X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvnet%2Ftcp%2Ftcp.c;h=a2214158c1b3e1021ac9bc55b43ce5043acc802d;hb=6534b7aa13bc5bed15ed87f47bb766405963e9e8;hp=e5feaeb1e0338283888b3e6332a26a07c64f20b2;hpb=e04c29942af6a130591059679531c9ffa3d7237a;p=vpp.git

diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index e5feaeb1e03..a2214158c1b 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -16,12 +16,13 @@
 #include <vnet/tcp/tcp.h>
 #include <vnet/session/session.h>
 #include <vnet/fib/fib.h>
+#include <vnet/dpo/load_balance.h>
 #include <math.h>
 
 tcp_main_t tcp_main;
 
 static u32
-tcp_connection_bind (vlib_main_t * vm, u32 session_index, ip46_address_t * ip,
+tcp_connection_bind (u32 session_index, ip46_address_t * ip,
 		     u16 port_host_byte_order, u8 is_ip4)
 {
   tcp_main_t *tm = &tcp_main;
@@ -34,51 +35,62 @@ tcp_connection_bind (vlib_main_t * vm, u32 session_index, ip46_address_t * ip,
   listener->c_lcl_port = clib_host_to_net_u16 (port_host_byte_order);
 
   if (is_ip4)
-    listener->c_lcl_ip4.as_u32 = ip->ip4.as_u32;
+    {
+      listener->c_lcl_ip4.as_u32 = ip->ip4.as_u32;
+      listener->c_is_ip4 = 1;
+      listener->c_proto = SESSION_TYPE_IP4_TCP;
+    }
   else
-    clib_memcpy (&listener->c_lcl_ip6, &ip->ip6, sizeof (ip6_address_t));
+    {
+      clib_memcpy (&listener->c_lcl_ip6, &ip->ip6, sizeof (ip6_address_t));
+      listener->c_proto = SESSION_TYPE_IP6_TCP;
+    }
 
   listener->c_s_index = session_index;
-  listener->c_proto = SESSION_TYPE_IP4_TCP;
   listener->state = TCP_STATE_LISTEN;
-  listener->c_is_ip4 = 1;
+
+  tcp_connection_timers_init (listener);
+
+  TCP_EVT_DBG (TCP_EVT_BIND, listener);
 
   return listener->c_c_index;
 }
 
 u32
-tcp_session_bind_ip4 (vlib_main_t * vm, u32 session_index,
-		      ip46_address_t * ip, u16 port_host_byte_order)
+tcp_session_bind_ip4 (u32 session_index, ip46_address_t * ip,
+		      u16 port_host_byte_order)
 {
-  return tcp_connection_bind (vm, session_index, ip, port_host_byte_order, 1);
+  return tcp_connection_bind (session_index, ip, port_host_byte_order, 1);
 }
 
 u32
-tcp_session_bind_ip6 (vlib_main_t * vm, u32 session_index,
-		      ip46_address_t * ip, u16 port_host_byte_order)
+tcp_session_bind_ip6 (u32 session_index, ip46_address_t * ip,
+		      u16 port_host_byte_order)
 {
-  return tcp_connection_bind (vm, session_index, ip, port_host_byte_order, 0);
-
+  return tcp_connection_bind (session_index, ip, port_host_byte_order, 0);
 }
 
 static void
-tcp_session_unbind (u32 listener_index)
+tcp_connection_unbind (u32 listener_index)
 {
   tcp_main_t *tm = vnet_get_tcp_main ();
-  pool_put_index (tm->listener_pool, listener_index);
-}
+  tcp_connection_t *tc;
 
-u32
-tcp_session_unbind_ip4 (vlib_main_t * vm, u32 listener_index)
-{
-  tcp_session_unbind (listener_index);
-  return 0;
+  tc = pool_elt_at_index (tm->listener_pool, listener_index);
+
+  TCP_EVT_DBG (TCP_EVT_UNBIND, tc);
+
+  /* Poison the entry */
+  if (CLIB_DEBUG > 0)
+    memset (tc, 0xFA, sizeof (*tc));
+
+  pool_put_index (tm->listener_pool, listener_index);
 }
 
 u32
-tcp_session_unbind_ip6 (vlib_main_t * vm, u32 listener_index)
+tcp_session_unbind (u32 listener_index)
 {
-  tcp_session_unbind (listener_index);
+  tcp_connection_unbind (listener_index);
   return 0;
 }
 
@@ -120,9 +132,20 @@ tcp_connection_cleanup (tcp_connection_t * tc)
 
   /* Check if half-open */
   if (tc->state == TCP_STATE_SYN_SENT)
-    pool_put (tm->half_open_connections, tc);
+    {
+      /* Poison the entry */
+      if (CLIB_DEBUG > 0)
+	memset (tc, 0xFA, sizeof (*tc));
+      pool_put (tm->half_open_connections, tc);
+    }
   else
-    pool_put (tm->connections[tc->c_thread_index], tc);
+    {
+      int thread_index = tc->c_thread_index;
+      /* Poison the entry */
+      if (CLIB_DEBUG > 0)
+	memset (tc, 0xFA, sizeof (*tc));
+      pool_put (tm->connections[thread_index], tc);
+    }
 }
 
 /**
@@ -135,10 +158,79 @@ tcp_connection_cleanup (tcp_connection_t * tc)
 void
 tcp_connection_del (tcp_connection_t * tc)
 {
+  TCP_EVT_DBG (TCP_EVT_DELETE, tc);
   stream_session_delete_notify (&tc->connection);
   tcp_connection_cleanup (tc);
 }
 
