http: state machine improvement

Split in two, one for rx and second for tx, which is more suitable for
http tunnels. Updated state names too, some of them were bit confusing.

Type: improvement

Change-Id: I2310deaa49196819f9d8147a5d9af188465dbd65
Signed-off-by: Matus Fabian <matfabia@cisco.com>

3 files changed, 235 insertions, 233 deletions

diff --git a/src/plugins/http/http.c b/src/plugins/http/http.c
index 6659de9689f..1ea5a08fbf6 100644
--- a/src/plugins/http/http.c
+++ b/src/plugins/http/http.c
@@ -36,57 +36,52 @@ const http_buffer_type_t msg_to_buf_type[] = {
 };
 
 static u8 *
-format_http_state (u8 *s, va_list *va)
+format_http_req_state (u8 *s, va_list *va)
 {
-  http_state_t state = va_arg (*va, http_state_t);
+  http_req_state_t state = va_arg (*va, http_req_state_t);
+  u8 *t = 0;
 
   switch (state)
     {
-    case HTTP_STATE_IDLE:
-      return format (s, "idle");
-    case HTTP_STATE_WAIT_APP_METHOD:
-      return format (s, "wait app method");
-    case HTTP_STATE_WAIT_SERVER_REPLY:
-      return format (s, "wait server reply");
-    case HTTP_STATE_CLIENT_IO_MORE_DATA:
-      return format (s, "client io more data");
-    case HTTP_STATE_WAIT_CLIENT_METHOD:
-      return format (s, "wait client method");
-    case HTTP_STATE_WAIT_APP_REPLY:
-      return format (s, "wait app reply");
-    case HTTP_STATE_APP_IO_MORE_DATA:
-      return format (s, "app io more data");
-    default:
-      break;
-    }
-  return format (s, "unknown");
-}
-
-#define http_state_change(_hc, _state)                                        \
+#define _(n, s, str)                                                          \
+  case HTTP_REQ_STATE_##s:                                                    \
+    t = (u8 *) str;                                                           \
+    break;
+      foreach_http_req_state
+#undef _
+	default : return format (s, "unknown");
+    }
+  return format (s, "%s", t);
+}
+
+#define http_req_state_change(_hc, _state)                                    \
   do                                                                          \
     {                                                                         \
-      HTTP_DBG (1, "changing http state %U -> %U", format_http_state,         \
-		(_hc)->http_state, format_http_state, _state);                \
-      (_hc)->http_state = _state;                                             \
+      HTTP_DBG (1, "changing http req state: %U -> %U",                       \
+		format_http_req_state, (_hc)->req_state,                      \
+		format_http_req_state, _state);                               \
+      ASSERT ((_hc)->req_state != HTTP_REQ_STATE_TUNNEL);                     \
+      (_hc)->req_state = _state;                                              \
     }                                                                         \
   while (0)
 
-static inline int
-http_state_is_tx_valid (http_conn_t *hc)
+static u8 *
+format_http_conn_state (u8 *s, va_list *args)
 {
-  http_state_t state = hc->http_state;
-  return (state == HTTP_STATE_APP_IO_MORE_DATA ||
-	  state == HTTP_STATE_WAIT_APP_REPLY ||
-	  state == HTTP_STATE_WAIT_APP_METHOD);
-}
+  http_conn_t *hc = va_arg (*args, http_conn_t *);
+  u8 *t = 0;
 
-static inline int
-http_state_is_rx_valid (http_conn_t *hc)
-{
-  http_state_t state = hc->http_state;
-  return (state == HTTP_STATE_WAIT_SERVER_REPLY ||
-	  state == HTTP_STATE_CLIENT_IO_MORE_DATA ||
-	  state == HTTP_STATE_WAIT_CLIENT_METHOD);
+  switch (hc->state)
+    {
+#define _(s, str)                                                             \
+  case HTTP_CONN_STATE_##s:                                                   \
+    t = (u8 *) str;                                                           \
+    break;
+      foreach_http_conn_state
+#undef _
+	default : return format (s, "unknown");
+    }
+  return format (s, "%s", t);
 }
 
 static inline http_worker_t *
@@ -274,7 +269,7 @@ http_ts_accept_callback (session_t *ts)
   hc->c_flags |= TRANSPORT_CONNECTION_F_NO_LOOKUP;
 
