X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvnet%2Ftcp%2Ftcp_output.c;h=7b0303f30335f31e50adef9f60430c87bc5e9083;hb=1cfcb78940580c8e3645fca0419d32f9286e942d;hp=5a5c7fe4b8bf7b31582b316a19cda9af0a4575fe;hpb=679b78f7155b18efa690b0d2a4a0b51c00090522;p=vpp.git

diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 5a5c7fe4b8b..7b0303f3033 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -49,10 +49,6 @@ typedef struct
   tcp_connection_t tcp_connection;
 } tcp_tx_trace_t;
 
-#ifndef CLIB_MARCH_VARIANT
-u16 dummy_mtu = 1460;
-#endif /* CLIB_MARCH_VARIANT */
-
 static u8 *
 format_tcp_tx_trace (u8 * s, va_list * args)
 {
@@ -89,7 +85,7 @@ void
 tcp_update_rcv_mss (tcp_connection_t * tc)
 {
   /* TODO find our iface MTU */
-  tc->mss = dummy_mtu - sizeof (tcp_header_t);
+  tc->mss = tcp_main.default_mtu - sizeof (tcp_header_t);
 }
 
 /**
@@ -134,20 +130,19 @@ tcp_initial_window_to_advertise (tcp_connection_t * tc)
   return clib_min (tc->rcv_wnd, TCP_WND_MAX);
 }
 
-static void
+static inline void
 tcp_update_rcv_wnd (tcp_connection_t * tc)
 {
+  u32 available_space, wnd;
   i32 observed_wnd;
-  u32 available_space, max_fifo, wnd;
+
+  ASSERT (tc->rcv_opts.mss < transport_rx_fifo_size (&tc->connection));
 
   /*
    * Figure out how much space we have available
    */
   available_space = transport_max_rx_enqueue (&tc->connection);
-  max_fifo = transport_rx_fifo_size (&tc->connection);
-
-  ASSERT (tc->rcv_opts.mss < max_fifo);
-  if (available_space < tc->rcv_opts.mss && available_space < max_fifo >> 3)
+  if (PREDICT_FALSE (available_space < tc->rcv_opts.mss))
     available_space = 0;
 
   /*
@@ -155,13 +150,11 @@ tcp_update_rcv_wnd (tcp_connection_t * tc)
    * to compute the new window
    */
   observed_wnd = (i32) tc->rcv_wnd - (tc->rcv_nxt - tc->rcv_las);
-  if (observed_wnd < 0)
-    observed_wnd = 0;
 
   /* Bad. Thou shalt not shrink */
-  if (available_space < observed_wnd)
+  if (PREDICT_FALSE ((i32) available_space < observed_wnd))
     {
-      wnd = observed_wnd;
+      wnd = clib_max (observed_wnd, 0);
       TCP_EVT_DBG (TCP_EVT_RCV_WND_SHRUNK, tc, observed_wnd, available_space);
     }
   else
@@ -183,23 +176,13 @@ tcp_update_rcv_wnd (tcp_connection_t * tc)
 /**
  * Compute and return window to advertise, scaled as per RFC1323
  */
-static u32
+static inline u32
 tcp_window_to_advertise (tcp_connection_t * tc, tcp_state_t state)
 {
   if (state < TCP_STATE_ESTABLISHED)
     return tcp_initial_window_to_advertise (tc);
 
   tcp_update_rcv_wnd (tc);
-
-  if (tc->rcv_wnd == 0)
-    {
-      tc->flags |= TCP_CONN_SENT_RCV_WND0;
-    }
-  else
-    {
-      tc->flags &= ~TCP_CONN_SENT_RCV_WND0;
-    }
-
   return tc->rcv_wnd >> tc->rcv_wscale;
 }
 
