Cleanup URI code and TCP bugfixing

- Add CLI/API to enable session layer, by default it's disabled
- Improve rcv wnd computation
- Improvements to tx path
- URI code cleanup
- Builtin test tcp server
- Improve src port allocation

Change-Id: I2ace498e76a0771d4c31a8075cc14fe33d7dfa38
Signed-off-by: Florin Coras <fcoras@cisco.com>

5 files changed, 257 insertions, 76 deletions

diff --git a/src/vnet/tcp/builtin_server.c b/src/vnet/tcp/builtin_server.c
new file mode 100644
index 00000000..be65642a
--- /dev/null
+++ b/src/vnet/tcp/builtin_server.c
@@ -0,0 +1,135 @@
+/*
+* Copyright (c) 2015-2017 Cisco and/or its affiliates.
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at:
+*
+*     http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+#include <vnet/vnet.h>
+#include <vlibmemory/api.h>
+#include <vnet/session/application.h>
+#include <vnet/session/application_interface.h>
+
+int
+builtin_session_accept_callback (stream_session_t * s)
+{
+  clib_warning ("called...");
+  s->session_state = SESSION_STATE_READY;
+  return 0;
+}
+
+void
+builtin_session_disconnect_callback (stream_session_t * s)
+{
+  clib_warning ("called...");
+}
+
+int
+builtin_session_connected_callback (u32 client_index,
+				    stream_session_t * s, u8 is_fail)
+{
+  clib_warning ("called...");
+  return -1;
+}
+
+int
+builtin_add_segment_callback (u32 client_index,
+			      const u8 * seg_name, u32 seg_size)
+{
+  clib_warning ("called...");
+  return -1;
+}
+
+int
+builtin_redirect_connect_callback (u32 client_index, void *mp)
+{
+  clib_warning ("called...");
+  return -1;
+}
+
+int
+builtin_server_rx_callback (stream_session_t * s)
+{
+  clib_warning ("called...");
+  return 0;
+}
+
+static session_cb_vft_t builtin_session_cb_vft = {
+  .session_accept_callback = builtin_session_accept_callback,
+  .session_disconnect_callback = builtin_session_disconnect_callback,
+  .session_connected_callback = builtin_session_connected_callback,
+  .add_segment_callback = builtin_add_segment_callback,
+  .redirect_connect_callback = builtin_redirect_connect_callback,
+  .builtin_server_rx_callback = builtin_server_rx_callback
+};
+
+static int
+server_create (vlib_main_t * vm)
+{
+  vnet_bind_args_t _a, *a = &_a;
+  u64 options[SESSION_OPTIONS_N_OPTIONS];
+  char segment_name[128];
+
+  memset (a, 0, sizeof (*a));
+  memset (options, 0, sizeof (options));
+
+  a->uri = "tcp://0.0.0.0/80";
+  a->api_client_index = ~0;
+  a->session_cb_vft = &builtin_session_cb_vft;
+  a->options = options;
+  a->options[SESSION_OPTIONS_SEGMENT_SIZE] = 256 << 10;
+  a->options[SESSION_OPTIONS_RX_FIFO_SIZE] = 64 << 10;
+  a->options[SESSION_OPTIONS_TX_FIFO_SIZE] = 64 << 10;
+  a->segment_name = segment_name;
+  a->segment_name_length = ARRAY_LEN (segment_name);
+
+  return vnet_bind_uri (a);
+}
+
+static clib_error_t *
+server_create_command_fn (vlib_main_t * vm,
+			  unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+  int rv;
+#if 0
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "whatever %d", &whatever))
+	;
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+#endif
+
+  rv = server_create (vm);
+  switch (rv)
+    {
+    case 0:
+      break;
+    default:
+      return clib_error_return (0, "server_create returned %d", rv);
+    }
+  return 0;
+}
+
+VLIB_CLI_COMMAND (server_create_command, static) =
+{
+.path = "test server",.short_help = "test server",.function =
+    server_create_command_fn,};
+
+/*
+* fd.io coding-style-patch-verification: ON
+*
+* Local Variables:
+* eval: (c-set-style "gnu")
+* End:
+*/
diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index 0f9b7097..e5feaeb1 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -217,6 +217,7 @@ ip_interface_get_first_ip (u32 sw_if_index, u8 is_ip4)
   return 0;
 }
 