   hc->state = HTTP_CONN_STATE_ESTABLISHED;
-  http_state_change (hc, HTTP_STATE_WAIT_CLIENT_METHOD);
+  http_req_state_change (hc, HTTP_REQ_STATE_WAIT_TRANSPORT_METHOD);
 
   ts->session_state = SESSION_STATE_READY;
   ts->opaque = hc_index;
@@ -365,7 +360,7 @@ http_ts_connected_callback (u32 http_app_index, u32 ho_hc_index, session_t *ts,
   hc->c_c_index = new_hc_index;
   hc->c_flags |= TRANSPORT_CONNECTION_F_NO_LOOKUP;
   hc->state = HTTP_CONN_STATE_ESTABLISHED;
-  http_state_change (hc, HTTP_STATE_WAIT_APP_METHOD);
+  http_req_state_change (hc, HTTP_REQ_STATE_WAIT_APP_METHOD);
 
   ts->session_state = SESSION_STATE_READY;
   ts->opaque = new_hc_index;
@@ -428,7 +423,7 @@ http_ts_reset_callback (session_t *ts)
 
   hc->state = HTTP_CONN_STATE_CLOSED;
   http_buffer_free (&hc->tx_buf);
-  http_state_change (hc, HTTP_STATE_WAIT_CLIENT_METHOD);
+  http_req_state_change (hc, HTTP_REQ_STATE_WAIT_TRANSPORT_METHOD);
   session_transport_reset_notify (&hc->connection);
 
   http_disconnect_transport (hc);
@@ -1037,7 +1032,8 @@ http_identify_message_body (http_conn_t *hc, http_status_code_t *ec)
 }
 
 static http_sm_result_t
-http_state_wait_server_reply (http_conn_t *hc, transport_send_params_t *sp)
+http_req_state_wait_transport_reply (http_conn_t *hc,
+				     transport_send_params_t *sp)
 {
   int rv;
   http_msg_t msg = {};
@@ -1110,12 +1106,12 @@ http_state_wait_server_reply (http_conn_t *hc, transport_send_params_t *sp)
   if (hc->to_recv == 0)
     {
       /* all sent, we are done */
-      http_state_change (hc, HTTP_STATE_WAIT_APP_METHOD);
+      http_req_state_change (hc, HTTP_REQ_STATE_WAIT_APP_METHOD);
     }
   else
     {
       /* stream rest of the response body */
-      http_state_change (hc, HTTP_STATE_CLIENT_IO_MORE_DATA);
+      http_req_state_change (hc, HTTP_REQ_STATE_TRANSPORT_IO_MORE_DATA);
     }
 
   app_wrk = app_worker_get_if_valid (as->app_wrk_index);
@@ -1132,7 +1128,8 @@ error:
 }
 
 static http_sm_result_t
-http_state_wait_client_method (http_conn_t *hc, transport_send_params_t *sp)
+http_req_state_wait_transport_method (http_conn_t *hc,
+				      transport_send_params_t *sp)
 {
   http_status_code_t ec;
   app_worker_t *app_wrk;
@@ -1210,13 +1207,13 @@ http_state_wait_client_method (http_conn_t *hc, transport_send_params_t *sp)
       /* drop everything, we do not support pipelining */
       http_read_message_drop_all (hc);
       /* all sent, we are done */
-      http_state_change (hc, HTTP_STATE_WAIT_APP_REPLY);
+      http_req_state_change (hc, HTTP_REQ_STATE_WAIT_APP_REPLY);
     }
   else
     {
       http_read_message_drop (hc, len);
       /* stream rest of the response body */
-      http_state_change (hc, HTTP_STATE_CLIENT_IO_MORE_DATA);
+      http_req_state_change (hc, HTTP_REQ_STATE_TRANSPORT_IO_MORE_DATA);
     }
 
   app_wrk = app_worker_get_if_valid (as->app_wrk_index);
@@ -1235,7 +1232,7 @@ error:
 }
 
 static http_sm_result_t
-http_state_wait_app_reply (http_conn_t *hc, transport_send_params_t *sp)
+http_req_state_wait_app_reply (http_conn_t *hc, transport_send_params_t *sp)
 {
   http_main_t *hm = &http_main;
   u8 *response;
@@ -1246,6 +1243,7 @@ http_state_wait_app_reply (http_conn_t *hc, transport_send_params_t *sp)
   http_msg_t msg;
   int rv;
   http_sm_result_t sm_result = HTTP_SM_ERROR;
+  http_req_state_t next_state = HTTP_REQ_STATE_WAIT_TRANSPORT_METHOD;
 
   as = session_get_from_handle (hc->h_pa_session_handle);
 
