udp/session: refactor to support dgram mode

- adds session layer support for datagram based protocols
- updates udp to work in pure connectionless and datagram mode. The
  existing connected mode is now 'accessible' for apps as a dummy UDPC,
  as in, connected udp, protocol.
- updates udp_echo, echo client, echo server code to work in datagram
  mode.

Change-Id: I2960c0d2d246cb166005f545794ec31fe0d546dd
Signed-off-by: Florin Coras <fcoras@cisco.com>

12 files changed, 474 insertions, 107 deletions

diff --git a/src/vnet/session/application.c b/src/vnet/session/application.c
index 1c46e786e13..68bbd59098e 100644
--- a/src/vnet/session/application.c
+++ b/src/vnet/session/application.c
@@ -445,13 +445,9 @@ application_start_listen (application_t * srv, session_endpoint_t * sep,
   s = listen_session_new (0, sst);
   s->app_index = srv->index;
 
-  if (stream_session_listen (s, sep))
-    goto err;
-
   /* Allocate segment manager. All sessions derived out of a listen session
    * have fifos allocated by the same segment manager. */
-  sm = application_alloc_segment_manager (srv);
-  if (sm == 0)
+  if (!(sm = application_alloc_segment_manager (srv)))
     goto err;
 
   /* Add to app's listener table. Useful to find all child listeners
@@ -459,6 +455,13 @@ application_start_listen (application_t * srv, session_endpoint_t * sep,
   handle = listen_session_get_handle (s);
   hash_set (srv->listeners_table, handle, segment_manager_index (sm));
 
+  if (stream_session_listen (s, sep))
+    {
+      segment_manager_del (sm);
+      hash_unset (srv->listeners_table, handle);
+      goto err;
+    }
+
   *res = handle;
   return 0;
 
diff --git a/src/vnet/session/application_interface.h b/src/vnet/session/application_interface.h
index 5dc237f6e7b..5fd218533dc 100644
--- a/src/vnet/session/application_interface.h
+++ b/src/vnet/session/application_interface.h
@@ -173,6 +173,163 @@ extern const u32 test_srv_crt_rsa_len;
 extern const char test_srv_key_rsa[];
 extern const u32 test_srv_key_rsa_len;
 