+/**
+ * Cleanup half-open connection
+ */
+void
+tcp_half_open_connection_del (tcp_connection_t * tc)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+  if (CLIB_DEBUG)
+    memset (tc, 0xFA, sizeof (*tc));
+  clib_spinlock_lock (&tm->half_open_lock);
+  pool_put (tm->half_open_connections, tc);
+  clib_spinlock_unlock (&tm->half_open_lock);
+}
+
+tcp_connection_t *
+tcp_connection_new (u8 thread_index)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+  tcp_connection_t *tc;
+
+  pool_get (tm->connections[thread_index], tc);
+  memset (tc, 0, sizeof (*tc));
+  tc->c_c_index = tc - tm->connections[thread_index];
+  tc->c_thread_index = thread_index;
+  return tc;
+}
+
+/** Notify session that connection has been reset.
+ *
+ * Switch state to closed and wait for session to call cleanup.
+ */
+void
+tcp_connection_reset (tcp_connection_t * tc)
+{
+  TCP_EVT_DBG (TCP_EVT_RST_RCVD, tc);
+  switch (tc->state)
+    {
+    case TCP_STATE_SYN_RCVD:
+      /* Cleanup everything. App wasn't notified yet */
+      stream_session_delete_notify (&tc->connection);
+      tcp_connection_cleanup (tc);
+      break;
+    case TCP_STATE_SYN_SENT:
+      /* XXX remove sst from call */
+      stream_session_connect_notify (&tc->connection, tc->connection.proto,
+				     1 /* fail */ );
+      tcp_connection_cleanup (tc);
+      break;
+    case TCP_STATE_ESTABLISHED:
+    case TCP_STATE_CLOSE_WAIT:
+    case TCP_STATE_FIN_WAIT_1:
+    case TCP_STATE_FIN_WAIT_2:
+    case TCP_STATE_CLOSING:
+      tc->state = TCP_STATE_CLOSED;
+      TCP_EVT_DBG (TCP_EVT_STATE_CHANGE, tc);
+
+      /* Make sure all timers are cleared */
+      tcp_connection_timers_reset (tc);
+      stream_session_reset_notify (&tc->connection);
+
+      /* Wait for cleanup from session layer but not forever */
+      tcp_timer_set (tc, TCP_TIMER_WAITCLOSE, TCP_CLEANUP_TIME);
+      break;
+    case TCP_STATE_CLOSED:
+      return;
+    }
+}
+
 /**
  * Begin connection closing procedure.
  *
@@ -149,13 +241,17 @@ tcp_connection_del (tcp_connection_t * tc)
  * calls cleanup.
  * 2) TIME_WAIT (active close) whereby after 2MSL the 2MSL timer triggers
  * and cleanup is called.
+ *
+ * N.B. Half-close connections are not supported
  */
 void
 tcp_connection_close (tcp_connection_t * tc)
 {
+  TCP_EVT_DBG (TCP_EVT_CLOSE, tc);
+
   /* Send FIN if needed */
-  if (tc->state == TCP_STATE_ESTABLISHED || tc->state == TCP_STATE_SYN_RCVD
-      || tc->state == TCP_STATE_CLOSE_WAIT)
+  if (tc->state == TCP_STATE_ESTABLISHED
+      || tc->state == TCP_STATE_SYN_RCVD || tc->state == TCP_STATE_CLOSE_WAIT)
     tcp_send_fin (tc);
 
   /* Switch state */
@@ -165,10 +261,11 @@ tcp_connection_close (tcp_connection_t * tc)
     tc->state = TCP_STATE_CLOSED;
   else if (tc->state == TCP_STATE_CLOSE_WAIT)
     tc->state = TCP_STATE_LAST_ACK;
+  TCP_EVT_DBG (TCP_EVT_STATE_CHANGE, tc);
 
-  /* Half-close connections are not supported XXX */
-
-  if (tc->state == TCP_STATE_CLOSED)
+  /* If in CLOSED and WAITCLOSE timer is not set, delete connection now */
+  if (tc->timers[TCP_TIMER_WAITCLOSE] == TCP_TIMER_HANDLE_INVALID
+      && tc->state == TCP_STATE_CLOSED)
     tcp_connection_del (tc);
 }
 
@@ -185,7 +282,11 @@ tcp_session_cleanup (u32 conn_index, u32 thread_index)
 {
   tcp_connection_t *tc;
   tc = tcp_connection_get (conn_index, thread_index);
-  tcp_connection_cleanup (tc);
+
+  /* Wait for the session tx events to clear */
+  tc->state = TCP_STATE_CLOSED;
+  TCP_EVT_DBG (TCP_EVT_STATE_CHANGE, tc);
+  tcp_timer_update (tc, TCP_TIMER_WAITCLOSE, TCP_CLEANUP_TIME);
 }
 
 void *
@@ -222,16 +323,20 @@ ip_interface_get_first_ip (u32 sw_if_index, u8 is_ip4)
  * Allocate local port and add if successful add entry to local endpoint
  * table to mark the pair as used.
  */
-u16
+int
 tcp_allocate_local_port (tcp_main_t * tm, ip46_address_t * ip)
 {
   transport_endpoint_t *tep;
   u32 time_now, tei;
-  u16 min = 1024, max = 65535, tries;	/* XXX configurable ? */
+  u16 min = 1024, max = 65535;	/* XXX configurable ? */
+  int tries;
 
   tries = max - min;
   time_now = tcp_time_now ();
 
+  /* Only support active opens from thread 0 */
+  ASSERT (vlib_get_thread_index () == 0);
+
   /* Start at random point or max */
   pool_get (tm->local_endpoints, tep);
   clib_memcpy (&tep->ip, ip, sizeof (*ip));
@@ -297,6 +402,101 @@ tcp_connection_timers_reset (tcp_connection_t * tc)
     }
 }
 
+#if 0
+typedef struct ip4_tcp_hdr
+{
+  ip4_header_t ip;
+  tcp_header_t tcp;
+} ip4_tcp_hdr_t;
+
+typedef struct ip6_tcp_hdr
+{
+  ip6_header_t ip;
+  tcp_header_t tcp;
+} ip6_tcp_hdr_t;
+
+static void
+tcp_connection_select_lb_bucket (tcp_connection_t * tc, const dpo_id_t * dpo,
+				 dpo_id_t * result)
+{
+  const dpo_id_t *choice;
+  load_balance_t *lb;
+  int hash;
+
+  lb = load_balance_get (dpo->dpoi_index);
+  if (tc->c_is_ip4)
+    {
+      ip4_tcp_hdr_t hdr;
+      memset (&hdr, 0, sizeof (hdr));
+      hdr.ip.protocol = IP_PROTOCOL_TCP;
+      hdr.ip.address_pair.src.as_u32 = tc->c_lcl_ip.ip4.as_u32;
+      hdr.ip.address_pair.dst.as_u32 = tc->c_rmt_ip.ip4.as_u32;
+      hdr.tcp.src_port = tc->c_lcl_port;
+      hdr.tcp.dst_port = tc->c_rmt_port;
+      hash = ip4_compute_flow_hash (&hdr.ip, lb->lb_hash_config);
+    }
+  else
+    {
+      ip6_tcp_hdr_t hdr;
+      memset (&hdr, 0, sizeof (hdr));
+      hdr.ip.protocol = IP_PROTOCOL_TCP;
+      clib_memcpy (&hdr.ip.src_address, &tc->c_lcl_ip.ip6,
+		   sizeof (ip6_address_t));
+      clib_memcpy (&hdr.ip.dst_address, &tc->c_rmt_ip.ip6,
+		   sizeof (ip6_address_t));
+      hdr.tcp.src_port = tc->c_lcl_port;
+      hdr.tcp.dst_port = tc->c_rmt_port;
+      hash = ip6_compute_flow_hash (&hdr.ip, lb->lb_hash_config);
+    }
+  choice = load_balance_get_bucket_i (lb, hash & lb->lb_n_buckets_minus_1);
+  dpo_copy (result, choice);
+}
+
+fib_node_index_t
+tcp_lookup_rmt_in_fib (tcp_connection_t * tc)
+{
+  fib_prefix_t prefix;
+
+  clib_memcpy (&prefix.fp_addr, &tc->c_rmt_ip, sizeof (prefix.fp_addr));
+  prefix.fp_proto = tc->c_is_ip4 ? FIB_PROTOCOL_IP4 : FIB_PROTOCOL_IP6;
+  prefix.fp_len = tc->c_is_ip4 ? 32 : 128;
+  return fib_table_lookup (0, &prefix);
+}
+
+static int
+tcp_connection_stack_on_fib_entry (tcp_connection_t * tc)
+{
+  dpo_id_t choice = DPO_INVALID;
+  u32 output_node_index;
+  fib_entry_t *fe;
+
+  fe = fib_entry_get (tc->c_rmt_fei);
+  if (fe->fe_lb.dpoi_type != DPO_LOAD_BALANCE)
+    return -1;
+
+  tcp_connection_select_lb_bucket (tc, &fe->fe_lb, &choice);
+
+  output_node_index =
+    tc->c_is_ip4 ? tcp4_output_node.index : tcp6_output_node.index;
+  dpo_stack_from_node (output_node_index, &tc->c_rmt_dpo, &choice);
+  return 0;
+}
+
+/** Stack tcp connection on peer's fib entry.
+ *
+ * This ultimately populates the dpo the connection will use to send packets.
+ */
+static void
+tcp_connection_fib_attach (tcp_connection_t * tc)
+{
+  tc->c_rmt_fei = tcp_lookup_rmt_in_fib (tc);
+
+  ASSERT (tc->c_rmt_fei != FIB_NODE_INDEX_INVALID);
+
+  tcp_connection_stack_on_fib_entry (tc);
+}
+#endif /* 0 */
+
 /** Initialize tcp connection variables
  *
  * Should be called after having received a msg from the peer, i.e., a SYN or
@@ -305,9 +505,10 @@ void
 tcp_connection_init_vars (tcp_connection_t * tc)
 {
   tcp_connection_timers_init (tc);
-  tcp_set_snd_mss (tc);
-  tc->sack_sb.head = TCP_INVALID_SACK_HOLE_INDEX;
+  tcp_init_mss (tc);
+  scoreboard_init (&tc->sack_sb);
   tcp_cc_init (tc);
+  //  tcp_connection_fib_attach (tc);
 }
 
 int
@@ -316,9 +517,10 @@ tcp_connection_open (ip46_address_t * rmt_addr, u16 rmt_port, u8 is_ip4)
   tcp_main_t *tm = vnet_get_tcp_main ();
   tcp_connection_t *tc;
   fib_prefix_t prefix;
-  u32 fei, sw_if_index;
+  fib_node_index_t fei;
+  u32 sw_if_index;
   ip46_address_t lcl_addr;
-  u16 lcl_port;
+  int lcl_port;
 
   /*
    * Find the local address and allocate port
@@ -334,24 +536,55 @@ tcp_connection_open (ip46_address_t * rmt_addr, u16 rmt_port, u8 is_ip4)
 
   /* Couldn't find route to destination. Bail out. */
   if (fei == FIB_NODE_INDEX_INVALID)
-    return -1;
+    {
+      clib_warning ("no route to destination");
+      return -1;
+    }
 
   sw_if_index = fib_entry_get_resolving_interface (fei);
 
   if (sw_if_index == (u32) ~ 0)
-    return -1;
+    {
+      clib_warning ("no resolving interface for %U", format_ip46_address,
+		    rmt_addr, IP46_TYPE_IP4);
+      return -1;
+    }
 
   if (is_ip4)
     {
       ip4_address_t *ip4;
-      ip4 = ip_interface_get_first_ip (sw_if_index, 1);
-      lcl_addr.ip4.as_u32 = ip4->as_u32;
+      int index;
+      if (vec_len (tm->ip4_src_addresses))
+	{
+	  index = tm->last_v4_address_rotor++;
+	  if (tm->last_v4_address_rotor >= vec_len (tm->ip4_src_addresses))
+	    tm->last_v4_address_rotor = 0;
+	  lcl_addr.ip4.as_u32 = tm->ip4_src_addresses[index].as_u32;
+	}
+      else
+	{
+	  ip4 = ip_interface_get_first_ip (sw_if_index, 1);
+	  lcl_addr.ip4.as_u32 = ip4->as_u32;
+	}
     }
   else
     {
       ip6_address_t *ip6;
-      ip6 = ip_interface_get_first_ip (sw_if_index, 0);
-      clib_memcpy (&lcl_addr.ip6, ip6, sizeof (*ip6));
+      int index;
+
+      if (vec_len (tm->ip6_src_addresses))
+	{
+	  index = tm->last_v6_address_rotor++;
+	  if (tm->last_v6_address_rotor >= vec_len (tm->ip6_src_addresses))
+	    tm->last_v6_address_rotor = 0;
+	  clib_memcpy (&lcl_addr.ip6, &tm->ip6_src_addresses[index],
+		       sizeof (*ip6));
+	}
+      else
+	{
+	  ip6 = ip_interface_get_first_ip (sw_if_index, 0);
+	  clib_memcpy (&lcl_addr.ip6, ip6, sizeof (*ip6));
+	}
     }
 
   /* Allocate source port */
@@ -375,13 +608,14 @@ tcp_connection_open (ip46_address_t * rmt_addr, u16 rmt_port, u8 is_ip4)
   tc->c_lcl_port = clib_host_to_net_u16 (lcl_port);
   tc->c_c_index = tc - tm->half_open_connections;
   tc->c_is_ip4 = is_ip4;
+  tc->c_proto = is_ip4 ? SESSION_TYPE_IP4_TCP : SESSION_TYPE_IP6_TCP;
 
   /* The other connection vars will be initialized after SYN ACK */
   tcp_connection_timers_init (tc);
 
-  tcp_send_syn (tc);
-
+  TCP_EVT_DBG (TCP_EVT_OPEN, tc);
   tc->state = TCP_STATE_SYN_SENT;
+  tcp_send_syn (tc);
 
   return tc->c_c_index;
 }
@@ -398,81 +632,261 @@ tcp_session_open_ip6 (ip46_address_t * addr, u16 port)
   return tcp_connection_open (addr, port, 0);
 }
 
+const char *tcp_dbg_evt_str[] = {
+#define _(sym, str) str,
+  foreach_tcp_dbg_evt
+#undef _
+};
+
+const char *tcp_fsm_states[] = {
+#define _(sym, str) str,
+  foreach_tcp_fsm_state
+#undef _
+};
+
 u8 *
-format_tcp_session_ip4 (u8 * s, va_list * args)
+format_tcp_state (u8 * s, va_list * args)
 {
-  u32 tci = va_arg (*args, u32);
-  u32 thread_index = va_arg (*args, u32);
-  tcp_connection_t *tc;
+  u32 state = va_arg (*args, u32);
 
