Add support for tcp/session buffer chains

Change-Id: I01c6e3dc3a1b2785df37bb66b19c4b5cbb8f3211
Signed-off-by: Florin Coras <fcoras@cisco.com>

7 files changed, 266 insertions, 85 deletions

diff --git a/src/scripts/vnet/uri/dummy_app.py b/src/scripts/vnet/uri/dummy_app.py
index 50333923d6e..ff00f2fc8c6 100644
--- a/src/scripts/vnet/uri/dummy_app.py
+++ b/src/scripts/vnet/uri/dummy_app.py
@@ -6,14 +6,28 @@ import time
 
 # action can be reflect or drop 
 action = "drop"
+test = 0
+
+def test_data (data, n_rcvd):
+    n_read = len (data);
+    for i in range(n_read):
+        expected = (n_rcvd + i) & 0xff
+        byte_got = ord (data[i])
+        if (byte_got != expected):
+            print("Difference at byte {}. Expected {} got {}"
+                  .format(n_rcvd + i, expected, byte_got))
+    return n_read
 
 def handle_connection (connection, client_address):
     print("Received connection from {}".format(repr(client_address)))
+    n_rcvd = 0
     try:
         while True:
             data = connection.recv(4096)
             if not data:
                 break;
+            if (test == 1):
+                n_rcvd += test_data (data, n_rcvd)
             if (action != "drop"):
                 connection.sendall(data)
     finally:
@@ -78,8 +92,9 @@ def run(mode, ip, port):
 
 if __name__ == "__main__":
     if (len(sys.argv)) < 4:
-        raise Exception("Usage: ./dummy_app <mode> <ip> <port> [<action>]")
-    if (len(sys.argv) == 5):
+        raise Exception("Usage: ./dummy_app <mode> <ip> <port> [<action> <test>]")
+    if (len(sys.argv) == 6):
         action = sys.argv[4]
+        test = int(sys.argv[5])
 
     run (sys.argv[1], sys.argv[2], int(sys.argv[3]))
diff --git a/src/uri/uri_socket_server.c b/src/uri/uri_socket_server.c
index 64d3b49252a..2366f420126 100644
--- a/src/uri/uri_socket_server.c
+++ b/src/uri/uri_socket_server.c
@@ -17,6 +17,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
+#include <arpa/inet.h>
 #include <netdb.h>
 #include <vppinfra/format.h>
 #include <signal.h>
@@ -72,32 +73,59 @@ setup_signal_handler (void)
 int
 main (int argc, char *argv[])
 {
-  int sockfd, portno, n, sent, accfd;
+  int sockfd, portno, n, sent, accfd, reuse;
+  socklen_t client_addr_len;
   struct sockaddr_in serv_addr;
+  struct sockaddr_in client;
   struct hostent *server;
   u8 *rx_buffer = 0;
 
-  if (0 && argc < 3)
+  if (argc > 1 && argc < 3)
     {
-      fformat (stderr, "usage %s hostname port\n", argv[0]);
+      fformat (stderr, "usage %s host port\n", argv[0]);
       exit (0);
     }
 
+  if (argc >= 3)
+    {
+      portno = atoi (argv[2]);
+      server = gethostbyname (argv[1]);
+      if (server == NULL)
+	{
+	  clib_unix_warning ("gethostbyname");
+	  exit (1);
+	}
+    }
+  else
+    {
+      /* Defaults */
+      portno = 1234;
+      server = gethostbyname ("6.0.1.1");
+      if (server == NULL)
+	{
+	  clib_unix_warning ("gethostbyname");
+	  exit (1);
+	}
+    }
+
+
   setup_signal_handler ();
 
-  portno = 1234;		// atoi(argv[2]);
   sockfd = socket (AF_INET, SOCK_STREAM, 0);
   if (sockfd < 0)
     {
       clib_unix_error ("socket");
       exit (1);
     }
-  server = gethostbyname ("6.0.1.1");
-  if (server == NULL)
+
+  reuse = 1;
+  if (setsockopt (sockfd, SOL_SOCKET, SO_REUSEADDR, (const char *) &reuse,
+		  sizeof (reuse)) < 0)
     {
-      clib_unix_warning ("gethostbyname");
+      clib_unix_error ("setsockopt(SO_REUSEADDR) failed");
       exit (1);
     }
+
   bzero ((char *) &serv_addr, sizeof (serv_addr));
   serv_addr.sin_family = AF_INET;
   bcopy ((char *) server->h_addr,
@@ -123,12 +151,15 @@ main (int argc, char *argv[])
       if (signal_received)
 	break;
 