+#define PORT_MASK ((1 << 16)- 1)
 /**
  * Allocate local port and add if successful add entry to local endpoint
  * table to mark the pair as used.
@@ -224,7 +225,6 @@ ip_interface_get_first_ip (u32 sw_if_index, u8 is_ip4)
 u16
 tcp_allocate_local_port (tcp_main_t * tm, ip46_address_t * ip)
 {
-  u8 unique = 0;
   transport_endpoint_t *tep;
   u32 time_now, tei;
   u16 min = 1024, max = 65535, tries;	/* XXX configurable ? */
@@ -235,37 +235,34 @@ tcp_allocate_local_port (tcp_main_t * tm, ip46_address_t * ip)
   /* Start at random point or max */
   pool_get (tm->local_endpoints, tep);
   clib_memcpy (&tep->ip, ip, sizeof (*ip));
-  tep->port = random_u32 (&time_now) << 16;
-  tep->port = tep->port < min ? max : tep->port;
 
   /* Search for first free slot */
-  while (tries)
+  for (; tries >= 0; tries--)
     {
+      u16 port = 0;
+
+      /* Find a port in the specified range */
+      while (1)
+	{
+	  port = random_u32 (&time_now) & PORT_MASK;
+	  if (PREDICT_TRUE (port >= min && port < max))
+	    break;
+	}
+
+      tep->port = port;
+
+      /* Look it up */
       tei = transport_endpoint_lookup (&tm->local_endpoints_table, &tep->ip,
 				       tep->port);
+      /* If not found, we're done */
       if (tei == TRANSPORT_ENDPOINT_INVALID_INDEX)
 	{
-	  unique = 1;
-	  break;
+	  transport_endpoint_table_add (&tm->local_endpoints_table, tep,
+					tep - tm->local_endpoints);
+	  return tep->port;
 	}
-
-      tep->port--;
-
-      if (tep->port < min)
-	tep->port = max;
-
-      tries--;
     }
-
-  if (unique)
-    {
-      transport_endpoint_table_add (&tm->local_endpoints_table, tep,
-				    tep - tm->local_endpoints);
-
-      return tep->port;
-    }
-
-  /* Failed */
+  /* No free ports */
   pool_put (tm->local_endpoints, tep);
   return -1;
 }
@@ -360,7 +357,10 @@ tcp_connection_open (ip46_address_t * rmt_addr, u16 rmt_port, u8 is_ip4)
   /* Allocate source port */
   lcl_port = tcp_allocate_local_port (tm, &lcl_addr);
   if (lcl_port < 1)
-    return -1;
+    {
+      clib_warning ("Failed to allocate src port");
+      return -1;
+    }
 
   /*
    * Create connection and send SYN
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 22f00a63..3560509d 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -30,7 +30,8 @@
 #define TCP_MAX_OPTION_SPACE 40
 
 #define TCP_DUPACK_THRESHOLD 3
-#define TCP_DEFAULT_RX_FIFO_SIZE 64 << 10
+#define TCP_MAX_RX_FIFO_SIZE 2 << 20
+#define TCP_IW_N_SEGMENTS 10
 
 /** TCP FSM state definitions as per RFC793. */
 #define foreach_tcp_fsm_state   \
@@ -590,7 +591,6 @@ vlib_buffer_push_tcp_net_order (vlib_buffer_t * b, u16 sp, u16 dp, u32 seq,
 /**
  * Push TCP header to buffer
  *
- * @param vm - vlib_main
  * @param b - buffer to write the header to
  * @param sp_net - source port net order
  * @param dp_net - destination port net order
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index daa0683b..0a907d0a 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -711,7 +711,7 @@ tcp_rcv_ack (tcp_connection_t * tc, vlib_buffer_t * b,
   if (tcp_opts_sack_permitted (&tc->opt))
     tcp_rcv_sacks (tc, vnet_buffer (b)->tcp.ack_number);
 
-  new_snd_wnd = clib_net_to_host_u32 (th->window) << tc->snd_wscale;
+  new_snd_wnd = clib_net_to_host_u16 (th->window) << tc->snd_wscale;
 
   if (tcp_ack_is_dupack (tc, b, new_snd_wnd))
     {
@@ -1320,7 +1320,6 @@ tcp46_syn_sent_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 
 	  /* Parse options */
 	  tcp_options_parse (tcp0, &new_tc0->opt);
-	  tcp_connection_init_vars (new_tc0);
 
 	  if (tcp_opts_tstamp (&new_tc0->opt))
 	    {
@@ -1331,11 +1330,13 @@ tcp46_syn_sent_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  if (tcp_opts_wscale (&new_tc0->opt))
 	    new_tc0->snd_wscale = new_tc0->opt.wscale;
 