-  tc = tcp_connection_get (tci, thread_index);
+  if (state < TCP_N_STATES)
+    s = format (s, "%s", tcp_fsm_states[state]);
+  else
+    s = format (s, "UNKNOWN (%d (0x%x))", state, state);
+  return s;
+}
 
-  s = format (s, "[%s] %U:%d->%U:%d", "tcp", format_ip4_address,
-	      &tc->c_lcl_ip4, clib_net_to_host_u16 (tc->c_lcl_port),
-	      format_ip4_address, &tc->c_rmt_ip4,
-	      clib_net_to_host_u16 (tc->c_rmt_port));
+const char *tcp_conn_timers[] = {
+#define _(sym, str) str,
+  foreach_tcp_timer
+#undef _
+};
+
+u8 *
+format_tcp_timers (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  int i, last = -1;
+
+  for (i = 0; i < TCP_N_TIMERS; i++)
+    if (tc->timers[i] != TCP_TIMER_HANDLE_INVALID)
+      last = i;
+
+  s = format (s, "[");
+  for (i = 0; i < last; i++)
+    {
+      if (tc->timers[i] != TCP_TIMER_HANDLE_INVALID)
+	s = format (s, "%s,", tcp_conn_timers[i]);
+    }
+
+  if (last >= 0)
+    s = format (s, "%s]", tcp_conn_timers[i]);
+  else
+    s = format (s, "]");
 
   return s;
 }
 
 u8 *
-format_tcp_session_ip6 (u8 * s, va_list * args)
+format_tcp_congestion_status (u8 * s, va_list * args)
 {
-  u32 tci = va_arg (*args, u32);
-  u32 thread_index = va_arg (*args, u32);
-  tcp_connection_t *tc = tcp_connection_get (tci, thread_index);
-  s = format (s, "[%s] %U:%d->%U:%d", "tcp", format_ip6_address,
-	      &tc->c_lcl_ip6, clib_net_to_host_u16 (tc->c_lcl_port),
-	      format_ip6_address, &tc->c_rmt_ip6,
-	      clib_net_to_host_u16 (tc->c_rmt_port));
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  if (tcp_in_recovery (tc))
+    s = format (s, "recovery");
+  else if (tcp_in_fastrecovery (tc))
+    s = format (s, "fastrecovery");
+  else
+    s = format (s, "none");
+  return s;
+}
+
+u8 *
+format_tcp_vars (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  s = format (s, " snd_una %u snd_nxt %u snd_una_max %u",
+	      tc->snd_una - tc->iss, tc->snd_nxt - tc->iss,
+	      tc->snd_una_max - tc->iss);
+  s = format (s, " rcv_nxt %u rcv_las %u\n",
+	      tc->rcv_nxt - tc->irs, tc->rcv_las - tc->irs);
+  s = format (s, " snd_wnd %u rcv_wnd %u snd_wl1 %u snd_wl2 %u\n",
+	      tc->snd_wnd, tc->rcv_wnd, tc->snd_wl1 - tc->irs,
+	      tc->snd_wl2 - tc->iss);
+  s = format (s, " flight size %u send space %u rcv_wnd_av %d\n",
+	      tcp_flight_size (tc), tcp_available_snd_space (tc),
+	      tcp_rcv_wnd_available (tc));
+  s = format (s, " cong %U ", format_tcp_congestion_status, tc);
+  s = format (s, "cwnd %u ssthresh %u rtx_bytes %u bytes_acked %u\n",
+	      tc->cwnd, tc->ssthresh, tc->snd_rxt_bytes, tc->bytes_acked);
+  s = format (s, " prev_ssthresh %u snd_congestion %u dupack %u",
+	      tc->prev_ssthresh, tc->snd_congestion - tc->iss,
+	      tc->rcv_dupacks);
+  s = format (s, " limited_transmit %u\n", tc->limited_transmit - tc->iss);
+  s = format (s, " tsecr %u tsecr_last_ack %u\n", tc->rcv_opts.tsecr,
+	      tc->tsecr_last_ack);
+  s = format (s, " rto %u rto_boff %u srtt %u rttvar %u rtt_ts %u ", tc->rto,
+	      tc->rto_boff, tc->srtt, tc->rttvar, tc->rtt_ts);
+  s = format (s, "rtt_seq %u\n", tc->rtt_seq);
+  s = format (s, " tsval_recent %u tsval_recent_age %u\n", tc->tsval_recent,
+	      tcp_time_now () - tc->tsval_recent_age);
+  s = format (s, " scoreboard: %U\n", format_tcp_scoreboard, &tc->sack_sb);
+  if (vec_len (tc->snd_sacks))
+    s = format (s, " sacks tx: %U\n", format_tcp_sacks, tc);
+
   return s;
 }
 
 u8 *
-format_tcp_listener_session_ip4 (u8 * s, va_list * args)
+format_tcp_connection_id (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  if (!tc)
+    return s;
+  if (tc->c_is_ip4)
+    {
+      s = format (s, "[#%d][%s] %U:%d->%U:%d", tc->c_thread_index, "T",
+		  format_ip4_address, &tc->c_lcl_ip4,
+		  clib_net_to_host_u16 (tc->c_lcl_port), format_ip4_address,
+		  &tc->c_rmt_ip4, clib_net_to_host_u16 (tc->c_rmt_port));
+    }
+  else
+    {
+      s = format (s, "[#%d][%s] %U:%d->%U:%d", tc->c_thread_index, "T",
+		  format_ip6_address, &tc->c_lcl_ip6,
+		  clib_net_to_host_u16 (tc->c_lcl_port), format_ip6_address,
+		  &tc->c_rmt_ip6, clib_net_to_host_u16 (tc->c_rmt_port));
+    }
+
+  return s;
+}
+
+u8 *
+format_tcp_connection (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  u32 verbose = va_arg (*args, u32);
+
+  s = format (s, "%-50U", format_tcp_connection_id, tc);
+  if (verbose)
+    {
+      s = format (s, "%-15U", format_tcp_state, tc->state);
+      if (verbose > 1)
+	s = format (s, " %U\n%U", format_tcp_timers, tc, format_tcp_vars, tc);
+    }
+
+  return s;
+}
+
+u8 *
+format_tcp_session (u8 * s, va_list * args)
 {
   u32 tci = va_arg (*args, u32);
-  tcp_connection_t *tc = tcp_listener_get (tci);
-  s = format (s, "[%s] %U:%d->%U:%d", "tcp", format_ip4_address,
-	      &tc->c_lcl_ip4, clib_net_to_host_u16 (tc->c_lcl_port),
-	      format_ip4_address, &tc->c_rmt_ip4,
-	      clib_net_to_host_u16 (tc->c_rmt_port));
+  u32 thread_index = va_arg (*args, u32);
+  u32 verbose = va_arg (*args, u32);
+  tcp_connection_t *tc;
+
+  tc = tcp_connection_get (tci, thread_index);
+  if (tc)
+    s = format (s, "%U", format_tcp_connection, tc, verbose);
+  else
+    s = format (s, "empty");
   return s;
 }
 