-      accfd = accept (sockfd, 0 /* don't care */ , 0);
+      client_addr_len = sizeof (struct sockaddr);
+      accfd = accept (sockfd, (struct sockaddr *) &client, &client_addr_len);
       if (accfd < 0)
 	{
 	  clib_unix_warning ("accept");
 	  continue;
 	}
+      fformat (stderr, "Accepted connection from: %s : %d\n",
+	       inet_ntoa (client.sin_addr), client.sin_port);
       while (1)
 	{
 	  n = recv (accfd, rx_buffer, vec_len (rx_buffer), 0 /* flags */ );
diff --git a/src/vnet/session/node.c b/src/vnet/session/node.c
index 2d12ee2bac9..ce7c38683f5 100644
--- a/src/vnet/session/node.c
+++ b/src/vnet/session/node.c
@@ -70,6 +70,58 @@ static u32 session_type_to_next[] = {
   SESSION_QUEUE_NEXT_IP6_LOOKUP,
 };
 
+always_inline void
+session_tx_fifo_chain_tail (session_manager_main_t * smm, vlib_main_t * vm,
+			    u8 thread_index, svm_fifo_t * fifo,
+			    vlib_buffer_t * b0, u32 bi0, u8 n_bufs_per_seg,
+			    u32 * left_to_snd0, u16 * n_bufs, u32 * rx_offset,
+			    u16 deq_per_buf, u8 peek_data)
+{
+  vlib_buffer_t *chain_b0, *prev_b0;
+  u32 chain_bi0;
+  u16 len_to_deq0, n_bytes_read;
+  u8 *data0, j;
+
+  chain_bi0 = bi0;
+  chain_b0 = b0;
+  for (j = 1; j < n_bufs_per_seg; j++)
+    {
+      prev_b0 = chain_b0;
+      len_to_deq0 = clib_min (*left_to_snd0, deq_per_buf);
+
+      *n_bufs -= 1;
+      chain_bi0 = smm->tx_buffers[thread_index][*n_bufs];
+      _vec_len (smm->tx_buffers[thread_index]) = *n_bufs;
+
+      chain_b0 = vlib_get_buffer (vm, chain_bi0);
+      chain_b0->current_data = 0;
+      data0 = vlib_buffer_get_current (chain_b0);
+      if (peek_data)
+	{
+	  n_bytes_read = svm_fifo_peek (fifo, *rx_offset, len_to_deq0, data0);
+	  *rx_offset += n_bytes_read;
+	}
+      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;
+      b0->total_length_not_including_first_buffer += chain_b0->current_length;
+
+      /* update previous buffer */
+      prev_b0->next_buffer = chain_bi0;
+      prev_b0->flags |= VLIB_BUFFER_NEXT_PRESENT;
+
+      /* update current buffer */
+      chain_b0->next_buffer = 0;
+
+      *left_to_snd0 -= n_bytes_read;
+      if (*left_to_snd0 == 0)
+	break;
+    }
+}
+
 always_inline int
 session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 				session_manager_main_t * smm,
@@ -78,16 +130,17 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 				int *n_tx_packets, u8 peek_data)
 {
   u32 n_trace = vlib_get_trace_count (vm, node);
-  u32 left_to_snd0, max_len_to_snd0, len_to_deq0, n_bufs, snd_space0;
-  u32 n_frame_bytes, n_frames_per_evt;
+  u32 left_to_snd0, max_len_to_snd0, len_to_deq0, snd_space0;
+  u32 n_bufs_per_evt, n_frames_per_evt;
   transport_connection_t *tc0;
   transport_proto_vft_t *transport_vft;
   u32 next_index, next0, *to_next, n_left_to_next, bi0;
   vlib_buffer_t *b0;
-  u32 rx_offset = 0, max_dequeue0;
-  u16 snd_mss0;
+  u32 rx_offset = 0, max_dequeue0, n_bytes_per_seg;
+  u16 snd_mss0, n_bufs_per_seg, n_bufs;
   u8 *data0;
   int i, n_bytes_read;
+  u32 n_bytes_per_buf, deq_per_buf;
 
   next_index = next0 = session_type_to_next[s0->session_type];
 
@@ -134,8 +187,15 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
       max_len_to_snd0 = snd_space0;
     }
 