+typedef struct app_session_transport_
+{
+  ip46_address_t rmt_ip;	/**< remote ip */
+  ip46_address_t lcl_ip;	/**< local ip */
+  u16 rmt_port;			/**< remote port */
+  u16 lcl_port;			/**< local port */
+  u8 is_ip4;			/**< set if uses ip4 networking */
+} app_session_transport_t;
+
+typedef struct app_session_
+{
+  svm_fifo_t *rx_fifo;			/**< rx fifo */
+  svm_fifo_t *tx_fifo;			/**< tx fifo */
+  session_type_t session_type;		/**< session type */
+  volatile u8 session_state;		/**< session state */
+  u32 session_index;			/**< index in owning pool */
+  app_session_transport_t transport;	/**< transport info */
+  svm_queue_t *vpp_evt_q;		/**< vpp event queue for session */
+  u8 is_dgram;				/**< set if it works in dgram mode */
+} app_session_t;
+
+always_inline int
+app_send_dgram_raw (svm_fifo_t * f, app_session_transport_t * at,
+		    svm_queue_t * vpp_evt_q, u8 * data, u32 len, u8 noblock)
+{
+  u32 max_enqueue, actual_write;
+  session_dgram_hdr_t hdr;
+  session_fifo_event_t evt;
+  int rv;
+
+  max_enqueue = svm_fifo_max_enqueue (f);
+  if (svm_fifo_max_enqueue (f) <= sizeof (session_dgram_hdr_t))
+    return 0;
+
+  max_enqueue -= sizeof (session_dgram_hdr_t);
+  actual_write = clib_min (len, max_enqueue);
+  hdr.data_length = actual_write;
+  hdr.data_offset = 0;
+  clib_memcpy (&hdr.rmt_ip, &at->rmt_ip, sizeof (ip46_address_t));
+  hdr.is_ip4 = at->is_ip4;
+  hdr.rmt_port = at->rmt_port;
+  clib_memcpy (&hdr.lcl_ip, &at->lcl_ip, sizeof (ip46_address_t));
+  hdr.lcl_port = at->lcl_port;
+  rv = svm_fifo_enqueue_nowait (f, sizeof (hdr), (u8 *) & hdr);
+  if (rv <= 0)
+    return 0;
+
+  ASSERT (rv == sizeof (hdr));
+
+  if ((rv = svm_fifo_enqueue_nowait (f, actual_write, data)) > 0)
+    {
+      if (svm_fifo_set_event (f))
+	{
+	  evt.fifo = f;
+	  evt.event_type = FIFO_EVENT_APP_TX;
+	  svm_queue_add (vpp_evt_q, (u8 *) & evt, noblock);
+	}
+    }
+  return rv;
+}
+
+always_inline int
+app_send_dgram (app_session_t * s, u8 * data, u32 len, u8 noblock)
+{
+  return app_send_dgram_raw (s->tx_fifo, &s->transport, s->vpp_evt_q, data,
+			     len, noblock);
+}
+
+always_inline int
+app_send_stream_raw (svm_fifo_t * f, svm_queue_t * vpp_evt_q, u8 * data,
+		     u32 len, u8 noblock)
+{
+  session_fifo_event_t evt;
+  int rv;
+
+  if ((rv = svm_fifo_enqueue_nowait (f, len, data)) > 0)
+    {
+      if (svm_fifo_set_event (f))
+	{
+	  evt.fifo = f;
+	  evt.event_type = FIFO_EVENT_APP_TX;
+	  svm_queue_add (vpp_evt_q, (u8 *) & evt, noblock);
+	}
+    }
+  return rv;
+}
+
+always_inline int
+app_send_stream (app_session_t * s, u8 * data, u32 len, u8 noblock)
+{
+  return app_send_stream_raw (s->tx_fifo, s->vpp_evt_q, data, len, noblock);
+}
+
+always_inline int
+app_send (app_session_t * s, u8 * data, u32 len, u8 noblock)
+{
+  if (s->is_dgram)
+    return app_send_dgram (s, data, len, noblock);
+  return app_send_stream (s, data, len, noblock);
+}
+
+always_inline int
+app_recv_dgram_raw (svm_fifo_t * f, u8 * buf, u32 len,
+		    app_session_transport_t * at, u8 clear_evt)
+{
+  session_dgram_pre_hdr_t ph;
+  u32 max_deq;
+  int rv;
+
+  if (clear_evt)
+    svm_fifo_unset_event (f);
+  max_deq = svm_fifo_max_dequeue (f);
+  if (max_deq < sizeof (session_dgram_hdr_t))
+    return 0;
+
+  svm_fifo_peek (f, 0, sizeof (ph), (u8 *) & ph);
+  ASSERT (ph.data_length >= ph.data_offset);
+  if (!ph.data_offset)
+    svm_fifo_peek (f, sizeof (ph), sizeof (*at), (u8 *) at);
+  len = clib_min (len, ph.data_length - ph.data_offset);
+  rv = svm_fifo_peek (f, ph.data_offset + SESSION_CONN_HDR_LEN, len, buf);
+  ph.data_offset += rv;
+  if (ph.data_offset == ph.data_length)
+    svm_fifo_dequeue_drop (f, ph.data_length + SESSION_CONN_HDR_LEN);
+  else
+    svm_fifo_overwrite_head (f, (u8 *) & ph, sizeof (ph));
+  return rv;
+}
+
+always_inline int
+app_recv_dgram (app_session_t * s, u8 * buf, u32 len)
+{
+  return app_recv_dgram_raw (s->rx_fifo, buf, len, &s->transport, 1);
+}
+
+always_inline int
+app_recv_stream_raw (svm_fifo_t * f, u8 * buf, u32 len, u8 clear_evt)
+{
+  if (clear_evt)
+    svm_fifo_unset_event (f);
+  return svm_fifo_dequeue_nowait (f, len, buf);
+}
+
+always_inline int
+app_recv_stream (app_session_t * s, u8 * buf, u32 len)
+{
+  return app_recv_stream_raw (s->rx_fifo, buf, len, 1);
+}
+
+always_inline int
+app_recv (app_session_t * s, u8 * data, u32 len)
+{
+  if (s->is_dgram)
+    return app_recv_dgram (s, data, len);
+  return app_recv_stream (s, data, len);
+}
+
 #endif /* __included_uri_h__ */
 
 /*
diff --git a/src/vnet/session/session.api b/src/vnet/session/session.api
index bf88e82f336..98748d8fbbb 100644
--- a/src/vnet/session/session.api
+++ b/src/vnet/session/session.api
@@ -13,7 +13,7 @@
  * limitations under the License.
  */
 
-option version = "1.0.2";
+option version = "1.0.3";
 
 /** \brief client->vpp, attach application to session layer
     @param client_index - opaque cookie to identify the sender
@@ -119,13 +119,25 @@ autoreply define unmap_segment {
                  "tcp://::/0/80" [ipv6] etc.
     @param options - socket options, fifo sizes, etc.
 */
-autoreply define bind_uri {
+define bind_uri {
   u32 client_index;
   u32 context;
   u32 accept_cookie;
   u8 uri[128];
 };
 
+define bind_uri_reply {
+  u32 context;
+  u64 handle;
+  i32 retval;
+  u64 rx_fifo;
+  u64 tx_fifo;
+  u8 lcl_is_ip4;
+  u8 lcl_ip[16];
+  u16 lcl_port;
+  u64 vpp_evt_q;
+};
+
 /** \brief Unbind a given URI
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
@@ -314,8 +326,12 @@ autoreply define connect_sock {
     @param context - sender context, to match reply w/ request
     @param handle - bind handle
     @param retval - return code for the request
-    @param event_queue_address - vpp event queue address or 0 if this 
-                                 connection shouldn't send events
+    @param lcl_is_ip4 - local ip address type
+    @param lcl_ip6 - local ip address
+    @param lcl_port - local port
+    @param rx_fifo - rx fifo address if allocated (connectionless)
+    @param tx_fifo - tx fifo address if allocated (connectionless) 
+    @param vpp_evt_q - vpp event queue address (connectionless)
     @param segment_name_length - length of segment name 
     @param segment_name - name of segment client needs to attach to
 */
@@ -323,10 +339,12 @@ define bind_sock_reply {
   u32 context;
   u64 handle;
   i32 retval;
-  u64 server_event_queue_address;
   u8 lcl_is_ip4;
   u8 lcl_ip[16];
   u16 lcl_port;
+  u64 rx_fifo;
+  u64 tx_fifo;
+  u64 vpp_evt_q;
   u32 segment_size;
   u8 segment_name_length;
   u8 segment_name[128];
diff --git a/src/vnet/session/session.c b/src/vnet/session/session.c
index d258b82c983..dfc967b12dc 100644
--- a/src/vnet/session/session.c
+++ b/src/vnet/session/session.c
@@ -355,14 +355,19 @@ session_enqueue_stream_connection (transport_connection_t * tc,
   return enqueued;
 }
 
