, s->thread_index);
+  s->session_state = SESSION_STATE_CLOSED;
+}
+
+/**
+ * Cleanup transport and session state.
+ */
+void
+stream_session_cleanup (stream_session_t * s)
+{
+  tp_vfts[s->session_type].cleanup (s->connection_index, s->thread_index);
+  stream_session_delete (s);
+}
+
+void
+session_register_transport (u8 type, const transport_proto_vft_t * vft)
+{
+  session_manager_main_t *smm = vnet_get_session_manager_main ();
+
+  vec_validate (tp_vfts, type);
+  tp_vfts[type] = *vft;
+
+  /* If an offset function is provided, then peek instead of dequeue */
+  smm->session_rx_fns[type] =
+    (vft->rx_fifo_offset) ? session_fifo_rx_peek : session_fifo_rx_dequeue;
+}
+
+transport_proto_vft_t *
+session_get_transport_vft (u8 type)
+{
+  if (type >= vec_len (tp_vfts))
+    return 0;
+  return &tp_vfts[type];
+}
+
+static clib_error_t *
+session_manager_main_init (vlib_main_t * vm)
+{
+  u32 num_threads;
+  vlib_thread_main_t *vtm = vlib_get_thread_main ();
+  session_manager_main_t *smm = &session_manager_main;
+  int i;
+
+  smm->vlib_main = vm;
+  smm->vnet_main = vnet_get_main ();
+
+  num_threads = 1 /* main thread */  + vtm->n_threads;
+
+  if (num_threads < 1)
+    return clib_error_return (0, "n_thread_stacks not set");
+
+  /* $$$ config parameters */
+  svm_fifo_segment_init (0x200000000ULL /* first segment base VA */ ,
+			 20 /* timeout in seconds */ );
+
+  /* configure per-thread ** vectors */
+  vec_validate (smm->sessions, num_threads - 1);
+  vec_validate (smm->session_indices_to_enqueue_by_thread, num_threads - 1);
+  vec_validate (smm->tx_buffers, num_threads - 1);
+  vec_validate (smm->fifo_events, num_threads - 1);
+  vec_validate (smm->evts_partially_read, num_threads - 1);
+  vec_validate (smm->current_enqueue_epoch, num_threads - 1);
+  vec_validate (smm->vpp_event_queues, num_threads - 1);
+
+  /* $$$$ preallocate hack config parameter */
+  for (i = 0; i < 200000; i++)
+    {
+      stream_session_t *ss;
+      pool_get (smm->sessions[0], ss);
+      memset (ss, 0, sizeof (*ss));
+    }
+
+  for (i = 0; i < 200000; i++)
+    pool_put_index (smm->sessions[0], i);
+
+  clib_bihash_init_16_8 (&smm->v4_session_hash, "v4 session table",
+			 200000 /* $$$$ config parameter nbuckets */ ,
+			 (64 << 20) /*$$$ config parameter table size */ );
+  clib_bihash_init_48_8 (&smm->v6_session_hash, "v6 session table",
+			 200000 /* $$$$ config parameter nbuckets */ ,
+			 (64 << 20) /*$$$ config parameter table size */ );
+
+  clib_bihash_init_16_8 (&smm->v4_half_open_hash, "v4 half-open table",
+			 200000 /* $$$$ config parameter nbuckets */ ,
+			 (64 << 20) /*$$$ config parameter table size */ );
+  clib_bihash_init_48_8 (&smm->v6_half_open_hash, "v6 half-open table",
+			 200000 /* $$$$ config parameter nbuckets */ ,
+			 (64 << 20) /*$$$ config parameter table size */ );
+
+  for (i = 0; i < SESSION_N_TYPES; i++)
+    smm->connect_manager_index[i] = INVALID_INDEX;
+
+  return 0;
+}
+
+VLIB_INIT_FUNCTION (session_manager_main_init);
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */