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authorFlorin Coras <fcoras@cisco.com>2018-05-23 21:01:30 -0700
committerDamjan Marion <dmarion.lists@gmail.com>2018-05-26 18:56:43 +0000
commitca1c8f3e782dc68a51aa2792771d9b4aac696ddd (patch)
tree890c7250af97dd65357363242e2c7272a199feca /src/vnet/tcp/tcp_input.c
parenta34c08c8c5a505e55178a9a8ef5391224d5460a5 (diff)
tcp: loss recovery improvements/fixes
- fix newreno cwnd computation - reset snd_una_max on entering recovery - accept acks beyond snd_nxt but less than snd_congestion when in recovery - avoid entering fast recovery multiple times when using sacks - avoid as much as possible sending small segments when doing fast retransmit - more event logging Change-Id: I19dd151d7704e39d4eae06de3a26f5e124875366 Signed-off-by: Florin Coras <fcoras@cisco.com>
Diffstat (limited to 'src/vnet/tcp/tcp_input.c')
-rw-r--r--src/vnet/tcp/tcp_input.c69
1 files changed, 47 insertions, 22 deletions
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index c86432037fd..19ecc7deef8 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -275,6 +275,14 @@ tcp_segment_validate (vlib_main_t * vm, tcp_connection_t * tc0,
vlib_buffer_t * b0, tcp_header_t * th0,
u32 * next0, u32 * error0)
{
+ /* We could get a burst of RSTs interleaved with acks */
+ if (PREDICT_FALSE (tc0->state == TCP_STATE_CLOSED))
+ {
+ tcp_send_reset (tc0);
+ *error0 = TCP_ERROR_CONNECTION_CLOSED;
+ goto drop;
+ }
+
if (PREDICT_FALSE (!tcp_ack (th0) && !tcp_rst (th0) && !tcp_syn (th0)))
{
*error0 = TCP_ERROR_SEGMENT_INVALID;
@@ -292,13 +300,7 @@ tcp_segment_validate (vlib_main_t * vm, tcp_connection_t * tc0,
{
*error0 = TCP_ERROR_PAWS;
if (CLIB_DEBUG > 2)
- {
- clib_warning ("paws failed\n%U", format_tcp_connection, tc0, 2);
- clib_warning ("seq %u seq_end %u ack %u",
- vnet_buffer (b0)->tcp.seq_number - tc0->irs,
- vnet_buffer (b0)->tcp.seq_end - tc0->irs,
- vnet_buffer (b0)->tcp.ack_number - tc0->iss);
- }
+ clib_warning ("paws failed\n%U", format_tcp_connection, tc0, 2);
TCP_EVT_DBG (TCP_EVT_PAWS_FAIL, tc0, vnet_buffer (b0)->tcp.seq_number,
vnet_buffer (b0)->tcp.seq_end);
@@ -317,7 +319,7 @@ tcp_segment_validate (vlib_main_t * vm, tcp_connection_t * tc0,
if (!tcp_rst (th0))
{
tcp_make_ack (tc0, b0);
- TCP_EVT_DBG (TCP_EVT_DUPACK_SENT, tc0);
+ TCP_EVT_DBG (TCP_EVT_DUPACK_SENT, tc0, vnet_buffer (b0)->tcp);
goto error;
}
}
@@ -329,7 +331,6 @@ tcp_segment_validate (vlib_main_t * vm, tcp_connection_t * tc0,
vnet_buffer (b0)->tcp.seq_end))
{
*error0 = TCP_ERROR_RCV_WND;
-
/* If our window is 0 and the packet is in sequence, let it pass
* through for ack processing. It should be dropped later. */
if (!(tc0->rcv_wnd == 0
@@ -339,7 +340,7 @@ tcp_segment_validate (vlib_main_t * vm, tcp_connection_t * tc0,
if (!tcp_rst (th0))
{
tcp_make_ack (tc0, b0);
- TCP_EVT_DBG (TCP_EVT_DUPACK_SENT, tc0);
+ TCP_EVT_DBG (TCP_EVT_DUPACK_SENT, tc0, vnet_buffer (b0)->tcp);
goto error;
}
goto drop;
@@ -889,13 +890,14 @@ tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
scoreboard_update_bytes (tc, sb);
sb->last_sacked_bytes = sb->sacked_bytes
- (old_sacked_bytes - sb->last_bytes_delivered);
- ASSERT (sb->last_sacked_bytes <= sb->sacked_bytes);
+ ASSERT (sb->last_sacked_bytes <= sb->sacked_bytes || tcp_in_recovery (tc));
ASSERT (sb->sacked_bytes == 0
|| sb->sacked_bytes < tc->snd_una_max - seq_max (tc->snd_una, ack));
ASSERT (sb->last_sacked_bytes + sb->lost_bytes <= tc->snd_una_max
- seq_max (tc->snd_una, ack));
ASSERT (sb->head == TCP_INVALID_SACK_HOLE_INDEX || tcp_in_recovery (tc)
|| sb->holes[sb->head].start == ack + sb->snd_una_adv);
+ TCP_EVT_DBG (TCP_EVT_CC_SCOREBOARD, tc);
}
/**
@@ -1063,11 +1065,18 @@ tcp_cc_handle_event (tcp_connection_t * tc, u32 is_dack)
{
u32 rxt_delivered;
+ if (tcp_in_fastrecovery (tc) && tcp_opts_sack_permitted (&tc->rcv_opts))
+ {
+ if (tc->bytes_acked)
+ goto partial_ack;
+ tcp_fast_retransmit (tc);
+ return;
+ }
/*
* Duplicate ACK. Check if we should enter fast recovery, or if already in
* it account for the bytes that left the network.