@@ -1290,7 +1288,7 @@ http_state_wait_app_reply (http_conn_t *hc, transport_send_params_t *sp)
   if (hc->is_tunnel && http_status_code_str[msg.code][0] == '2')
     {
       ASSERT (msg.data.body_len == 0);
-      hc->state = HTTP_CONN_STATE_TUNNEL;
+      next_state = HTTP_REQ_STATE_TUNNEL;
       /* cleanup some stuff we don't need anymore in tunnel mode */
       http_conn_timer_stop (hc);
       vec_free (hc->rx_buf);
@@ -1342,30 +1340,30 @@ http_state_wait_app_reply (http_conn_t *hc, transport_send_params_t *sp)
       /* Start sending the actual data */
       http_buffer_init (&hc->tx_buf, msg_to_buf_type[msg.data.type],
 			as->tx_fifo, msg.data.body_len);
-      http_state_change (hc, HTTP_STATE_APP_IO_MORE_DATA);
+      next_state = HTTP_REQ_STATE_APP_IO_MORE_DATA;
       sm_result = HTTP_SM_CONTINUE;
     }
   else
     {
       /* No response body, we are done */
-      http_state_change (hc, HTTP_STATE_WAIT_CLIENT_METHOD);
       sm_result = HTTP_SM_STOP;
     }
 
+  http_req_state_change (hc, next_state);
+
   ASSERT (sp->max_burst_size >= sent);
   sp->max_burst_size -= sent;
   return sm_result;
 
 error:
   http_send_error (hc, sc);
-  http_state_change (hc, HTTP_STATE_WAIT_CLIENT_METHOD);
   session_transport_closing_notify (&hc->connection);
   http_disconnect_transport (hc);
   return HTTP_SM_STOP;
 }
 
 static http_sm_result_t
-http_state_wait_app_method (http_conn_t *hc, transport_send_params_t *sp)
+http_req_state_wait_app_method (http_conn_t *hc, transport_send_params_t *sp)
 {
   http_msg_t msg;
   session_t *as;
@@ -1373,7 +1371,7 @@ http_state_wait_app_method (http_conn_t *hc, transport_send_params_t *sp)
   u32 sent;
   int rv;
   http_sm_result_t sm_result = HTTP_SM_ERROR;
-  http_state_t next_state;
+  http_req_state_t next_state;
 
   as = session_get_from_handle (hc->h_pa_session_handle);
 
@@ -1433,7 +1431,7 @@ http_state_wait_app_method (http_conn_t *hc, transport_send_params_t *sp)
 			/* Any headers from app? */
 			msg.data.headers_len ? "" : "\r\n");
 
-      next_state = HTTP_STATE_WAIT_SERVER_REPLY;
+      next_state = HTTP_REQ_STATE_WAIT_TRANSPORT_REPLY;
       sm_result = HTTP_SM_STOP;
     }
   else if (msg.method_type == HTTP_REQ_POST)
@@ -1464,7 +1462,7 @@ http_state_wait_app_method (http_conn_t *hc, transport_send_params_t *sp)
       http_buffer_init (&hc->tx_buf, msg_to_buf_type[msg.data.type],
 			as->tx_fifo, msg.data.body_len);
 
-      next_state = HTTP_STATE_APP_IO_MORE_DATA;
+      next_state = HTTP_REQ_STATE_APP_IO_MORE_DATA;
       sm_result = HTTP_SM_CONTINUE;
     }
   else
@@ -1504,7 +1502,7 @@ http_state_wait_app_method (http_conn_t *hc, transport_send_params_t *sp)
       goto error;
     }
 