+
 int
-session_enqueue_dgram_connection (stream_session_t * s, vlib_buffer_t * b,
-				  u8 proto, u8 queue_event)
+session_enqueue_dgram_connection (stream_session_t * s,
+				  session_dgram_hdr_t * hdr,
+				  vlib_buffer_t * b, u8 proto, u8 queue_event)
 {
   int enqueued = 0, rv, in_order_off;
 
-  if (svm_fifo_max_enqueue (s->server_rx_fifo) < b->current_length)
-    return -1;
+  ASSERT (svm_fifo_max_enqueue (s->server_rx_fifo)
+	  >= b->current_length + sizeof (*hdr));
+
+  svm_fifo_enqueue_nowait (s->server_rx_fifo, sizeof (session_dgram_hdr_t),
+			   (u8 *) hdr);
   enqueued = svm_fifo_enqueue_nowait (s->server_rx_fifo, b->current_length,
 				      vlib_buffer_get_current (b));
   if (PREDICT_FALSE ((b->flags & VLIB_BUFFER_NEXT_PRESENT) && enqueued >= 0))
@@ -530,6 +535,16 @@ session_manager_flush_enqueue_events (u8 transport_proto, u32 thread_index)
   return errors;
 }
 
+int
+session_manager_flush_all_enqueue_events (u8 transport_proto)
+{
+  vlib_thread_main_t *vtm = vlib_get_thread_main ();
+  int i, errors = 0;
+  for (i = 0; i < 1 + vtm->n_threads; i++)
+    errors += session_manager_flush_enqueue_events (transport_proto, i);
+  return errors;
+}
+
 /**
  * Init fifo tail and head pointers
  *
@@ -825,7 +840,7 @@ session_open_cl (u32 app_index, session_endpoint_t * rmt, u32 opaque)
   if (session_alloc_and_init (sm, tc, 1, &s))
     return -1;
   s->app_index = app->index;
-  s->session_state = SESSION_STATE_CONNECTING_READY;
+  s->session_state = SESSION_STATE_OPENED;
 
   /* Tell the app about the new event fifo for this session */
   app->cb_fns.session_connected_callback (app->index, opaque, s, 0);
@@ -841,10 +856,6 @@ session_open_vc (u32 app_index, session_endpoint_t * rmt, u32 opaque)
   u64 handle;
   int rv;
 
-  /* TODO until udp is fixed */
-  if (rmt->transport_proto == TRANSPORT_PROTO_UDP)
-    return session_open_cl (app_index, rmt, opaque);
-
   tep = session_endpoint_to_transport (rmt);
   rv = tp_vfts[rmt->transport_proto].open (tep);
   if (rv < 0)
@@ -912,14 +923,6 @@ session_open (u32 app_index, session_endpoint_t * rmt, u32 opaque)
   return session_open_srv_fns[tst] (app_index, rmt, opaque);
 }
 
-/**
- * Ask transport to listen on local transport endpoint.
- *
- * @param s Session for which listen will be called. Note that unlike
- * 	    established sessions, listen sessions are not associated to a
- * 	    thread.
- * @param tep Local endpoint to be listened on.
- */
 int
 session_listen_vc (stream_session_t * s, session_endpoint_t * sep)
 {
@@ -948,6 +951,40 @@ session_listen_vc (stream_session_t * s, session_endpoint_t * sep)
 }
 
 int
+session_listen_cl (stream_session_t * s, session_endpoint_t * sep)
+{
+  transport_connection_t *tc;
+  application_t *server;
+  segment_manager_t *sm;
+  u32 tci;
+
+  /* Transport bind/listen  */
+  tci = tp_vfts[sep->transport_proto].bind (s->session_index,
+					    session_endpoint_to_transport
+					    (sep));
+
+  if (tci == (u32) ~ 0)
+    return -1;
+
+  /* Attach transport to session */
+  s->connection_index = tci;
+  tc = tp_vfts[sep->transport_proto].get_listener (tci);
+
+  /* Weird but handle it ... */
+  if (tc == 0)
+    return -1;
+
+  server = application_get (s->app_index);
+  sm = application_get_listen_segment_manager (server, s);
+  if (session_alloc_fifos (sm, s))
+    return -1;
+
+  /* Add to the main lookup table */
+  session_lookup_add_connection (tc, s->session_index);
+  return 0;
+}
+
+int
 session_listen_app (stream_session_t * s, session_endpoint_t * sep)
 {
   session_endpoint_extended_t esep;
@@ -965,11 +1002,19 @@ typedef int (*session_listen_service_fn) (stream_session_t *,
 static session_listen_service_fn
 session_listen_srv_fns[TRANSPORT_N_SERVICES] = {
   session_listen_vc,
-  session_listen_vc,
+  session_listen_cl,
   session_listen_app,
 };
 /* *INDENT-ON* */
 
+/**
+ * Ask transport to listen on local transport endpoint.
+ *
+ * @param s Session for which listen will be called. Note that unlike
+ * 	    established sessions, listen sessions are not associated to a
+ * 	    thread.
+ * @param tep Local endpoint to be listened on.
+ */
 int
 stream_session_listen (stream_session_t * s, session_endpoint_t * sep)
 {
@@ -1125,7 +1170,8 @@ session_manager_get_evt_q_segment (void)
 static session_fifo_rx_fn *session_tx_fns[TRANSPORT_TX_N_FNS] = {
     session_tx_fifo_peek_and_snd,
     session_tx_fifo_dequeue_and_snd,
-    session_tx_fifo_dequeue_internal
+    session_tx_fifo_dequeue_internal,
+    session_tx_fifo_dequeue_and_snd
 };
 /* *INDENT-ON* */
 
@@ -1228,11 +1274,12 @@ session_manager_main_enable (vlib_main_t * vm)
   vec_validate (smm->peekers_rw_locks, num_threads - 1);
 
   for (i = 0; i < TRANSPORT_N_PROTO; i++)
-    for (j = 0; j < num_threads; j++)
-      {
-	vec_validate (smm->session_to_enqueue[i], num_threads - 1);
-	vec_validate (smm->current_enqueue_epoch[i], num_threads - 1);
-      }
+    {
+      vec_validate (smm->current_enqueue_epoch[i], num_threads - 1);
+      vec_validate (smm->session_to_enqueue[i], num_threads - 1);
+      for (j = 0; j < num_threads; j++)
+	smm->current_enqueue_epoch[i][j] = 1;
+    }
 
   for (i = 0; i < num_threads; i++)
     {
diff --git a/src/vnet/session/session.h b/src/vnet/session/session.h
index 0b53f61a10a..9d534aec19b 100644
--- a/src/vnet/session/session.h
+++ b/src/vnet/session/session.h
@@ -204,6 +204,31 @@ struct _session_manager_main
 
 };
 
+typedef struct session_dgram_pre_hdr_
+{
+  u32 data_length;
+  u32 data_offset;
+} session_dgram_pre_hdr_t;
+
+/* *INDENT-OFF* */
+typedef CLIB_PACKED (struct session_dgram_header_
+{
+  u32 data_length;
+  u32 data_offset;
+  ip46_address_t rmt_ip;
+  ip46_address_t lcl_ip;
+  u16 rmt_port;
+  u16 lcl_port;
+  u8 is_ip4;
+}) session_dgram_hdr_t;
+/* *INDENT-ON* */
+
+#define SESSION_CONN_ID_LEN 37
+#define SESSION_CONN_HDR_LEN 45
+
+STATIC_ASSERT (sizeof (session_dgram_hdr_t) == (SESSION_CONN_ID_LEN + 8),
+	       "session conn id wrong length");
+
 extern session_manager_main_t session_manager_main;
 extern vlib_node_registration_t session_queue_node;
 
@@ -342,6 +367,14 @@ session_has_transport (stream_session_t * s)
   return (session_get_transport_proto (s) != TRANSPORT_PROTO_NONE);
 }
 
+always_inline transport_service_type_t
+session_transport_service_type (stream_session_t * s)
+{
+  transport_proto_t tp;
+  tp = session_get_transport_proto (s);
+  return transport_protocol_service_type (tp);
+}
+
 /**
  * Acquires a lock that blocks a session pool from expanding.
  *
@@ -442,8 +475,10 @@ int
 session_enqueue_stream_connection (transport_connection_t * tc,
 				   vlib_buffer_t * b, u32 offset,
 				   u8 queue_event, u8 is_in_order);
-int session_enqueue_dgram_connection (stream_session_t * s, vlib_buffer_t * b,
-				      u8 proto, u8 queue_event);
+int session_enqueue_dgram_connection (stream_session_t * s,
+				      session_dgram_hdr_t * hdr,
+				      vlib_buffer_t * b, u8 proto,
+				      u8 queue_event);
 int stream_session_peek_bytes (transport_connection_t * tc, u8 * buffer,
 			       u32 offset, u32 max_bytes);
 u32 stream_session_dequeue_drop (transport_connection_t * tc, u32 max_bytes);
@@ -490,6 +525,7 @@ session_manager_get_vpp_event_queue (u32 thread_index)
 }
 
 int session_manager_flush_enqueue_events (u8 proto, u32 thread_index);
+int session_manager_flush_all_enqueue_events (u8 transport_proto);
 
 always_inline u64
 listen_session_get_handle (stream_session_t * s)
diff --git a/src/vnet/session/session_api.c b/src/vnet/session/session_api.c
index 2a74a196201..67c42faf692 100755
--- a/src/vnet/session/session_api.c
+++ b/src/vnet/session/session_api.c
@@ -480,9 +480,12 @@ done:
 static void
 vl_api_bind_uri_t_handler (vl_api_bind_uri_t * mp)
 {
-  vl_api_bind_uri_reply_t *rmp;
+  transport_connection_t *tc = 0;
   vnet_bind_args_t _a, *a = &_a;
-  application_t *app;
+  vl_api_bind_uri_reply_t *rmp;
+  stream_session_t *s;
+  application_t *app = 0;
+  svm_queue_t *vpp_evt_q;
   int rv;
 
   if (session_manager_is_enabled () == 0)
@@ -505,7 +508,30 @@ vl_api_bind_uri_t_handler (vl_api_bind_uri_t * mp)
     }
 
 done:
-  REPLY_MACRO (VL_API_BIND_URI_REPLY);
+
+  /* *INDENT-OFF* */
+  REPLY_MACRO2 (VL_API_BIND_URI_REPLY, ({
+    if (!rv)
+      {
+        rmp->handle = a->handle;
+	rmp->lcl_is_ip4 = tc->is_ip4;
+  	rmp->lcl_port = tc->lcl_port;
+        if (app && application_has_global_scope (app))
+            {
+              s = listen_session_get_from_handle (a->handle);
+              tc = listen_session_get_transport (s);
+              clib_memcpy (rmp->lcl_ip, &tc->lcl_ip, sizeof(tc->lcl_ip));
+              if (session_transport_service_type (s) == TRANSPORT_SERVICE_CL)
+                {
+                  rmp->rx_fifo = pointer_to_uword (s->server_rx_fifo);
+                  rmp->tx_fifo = pointer_to_uword (s->server_tx_fifo);
+                  vpp_evt_q = session_manager_get_vpp_event_queue (0);
+                  rmp->vpp_evt_q = pointer_to_uword (vpp_evt_q);
+                }
+            }
+      }
+  }));
+  /* *INDENT-ON* */
 }
 
 static void
@@ -733,6 +759,7 @@ vl_api_bind_sock_t_handler (vl_api_bind_sock_t * mp)
   stream_session_t *s;
   transport_connection_t *tc = 0;
   ip46_address_t *ip46;
+  svm_queue_t *vpp_evt_q;
 
   if (session_manager_is_enabled () == 0)
     {
@@ -775,8 +802,14 @@ done:
 	  {
 	    s = listen_session_get_from_handle (a->handle);
 	    tc = listen_session_get_transport (s);
-            rmp->lcl_is_ip4 = tc->is_ip4;
             clib_memcpy (rmp->lcl_ip, &tc->lcl_ip, sizeof (tc->lcl_ip));
+            if (session_transport_service_type (s) == TRANSPORT_SERVICE_CL)
+              {
+        	rmp->rx_fifo = pointer_to_uword (s->server_rx_fifo);
+        	rmp->tx_fifo = pointer_to_uword (s->server_tx_fifo);
+        	vpp_evt_q = session_manager_get_vpp_event_queue (0);
+        	rmp->vpp_evt_q = pointer_to_uword (vpp_evt_q);
+              }
 	  }
       }
   }));
diff --git a/src/vnet/session/session_cli.c b/src/vnet/session/session_cli.c
index 52833554a53..201f6f1d66e 100755
--- a/src/vnet/session/session_cli.c
+++ b/src/vnet/session/session_cli.c
@@ -23,6 +23,9 @@ format_stream_session_fifos (u8 * s, va_list * args)
   session_fifo_event_t _e, *e = &_e;
   u8 found;
 
+  if (!ss->server_rx_fifo || !ss->server_tx_fifo)
+    return s;
+
   s = format (s, " Rx fifo: %U", format_svm_fifo, ss->server_rx_fifo, 1);
   if (verbose > 2 && ss->server_rx_fifo->has_event)
     {
@@ -76,6 +79,8 @@ format_stream_session (u8 * s, va_list * args)
     {
       s = format (s, "%-40U%v", tp_vft->format_listener, ss->connection_index,
 		  str);
+      if (verbose > 1)
+	s = format (s, "\n%U", format_stream_session_fifos, ss, verbose);
     }
   else if (ss->session_state == SESSION_STATE_CONNECTING)
     {
diff --git a/src/vnet/session/session_node.c b/src/vnet/session/session_node.c
index b8f429eb1d7..14716965547 100644
--- a/src/vnet/session/session_node.c
+++ b/src/vnet/session/session_node.c
@@ -70,7 +70,7 @@ session_tx_fifo_chain_tail (session_manager_main_t * smm, vlib_main_t * vm,
 			    vlib_buffer_t * b0, u32 bi0, u8 n_bufs_per_seg,
 			    u32 left_from_seg, u32 * left_to_snd0,
 			    u16 * n_bufs, u32 * tx_offset, u16 deq_per_buf,
-			    u8 peek_data)
+			    u8 peek_data, transport_tx_fn_type_t tx_type)
 {
   vlib_buffer_t *chain_b0, *prev_b0;
   u32 chain_bi0, to_deq;
@@ -102,7 +102,23 @@ session_tx_fifo_chain_tail (session_manager_main_t * smm, vlib_main_t * vm,
 	}
       else
 	{
-	  n_bytes_read = svm_fifo_dequeue_nowait (fifo, len_to_deq0, data0);
+	  if (tx_type == TRANSPORT_TX_DGRAM)
+	    {
+	      session_dgram_hdr_t *hdr;
+	      u16 deq_now;
+	      hdr = (session_dgram_hdr_t *) svm_fifo_head (fifo);
+	      deq_now = clib_min (hdr->data_length - hdr->data_offset,
+				  len_to_deq0);
+	      n_bytes_read = svm_fifo_peek (fifo, hdr->data_offset, deq_now,
+					    data0);
+	      ASSERT (n_bytes_read > 0);
+
+	      hdr->data_offset += n_bytes_read;
+	      if (hdr->data_offset == hdr->data_length)
+		svm_fifo_dequeue_drop (fifo, hdr->data_length);
+	    }
+	  else
+	    n_bytes_read = svm_fifo_dequeue_nowait (fifo, len_to_deq0, data0);
 	}
       ASSERT (n_bytes_read == len_to_deq0);
       chain_b0->current_length = n_bytes_read;
@@ -145,12 +161,35 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
   int i, n_bytes_read;
   u32 n_bytes_per_buf, deq_per_buf, deq_per_first_buf;
   u32 bufs_alloc, bufs_now;
+  session_dgram_hdr_t hdr;
 