@@ -293,7 +276,7 @@ tcp_make_syn_options (tcp_options_t * opts, u8 wnd_scale)
   u8 len = 0;
 
   opts->flags |= TCP_OPTS_FLAG_MSS;
-  opts->mss = dummy_mtu;	/*XXX discover that */
+  opts->mss = tcp_main.default_mtu;	/*XXX discover that */
   len += TCP_OPTION_LEN_MSS;
 
   opts->flags |= TCP_OPTS_FLAG_WSCALE;
@@ -361,7 +344,7 @@ tcp_make_established_options (tcp_connection_t * tc, tcp_options_t * opts)
   if (tcp_opts_tstamp (&tc->rcv_opts))
     {
       opts->flags |= TCP_OPTS_FLAG_TSTAMP;
-      opts->tsval = tcp_time_now_w_thread (tc->c_thread_index);
+      opts->tsval = tcp_tstamp (tc);
       opts->tsecr = tc->tsval_recent;
       len += TCP_OPTION_LEN_TIMESTAMP;
     }
@@ -439,6 +422,12 @@ tcp_update_burst_snd_vars (tcp_connection_t * tc)
 		     &tc->snd_opts);
 
   tcp_update_rcv_wnd (tc);
+
+  if (tc->flags & TCP_CONN_RATE_SAMPLE)
+    tc->flags |= TCP_CONN_TRACK_BURST;
+
+  if (tc->snd_una == tc->snd_nxt)
+    tcp_cc_event (tc, TCP_CC_EVT_START_TX);
 }
 
 void
@@ -519,6 +508,11 @@ tcp_make_ack_i (tcp_connection_t * tc, vlib_buffer_t * b, tcp_state_t state,
 
   tcp_options_write ((u8 *) (th + 1), snd_opts);
   vnet_buffer (b)->tcp.connection_index = tc->c_c_index;
+
+  if (wnd == 0)
+    tcp_zero_rwnd_sent_on (tc);
+  else
+    tcp_zero_rwnd_sent_off (tc);
 }
 
 /**
@@ -539,9 +533,6 @@ void
 tcp_make_fin (tcp_connection_t * tc, vlib_buffer_t * b)
 {
   tcp_make_ack_i (tc, b, TCP_STATE_ESTABLISHED, TCP_FLAG_FIN | TCP_FLAG_ACK);
-
-  /* Reset flags, make sure ack is sent */
-  vnet_buffer (b)->tcp.flags &= ~TCP_BUF_FLAG_DUPACK;
 }
 
 /**
@@ -1052,14 +1043,14 @@ tcp_send_fin (tcp_connection_t * tc)
 
   fin_snt = tc->flags & TCP_CONN_FINSNT;
   if (fin_snt)
-    tc->snd_nxt = tc->snd_una;
+    tc->snd_nxt -= 1;
 
   if (PREDICT_FALSE (!vlib_buffer_alloc (vm, &bi, 1)))
     {
       /* Out of buffers so program fin retransmit ASAP */
       tcp_timer_update (tc, TCP_TIMER_RETRANSMIT, 1);
       if (fin_snt)
-	tc->snd_nxt = tc->snd_una_max;
+	tc->snd_nxt += 1;
       else
 	/* Make sure retransmit retries a fin not data */
 	tc->flags |= TCP_CONN_FINSNT;
@@ -1072,53 +1063,26 @@ tcp_send_fin (tcp_connection_t * tc)
   tcp_make_fin (tc, b);
   tcp_enqueue_to_output_now (wrk, b, bi, tc->c_is_ip4);
   TCP_EVT_DBG (TCP_EVT_FIN_SENT, tc);
-
+  /* Account for the FIN */
+  tc->snd_nxt += 1;
   if (!fin_snt)
     {
       tc->flags |= TCP_CONN_FINSNT;
       tc->flags &= ~TCP_CONN_FINPNDG;
-      /* Account for the FIN */
-      tc->snd_una_max += 1;
-      tc->snd_nxt = tc->snd_una_max;
-    }
-  else
-    {
-      tc->snd_nxt = tc->snd_una_max;
+      tc->snd_una_max = seq_max (tc->snd_una_max, tc->snd_nxt);
     }
 }
 