-  http_state_change (hc, next_state);
+  http_req_state_change (hc, next_state);
   goto done;
 
 error:
@@ -1520,7 +1518,8 @@ done:
 }
 
 static http_sm_result_t
-http_state_client_io_more_data (http_conn_t *hc, transport_send_params_t *sp)
+http_req_state_transport_io_more_data (http_conn_t *hc,
+				       transport_send_params_t *sp)
 {
   session_t *as, *ts;
   app_worker_t *app_wrk;
@@ -1567,18 +1566,18 @@ http_state_client_io_more_data (http_conn_t *hc, transport_send_params_t *sp)
       clib_warning ("http protocol error: received more data than expected");
       session_transport_closing_notify (&hc->connection);
       http_disconnect_transport (hc);
-      http_state_change (hc, HTTP_STATE_WAIT_APP_METHOD);
+      http_req_state_change (hc, HTTP_REQ_STATE_WAIT_APP_METHOD);
       return HTTP_SM_ERROR;
     }
   hc->to_recv -= rv;
   HTTP_DBG (1, "drained %d from ts; remains %lu", rv, hc->to_recv);
 
   /* Finished transaction:
-   * server back to HTTP_STATE_WAIT_APP_REPLY
-   * client to HTTP_STATE_WAIT_APP_METHOD */
+   * server back to HTTP_REQ_STATE_WAIT_APP_REPLY
+   * client to HTTP_REQ_STATE_WAIT_APP_METHOD */
   if (hc->to_recv == 0)
-    http_state_change (hc, hc->is_server ? HTTP_STATE_WAIT_APP_REPLY :
-					   HTTP_STATE_WAIT_APP_METHOD);
+    http_req_state_change (hc, hc->is_server ? HTTP_REQ_STATE_WAIT_APP_REPLY :
+					       HTTP_REQ_STATE_WAIT_APP_METHOD);
 
   app_wrk = app_worker_get_if_valid (as->app_wrk_index);
   if (app_wrk)
@@ -1591,7 +1590,7 @@ http_state_client_io_more_data (http_conn_t *hc, transport_send_params_t *sp)
 }
 
 static http_sm_result_t
-http_state_app_io_more_data (http_conn_t *hc, transport_send_params_t *sp)
+http_req_state_app_io_more_data (http_conn_t *hc, transport_send_params_t *sp)
 {
   u32 max_send = 64 << 10, n_segs;
   http_buffer_t *hb = &hc->tx_buf;
@@ -1633,74 +1632,43 @@ http_state_app_io_more_data (http_conn_t *hc, transport_send_params_t *sp)
 	session_program_tx_io_evt (ts->handle, SESSION_IO_EVT_TX_FLUSH);
 
       /* Finished transaction:
-       * server back to HTTP_STATE_WAIT_METHOD
-       * client to HTTP_STATE_WAIT_SERVER_REPLY */
-      http_state_change (hc, hc->is_server ? HTTP_STATE_WAIT_CLIENT_METHOD :
-						   HTTP_STATE_WAIT_SERVER_REPLY);
+       * server back to HTTP_REQ_STATE_WAIT_TRANSPORT_METHOD
+       * client to HTTP_REQ_STATE_WAIT_TRANSPORT_REPLY */
+      http_req_state_change (hc, hc->is_server ?
+				   HTTP_REQ_STATE_WAIT_TRANSPORT_METHOD :
+				   HTTP_REQ_STATE_WAIT_TRANSPORT_REPLY);
       http_buffer_free (&hc->tx_buf);
     }
 
   return HTTP_SM_STOP;
 }
 
-typedef http_sm_result_t (*http_sm_handler) (http_conn_t *,
-					     transport_send_params_t *sp);
-
-static http_sm_handler state_funcs[HTTP_N_STATES] = {
-  0, /* idle state */
-  http_state_wait_app_method,
-  http_state_wait_client_method,
-  http_state_wait_server_reply,
-  http_state_wait_app_reply,
-  http_state_client_io_more_data,
-  http_state_app_io_more_data,
-};
-
-static void
-http_req_run_state_machine (http_conn_t *hc, transport_send_params_t *sp)
-{
-  http_sm_result_t res;
-
-  do
-    {
-      res = state_funcs[hc->http_state](hc, sp);
-      if (res == HTTP_SM_ERROR)
-	{
-	  HTTP_DBG (1, "error in state machine %d", res);
-	  return;
-	}
-    }
-  while (res == HTTP_SM_CONTINUE);
-
-  /* Reset the session expiration timer */
-  http_conn_timer_update (hc);
-}
-
-static int
-http_tunnel_rx (session_t *ts, http_conn_t *hc)
+static http_sm_result_t
+http_req_state_tunnel_rx (http_conn_t *hc, transport_send_params_t *sp)
 {
   u32 max_deq, max_enq, max_read, n_segs = 2;
   svm_fifo_seg_t segs[n_segs];
   int n_written = 0;
-  session_t *as;
+  session_t *as, *ts;
   app_worker_t *app_wrk;
 