   next_index = next0 = smm->session_type_to_next[s0->session_type];
-
   tp = session_get_transport_proto (s0);
   transport_vft = transport_protocol_get_vft (tp);
-  tc0 = transport_vft->get_connection (s0->connection_index, thread_index);
+  if (peek_data)
+    {
+      if (PREDICT_FALSE (s0->session_state < SESSION_STATE_READY))
+	{
+	  /* Can retransmit for closed sessions but can't send new data if
+	   * session is not ready or closed */
+	  vec_add1 (smm->pending_event_vector[thread_index], *e0);
+	  return 0;
+	}
+      tc0 =
+	transport_vft->get_connection (s0->connection_index, thread_index);
+    }
+  else
+    {
+      if (s0->session_state == SESSION_STATE_LISTENING)
+	tc0 = transport_vft->get_listener (s0->connection_index);
+      else
+	{
+	  if (PREDICT_FALSE (s0->session_state == SESSION_STATE_CLOSED))
+	    return 0;
+	  tc0 = transport_vft->get_connection (s0->connection_index,
+					       thread_index);
+	}
+    }
 
   /* Make sure we have space to send and there's something to dequeue */
   snd_mss0 = transport_vft->send_mss (tc0);
@@ -168,20 +207,26 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 
   /* Check how much we can pull. */
   max_dequeue0 = svm_fifo_max_dequeue (s0->server_tx_fifo);
-
   if (peek_data)
     {
       /* Offset in rx fifo from where to peek data */
       tx_offset = transport_vft->tx_fifo_offset (tc0);
       if (PREDICT_FALSE (tx_offset >= max_dequeue0))
-	max_dequeue0 = 0;
-      else
-	max_dequeue0 -= tx_offset;
+	return 0;
+      max_dequeue0 -= tx_offset;
     }
-
-  /* Nothing to read return */
-  if (max_dequeue0 == 0)
-    return 0;
+  else
+    {
+      if (transport_vft->tx_type == TRANSPORT_TX_DGRAM)
+	{
+	  if (max_dequeue0 < sizeof (hdr))
+	    return 0;
+	  svm_fifo_peek (s0->server_tx_fifo, 0, sizeof (hdr), (u8 *) & hdr);
+	  ASSERT (hdr.data_length > hdr.data_offset);
+	  max_dequeue0 = hdr.data_length - hdr.data_offset;
+	}
+    }
+  ASSERT (max_dequeue0 > 0);
 
   /* Ensure we're not writing more than transport window allows */
   if (max_dequeue0 < snd_space0)
@@ -286,14 +331,42 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    }
 	  else
 	    {
-	      n_bytes_read = svm_fifo_dequeue_nowait (s0->server_tx_fifo,
-						      len_to_deq0, data0);
-	      if (n_bytes_read <= 0)
-		goto dequeue_fail;
+	      if (transport_vft->tx_type == TRANSPORT_TX_DGRAM)
+		{
+		  svm_fifo_t *f = s0->server_tx_fifo;
+		  u16 deq_now;
+		  u32 offset;
+
+		  ASSERT (hdr.data_length > hdr.data_offset);
+		  deq_now = clib_min (hdr.data_length - hdr.data_offset,
+				      len_to_deq0);
+		  offset = hdr.data_offset + SESSION_CONN_HDR_LEN;
+		  n_bytes_read = svm_fifo_peek (f, offset, deq_now, data0);
+		  if (PREDICT_FALSE (n_bytes_read <= 0))
+		    goto dequeue_fail;
+
+		  if (s0->session_state == SESSION_STATE_LISTENING)
+		    {
+		      ip_copy (&tc0->rmt_ip, &hdr.rmt_ip, tc0->is_ip4);
+		      tc0->rmt_port = hdr.rmt_port;
+		    }
+		  hdr.data_offset += n_bytes_read;
+		  if (hdr.data_offset == hdr.data_length)
+		    {
+		      offset = hdr.data_length + SESSION_CONN_HDR_LEN;
+		      svm_fifo_dequeue_drop (f, offset);
+		    }
+		}
+	      else
+		{
+		  n_bytes_read = svm_fifo_dequeue_nowait (s0->server_tx_fifo,
+							  len_to_deq0, data0);
+		  if (n_bytes_read <= 0)
+		    goto dequeue_fail;
+		}
 	    }
 
 	  b0->current_length = n_bytes_read;
-
 	  left_to_snd0 -= n_bytes_read;
 	  *n_tx_packets = *n_tx_packets + 1;
 