-always_inline u8
-tcp_make_state_flags (tcp_connection_t * tc, tcp_state_t next_state)
-{
-  switch (next_state)
-    {
-    case TCP_STATE_ESTABLISHED:
-    case TCP_STATE_CLOSE_WAIT:
-    case TCP_STATE_TIME_WAIT:
-    case TCP_STATE_FIN_WAIT_2:
-    case TCP_STATE_CLOSING:
-    case TCP_STATE_LAST_ACK:
-    case TCP_STATE_FIN_WAIT_1:
-      return TCP_FLAG_ACK;
-    case TCP_STATE_SYN_RCVD:
-      return TCP_FLAG_SYN | TCP_FLAG_ACK;
-    case TCP_STATE_SYN_SENT:
-      return TCP_FLAG_SYN;
-    default:
-      clib_warning ("Shouldn't be here!");
-    }
-  return 0;
-}
-
 /**
- * Push TCP header and update connection variables
+ * Push TCP header and update connection variables. Should only be called
+ * for segments with data, not for 'control' packets.
  */
 always_inline void
-tcp_push_hdr_i (tcp_connection_t * tc, vlib_buffer_t * b,
-		tcp_state_t next_state, u8 compute_opts, u8 maybe_burst)
+tcp_push_hdr_i (tcp_connection_t * tc, vlib_buffer_t * b, u32 snd_nxt,
+		u8 compute_opts, u8 maybe_burst, u8 update_snd_nxt)
 {
+  u8 tcp_hdr_opts_len, flags = TCP_FLAG_ACK;
   u32 advertise_wnd, data_len;
-  u8 tcp_hdr_opts_len, flags;
   tcp_main_t *tm = &tcp_main;
   tcp_header_t *th;
 
@@ -1137,16 +1101,15 @@ tcp_push_hdr_i (tcp_connection_t * tc, vlib_buffer_t * b,
   if (maybe_burst)
     advertise_wnd = tc->rcv_wnd >> tc->rcv_wscale;
   else
-    advertise_wnd = tcp_window_to_advertise (tc, next_state);
+    advertise_wnd = tcp_window_to_advertise (tc, TCP_STATE_ESTABLISHED);
 
-  flags = tcp_make_state_flags (tc, next_state);
   if (PREDICT_FALSE (tc->flags & TCP_CONN_PSH_PENDING))
     {
-      if (seq_geq (tc->psh_seq, tc->snd_nxt)
-	  && seq_lt (tc->psh_seq, tc->snd_nxt + data_len))
+      if (seq_geq (tc->psh_seq, snd_nxt)
+	  && seq_lt (tc->psh_seq, snd_nxt + data_len))
 	flags |= TCP_FLAG_PSH;
     }
-  th = vlib_buffer_push_tcp (b, tc->c_lcl_port, tc->c_rmt_port, tc->snd_nxt,
+  th = vlib_buffer_push_tcp (b, tc->c_lcl_port, tc->c_rmt_port, snd_nxt,
 			     tc->rcv_nxt, tcp_hdr_opts_len, flags,
 			     advertise_wnd);
 
@@ -1166,7 +1129,8 @@ tcp_push_hdr_i (tcp_connection_t * tc, vlib_buffer_t * b,
    * Update connection variables
    */
 
-  tc->snd_nxt += data_len;
+  if (update_snd_nxt)
+    tc->snd_nxt += data_len;
   tc->rcv_las = tc->rcv_nxt;
 