   HTTP_DBG (1, "tunnel received data from client");
 
   as = session_get_from_handle (hc->h_pa_session_handle);
+  ts = session_get_from_handle (hc->h_tc_session_handle);
 
   max_deq = svm_fifo_max_dequeue (ts->rx_fifo);
   if (PREDICT_FALSE (max_deq == 0))
     {
       HTTP_DBG (1, "max_deq == 0");
-      return 0;
+      return HTTP_SM_STOP;
     }
   max_enq = svm_fifo_max_enqueue (as->rx_fifo);
   if (max_enq == 0)
     {
       HTTP_DBG (1, "app's rx fifo full");
       svm_fifo_add_want_deq_ntf (as->rx_fifo, SVM_FIFO_WANT_DEQ_NOTIF);
-      return 0;
+      return HTTP_SM_STOP;
     }
   max_read = clib_min (max_enq, max_deq);
   svm_fifo_segments (ts->rx_fifo, 0, segs, &n_segs, max_read);
@@ -1714,7 +1682,117 @@ http_tunnel_rx (session_t *ts, http_conn_t *hc)
   if (svm_fifo_max_dequeue_cons (ts->rx_fifo))
     session_program_rx_io_evt (session_handle (ts));
 
-  return 0;
+  return HTTP_SM_STOP;
+}
+
+static http_sm_result_t
+http_req_state_tunnel_tx (http_conn_t *hc, transport_send_params_t *sp)
+{
+  u32 max_deq, max_enq, max_read, n_segs = 2;
+  svm_fifo_seg_t segs[n_segs];
+  session_t *as, *ts;
+  int n_written = 0;
+
+  HTTP_DBG (1, "tunnel received data from target");
+
+  as = session_get_from_handle (hc->h_pa_session_handle);
+  ts = session_get_from_handle (hc->h_tc_session_handle);
+
+  max_deq = svm_fifo_max_dequeue_cons (as->tx_fifo);
+  if (PREDICT_FALSE (max_deq == 0))
+    {
+      HTTP_DBG (1, "max_deq == 0");
+      goto check_fifo;
+    }
+  max_enq = svm_fifo_max_enqueue_prod (ts->tx_fifo);
+  if (max_enq == 0)
+    {
+      HTTP_DBG (1, "ts tx fifo full");
+      goto check_fifo;
+    }
+  max_read = clib_min (max_enq, max_deq);
+  max_read = clib_min (max_read, sp->max_burst_size);
+  svm_fifo_segments (as->tx_fifo, 0, segs, &n_segs, max_read);
+  n_written = svm_fifo_enqueue_segments (ts->tx_fifo, segs, n_segs, 0);
+  ASSERT (n_written > 0);
+  HTTP_DBG (1, "transfered %u bytes", n_written);
+  sp->bytes_dequeued += n_written;
+  sp->max_burst_size -= n_written;
+  svm_fifo_dequeue_drop (as->tx_fifo, n_written);
+  if (svm_fifo_set_event (ts->tx_fifo))
+    session_program_tx_io_evt (ts->handle, SESSION_IO_EVT_TX);
+
+check_fifo:
+  /* Deschedule and wait for deq notification if ts fifo is almost full */
+  if (svm_fifo_max_enqueue (ts->tx_fifo) < HTTP_FIFO_THRESH)
+    {
+      svm_fifo_add_want_deq_ntf (ts->tx_fifo, SVM_FIFO_WANT_DEQ_NOTIF);
+      transport_connection_deschedule (&hc->connection);
+      sp->flags |= TRANSPORT_SND_F_DESCHED;
+    }
+
+  return HTTP_SM_STOP;
+}
+
+typedef http_sm_result_t (*http_sm_handler) (http_conn_t *,
+					     transport_send_params_t *sp);
+
+static http_sm_handler tx_state_funcs[HTTP_REQ_N_STATES] = {
+  0, /* idle */
+  http_req_state_wait_app_method,
+  0, /* wait transport reply */
+  0, /* transport io more data */
+  0, /* wait transport method */
+  http_req_state_wait_app_reply,
+  http_req_state_app_io_more_data,
+  http_req_state_tunnel_tx,
+};
+
+static_always_inline int
+http_req_state_is_tx_valid (http_conn_t *hc)
+{
+  return tx_state_funcs[hc->req_state] ? 1 : 0;
+}
+
+static http_sm_handler rx_state_funcs[HTTP_REQ_N_STATES] = {
+  0, /* idle */
+  0, /* wait app method */
+  http_req_state_wait_transport_reply,
+  http_req_state_transport_io_more_data,
+  http_req_state_wait_transport_method,
+  0, /* wait app reply */
+  0, /* app io more data */
+  http_req_state_tunnel_rx,
+};
+
+static_always_inline int
+http_req_state_is_rx_valid (http_conn_t *hc)
+{
+  return rx_state_funcs[hc->req_state] ? 1 : 0;
+}
+
+static_always_inline void
+http_req_run_state_machine (http_conn_t *hc, transport_send_params_t *sp,
+			    u8 is_tx)
+{
+  http_sm_result_t res;
+
+  do
+    {
+      if (is_tx)
+	res = tx_state_funcs[hc->req_state](hc, sp);
+      else
+	res = rx_state_funcs[hc->req_state](hc, sp);
+      if (res == HTTP_SM_ERROR)
+	{
+	  HTTP_DBG (1, "error in state machine %d", res);
+	  return;
+	}
+    }
+  while (res == HTTP_SM_CONTINUE);
+
+  /* Reset the session expiration timer */
+  http_conn_timer_update (hc);
 }
 