 u8 *
-format_tcp_listener_session_ip6 (u8 * s, va_list * args)
+format_tcp_listener_session (u8 * s, va_list * args)
 {
   u32 tci = va_arg (*args, u32);
   tcp_connection_t *tc = tcp_listener_get (tci);
-  s = format (s, "[%s] %U:%d->%U:%d", "tcp", format_ip6_address,
-	      &tc->c_lcl_ip6, clib_net_to_host_u16 (tc->c_lcl_port),
-	      format_ip6_address, &tc->c_rmt_ip6,
-	      clib_net_to_host_u16 (tc->c_rmt_port));
-  return s;
+  return format (s, "%U", format_tcp_connection_id, tc);
 }
 
 u8 *
-format_tcp_half_open_session_ip4 (u8 * s, va_list * args)
+format_tcp_half_open_session (u8 * s, va_list * args)
 {
   u32 tci = va_arg (*args, u32);
   tcp_connection_t *tc = tcp_half_open_connection_get (tci);
-  s = format (s, "[%s] %U:%d->%U:%d", "tcp", format_ip4_address,
-	      &tc->c_lcl_ip4, clib_net_to_host_u16 (tc->c_lcl_port),
-	      format_ip4_address, &tc->c_rmt_ip4,
-	      clib_net_to_host_u16 (tc->c_rmt_port));
+  return format (s, "%U", format_tcp_connection_id, tc);
+}
+
+u8 *
+format_tcp_sacks (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  sack_block_t *sacks = tc->snd_sacks;
+  sack_block_t *block;
+  int i, len = 0;
+
+  len = vec_len (sacks);
+  for (i = 0; i < len - 1; i++)
+    {
+      block = &sacks[i];
+      s = format (s, " start %u end %u\n", block->start - tc->irs,
+		  block->end - tc->irs);
+    }
+  if (len)
+    {
+      block = &sacks[len - 1];
+      s = format (s, " start %u end %u", block->start - tc->irs,
+		  block->end - tc->irs);
+    }
   return s;
 }
 
 u8 *
-format_tcp_half_open_session_ip6 (u8 * s, va_list * args)
+format_tcp_rcv_sacks (u8 * s, va_list * args)
 {
-  u32 tci = va_arg (*args, u32);
-  tcp_connection_t *tc = tcp_half_open_connection_get (tci);
-  s = format (s, "[%s] %U:%d->%U:%d", "tcp", format_ip6_address,
-	      &tc->c_lcl_ip6, clib_net_to_host_u16 (tc->c_lcl_port),
-	      format_ip6_address, &tc->c_rmt_ip6,
-	      clib_net_to_host_u16 (tc->c_rmt_port));
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  sack_block_t *sacks = tc->rcv_opts.sacks;
+  sack_block_t *block;
+  int i, len = 0;
+
+  len = vec_len (sacks);
+  for (i = 0; i < len - 1; i++)
+    {
+      block = &sacks[i];
+      s = format (s, " start %u end %u\n", block->start - tc->iss,
+		  block->end - tc->iss);
+    }
+  if (len)
+    {
+      block = &sacks[len - 1];
+      s = format (s, " start %u end %u", block->start - tc->iss,
+		  block->end - tc->iss);
+    }
+  return s;
+}
+
+u8 *
+format_tcp_sack_hole (u8 * s, va_list * args)
+{
+  sack_scoreboard_hole_t *hole = va_arg (*args, sack_scoreboard_hole_t *);
+  s = format (s, "[%u, %u]", hole->start, hole->end);
+  return s;
+}
+
+u8 *
+format_tcp_scoreboard (u8 * s, va_list * args)
+{
+  sack_scoreboard_t *sb = va_arg (*args, sack_scoreboard_t *);
+  sack_scoreboard_hole_t *hole;
+  s = format (s, "sacked_bytes %u last_sacked_bytes %u lost_bytes %u\n",
+	      sb->sacked_bytes, sb->last_sacked_bytes, sb->lost_bytes);
+  s = format (s, " last_bytes_delivered %u high_sacked %u snd_una_adv %u\n",
+	      sb->last_bytes_delivered, sb->high_sacked, sb->snd_una_adv);
+  s = format (s, " cur_rxt_hole %u high_rxt %u rescue_rxt %u",
+	      sb->cur_rxt_hole, sb->high_rxt, sb->rescue_rxt);
+
+  hole = scoreboard_first_hole (sb);
+  if (hole)
+    s = format (s, "\n head %u tail %u holes:\n", sb->head, sb->tail);
+
+  while (hole)
+    {
+      s = format (s, "%U", format_tcp_sack_hole, hole);
+      hole = scoreboard_next_hole (sb, hole);
+    }
+
   return s;
 }
 
@@ -490,31 +904,130 @@ tcp_half_open_session_get_transport (u32 conn_index)
   return &tc->connection;
 }
 
+/**
+ * Compute maximum segment size for session layer.
+ *
+ * Since the result needs to be the actual data length, it first computes
+ * the tcp options to be used in the next burst and subtracts their
+ * length from the connection's snd_mss.
+ */
 u16
 tcp_session_send_mss (transport_connection_t * trans_conn)
 {
   tcp_connection_t *tc = (tcp_connection_t *) trans_conn;
+
+  /* Ensure snd_mss does accurately reflect the amount of data we can push
+   * in a segment. This also makes sure that options are updated according to
+   * the current state of the connection. */
+  tcp_update_snd_mss (tc);
+
   return tc->snd_mss;
 }
 