-  n_frame_bytes = snd_mss0 * VLIB_FRAME_SIZE;
-  n_frames_per_evt = ceil ((double) max_len_to_snd0 / n_frame_bytes);
+  n_bytes_per_buf = vlib_buffer_free_list_buffer_size (vm,
+						       VLIB_BUFFER_DEFAULT_FREE_LIST_INDEX);
+  n_bytes_per_seg = MAX_HDRS_LEN + snd_mss0;
+  n_bufs_per_seg = ceil ((double) n_bytes_per_seg / n_bytes_per_buf);
+  n_bufs_per_evt = (ceil ((double) max_len_to_snd0 / n_bytes_per_seg))
+    * n_bufs_per_seg;
+  n_frames_per_evt = ceil ((double) n_bufs_per_evt / VLIB_FRAME_SIZE);
+
+  deq_per_buf = clib_min (snd_mss0, n_bytes_per_buf);
 
   n_bufs = vec_len (smm->tx_buffers[thread_index]);
   left_to_snd0 = max_len_to_snd0;
@@ -146,9 +206,9 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 	{
 	  vec_validate (smm->tx_buffers[thread_index],
 			n_bufs + VLIB_FRAME_SIZE - 1);
-	  n_bufs +=
-	    vlib_buffer_alloc (vm, &smm->tx_buffers[thread_index][n_bufs],
-			       VLIB_FRAME_SIZE);
+	  n_bufs += vlib_buffer_alloc (vm,
+				       &smm->tx_buffers[thread_index][n_bufs],
+				       VLIB_FRAME_SIZE);
 
 	  /* buffer shortage
 	   * XXX 0.9 because when debugging we might not get a full frame */
@@ -165,11 +225,14 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 	}
 
       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
-      while (left_to_snd0 && n_left_to_next)
+      while (left_to_snd0 && n_left_to_next >= n_bufs_per_seg)
 	{
+	  /*
+	   * Handle first buffer in chain separately
+	   */
+
 	  /* Get free buffer */
-	  n_bufs--;
-	  bi0 = smm->tx_buffers[thread_index][n_bufs];
+	  bi0 = smm->tx_buffers[thread_index][--n_bufs];
 	  _vec_len (smm->tx_buffers[thread_index]) = n_bufs;
 
 	  b0 = vlib_get_buffer (vm, bi0);
@@ -177,52 +240,19 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  b0->flags = VLIB_BUFFER_TOTAL_LENGTH_VALID
 	    | VNET_BUFFER_LOCALLY_ORIGINATED;
 	  b0->current_data = 0;
+	  b0->total_length_not_including_first_buffer = 0;
 
 	  /* RX on the local interface. tx in default fib */
 	  vnet_buffer (b0)->sw_if_index[VLIB_RX] = 0;
 	  vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 
-	  /* usual speculation, or the enqueue_x1 macro will barf */
-	  to_next[0] = bi0;
-	  to_next += 1;
-	  n_left_to_next -= 1;
-
-	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
-	  if (PREDICT_FALSE (n_trace > 0))
-	    {
-	      session_queue_trace_t *t0;
-	      vlib_trace_buffer (vm, node, next_index, b0,
-				 1 /* follow_chain */ );
-	      vlib_set_trace_count (vm, node, --n_trace);
-	      t0 = vlib_add_trace (vm, node, b0, sizeof (*t0));
-	      t0->session_index = s0->session_index;
-	      t0->server_thread_index = s0->thread_index;
-	    }
+	  len_to_deq0 = clib_min (left_to_snd0, deq_per_buf);
 
-	  len_to_deq0 = (left_to_snd0 < snd_mss0) ? left_to_snd0 : snd_mss0;
-
-	  /* *INDENT-OFF* */
-	  SESSION_EVT_DBG(SESSION_EVT_DEQ, s0, ({
-	      ed->data[0] = e0->event_id;
-	      ed->data[1] = max_dequeue0;
-	      ed->data[2] = len_to_deq0;
-	      ed->data[3] = left_to_snd0;
-	  }));
-	  /* *INDENT-ON* */
-
-	  /* Make room for headers */
 	  data0 = vlib_buffer_make_headroom (b0, MAX_HDRS_LEN);
-
-	  /* Dequeue the data
-	   * TODO 1) peek instead of dequeue
-	   *      2) buffer chains */
 	  if (peek_data)
 	    {
 	      n_bytes_read = svm_fifo_peek (s0->server_tx_fifo, rx_offset,
 					    len_to_deq0, data0);
-	      if (n_bytes_read <= 0)
-		goto dequeue_fail;
-
 	      /* Keep track of progress locally, transport is also supposed to
 	       * increment it independently when pushing the header */
 	      rx_offset += n_bytes_read;
@@ -231,18 +261,56 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    {
 	      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;
+	  if (n_bytes_read <= 0)
+	    goto dequeue_fail;
 