 static int
@@ -1729,24 +1807,22 @@ http_ts_rx_callback (session_t *ts)
   if (hc->state == HTTP_CONN_STATE_CLOSED)
     {
       HTTP_DBG (1, "conn closed");
-      svm_fifo_dequeue_drop_all (ts->tx_fifo);
+      svm_fifo_dequeue_drop_all (ts->rx_fifo);
       return 0;
     }
 
-  if (hc->state == HTTP_CONN_STATE_TUNNEL)
-    return http_tunnel_rx (ts, hc);
-
-  if (!http_state_is_rx_valid (hc))
+  if (!http_req_state_is_rx_valid (hc))
     {
-      if (hc->state != HTTP_CONN_STATE_CLOSED)
-	clib_warning ("app data req state '%U' session state %u",
-		      format_http_state, hc->http_state, hc->state);
-      svm_fifo_dequeue_drop_all (ts->tx_fifo);
+      clib_warning ("hc [%u]%x invalid rx state: http req state "
+		    "'%U', session state '%U'",
+		    ts->thread_index, ts->opaque, format_http_req_state,
+		    hc->req_state, format_http_conn_state, hc);
+      svm_fifo_dequeue_drop_all (ts->rx_fifo);
       return 0;
     }
 
   HTTP_DBG (1, "run state machine");
-  http_req_run_state_machine (hc, 0);
+  http_req_run_state_machine (hc, 0, 0);
 
   if (hc->state == HTTP_CONN_STATE_TRANSPORT_CLOSED)
     {
@@ -2090,54 +2166,6 @@ http_transport_get_listener (u32 listener_index)
 }
 