+always_inline u32
+tcp_round_snd_space (tcp_connection_t * tc, u32 snd_space)
+{
+  if (PREDICT_FALSE (tc->snd_wnd < tc->snd_mss))
+    {
+      return tc->snd_wnd <= snd_space ? tc->snd_wnd : 0;
+    }
+
+  /* If we can't write at least a segment, don't try at all */
+  if (PREDICT_FALSE (snd_space < tc->snd_mss))
+    {
+      if (snd_space > clib_min (tc->mss, tc->rcv_opts.mss) - TCP_HDR_LEN_MAX)
+	return snd_space;
+      return 0;
+    }
+
+  /* round down to mss multiple */
+  return snd_space - (snd_space % tc->snd_mss);
+}
+
+/**
+ * Compute tx window session is allowed to fill.
+ *
+ * Takes into account available send space, snd_mss and the congestion
+ * state of the connection. If possible, the value returned is a multiple
+ * of snd_mss.
+ *
+ * @param tc tcp connection
+ * @return number of bytes session is allowed to write
+ */
+u32
+tcp_snd_space (tcp_connection_t * tc)
+{
+  int snd_space, snt_limited;
+
+  if (PREDICT_TRUE (tcp_in_cong_recovery (tc) == 0))
+    {
+      snd_space = tcp_available_snd_space (tc);
+
+      /* If we haven't gotten dupacks or if we did and have gotten sacked
+       * bytes then we can still send as per Limited Transmit (RFC3042) */
+      if (PREDICT_FALSE (tc->rcv_dupacks != 0
+			 && (tcp_opts_sack_permitted (tc)
+			     && tc->sack_sb.last_sacked_bytes == 0)))
+	{
+	  if (tc->rcv_dupacks == 1 && tc->limited_transmit != tc->snd_nxt)
+	    tc->limited_transmit = tc->snd_nxt;
+	  ASSERT (seq_leq (tc->limited_transmit, tc->snd_nxt));
+
+	  snt_limited = tc->snd_nxt - tc->limited_transmit;
+	  snd_space = clib_max (2 * tc->snd_mss - snt_limited, 0);
+	}
+      return tcp_round_snd_space (tc, snd_space);
+    }
+
+  if (tcp_in_recovery (tc))
+    {
+      tc->snd_nxt = tc->snd_una_max;
+      snd_space = tcp_available_wnd (tc) - tc->snd_rxt_bytes
+	- (tc->snd_una_max - tc->snd_congestion);
+      if (snd_space <= 0 || (tc->snd_una_max - tc->snd_una) >= tc->snd_wnd)
+	return 0;
+      return tcp_round_snd_space (tc, snd_space);
+    }
+
+  /* If in fast recovery, send 1 SMSS if wnd allows */
+  if (tcp_in_fastrecovery (tc)
+      && tcp_available_snd_space (tc) && !tcp_fastrecovery_sent_1_smss (tc))
+    {
+      tcp_fastrecovery_1_smss_on (tc);
+      return tc->snd_mss;
+    }
+
+  return 0;
+}
+
 u32
 tcp_session_send_space (transport_connection_t * trans_conn)
 {
   tcp_connection_t *tc = (tcp_connection_t *) trans_conn;
-  return tcp_available_snd_space (tc);
+  return tcp_snd_space (tc);
+}
+
+i32
+tcp_rcv_wnd_available (tcp_connection_t * tc)
+{
+  return (i32) tc->rcv_wnd - (tc->rcv_nxt - tc->rcv_las);
 }
 
 u32
-tcp_session_rx_fifo_offset (transport_connection_t * trans_conn)
+tcp_session_tx_fifo_offset (transport_connection_t * trans_conn)
 {
   tcp_connection_t *tc = (tcp_connection_t *) trans_conn;
-  return (tc->snd_una_max - tc->snd_una);
+
+  ASSERT (seq_geq (tc->snd_nxt, tc->snd_una));
+
+  /* This still works if fast retransmit is on */
+  return (tc->snd_nxt - tc->snd_una);
 }
 
 /* *INDENT-OFF* */
 const static transport_proto_vft_t tcp4_proto = {
   .bind = tcp_session_bind_ip4,
-  .unbind = tcp_session_unbind_ip4,
+  .unbind = tcp_session_unbind,
   .push_header = tcp_push_header,
   .get_connection = tcp_session_get_transport,
   .get_listener = tcp_session_get_listener,
@@ -524,15 +1037,15 @@ const static transport_proto_vft_t tcp4_proto = {
   .cleanup = tcp_session_cleanup,
   .send_mss = tcp_session_send_mss,
   .send_space = tcp_session_send_space,
-  .rx_fifo_offset = tcp_session_rx_fifo_offset,
-  .format_connection = format_tcp_session_ip4,
-  .format_listener = format_tcp_listener_session_ip4,
-  .format_half_open = format_tcp_half_open_session_ip4
+  .tx_fifo_offset = tcp_session_tx_fifo_offset,
+  .format_connection = format_tcp_session,
+  .format_listener = format_tcp_listener_session,
+  .format_half_open = format_tcp_half_open_session,
 };
 
 const static transport_proto_vft_t tcp6_proto = {
   .bind = tcp_session_bind_ip6,
-  .unbind = tcp_session_unbind_ip6,
+  .unbind = tcp_session_unbind,
   .push_header = tcp_push_header,
   .get_connection = tcp_session_get_transport,
   .get_listener = tcp_session_get_listener,
@@ -542,20 +1055,20 @@ const static transport_proto_vft_t tcp6_proto = {
   .cleanup = tcp_session_cleanup,
   .send_mss = tcp_session_send_mss,
   .send_space = tcp_session_send_space,
-  .rx_fifo_offset = tcp_session_rx_fifo_offset,
-  .format_connection = format_tcp_session_ip6,
-  .format_listener = format_tcp_listener_session_ip6,
-  .format_half_open = format_tcp_half_open_session_ip6
+  .tx_fifo_offset = tcp_session_tx_fifo_offset,
+  .format_connection = format_tcp_session,
+  .format_listener = format_tcp_listener_session,
+  .format_half_open = format_tcp_half_open_session,
 };
 /* *INDENT-ON* */
 
 void
 tcp_timer_keep_handler (u32 conn_index)
 {
-  u32 cpu_index = os_get_cpu_number ();
+  u32 thread_index = vlib_get_thread_index ();
   tcp_connection_t *tc;
 
-  tc = tcp_connection_get (conn_index, cpu_index);
+  tc = tcp_connection_get (conn_index, thread_index);
   tc->timers[TCP_TIMER_KEEP] = TCP_TIMER_HANDLE_INVALID;
 
   tcp_connection_close (tc);
@@ -579,13 +1092,32 @@ tcp_timer_establish_handler (u32 conn_index)
 }
 
 void
-tcp_timer_2msl_handler (u32 conn_index)
+tcp_timer_waitclose_handler (u32 conn_index)
 {
-  u32 cpu_index = os_get_cpu_number ();
+  u32 thread_index = vlib_get_thread_index ();
   tcp_connection_t *tc;
 