@@ -307,7 +380,8 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 					  s0->server_tx_fifo, b0, bi0,
 					  n_bufs_per_seg, left_for_seg,
 					  &left_to_snd0, &n_bufs, &tx_offset,
-					  deq_per_buf, peek_data);
+					  deq_per_buf, peek_data,
+					  transport_vft->tx_type);
 	    }
 
 	  /* Ask transport to push header after current_length and
@@ -345,12 +419,18 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 
   /* If we couldn't dequeue all bytes mark as partially read */
   if (max_len_to_snd0 < max_dequeue0)
+    if (svm_fifo_set_event (s0->server_tx_fifo))
+      vec_add1 (smm->pending_event_vector[thread_index], *e0);
+
+  if (!peek_data && transport_vft->tx_type == TRANSPORT_TX_DGRAM)
     {
-      /* If we don't already have new event */
-      if (svm_fifo_set_event (s0->server_tx_fifo))
-	{
-	  vec_add1 (smm->pending_event_vector[thread_index], *e0);
-	}
+      /* Fix dgram pre header */
+      if (max_len_to_snd0 < max_dequeue0)
+	svm_fifo_overwrite_head (s0->server_tx_fifo, (u8 *) & hdr,
+				 sizeof (session_dgram_pre_hdr_t));
+      /* More data needs to be read */
+      else if (svm_fifo_max_dequeue (s0->server_tx_fifo) > 0)
+	vec_add1 (smm->pending_event_vector[thread_index], *e0);
     }
   return 0;
 
@@ -360,7 +440,6 @@ dequeue_fail:
    * read, return buff to free list and return
    */
   clib_warning ("dequeue fail");
-
   if (svm_fifo_set_event (s0->server_tx_fifo))
     {
       vec_add1 (smm->pending_event_vector[thread_index], *e0);
@@ -638,13 +717,6 @@ skip_dequeue:
 	      clib_warning ("It's dead, Jim!");
 	      continue;
 	    }
-	  /* Can retransmit for closed sessions but can't do anything if
-	   * session is not ready or closed */
-	  if (PREDICT_FALSE (s0->session_state < SESSION_STATE_READY))
-	    {
-	      vec_add1 (smm->pending_event_vector[my_thread_index], *e0);
-	      continue;
-	    }
 	  /* Spray packets in per session type frames, since they go to
 	   * different nodes */
 	  rv = (smm->session_tx_fns[s0->session_type]) (vm, node, smm, e0, s0,
diff --git a/src/vnet/session/stream_session.h b/src/vnet/session/stream_session.h
index b7a5eee4b12..9e0e4d98990 100644
--- a/src/vnet/session/stream_session.h
+++ b/src/vnet/session/stream_session.h
@@ -31,30 +31,19 @@ typedef enum
   SESSION_STATE_CONNECTING,
   SESSION_STATE_ACCEPTING,
   SESSION_STATE_READY,
-  SESSION_STATE_CONNECTING_READY,
+  SESSION_STATE_OPENED,
   SESSION_STATE_CLOSED,
   SESSION_STATE_N_STATES,
 } stream_session_state_t;
 
-/* TODO convert to macro once cleanup completed */
-typedef struct app_session_
+typedef struct generic_session_
 {
-  /** fifo pointers. Once allocated, these do not move */
-  svm_fifo_t *server_rx_fifo;
-  svm_fifo_t *server_tx_fifo;
-
-  /** Type */
-  session_type_t session_type;
-
-  /** State */
-  volatile u8 session_state;
-
-  /** Session index in owning pool */
-  u32 session_index;
-
-  /** Application index */
-  u32 app_index;
-} app_session_t;
+  svm_fifo_t *rx_fifo;		/**< rx fifo */
+  svm_fifo_t *tx_fifo;		/**< tx fifo */
+  session_type_t session_type;	/**< session type */
+  volatile u8 session_state;	/**< session state */
+  u32 session_index;		/**< index in owning pool */
+} generic_session_t;
 
 typedef struct _stream_session_t
 {
diff --git a/src/vnet/session/transport.c b/src/vnet/session/transport.c
index 797bdad1eaa..20b912929b4 100644
--- a/src/vnet/session/transport.c
+++ b/src/vnet/session/transport.c
@@ -57,6 +57,9 @@ format_transport_proto (u8 * s, va_list * args)
     case TRANSPORT_PROTO_SCTP:
       s = format (s, "SCTP");
       break;
+    case TRANSPORT_PROTO_UDPC:
+      s = format (s, "UDPC");
+      break;
     }
   return s;
 }
@@ -76,6 +79,9 @@ format_transport_proto_short (u8 * s, va_list * args)
     case TRANSPORT_PROTO_SCTP:
       s = format (s, "S");
       break;
+    case TRANSPORT_PROTO_UDPC:
+      s = format (s, "U");
+      break;
     }
   return s;
 }
@@ -100,6 +106,10 @@ unformat_transport_proto (unformat_input_t * input, va_list * args)
     *proto = TRANSPORT_PROTO_TLS;
   else if (unformat (input, "TLS"))
     *proto = TRANSPORT_PROTO_TLS;
+  else if (unformat (input, "udpc"))
+    *proto = TRANSPORT_PROTO_UDPC;
+  else if (unformat (input, "UDPC"))
+    *proto = TRANSPORT_PROTO_UDPC;
   else
     return 0;
   return 1;
@@ -185,6 +195,12 @@ transport_protocol_get_vft (transport_proto_t transport_proto)
   return &tp_vfts[transport_proto];
 }
 