 static int
-http_tunnel_tx (http_conn_t *hc, session_t *as, transport_send_params_t *sp)
-{
-  u32 max_deq, max_enq, max_read, n_segs = 2;
-  svm_fifo_seg_t segs[n_segs];
-  session_t *ts;
-  int n_written = 0;
-
-  HTTP_DBG (1, "tunnel received data from target");
-
-  ts = session_get_from_handle (hc->h_tc_session_handle);
-
-  max_deq = svm_fifo_max_dequeue_cons (as->tx_fifo);
-  if (PREDICT_FALSE (max_deq == 0))
-    {
-      HTTP_DBG (1, "max_deq == 0");
-      goto check_fifo;
-    }
-  max_enq = svm_fifo_max_enqueue_prod (ts->tx_fifo);
-  if (max_enq == 0)
-    {
-      HTTP_DBG (1, "ts tx fifo full");
-      goto check_fifo;
-    }
-  max_read = clib_min (max_enq, max_deq);
-  max_read = clib_min (max_read, sp->max_burst_size);
-  svm_fifo_segments (as->tx_fifo, 0, segs, &n_segs, max_read);
-  n_written = svm_fifo_enqueue_segments (ts->tx_fifo, segs, n_segs, 0);
-  ASSERT (n_written > 0);
-  HTTP_DBG (1, "transfered %u bytes", n_written);
-  sp->bytes_dequeued += n_written;
-  sp->max_burst_size -= n_written;
-  svm_fifo_dequeue_drop (as->tx_fifo, n_written);
-  if (svm_fifo_set_event (ts->tx_fifo))
-    session_program_tx_io_evt (ts->handle, SESSION_IO_EVT_TX);
-
-check_fifo:
-  /* Deschedule and wait for deq notification if ts fifo is almost full */
-  if (svm_fifo_max_enqueue (ts->tx_fifo) < HTTP_FIFO_THRESH)
-    {
-      svm_fifo_add_want_deq_ntf (ts->tx_fifo, SVM_FIFO_WANT_DEQ_NOTIF);
-      transport_connection_deschedule (&hc->connection);
-      sp->flags |= TRANSPORT_SND_F_DESCHED;
-    }
-
-  return n_written > 0 ? clib_max (n_written / TRANSPORT_PACER_MIN_MSS, 1) : 0;
-}
-
-static int
 http_app_tx_callback (void *session, transport_send_params_t *sp)
 {
   session_t *as = (session_t *) session;
@@ -2151,24 +2179,19 @@ http_app_tx_callback (void *session, transport_send_params_t *sp)
   max_burst_sz = sp->max_burst_size * TRANSPORT_PACER_MIN_MSS;
   sp->max_burst_size = max_burst_sz;
 
-  if (hc->state == HTTP_CONN_STATE_TUNNEL)
-    return http_tunnel_tx (hc, as, sp);
-
-  if (!http_state_is_tx_valid (hc))
+  if (!http_req_state_is_tx_valid (hc))
     {
-      if (hc->state != HTTP_CONN_STATE_CLOSED)
-	{
-	  clib_warning ("hc [%u]%x invalid tx state http state "
-			"'%U', session state %u",
-			as->thread_index, as->connection_index,
-			format_http_state, hc->http_state, hc->state);
-	}
+      clib_warning ("hc [%u]%x invalid tx state: http req state "
+		    "'%U', session state '%U'",
+		    as->thread_index, as->connection_index,
+		    format_http_req_state, hc->req_state,
+		    format_http_conn_state, hc);
       svm_fifo_dequeue_drop_all (as->tx_fifo);
       return 0;
     }
 
   HTTP_DBG (1, "run state machine");
-  http_req_run_state_machine (hc, sp);
+  http_req_run_state_machine (hc, sp, 1);
 
   if (hc->state == HTTP_CONN_STATE_APP_CLOSED)
     {
@@ -2186,10 +2209,9 @@ http_app_rx_evt_cb (transport_connection_t *tc)
 {
   http_conn_t *hc = (http_conn_t *) tc;
   HTTP_DBG (1, "hc [%u]%x", vlib_get_thread_index (), hc->h_hc_index);
-  session_t *ts = session_get_from_handle (hc->h_tc_session_handle);
 
-  if (hc->state == HTTP_CONN_STATE_TUNNEL)
-    return http_tunnel_rx (ts, hc);
+  if (hc->req_state == HTTP_REQ_STATE_TUNNEL)
+    http_req_state_tunnel_rx (hc, 0);
 
   return 0;
 }
@@ -2236,39 +2258,6 @@ format_http_listener (u8 *s, va_list *args)
 }
 