-  tc = tcp_connection_get (conn_index, cpu_index);
-  tc->timers[TCP_TIMER_2MSL] = TCP_TIMER_HANDLE_INVALID;
+  tc = tcp_connection_get (conn_index, thread_index);
+  tc->timers[TCP_TIMER_WAITCLOSE] = TCP_TIMER_HANDLE_INVALID;
+
+  /* Session didn't come back with a close(). Send FIN either way
+   * and switch to LAST_ACK. */
+  if (tc->state == TCP_STATE_CLOSE_WAIT)
+    {
+      if (tc->flags & TCP_CONN_FINSNT)
+	{
+	  clib_warning ("FIN was sent and still in CLOSE WAIT. Weird!");
+	}
+
+      tcp_send_fin (tc);
+      tc->state = TCP_STATE_LAST_ACK;
+
+      /* Make sure we don't wait in LAST ACK forever */
+      tcp_timer_set (tc, TCP_TIMER_WAITCLOSE, TCP_2MSL_TIME);
+
+      /* Don't delete the connection yet */
+      return;
+    }
 
   tcp_connection_del (tc);
 }
@@ -595,9 +1127,9 @@ static timer_expiration_handler *timer_expiration_handlers[TCP_N_TIMERS] =
 {
     tcp_timer_retransmit_handler,
     tcp_timer_delack_handler,
-    0,
+    tcp_timer_persist_handler,
     tcp_timer_keep_handler,
-    tcp_timer_2msl_handler,
+    tcp_timer_waitclose_handler,
     tcp_timer_retransmit_syn_handler,
     tcp_timer_establish_handler
 };
@@ -615,6 +1147,8 @@ tcp_expired_timers_dispatch (u32 * expired_timers)
       connection_index = expired_timers[i] & 0x0FFFFFFF;
       timer_id = expired_timers[i] >> 28;
 
+      TCP_EVT_DBG (TCP_EVT_TIMER_POP, connection_index, timer_id);
+
       /* Handle expiration */
       (*timer_expiration_handlers[timer_id]) (connection_index);
     }
@@ -624,26 +1158,27 @@ void
 tcp_initialize_timer_wheels (tcp_main_t * tm)
 {
   tw_timer_wheel_16t_2w_512sl_t *tw;
-  vec_foreach (tw, tm->timer_wheels)
-  {
+  /* *INDENT-OFF* */
+  foreach_vlib_main (({
+    tw = &tm->timer_wheels[ii];
     tw_timer_wheel_init_16t_2w_512sl (tw, tcp_expired_timers_dispatch,
 				      100e-3 /* timer period 100ms */ , ~0);
-    tw->last_run_time = vlib_time_now (tm->vlib_main);
-  }
+    tw->last_run_time = vlib_time_now (this_vlib_main);
+  }));
+  /* *INDENT-ON* */
 }
 
 clib_error_t *
-tcp_init (vlib_main_t * vm)
+tcp_main_enable (vlib_main_t * vm)
 {
-  ip_main_t *im = &ip_main;
-  ip_protocol_info_t *pi;
   tcp_main_t *tm = vnet_get_tcp_main ();
+  ip_protocol_info_t *pi;
+  ip_main_t *im = &ip_main;
   vlib_thread_main_t *vtm = vlib_get_thread_main ();
   clib_error_t *error = 0;
   u32 num_threads;
-
-  tm->vlib_main = vm;
-  tm->vnet_main = vnet_get_main ();
+  int thread, i;
+  tcp_connection_t *tc __attribute__ ((unused));
 
   if ((error = vlib_call_init_function (vm, ip_main_init)))
     return error;
@@ -676,6 +1211,27 @@ tcp_init (vlib_main_t * vm)
   num_threads = 1 /* main thread */  + vtm->n_threads;
   vec_validate (tm->connections, num_threads - 1);
 
+  /*
+   * Preallocate connections
+   */
+  for (thread = 0; thread < num_threads; thread++)
+    {
+      for (i = 0; i < tm->preallocated_connections; i++)
+	pool_get (tm->connections[thread], tc);
+
+      for (i = 0; i < tm->preallocated_connections; i++)
+	pool_put_index (tm->connections[thread], i);
+    }
+
+  /*
+   * Preallocate half-open connections
+   */
+  for (i = 0; i < tm->preallocated_half_open_connections; i++)
+    pool_get (tm->half_open_connections, tc);
+
+  for (i = 0; i < tm->preallocated_half_open_connections; i++)
+    pool_put_index (tm->half_open_connections, i);
+
   /* Initialize per worker thread tx buffers (used for control messages) */
   vec_validate (tm->tx_buffers, num_threads - 1);
 
@@ -683,8 +1239,6 @@ tcp_init (vlib_main_t * vm)
   vec_validate (tm->timer_wheels, num_threads - 1);
   tcp_initialize_timer_wheels (tm);
 
-  vec_validate (tm->delack_connections, num_threads - 1);
-
   /* Initialize clocks per tick for TCP timestamp. Used to compute
    * monotonically increasing timestamps. */
   tm->tstamp_ticks_per_clock = vm->clib_time.seconds_per_clock
@@ -693,12 +1247,314 @@ tcp_init (vlib_main_t * vm)
   clib_bihash_init_24_8 (&tm->local_endpoints_table, "local endpoint table",
 			 200000 /* $$$$ config parameter nbuckets */ ,
 			 (64 << 20) /*$$$ config parameter table size */ );
-
+  clib_spinlock_init (&tm->half_open_lock);
   return error;
 }
 
+clib_error_t *
+vnet_tcp_enable_disable (vlib_main_t * vm, u8 is_en)
+{
+  if (is_en)
+    {
+      if (tcp_main.is_enabled)
+	return 0;
+
+      return tcp_main_enable (vm);
+    }
+  else
+    {
+      tcp_main.is_enabled = 0;
+    }
+
+  return 0;
+}
+
+clib_error_t *
+tcp_init (vlib_main_t * vm)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+
+  tm->vnet_main = vnet_get_main ();
+  tm->is_enabled = 0;
+
+  return 0;
+}
+
 VLIB_INIT_FUNCTION (tcp_init);
 