-	  /* Ask transport to push header */
-	  transport_vft->push_header (tc0, b0);
+	  b0->current_length = n_bytes_read;
 
 	  left_to_snd0 -= n_bytes_read;
 	  *n_tx_packets = *n_tx_packets + 1;
 
+	  /*
+	   * Fill in the remaining buffers in the chain, if any
+	   */
+	  if (PREDICT_FALSE (n_bufs_per_seg > 1))
+	    session_tx_fifo_chain_tail (smm, vm, thread_index,
+					s0->server_tx_fifo, b0, bi0,
+					n_bufs_per_seg, &left_to_snd0,
+					&n_bufs, &rx_offset, deq_per_buf,
+					peek_data);
+
+	  /* Ask transport to push header after current_length and
+	   * total_length_not_including_first_buffer are updated */
+	  transport_vft->push_header (tc0, b0);
+
+	  /* *INDENT-OFF* */
+	  SESSION_EVT_DBG(SESSION_EVT_DEQ, s0, ({
+	      ed->data[0] = e0->event_id;
+	      ed->data[1] = max_dequeue0;
+	      ed->data[2] = len_to_deq0;
+	      ed->data[3] = left_to_snd0;
+	  }));
+	  /* *INDENT-ON* */
+
+	  /* usual speculation, or the enqueue_x1 macro will barf */
+	  to_next[0] = bi0;
+	  to_next += 1;
+	  n_left_to_next -= 1;
+
+	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
+	  if (PREDICT_FALSE (n_trace > 0))
+	    {
+	      session_queue_trace_t *t0;
+	      vlib_trace_buffer (vm, node, next_index, b0,
+				 1 /* follow_chain */ );
+	      vlib_set_trace_count (vm, node, --n_trace);
+	      t0 = vlib_add_trace (vm, node, b0, sizeof (*t0));
+	      t0->session_index = s0->session_index;
+	      t0->server_thread_index = s0->thread_index;
+	    }
+
 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 					   to_next, n_left_to_next,
 					   bi0, next0);
diff --git a/src/vnet/session/session.c b/src/vnet/session/session.c
index e92bb440601..6e129dde018 100644
--- a/src/vnet/session/session.c
+++ b/src/vnet/session/session.c
@@ -432,33 +432,97 @@ stream_session_create_i (segment_manager_t * sm, transport_connection_t * tc,
   return 0;
 }
 
+/** Enqueue buffer chain tail */
+always_inline int
+session_enqueue_chain_tail (stream_session_t * s, vlib_buffer_t * b,
+			    u32 offset, u8 is_in_order)
+{
+  vlib_buffer_t *chain_b;
+  u32 chain_bi = b->next_buffer;
+  vlib_main_t *vm = vlib_get_main ();
+  u8 *data, len;
+  u16 written = 0;
+  int rv = 0;
+
+  do
+    {
+      chain_b = vlib_get_buffer (vm, chain_bi);
+      data = vlib_buffer_get_current (chain_b);
+      len = chain_b->current_length;
+      if (is_in_order)
+	{
+	  rv = svm_fifo_enqueue_nowait (s->server_rx_fifo, len, data);
+	  if (rv < len)
+	    {
+	      return (rv > 0) ? (written + rv) : written;
+	    }
+	  written += rv;
+	}
+      else
+	{
+	  rv = svm_fifo_enqueue_with_offset (s->server_rx_fifo, offset, len,
+					     data);
+	  if (rv)
+	    return -1;
+	  offset += len;
+	}
+    }
+  while ((chain_bi = (chain_b->flags & VLIB_BUFFER_NEXT_PRESENT)
+	  ? chain_b->next_buffer : 0));
+
+  if (is_in_order)
+    return written;
+
+  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 b Buffer to be enqueued
+ * @param offset Offset at which to start enqueueing if out-of-order
  * @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.
+ * @param is_in_order Flag to indicate if data is in order
  * @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_enqueue_data (transport_connection_t * tc, vlib_buffer_t * b,
+			     u32 offset, u8 queue_event, u8 is_in_order)
 {
   stream_session_t *s;
-  int enqueued;
+  int enqueued = 0, rv;
 
   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, len, data);
+  if (is_in_order)
+    {
+      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))
+	{
+	  rv = session_enqueue_chain_tail (s, b, 0, 1);
+	  if (rv <= 0)
+	    return enqueued;
+	  enqueued += rv;
+	}
+    }
+  else
+    {
+      rv = svm_fifo_enqueue_with_offset (s->server_rx_fifo, offset,
+					 b->current_length,
+					 vlib_buffer_get_current (b));
+      if (PREDICT_FALSE ((b->flags & VLIB_BUFFER_NEXT_PRESENT) && !rv))
+	rv = session_enqueue_chain_tail (s, b, offset + b->current_length, 0);
+      if (rv)
+	return -1;
+    }
 
   if (queue_event)
     {
@@ -476,7 +540,10 @@ stream_session_enqueue_data (transport_connection_t * tc, u8 * data, u16 len,
 	}
     }
 