 static u8 *
-format_http_conn_state (u8 *s, va_list *args)
-{
-  http_conn_t *hc = va_arg (*args, http_conn_t *);
-
-  switch (hc->state)
-    {
-    case HTTP_CONN_STATE_LISTEN:
-      s = format (s, "LISTEN");
-      break;
-    case HTTP_CONN_STATE_CONNECTING:
-      s = format (s, "CONNECTING");
-      break;
-    case HTTP_CONN_STATE_ESTABLISHED:
-      s = format (s, "ESTABLISHED");
-      break;
-    case HTTP_CONN_STATE_TUNNEL:
-      s = format (s, "TUNNEL");
-      break;
-    case HTTP_CONN_STATE_TRANSPORT_CLOSED:
-      s = format (s, "TRANSPORT_CLOSED");
-      break;
-    case HTTP_CONN_STATE_APP_CLOSED:
-      s = format (s, "APP_CLOSED");
-      break;
-    case HTTP_CONN_STATE_CLOSED:
-      s = format (s, "CLOSED");
-      break;
-    }
-
-  return s;
-}
-
-static u8 *
 format_http_transport_connection (u8 *s, va_list *args)
 {
   u32 tc_index = va_arg (*args, u32);
diff --git a/src/plugins/http/http.h b/src/plugins/http/http.h
index a117f374efa..b293c125465 100644
--- a/src/plugins/http/http.h
+++ b/src/plugins/http/http.h
@@ -59,28 +59,38 @@ typedef struct
 
 #define http_token_lit(s) (s), sizeof (s) - 1
 
+#define foreach_http_conn_state                                               \
+  _ (LISTEN, "listen")                                                        \
+  _ (CONNECTING, "connecting")                                                \
+  _ (ESTABLISHED, "established")                                              \
+  _ (TRANSPORT_CLOSED, "transport-closed")                                    \
+  _ (APP_CLOSED, "app-closed")                                                \
+  _ (CLOSED, "closed")
+
 typedef enum http_conn_state_
 {
-  HTTP_CONN_STATE_LISTEN,
-  HTTP_CONN_STATE_CONNECTING,
-  HTTP_CONN_STATE_ESTABLISHED,
-  HTTP_CONN_STATE_TUNNEL,
-  HTTP_CONN_STATE_TRANSPORT_CLOSED,
-  HTTP_CONN_STATE_APP_CLOSED,
-  HTTP_CONN_STATE_CLOSED
+#define _(s, str) HTTP_CONN_STATE_##s,
+  foreach_http_conn_state
+#undef _
 } http_conn_state_t;
 
-typedef enum http_state_
+#define foreach_http_req_state                                                \
+  _ (0, IDLE, "idle")                                                         \
+  _ (1, WAIT_APP_METHOD, "wait app method")                                   \
+  _ (2, WAIT_TRANSPORT_REPLY, "wait transport reply")                         \
+  _ (3, TRANSPORT_IO_MORE_DATA, "transport io more data")                     \
+  _ (4, WAIT_TRANSPORT_METHOD, "wait transport method")                       \
+  _ (5, WAIT_APP_REPLY, "wait app reply")                                     \
+  _ (6, APP_IO_MORE_DATA, "app io more data")                                 \
+  _ (7, TUNNEL, "tunnel")
+
+typedef enum http_req_state_
 {
-  HTTP_STATE_IDLE = 0,
-  HTTP_STATE_WAIT_APP_METHOD,
-  HTTP_STATE_WAIT_CLIENT_METHOD,
-  HTTP_STATE_WAIT_SERVER_REPLY,
-  HTTP_STATE_WAIT_APP_REPLY,
-  HTTP_STATE_CLIENT_IO_MORE_DATA,
-  HTTP_STATE_APP_IO_MORE_DATA,
-  HTTP_N_STATES,
-} http_state_t;
+#define _(n, s, str) HTTP_REQ_STATE_##s = n,
+  foreach_http_req_state
+#undef _
+    HTTP_REQ_N_STATES
+} http_req_state_t;
 
 typedef enum http_req_method_
 {
@@ -399,7 +409,7 @@ typedef struct http_tc_
   /*
    * Current request
    */
-  http_state_t http_state;
+  http_req_state_t req_state;
   http_req_method_t method;
   u8 *rx_buf;
   u32 rx_buf_offset;
diff --git a/src/plugins/http_static/static_server.c b/src/plugins/http_static/static_server.c
index a37cc3f03b2..9cc3f5dd658 100644
--- a/src/plugins/http_static/static_server.c
+++ b/src/plugins/http_static/static_server.c
@@ -126,6 +126,9 @@ start_send_data (hss_session_t *hs, http_status_code_t status)
 	  ASSERT (rv == sizeof (headers));
 	}
 
+      if (!msg.data.body_len)
+	goto done;
+
       uword data = pointer_to_uword (hs->data);
       rv = svm_fifo_enqueue (ts->tx_fifo, sizeof (data), (u8 *) &data);
       ASSERT (rv == sizeof (data));