+
+static clib_error_t *
+tcp_config_fn (vlib_main_t * vm, unformat_input_t * input)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat
+	  (input, "preallocated-connections %d",
+	   &tm->preallocated_connections))
+	;
+      else if (unformat (input, "preallocated-half-open-connections %d",
+			 &tm->preallocated_half_open_connections))
+	;
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+  return 0;
+}
+
+VLIB_CONFIG_FUNCTION (tcp_config_fn, "tcp");
+
+static clib_error_t *
+tcp_src_address (vlib_main_t * vm,
+		 unformat_input_t * input, vlib_cli_command_t * cmd_arg)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+  ip4_address_t v4start, v4end;
+  ip6_address_t v6start, v6end;
+  int v4set = 0;
+  int v6set = 0;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U - %U", unformat_ip4_address, &v4start,
+		    unformat_ip4_address, &v4end))
+	v4set = 1;
+      else if (unformat (input, "%U", unformat_ip4_address, &v4start))
+	{
+	  memcpy (&v4end, &v4start, sizeof (v4start));
+	  v4set = 1;
+	}
+      else if (unformat (input, "%U - %U", unformat_ip6_address, &v6start,
+			 unformat_ip4_address, &v6end))
+	v6set = 1;
+      else if (unformat (input, "%U", unformat_ip6_address, &v6start))
+	{
+	  memcpy (&v6end, &v6start, sizeof (v4start));
+	  v6set = 1;
+	}
+      else
+	break;
+    }
+
+  if (!v4set && !v6set)
+    return clib_error_return (0, "at least one v4 or v6 address required");
+
+  if (v4set)
+    {
+      u32 tmp;
+
+      do
+	{
+	  vec_add1 (tm->ip4_src_addresses, v4start);
+	  tmp = clib_net_to_host_u32 (v4start.as_u32);
+	  tmp++;
+	  v4start.as_u32 = clib_host_to_net_u32 (tmp);
+	}
+      while (clib_host_to_net_u32 (v4start.as_u32) <=
+	     clib_host_to_net_u32 (v4end.as_u32));
+    }
+  if (v6set)
+    {
+      clib_warning ("v6 src address list unimplemented...");
+    }
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (tcp_src_address_command, static) =
+{
+  .path = "tcp src-address",
+  .short_help = "tcp src-address <ip-addr> [- <ip-addr>] add src address range",
+  .function = tcp_src_address,
+};
+/* *INDENT-ON* */
+
+static u8 *
+tcp_scoreboard_dump_trace (u8 * s, sack_scoreboard_t * sb)
+{
+#if TCP_SCOREBOARD_TRACE
+
+  scoreboard_trace_elt_t *block;
+  int i = 0;
+
+  if (!sb->trace)
+    return s;
+
+  s = format (s, "scoreboard trace:");
+  vec_foreach (block, sb->trace)
+  {
+    s = format (s, "{%u, %u, %u, %u, %u}, ", block->start, block->end,
+		block->ack, block->snd_una_max, block->group);
+    if ((++i % 3) == 0)
+      s = format (s, "\n");
+  }
+  return s;
+#else
+  return 0;
+#endif
+}
+
+static clib_error_t *
+tcp_show_scoreboard_trace_fn (vlib_main_t * vm, unformat_input_t * input,
+			      vlib_cli_command_t * cmd_arg)
+{
+  transport_connection_t *tconn = 0;
+  tcp_connection_t *tc;
+  u8 *s = 0;
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U", unformat_transport_connection, &tconn,
+		    TRANSPORT_PROTO_TCP))
+	;
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+
+  if (!TCP_SCOREBOARD_TRACE)
+    {
+      vlib_cli_output (vm, "scoreboard tracing not enabled");
+      return 0;
+    }
+
+  tc = tcp_get_connection_from_transport (tconn);
+  s = tcp_scoreboard_dump_trace (s, &tc->sack_sb);
+  vlib_cli_output (vm, "%v", s);
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (tcp_show_scoreboard_trace_command, static) =
+{
+  .path = "show tcp scoreboard trace",
+  .short_help = "show tcp scoreboard trace <connection>",
+  .function = tcp_show_scoreboard_trace_fn,
+};
+/* *INDENT-ON* */
+
+u8 *
+tcp_scoreboard_replay (u8 * s, tcp_connection_t * tc, u8 verbose)
+{
+  int i, trace_len;
+  scoreboard_trace_elt_t *trace;
+  u32 next_ack, left, group, has_new_ack = 0;
+  tcp_connection_t _dummy_tc, *dummy_tc = &_dummy_tc;
+  sack_block_t *block;
+
+  if (!tc)
+    return s;
+
+  memset (dummy_tc, 0, sizeof (*dummy_tc));
+  tcp_connection_timers_init (dummy_tc);
+  scoreboard_init (&dummy_tc->sack_sb);
+  dummy_tc->rcv_opts.flags |= TCP_OPTS_FLAG_SACK;
+
+#if TCP_SCOREBOARD_TRACE
+  trace = tc->sack_sb.trace;
+  trace_len = vec_len (tc->sack_sb.trace);
+#else
+  trace = 0;
+  trace_len = 0;
+#endif
+
+  for (i = 0; i < trace_len; i++)
+    {
+      if (trace[i].ack != 0)
+	{
+	  dummy_tc->snd_una = trace[i].ack - 1448;
+	  dummy_tc->snd_una_max = trace[i].ack;
+	}
+    }
+
+  left = 0;
+  while (left < trace_len)
+    {
+      group = trace[left].group;
+      vec_reset_length (dummy_tc->rcv_opts.sacks);
+      has_new_ack = 0;
+      while (trace[left].group == group)
+	{
+	  if (trace[left].ack != 0)
+	    {
+	      if (verbose)
+		s = format (s, "Adding ack %u, snd_una_max %u, segs: ",
+			    trace[left].ack, trace[left].snd_una_max);
+	      dummy_tc->snd_una_max = trace[left].snd_una_max;
+	      next_ack = trace[left].ack;
+	      has_new_ack = 1;
+	    }
+	  else
+	    {
+	      if (verbose)
+		s = format (s, "[%u, %u], ", trace[left].start,
+			    trace[left].end);
+	      vec_add2 (dummy_tc->rcv_opts.sacks, block, 1);
+	      block->start = trace[left].start;
+	      block->end = trace[left].end;
+	    }
+	  left++;
+	}
+
+      /* Push segments */
+      tcp_rcv_sacks (dummy_tc, next_ack);
+      if (has_new_ack)
+	dummy_tc->snd_una = next_ack + dummy_tc->sack_sb.snd_una_adv;
+
+      if (verbose)
+	s = format (s, "result: %U", format_tcp_scoreboard,
+		    &dummy_tc->sack_sb);
+
+    }
+  s = format (s, "result: %U", format_tcp_scoreboard, &dummy_tc->sack_sb);
+
+  return s;
+}
+
+static clib_error_t *
+tcp_scoreboard_trace_fn (vlib_main_t * vm, unformat_input_t * input,
+			 vlib_cli_command_t * cmd_arg)
+{
+  transport_connection_t *tconn = 0;
+  tcp_connection_t *tc = 0;
+  u8 *str = 0;
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U", unformat_transport_connection, &tconn,
+		    TRANSPORT_PROTO_TCP))
+	;
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+
+  if (!TCP_SCOREBOARD_TRACE)
+    {
+      vlib_cli_output (vm, "scoreboard tracing not enabled");
+      return 0;
+    }
+
+  tc = tcp_get_connection_from_transport (tconn);
+  if (!tc)
+    {
+      vlib_cli_output (vm, "connection not found");
+      return 0;
+    }
+  str = tcp_scoreboard_replay (str, tc, 1);
+  vlib_cli_output (vm, "%v", str);
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (tcp_replay_scoreboard_command, static) =
+{
+  .path = "tcp replay scoreboard",
+  .short_help = "tcp replay scoreboard <connection>",
+  .function = tcp_scoreboard_trace_fn,
+};
+/* *INDENT-ON* */
+
 /*
  * fd.io coding-style-patch-verification: ON
  *