-	  new_tc0->snd_wnd = clib_net_to_host_u32 (tcp0->window)
-	    << new_tc0->snd_wscale;
+	  /* No scaling */
+	  new_tc0->snd_wnd = clib_net_to_host_u16 (tcp0->window);
 	  new_tc0->snd_wl1 = seq0;
 	  new_tc0->snd_wl2 = ack0;
 
+	  tcp_connection_init_vars (new_tc0);
+
 	  /* SYN-ACK: See if we can switch to ESTABLISHED state */
 	  if (tcp_ack (tcp0))
 	    {
@@ -1345,6 +1346,9 @@ tcp46_syn_sent_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	      new_tc0->snd_una = ack0;
 	      new_tc0->state = TCP_STATE_ESTABLISHED;
 
+	      /* Make sure las is initialized for the wnd computation */
+	      new_tc0->rcv_las = new_tc0->rcv_nxt;
+
 	      /* Notify app that we have connection */
 	      stream_session_connect_notify (&new_tc0->connection, sst, 0);
 
@@ -1575,7 +1579,7 @@ tcp46_rcv_process_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 
 	      /* Initialize session variables */
 	      tc0->snd_una = vnet_buffer (b0)->tcp.ack_number;
-	      tc0->snd_wnd = clib_net_to_host_u32 (tcp0->window)
+	      tc0->snd_wnd = clib_net_to_host_u16 (tcp0->window)
 		<< tc0->opt.wscale;
 	      tc0->snd_wl1 = vnet_buffer (b0)->tcp.seq_number;
 	      tc0->snd_wl2 = vnet_buffer (b0)->tcp.ack_number;
@@ -1899,7 +1903,6 @@ tcp46_listen_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    }
 
 	  tcp_options_parse (th0, &child0->opt);
-	  tcp_connection_init_vars (child0);
 
 	  child0->irs = vnet_buffer (b0)->tcp.seq_number;
 	  child0->rcv_nxt = vnet_buffer (b0)->tcp.seq_number + 1;
@@ -1913,6 +1916,16 @@ tcp46_listen_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	      child0->tsval_recent_age = tcp_time_now ();
 	    }
 
+	  if (tcp_opts_wscale (&child0->opt))
+	    child0->snd_wscale = child0->opt.wscale;
+
+	  /* No scaling */
+	  child0->snd_wnd = clib_net_to_host_u16 (th0->window);
+	  child0->snd_wl1 = vnet_buffer (b0)->tcp.seq_number;
+	  child0->snd_wl2 = vnet_buffer (b0)->tcp.ack_number;
+
+	  tcp_connection_init_vars (child0);
+
 	  /* Reuse buffer to make syn-ack and send */
 	  tcp_make_synack (child0, b0);
 	  next0 = tcp_next_output (is_ip4);
@@ -1923,7 +1936,7 @@ tcp46_listen_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 
 	    }
 
-	  b0->error = error0 ? node->errors[error0] : 0;
+	  b0->error = node->errors[error0];
 
 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
 					   n_left_to_next, bi0, next0);
@@ -2069,7 +2082,6 @@ tcp46_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
   u32 n_left_from, next_index, *from, *to_next;
   u32 my_thread_index = vm->cpu_index;
   tcp_main_t *tm = vnet_get_tcp_main ();
-  session_manager_main_t *ssm = vnet_get_session_manager_main ();
 
   from = vlib_frame_vector_args (from_frame);
   n_left_from = from_frame->n_vectors;
@@ -2109,26 +2121,26 @@ tcp46_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 
 	      /* lookup session */
 	      tc0 =
-		(tcp_connection_t *) stream_session_lookup_transport4 (ssm,
-								       &ip40->dst_address,
-								       &ip40->src_address,
-								       tcp0->dst_port,
-								       tcp0->src_port,
-								       SESSION_TYPE_IP4_TCP,
-								       my_thread_index);
+		(tcp_connection_t *)
+		stream_session_lookup_transport4 (&ip40->dst_address,
+						  &ip40->src_address,
+						  tcp0->dst_port,
+						  tcp0->src_port,
+						  SESSION_TYPE_IP4_TCP,
+						  my_thread_index);
 	    }
 	  else
 	    {
 	      ip60 = vlib_buffer_get_current (b0);
 	      tcp0 = ip6_next_header (ip60);
 	      tc0 =
-		(tcp_connection_t *) stream_session_lookup_transport6 (ssm,
-								       &ip60->src_address,
-								       &ip60->dst_address,
-								       tcp0->src_port,
-								       tcp0->dst_port,
-								       SESSION_TYPE_IP6_TCP,
-								       my_thread_index);
+		(tcp_connection_t *)
+		stream_session_lookup_transport6 (&ip60->src_address,
+						  &ip60->dst_address,
+						  tcp0->src_port,
+						  tcp0->dst_port,
+						  SESSION_TYPE_IP6_TCP,
+						  my_thread_index);
 	    }
 