   TCP_EVT_DBG (TCP_EVT_PKTIZE, tc);
@@ -1176,10 +1140,18 @@ u32
 tcp_session_push_header (transport_connection_t * tconn, vlib_buffer_t * b)
 {
   tcp_connection_t *tc = (tcp_connection_t *) tconn;
-  tcp_push_hdr_i (tc, b, TCP_STATE_ESTABLISHED, /* compute opts */ 0,
-		  /* burst */ 1);
-  tc->snd_una_max = tc->snd_nxt;
-  ASSERT (seq_leq (tc->snd_una_max, tc->snd_una + tc->snd_wnd));
+
+  if (tc->flags & TCP_CONN_TRACK_BURST)
+    {
+      tcp_bt_check_app_limited (tc);
+      tcp_bt_track_tx (tc);
+      tc->flags &= ~TCP_CONN_TRACK_BURST;
+    }
+
+  tcp_push_hdr_i (tc, b, tc->snd_nxt, /* compute opts */ 0, /* burst */ 1,
+		  /* update_snd_nxt */ 1);
+
+  tc->snd_una_max = seq_max (tc->snd_nxt, tc->snd_una_max);
   tcp_validate_txf_size (tc, tc->snd_una_max - tc->snd_una);
   /* If not tracking an ACK, start tracking */
   if (tc->rtt_ts == 0 && !tcp_in_cong_recovery (tc))
@@ -1301,6 +1273,28 @@ tcp_timer_delack_handler (u32 index)
   tcp_send_ack (tc);
 }
 
+/**
+ * Send Window Update ACK,
+ * ensuring that it will be sent once, if RWND became non-zero,
+ * after zero RWND has been advertised in ACK before
+ */
+void
+tcp_send_window_update_ack (tcp_connection_t * tc)
+{
+  tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
+  u32 win;
+
+  if (tcp_zero_rwnd_sent (tc))
+    {
+      win = tcp_window_to_advertise (tc, tc->state);
+      if (win > 0)
+	{
+	  tcp_zero_rwnd_sent_off (tc);
+	  tcp_program_ack (wrk, tc);
+	}
+    }
+}
+
 /**
  * Allocate a new buffer and build a new tcp segment
  *
@@ -1345,9 +1339,8 @@ tcp_prepare_segment (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
 					    max_deq_bytes);
       ASSERT (n_bytes == max_deq_bytes);
       b[0]->current_length = n_bytes;
-      tcp_push_hdr_i (tc, *b, tc->state, /* compute opts */ 0, /* burst */ 0);
-      if (seq_gt (tc->snd_nxt, tc->snd_una_max))
-	tc->snd_una_max = tc->snd_nxt;
+      tcp_push_hdr_i (tc, *b, tc->snd_una + offset, /* compute opts */ 0,
+		      /* burst */ 0, /* update_snd_nxt */ 0);
     }
   /* Split mss into multiple buffers */
   else
@@ -1404,9 +1397,8 @@ tcp_prepare_segment (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
 	  b[0]->total_length_not_including_first_buffer += n_peeked;
 	}
 
-      tcp_push_hdr_i (tc, *b, tc->state, /* compute opts */ 0, /* burst */ 0);
-      if (seq_gt (tc->snd_nxt, tc->snd_una_max))
-	tc->snd_una_max = tc->snd_nxt;
+      tcp_push_hdr_i (tc, *b, tc->snd_una + offset, /* compute opts */ 0,
+		      /* burst */ 0, /* update_snd_nxt */ 0);
 
       if (PREDICT_FALSE (n_bufs))
 	{
@@ -1468,7 +1460,11 @@ tcp_prepare_retransmit_segment (tcp_worker_ctx_t * wrk,
     return 0;
 
   if (tcp_in_fastrecovery (tc))
-    tc->snd_rxt_bytes += n_bytes;
+    {
+      tc->snd_rxt_bytes += n_bytes;
+      if (tc->flags & TCP_CONN_RATE_SAMPLE)
+	tcp_bt_track_rxt (tc, start, start + n_bytes);
+    }
 
 done:
   TCP_EVT_DBG (TCP_EVT_CC_RTX, tc, offset, n_bytes);
@@ -1479,26 +1475,22 @@ done:
  * Reset congestion control, switch cwnd to loss window and try again.
  */
 static void
-tcp_rxt_timeout_cc (tcp_connection_t * tc)
+tcp_cc_init_rxt_timeout (tcp_connection_t * tc)
 {
   TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 6);
   tc->prev_ssthresh = tc->ssthresh;
   tc->prev_cwnd = tc->cwnd;
 
