tcp: retransmit and multi-buffer segment fixes and improvements

- set session state as closed on session manager delete
- enable retransmit as opposed to persist timer after persist timer completes
- properly discard buffer chain bytes when new data overlaps ooo
  segments
- don't use rxt bytes in snd space estimate used on tx path

Change-Id: Id9cab686e532e5fe70c775d5440260e8eb890a9f
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 16 insertions, 11 deletions

diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 6f9e4c7a2ce..95f9ade1369 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -1363,7 +1363,7 @@ always_inline int
 tcp_session_enqueue_data (tcp_connection_t * tc, vlib_buffer_t * b,
 			  u16 data_len)
 {
-  int written;
+  int written, error = TCP_ERROR_ENQUEUED;
 
   ASSERT (seq_geq (vnet_buffer (b)->tcp.seq_number, tc->rcv_nxt));
 
@@ -1381,12 +1381,12 @@ tcp_session_enqueue_data (tcp_connection_t * tc, vlib_buffer_t * b,
   /* Update rcv_nxt */
   if (PREDICT_TRUE (written == data_len))
     {
-      tc->rcv_nxt = vnet_buffer (b)->tcp.seq_end;
+      tc->rcv_nxt += written;
     }
   /* If more data written than expected, account for out-of-order bytes. */
   else if (written > data_len)
     {
-      tc->rcv_nxt = vnet_buffer (b)->tcp.seq_end + written - data_len;
+      tc->rcv_nxt += written;
 
       /* Send ACK confirming the update */
       tc->flags |= TCP_CONN_SNDACK;
@@ -1400,7 +1400,7 @@ tcp_session_enqueue_data (tcp_connection_t * tc, vlib_buffer_t * b,
        * not be enqueued. Inform peer */
       tc->flags |= TCP_CONN_SNDACK;
 
-      return TCP_ERROR_PARTIALLY_ENQUEUED;
+      error = TCP_ERROR_PARTIALLY_ENQUEUED;
     }
   else
     {
@@ -1415,7 +1415,7 @@ tcp_session_enqueue_data (tcp_connection_t * tc, vlib_buffer_t * b,
       tcp_update_sack_list (tc, tc->rcv_nxt, tc->rcv_nxt);
     }
 
-  return TCP_ERROR_ENQUEUED;
+  return error;
 }
 
 /** Enqueue out-of-order data */
@@ -1495,10 +1495,10 @@ tcp_can_delack (tcp_connection_t * tc)
 static int
 tcp_buffer_discard_bytes (vlib_buffer_t * b, u32 n_bytes_to_drop)
 {
-  u32 discard;
+  u32 discard, first = b->current_length;
   vlib_main_t *vm = vlib_get_main ();
 
-  /* Handle multi segment packets */
+  /* Handle multi-buffer segments */
   if (n_bytes_to_drop > b->current_length)
     {
       if (!(b->flags & VLIB_BUFFER_NEXT_PRESENT))
@@ -1511,7 +1511,12 @@ tcp_buffer_discard_bytes (vlib_buffer_t * b, u32 n_bytes_to_drop)
 	  n_bytes_to_drop -= discard;
 	}
       while (n_bytes_to_drop);
+      if (n_bytes_to_drop > first)
+	b->total_length_not_including_first_buffer -= n_bytes_to_drop - first;
     }
+  else
+    vlib_buffer_advance (b, n_bytes_to_drop);
+  vnet_buffer (b)->tcp.data_len -= n_bytes_to_drop;
   return 0;
 }
 
@@ -1908,7 +1913,7 @@ tcp46_syn_sent_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	      if (ack0 <= tc0->iss || ack0 > tc0->snd_nxt)
 		{
 		  if (!tcp_rst (tcp0))
-		    tcp_send_reset (tc0, b0, is_ip4);
+		    tcp_send_reset_w_pkt (tc0, b0, is_ip4);
 		  goto drop;
 		}
 
@@ -1995,7 +2000,7 @@ tcp46_syn_sent_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	       * allocate session send reset */
 	      if (stream_session_connect_notify (&new_tc0->connection, 0))
 		{
-		  tcp_send_reset (new_tc0, b0, is_ip4);
+		  tcp_send_reset_w_pkt (new_tc0, b0, is_ip4);
 		  tcp_connection_cleanup (new_tc0);
 		  goto drop;
 		}
@@ -2017,7 +2022,7 @@ tcp46_syn_sent_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	      if (stream_session_connect_notify (&new_tc0->connection, 0))
 		{
 		  tcp_connection_cleanup (new_tc0);
-		  tcp_send_reset (tc0, b0, is_ip4);
+		  tcp_send_reset_w_pkt (tc0, b0, is_ip4);
 		  TCP_EVT_DBG (TCP_EVT_RST_SENT, tc0);
 		  goto drop;
 		}
@@ -2221,7 +2226,7 @@ tcp46_rcv_process_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	       */
 	      if (!tcp_rcv_ack_is_acceptable (tc0, b0))
 		{
-		  tcp_send_reset (tc0, b0, is_ip4);
+		  tcp_send_reset_w_pkt (tc0, b0, is_ip4);
 		  goto drop;
 		}