-  return enqueued;
+  if (is_in_order)
+    return enqueued;
+
+  return 0;
 }
 
 /** Check if we have space in rx fifo to push more bytes */
diff --git a/src/vnet/session/session.h b/src/vnet/session/session.h
index f41a8a96eb5..f152a2be0e2 100644
--- a/src/vnet/session/session.h
+++ b/src/vnet/session/session.h
@@ -345,8 +345,8 @@ stream_session_fifo_size (transport_connection_t * tc)
 }
 
 int
-stream_session_enqueue_data (transport_connection_t * tc, u8 * data, u16 len,
-			     u8 queue_event);
+stream_session_enqueue_data (transport_connection_t * tc, vlib_buffer_t * b,
+			     u32 offset, u8 queue_event, u8 is_in_order);
 u32
 stream_session_peek_bytes (transport_connection_t * tc, u8 * buffer,
 			   u32 offset, u32 max_bytes);
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index d268251cb38..ceb00fc3e41 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -993,9 +993,8 @@ tcp_session_enqueue_data (tcp_connection_t * tc, vlib_buffer_t * b,
       return TCP_ERROR_PURE_ACK;
     }
 
-  written = stream_session_enqueue_data (&tc->connection,
-					 vlib_buffer_get_current (b),
-					 data_len, 1 /* queue event */ );
+  written = stream_session_enqueue_data (&tc->connection, b, 0,
+					 1 /* queue event */ , 1);
 
   TCP_EVT_DBG (TCP_EVT_INPUT, tc, 0, data_len, written);
 
@@ -1053,12 +1052,10 @@ tcp_session_enqueue_ooo (tcp_connection_t * tc, vlib_buffer_t * b,
       return TCP_ERROR_PURE_ACK;
     }
 
-  s0 = stream_session_get (tc->c_s_index, tc->c_thread_index);
-
   /* Enqueue out-of-order data with absolute offset */
-  rv = svm_fifo_enqueue_with_offset (s0->server_rx_fifo,
-				     vnet_buffer (b)->tcp.seq_number,
-				     data_len, vlib_buffer_get_current (b));
+  rv = stream_session_enqueue_data (&tc->connection, b,
+				    vnet_buffer (b)->tcp.seq_number,
+				    0 /* queue event */ , 0);
 
   /* Nothing written */
   if (rv)
@@ -1075,6 +1072,8 @@ tcp_session_enqueue_ooo (tcp_connection_t * tc, vlib_buffer_t * b,
       ooo_segment_t *newest;
       u32 start, end;
 
+      s0 = stream_session_get (tc->c_s_index, tc->c_thread_index);
+
       /* Get the newest segment from the fifo */
       newest = svm_fifo_newest_ooo_segment (s0->server_rx_fifo);
       start = ooo_segment_offset (s0->server_rx_fifo, newest);
@@ -2543,6 +2542,7 @@ do {                                                       	\
   _(FIN_WAIT_1, TCP_FLAG_FIN, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
   /* FIN confirming that the peer (app) has closed */
   _(FIN_WAIT_2, TCP_FLAG_FIN, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
+  _(FIN_WAIT_2, TCP_FLAG_ACK, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
   _(FIN_WAIT_2, TCP_FLAG_FIN | TCP_FLAG_ACK, TCP_INPUT_NEXT_RCV_PROCESS,
     TCP_ERROR_NONE);
   _(LAST_ACK, TCP_FLAG_ACK, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 2a1b140750c..33e599ece32 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -46,7 +46,7 @@ typedef struct
   tcp_connection_t tcp_connection;
 } tcp_tx_trace_t;
 
-u16 dummy_mtu = 400;
+u16 dummy_mtu = 1460;
 
 u8 *
 format_tcp_tx_trace (u8 * s, va_list * args)
@@ -923,7 +923,7 @@ tcp_push_hdr_i (tcp_connection_t * tc, vlib_buffer_t * b,
   u8 tcp_hdr_opts_len, opts_write_len, flags;
   tcp_header_t *th;
 
-  data_len = b->current_length;
+  data_len = b->current_length + b->total_length_not_including_first_buffer;
   vnet_buffer (b)->tcp.flags = 0;
 
   if (compute_opts)