-  /* Cleanly recover cc (also clears up fast retransmit) */
+  /* Clear fast recovery state if needed */
   if (tcp_in_fastrecovery (tc))
-    {
-      /* TODO be less aggressive about this */
-      scoreboard_clear (&tc->sack_sb);
-      tcp_cc_fastrecovery_exit (tc);
-    }
-  else
-    tc->rcv_dupacks = 0;
+    tcp_cc_fastrecovery_clear (tc);
+
+  /* Let cc algo decide loss cwnd and ssthresh */
+  tcp_cc_loss (tc);
 
   /* Start again from the beginning */
-  tc->cc_algo->congestion (tc);
-  tc->cwnd = tcp_loss_wnd (tc);
-  tc->snd_congestion = tc->snd_una_max;
+  tc->snd_congestion = tc->snd_nxt;
+  tc->rcv_dupacks = 0;
   tc->rtt_ts = 0;
   tc->cwnd_acc_bytes = 0;
   tcp_connection_tx_pacer_reset (tc, tc->cwnd, 2 * tc->snd_mss);
@@ -1550,7 +1542,7 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
 
       /* Shouldn't be here. This condition is tricky because it has to take
        * into account boff > 0 due to persist timeout. */
-      if ((tc->rto_boff == 0 && tc->snd_una == tc->snd_una_max)
+      if ((tc->rto_boff == 0 && tc->snd_una == tc->snd_nxt)
 	  || (tc->rto_boff > 0 && seq_geq (tc->snd_una, tc->snd_congestion)
 	      && !tcp_flight_size (tc)))
 	{
@@ -1567,21 +1559,37 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
 	  tcp_update_rto (tc);
 	}
 
+      /* Peer is dead or network connectivity is lost. Close connection.
+       * RFC 1122 section 4.2.3.5 recommends a value of at least 100s. For
+       * a min rto of 0.2s we need to retry about 8 times. */
+      if (tc->rto_boff >= TCP_RTO_BOFF_MAX)
+	{
+	  tcp_send_reset (tc);
+	  tcp_connection_set_state (tc, TCP_STATE_CLOSED);
+	  session_transport_closing_notify (&tc->connection);
+	  tcp_connection_timers_reset (tc);
+	  tcp_timer_update (tc, TCP_TIMER_WAITCLOSE, TCP_CLOSEWAIT_TIME);
+	  return;
+	}
+
       /* Increment RTO backoff (also equal to number of retries) and go back
        * to first un-acked byte  */
       tc->rto_boff += 1;
 
+      /* TODO be less aggressive about clearing scoreboard */
+      scoreboard_clear (&tc->sack_sb);
+
       /* First retransmit timeout */
       if (tc->rto_boff == 1)
-	tcp_rxt_timeout_cc (tc);
-      else
-	scoreboard_clear (&tc->sack_sb);
+	tcp_cc_init_rxt_timeout (tc);
+
+      if (tc->flags & TCP_CONN_RATE_SAMPLE)
+	tcp_bt_flush_samples (tc);
 
       /* If we've sent beyond snd_congestion, update it */
-      if (seq_gt (tc->snd_una_max, tc->snd_congestion))
-	tc->snd_congestion = tc->snd_una_max;
+      tc->snd_congestion = seq_max (tc->snd_nxt, tc->snd_congestion);
 
-      tc->snd_una_max = tc->snd_nxt = tc->snd_una;
+      tc->snd_nxt = tc->snd_una;
       tc->rto = clib_min (tc->rto << 1, TCP_RTO_MAX);
 
       /* Send one segment. Note that n_bytes may be zero due to buffer
@@ -1597,7 +1605,7 @@ tcp_timer_retransmit_handler_i (u32 index, u8 is_syn)
 