 	  /* Session exists */
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index dbcf1f74..7e431cd0 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -91,24 +91,30 @@ tcp_window_compute_scale (u32 available_space)
 }
 
 /**
+ * TCP's IW as recommended by RFC6928
+ */
+always_inline u32
+tcp_initial_wnd_unscaled (tcp_connection_t * tc)
+{
+  return TCP_IW_N_SEGMENTS * dummy_mtu;
+}
+
+/**
  * Compute initial window and scale factor. As per RFC1323, window field in
  * SYN and SYN-ACK segments is never scaled.
  */
 u32
 tcp_initial_window_to_advertise (tcp_connection_t * tc)
 {
-  u32 available_space;
+  u32 max_fifo;
 
   /* Initial wnd for SYN. Fifos are not allocated yet.
-   * Use some predefined value */
-  if (tc->state != TCP_STATE_SYN_RCVD)
-    {
-      return TCP_DEFAULT_RX_FIFO_SIZE;
-    }
+   * Use some predefined value. For SYN-ACK we still want the
+   * scale to be computed in the same way */
+  max_fifo = TCP_MAX_RX_FIFO_SIZE;
 
-  available_space = stream_session_max_enqueue (&tc->connection);
-  tc->rcv_wscale = tcp_window_compute_scale (available_space);
-  tc->rcv_wnd = clib_min (available_space, TCP_WND_MAX << tc->rcv_wscale);
+  tc->rcv_wscale = tcp_window_compute_scale (max_fifo);
+  tc->rcv_wnd = tcp_initial_wnd_unscaled (tc);
 
   return clib_min (tc->rcv_wnd, TCP_WND_MAX);
 }
@@ -119,23 +125,43 @@ tcp_initial_window_to_advertise (tcp_connection_t * tc)
 u32
 tcp_window_to_advertise (tcp_connection_t * tc, tcp_state_t state)
 {
-  u32 available_space, wnd, scaled_space;
+  u32 available_space, max_fifo, observed_wnd;
 
-  if (state != TCP_STATE_ESTABLISHED)
+  if (state < TCP_STATE_ESTABLISHED)
     return tcp_initial_window_to_advertise (tc);
 
+  /*
+   * Figure out how much space we have available
+   */
   available_space = stream_session_max_enqueue (&tc->connection);
-  scaled_space = available_space >> tc->rcv_wscale;
+  max_fifo = stream_session_fifo_size (&tc->connection);
+
+  ASSERT (tc->opt.mss < max_fifo);
+
+  if (available_space < tc->opt.mss && available_space < max_fifo / 8)
+    available_space = 0;
 
-  /* Need to update scale */
-  if (PREDICT_FALSE ((scaled_space == 0 && available_space != 0))
-      || (scaled_space >= TCP_WND_MAX))
-    tc->rcv_wscale = tcp_window_compute_scale (available_space);
+  /*
+   * Use the above and what we know about what we've previously advertised
+   * to compute the new window
+   */
+  observed_wnd = tc->rcv_wnd - (tc->rcv_nxt - tc->rcv_las);
 
-  wnd = clib_min (available_space, TCP_WND_MAX << tc->rcv_wscale);
-  tc->rcv_wnd = wnd;
+  /* Bad. Thou shalt not shrink */
+  if (available_space < observed_wnd)
+    {
+      if (available_space == 0)
+	clib_warning ("Didn't shrink rcv window despite not having space");
+    }
+
+  tc->rcv_wnd = clib_min (available_space, TCP_WND_MAX << tc->rcv_wscale);
+
+  if (tc->rcv_wnd == 0)
+    {
+      tc->flags |= TCP_CONN_SENT_RCV_WND0;
+    }
 
-  return wnd >> tc->rcv_wscale;
+  return tc->rcv_wnd >> tc->rcv_wscale;
 }
 
 /**
@@ -225,7 +251,7 @@ tcp_options_write (u8 * data, tcp_options_t * opts)
 }
 
 always_inline int
-tcp_make_syn_options (tcp_options_t * opts, u32 initial_wnd)
+tcp_make_syn_options (tcp_options_t * opts, u8 wnd_scale)
 {
   u8 len = 0;
 