+transport_service_type_t
+transport_protocol_service_type (transport_proto_t tp)
+{
+  return tp_vfts[tp].service_type;
+}
+
 #define PORT_MASK ((1 << 16)- 1)
 
 void
diff --git a/src/vnet/session/transport.h b/src/vnet/session/transport.h
index ed9eb02754e..8340fd859ac 100644
--- a/src/vnet/session/transport.h
+++ b/src/vnet/session/transport.h
@@ -35,10 +35,10 @@ typedef struct _transport_connection
     {
       ip46_address_t rmt_ip;	/**< Remote IP */
       ip46_address_t lcl_ip;	/**< Local IP */
-      u16 lcl_port;		/**< Local port */
       u16 rmt_port;		/**< Remote port */
-      u8 proto;			/**< Protocol id */
+      u16 lcl_port;		/**< Local port */
       u8 is_ip4;		/**< Flag if IP4 connection */
+      u8 proto;			/**< Protocol id */
       u32 fib_index;		/**< Network namespace */
     };
     /*
@@ -88,6 +88,7 @@ typedef enum _transport_proto
   TRANSPORT_PROTO_SCTP,
   TRANSPORT_PROTO_NONE,
   TRANSPORT_PROTO_TLS,
+  TRANSPORT_PROTO_UDPC,
   TRANSPORT_N_PROTO
 } transport_proto_t;
 
@@ -99,7 +100,7 @@ uword unformat_transport_proto (unformat_input_t * input, va_list * args);
   _(u32, sw_if_index) 	/**< interface endpoint is associated with  */	\
   _(ip46_address_t, ip) /**< ip address */				\
   _(u32, fib_index)	/**< fib table endpoint is associated with */	\
-  _(u8, is_ip4)	/**< 1 if ip4 */					\
+  _(u8, is_ip4)		/**< set if ip4 */				\
   _(u16, port)		/**< port in net order */			\
 
 typedef struct _transport_endpoint
@@ -125,18 +126,6 @@ transport_endpoint_fib_proto (transport_endpoint_t * tep)
   return tep->is_ip4 ? FIB_PROTOCOL_IP4 : FIB_PROTOCOL_IP6;
 }
 
-always_inline u8
-transport_is_stream (u8 proto)
-{
-  return ((proto == TRANSPORT_PROTO_TCP) || (proto == TRANSPORT_PROTO_SCTP));
-}
-
-always_inline u8
-transport_is_dgram (u8 proto)
-{
-  return (proto == TRANSPORT_PROTO_UDP);
-}
-
 int transport_alloc_local_port (u8 proto, ip46_address_t * ip);
 int transport_alloc_local_endpoint (u8 proto, transport_endpoint_t * rmt,
 				    ip46_address_t * lcl_addr,
diff --git a/src/vnet/session/transport_interface.h b/src/vnet/session/transport_interface.h
index 04a5ff263b1..f21e483c715 100644
--- a/src/vnet/session/transport_interface.h
+++ b/src/vnet/session/transport_interface.h
@@ -23,7 +23,8 @@ typedef enum transport_dequeue_type_
 {
   TRANSPORT_TX_PEEK,		/**< reliable transport protos */
   TRANSPORT_TX_DEQUEUE,		/**< unreliable transport protos */
-  TRANSPORT_TX_INTERNAL,		/**< apps acting as transports */
+  TRANSPORT_TX_INTERNAL,	/**< apps acting as transports */
+  TRANSPORT_TX_DGRAM,		/**< datagram mode */
   TRANSPORT_TX_N_FNS
 } transport_tx_fn_type_t;
 
@@ -31,7 +32,7 @@ typedef enum transport_service_type_
 {
   TRANSPORT_SERVICE_VC,		/**< virtual circuit service */
   TRANSPORT_SERVICE_CL,		/**< connectionless service */
-  TRANSPORT_SERVICE_APP,		/**< app transport service */
+  TRANSPORT_SERVICE_APP,	/**< app transport service */
   TRANSPORT_N_SERVICES
 } transport_service_type_t;
 
@@ -96,6 +97,7 @@ void transport_register_protocol (transport_proto_t transport_proto,
 				  const transport_proto_vft_t * vft,
 				  fib_protocol_t fib_proto, u32 output_node);
 transport_proto_vft_t *transport_protocol_get_vft (transport_proto_t tp);
+transport_service_type_t transport_protocol_service_type (transport_proto_t);
 void transport_update_time (f64 time_now, u8 thread_index);
 void transport_enable_disable (vlib_main_t * vm, u8 is_en);