       /* For first retransmit, record timestamp (Eifel detection RFC3522) */
       if (tc->rto_boff == 1)
-	tc->snd_rxt_ts = tcp_time_now_w_thread (tc->c_thread_index);
+	tc->snd_rxt_ts = tcp_tstamp (tc);
 
       tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
       tcp_retransmit_timer_force_update (tc);
@@ -1718,7 +1726,7 @@ tcp_timer_persist_handler (u32 index)
     return;
 
   available_bytes = transport_max_tx_dequeue (&tc->connection);
-  offset = tc->snd_una_max - tc->snd_una;
+  offset = tc->snd_nxt - tc->snd_una;
 
   /* Reprogram persist if no new bytes available to send. We may have data
    * next time */
@@ -1760,8 +1768,9 @@ tcp_timer_persist_handler (u32 index)
 			   || tc->snd_nxt == tc->snd_una_max
 			   || tc->rto_boff > 1));
 
-  tcp_push_hdr_i (tc, b, tc->state, /* compute opts */ 0, /* burst */ 0);
-  tc->snd_una_max = tc->snd_nxt;
+  tcp_push_hdr_i (tc, b, tc->snd_nxt, /* compute opts */ 0,
+		  /* burst */ 0, /* update_snd_nxt */ 1);
+  tc->snd_una_max = seq_max (tc->snd_nxt, tc->snd_una_max);
   tcp_validate_txf_size (tc, tc->snd_una_max - tc->snd_una);
   tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
 
@@ -1775,12 +1784,9 @@ tcp_timer_persist_handler (u32 index)
 int
 tcp_retransmit_first_unacked (tcp_worker_ctx_t * wrk, tcp_connection_t * tc)
 {
-  u32 bi, old_snd_nxt, n_bytes;
   vlib_main_t *vm = wrk->vm;
   vlib_buffer_t *b;
-
-  old_snd_nxt = tc->snd_nxt;
-  tc->snd_nxt = tc->snd_una;
+  u32 bi, n_bytes;
 
   TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 1);
 
@@ -1790,7 +1796,6 @@ tcp_retransmit_first_unacked (tcp_worker_ctx_t * wrk, tcp_connection_t * tc)
 
   bi = vlib_get_buffer_index (vm, b);
   tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
-  tc->snd_nxt = old_snd_nxt;
 
   return 0;
 }
@@ -1803,8 +1808,7 @@ tcp_fast_retransmit_unsent (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
   vlib_main_t *vm = wrk->vm;
   vlib_buffer_t *b = 0;
 
-  tc->snd_nxt = tc->snd_una_max;
-  offset = tc->snd_una_max - tc->snd_una;
+  offset = tc->snd_nxt - tc->snd_una;
   while (n_segs < burst_size)
     {
       n_written = tcp_prepare_segment (wrk, tc, offset, tc->snd_mss, &b);
@@ -1815,6 +1819,9 @@ tcp_fast_retransmit_unsent (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
       tcp_enqueue_to_output (wrk, b, bi, tc->c_is_ip4);
       offset += n_written;
       n_segs += 1;
+
+      tc->snd_nxt += n_written;
+      tc->snd_una_max = seq_max (tc->snd_nxt, tc->snd_una_max);
     }
 
 done:
@@ -1837,9 +1844,8 @@ tcp_fast_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
   vlib_main_t *vm = wrk->vm;
   vlib_buffer_t *b = 0;
   sack_scoreboard_t *sb;
-  u32 bi, old_snd_nxt;
+  u32 bi, max_deq;
   int snd_space;
-  u32 max_deq;
   u8 snd_limited = 0, can_rescue = 0;
 
   ASSERT (tcp_in_fastrecovery (tc));
@@ -1852,12 +1858,11 @@ tcp_fast_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
     }
 
   TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 0);
-  old_snd_nxt = tc->snd_nxt;
   sb = &tc->sack_sb;
   hole = scoreboard_get_hole (sb, sb->cur_rxt_hole);
 
   max_deq = transport_max_tx_dequeue (&tc->connection);
-  max_deq -= tc->snd_una_max - tc->snd_una;
+  max_deq -= tc->snd_nxt - tc->snd_una;
 
   while (snd_space > 0 && n_segs < burst_size)
     {
@@ -1890,7 +1895,6 @@ tcp_fast_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
 	  max_bytes = clib_min (max_bytes, snd_space);
 	  offset = tc->snd_congestion - tc->snd_una - max_bytes;
 	  sb->rescue_rxt = tc->snd_congestion;
-	  tc->snd_nxt = tc->snd_una + offset;
 	  n_written = tcp_prepare_retransmit_segment (wrk, tc, offset,
 						      max_bytes, &b);
 	  if (!n_written)
@@ -1908,7 +1912,6 @@ tcp_fast_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
 	break;
 
       offset = sb->high_rxt - tc->snd_una;
-      tc->snd_nxt = sb->high_rxt;
       n_written = tcp_prepare_retransmit_segment (wrk, tc, offset, max_bytes,
 						  &b);
       ASSERT (n_written <= snd_space);
@@ -1929,8 +1932,6 @@ tcp_fast_retransmit_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
     tcp_program_fastretransmit (wrk, tc);
 
 done:
-  /* If window allows, send 1 SMSS of new data */
-  tc->snd_nxt = old_snd_nxt;
   return n_segs;
 }
 
@@ -1941,22 +1942,21 @@ int
 tcp_fast_retransmit_no_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
 			     u32 burst_size)
 {
-  u32 n_written = 0, offset = 0, bi, old_snd_nxt, max_deq, n_segs_now;
+  u32 n_written = 0, offset = 0, bi, max_deq, n_segs_now;
   vlib_main_t *vm = wrk->vm;
   int snd_space, n_segs = 0;
   vlib_buffer_t *b;
 
   ASSERT (tcp_in_fastrecovery (tc));
   TCP_EVT_DBG (TCP_EVT_CC_EVT, tc, 0);
-  old_snd_nxt = tc->snd_nxt;
+
+  snd_space = tcp_available_cc_snd_space (tc);
 
   if (!tcp_fastrecovery_first (tc))
     goto send_unsent;
 
   /* RFC 6582: [If a partial ack], retransmit the first unacknowledged
    * segment. */
-  snd_space = tc->sack_sb.last_bytes_delivered;
-  tc->snd_nxt = tc->snd_una;
   while (snd_space > 0 && n_segs < burst_size)
     {
       n_written = tcp_prepare_retransmit_segment (wrk, tc, offset,
@@ -1979,12 +1979,11 @@ tcp_fast_retransmit_no_sack (tcp_worker_ctx_t * wrk, tcp_connection_t * tc,
 send_unsent:
 
   /* RFC 6582: Send a new segment if permitted by the new value of cwnd. */
-  snd_space = tcp_available_cc_snd_space (tc);
   if (snd_space < tc->snd_mss || tc->snd_mss == 0)
     goto done;
 
   max_deq = transport_max_tx_dequeue (&tc->connection);
-  max_deq -= tc->snd_una_max - tc->snd_una;
+  max_deq -= tc->snd_nxt - tc->snd_una;
   if (max_deq)
     {
       snd_space = clib_min (max_deq, snd_space);
@@ -1995,9 +1994,6 @@ send_unsent:
       n_segs += n_segs_now;
     }
 
-  /* Restore snd_nxt */
-  tc->snd_nxt = old_snd_nxt;
-
 done:
   tcp_fastrecovery_first_off (tc);
   return n_segs;
@@ -2112,6 +2108,13 @@ tcp_output_handle_packet (tcp_connection_t * tc0, vlib_buffer_t * b0,
       return;
     }
 
+  /* If next_index is not drop use it */
+  if (tc0->next_node_index)
+    {
+      *next0 = tc0->next_node_index;
+      vnet_buffer (b0)->tcp.next_node_opaque = tc0->next_node_opaque;
+    }
+
   vnet_buffer (b0)->sw_if_index[VLIB_TX] = tc0->c_fib_index;
   vnet_buffer (b0)->sw_if_index[VLIB_RX] = 0;