@@ -234,7 +260,7 @@ tcp_make_syn_options (tcp_options_t * opts, u32 initial_wnd)
   len += TCP_OPTION_LEN_MSS;
 
   opts->flags |= TCP_OPTS_FLAG_WSCALE;
-  opts->wscale = tcp_window_compute_scale (initial_wnd);
+  opts->wscale = wnd_scale;
   len += TCP_OPTION_LEN_WINDOW_SCALE;
 
   opts->flags |= TCP_OPTS_FLAG_TSTAMP;
@@ -327,8 +353,7 @@ tcp_make_options (tcp_connection_t * tc, tcp_options_t * opts,
     case TCP_STATE_SYN_RCVD:
       return tcp_make_synack_options (tc, opts);
     case TCP_STATE_SYN_SENT:
-      return tcp_make_syn_options (opts,
-				   tcp_initial_window_to_advertise (tc));
+      return tcp_make_syn_options (opts, tc->rcv_wscale);
     default:
       clib_warning ("Not handled!");
       return 0;
@@ -732,7 +757,7 @@ tcp_send_syn (tcp_connection_t * tc)
 
   /* Make and write options */
   memset (&snd_opts, 0, sizeof (snd_opts));
-  tcp_opts_len = tcp_make_syn_options (&snd_opts, initial_wnd);
+  tcp_opts_len = tcp_make_syn_options (&snd_opts, tc->rcv_wscale);
   tcp_hdr_opts_len = tcp_opts_len + sizeof (tcp_header_t);
 
   th = vlib_buffer_push_tcp (b, tc->c_lcl_port, tc->c_rmt_port, tc->iss,
@@ -900,7 +925,7 @@ tcp_prepare_retransmit_segment (tcp_connection_t * tc, vlib_buffer_t * b,
 
   tcp_reuse_buffer (vm, b);
 
-  ASSERT (tc->state == TCP_STATE_ESTABLISHED);
+  ASSERT (tc->state >= TCP_STATE_ESTABLISHED);
   ASSERT (max_bytes != 0);
 
   if (tcp_opts_sack_permitted (&tc->opt))
@@ -929,7 +954,6 @@ tcp_prepare_retransmit_segment (tcp_connection_t * tc, vlib_buffer_t * b,
 				       max_bytes);
   ASSERT (n_bytes != 0);
 
-  tc->snd_nxt += n_bytes;
   tcp_push_hdr_i (tc, b, tc->state);
 
   return n_bytes;
@@ -967,7 +991,7 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
   tcp_get_free_buffer_index (tm, &bi);
   b = vlib_get_buffer (vm, bi);
 
-  if (tc->state == TCP_STATE_ESTABLISHED)
+  if (tc->state >= TCP_STATE_ESTABLISHED)
     {
       tcp_fastrecovery_off (tc);
 
@@ -977,6 +1001,12 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
       /* Figure out what and how many bytes we can send */
       snd_space = tcp_available_snd_space (tc);
       max_bytes = clib_min (tc->snd_mss, snd_space);
+
+      if (max_bytes == 0)
+	{
+	  clib_warning ("no wnd to retransmit");
+	  return;
+	}
       tcp_prepare_retransmit_segment (tc, b, max_bytes);
 
       tc->rtx_bytes += max_bytes;
@@ -996,7 +1026,11 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
 	tc->rto = clib_min (tc->rto << 1, TCP_RTO_MAX);
 
       vlib_buffer_make_headroom (b, MAX_HDRS_LEN);
+
       tcp_push_hdr_i (tc, b, tc->state);
+
+      /* Account for the SYN */
+      tc->snd_nxt += 1;
     }
 
   if (!is_syn)
@@ -1163,8 +1197,8 @@ tcp46_output_inline (vlib_main_t * vm,
 	  if (PREDICT_FALSE
 	      (vnet_buffer (b0)->tcp.flags & TCP_BUF_FLAG_DUPACK))
 	    {
+	      ASSERT (tc0->snt_dupacks > 0);
 	      tc0->snt_dupacks--;
-	      ASSERT (tc0->snt_dupacks >= 0);
 	      if (!tcp_session_has_ooo_data (tc0))
 		{
 		  error0 = TCP_ERROR_FILTERED_DUPACKS;