*/
- if (is_dack && !tcp_in_recovery (tc))
+ else if (is_dack && !tcp_in_recovery (tc))
{
TCP_EVT_DBG (TCP_EVT_DUPACK_RCVD, tc, 1);
ASSERT (tc->snd_una != tc->snd_una_max
@@ -1128,7 +1137,6 @@ tcp_cc_handle_event (tcp_connection_t * tc, u32 is_dack)
{
tcp_fast_retransmit_no_sack (tc);
}
-
return;
}
else if (!tc->bytes_acked
@@ -1237,6 +1245,16 @@ tcp_rcv_ack (tcp_connection_t * tc, vlib_buffer_t * b,
/* If the ACK acks something not yet sent (SEG.ACK > SND.NXT) */
if (PREDICT_FALSE (seq_gt (vnet_buffer (b)->tcp.ack_number, tc->snd_nxt)))
{
+ /* When we entered recovery, we reset snd_nxt to snd_una. Seems peer
+ * still has the data so accept the ack */
+ if (tcp_in_recovery (tc)
+ && seq_leq (vnet_buffer (b)->tcp.ack_number, tc->snd_congestion)
+ && seq_geq (vnet_buffer (b)->tcp.ack_number, tc->snd_una))
+ {
+ tc->snd_una_max = tc->snd_nxt = vnet_buffer (b)->tcp.ack_number;
+ goto process_ack;
+ }
+
/* If we have outstanding data and this is within the window, accept it,
* probably retransmit has timed out. Otherwise ACK segment and then
* drop it */
@@ -1264,9 +1282,7 @@ tcp_rcv_ack (tcp_connection_t * tc, vlib_buffer_t * b,
TCP_EVT_DBG (TCP_EVT_ACK_RCV_ERR, tc, 1,
vnet_buffer (b)->tcp.ack_number);
if (tcp_in_fastrecovery (tc) && tc->rcv_dupacks == TCP_DUPACK_THRESHOLD)
- {
- tcp_cc_handle_event (tc, 1);
- }
+ tcp_cc_handle_event (tc, 1);
/* Don't drop yet */
return 0;
}
@@ -1274,7 +1290,7 @@ tcp_rcv_ack (tcp_connection_t * tc, vlib_buffer_t * b,
/*
* Looks okay, process feedback
*/
-
+process_ack:
if (tcp_opts_sack_permitted (&tc->rcv_opts))
tcp_rcv_sacks (tc, vnet_buffer (b)->tcp.ack_number);
@@ -1390,6 +1406,15 @@ tcp_update_sack_list (tcp_connection_t * tc, u32 start, u32 end)
ASSERT (tcp_sack_vector_is_sane (tc->snd_sacks));
}
+u32
+tcp_sack_list_bytes (tcp_connection_t * tc)
+{
+ u32 bytes = 0, i;
+ for (i = 0; i < vec_len (tc->snd_sacks); i++)
+ bytes += tc->snd_sacks[i].end - tc->snd_sacks[i].start;
+ return bytes;
+}
+
/** Enqueue data for delivery to application */
always_inline int
tcp_session_enqueue_data (tcp_connection_t * tc, vlib_buffer_t * b,
@@ -1416,6 +1441,7 @@ tcp_session_enqueue_data (tcp_connection_t * tc, vlib_buffer_t * b,
/* Send ACK confirming the update */
tc->flags |= TCP_CONN_SNDACK;
+ TCP_EVT_DBG (TCP_EVT_CC_INPUT, tc, data_len, written);
}
else if (written > 0)
{
@@ -1488,6 +1514,7 @@ tcp_session_enqueue_ooo (tcp_connection_t * tc, vlib_buffer_t * b,
end = start + ooo_segment_length (s0->server_rx_fifo, newest);
tcp_update_sack_list (tc, start, end);
svm_fifo_newest_ooo_segment_reset (s0->server_rx_fifo);
+ TCP_EVT_DBG (TCP_EVT_CC_SACKS, tc);
}
}
@@ -1508,7 +1535,7 @@ tcp_can_delack (tcp_connection_t * tc)
/* constrained to send ack */
|| (tc->flags & TCP_CONN_SNDACK) != 0
/* we're almost out of tx wnd */
- || tcp_available_snd_space (tc) < 4 * tc->snd_mss)
+ || tcp_available_cc_snd_space (tc) < 4 * tc->snd_mss)
return 0;
return 1;
@@ -1592,7 +1619,7 @@ tcp_segment_rcv (tcp_connection_t * tc, vlib_buffer_t * b, u32 * next0)
*next0 = tcp_next_output (tc->c_is_ip4);
tcp_make_ack (tc, b);
vnet_buffer (b)->tcp.flags = TCP_BUF_FLAG_DUPACK;
- TCP_EVT_DBG (TCP_EVT_DUPACK_SENT, tc);
+ TCP_EVT_DBG (TCP_EVT_DUPACK_SENT, tc, vnet_buffer (b)->tcp);
goto done;
}
@@ -1773,9 +1800,7 @@ tcp46_established_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
&error0)))
{
tcp_maybe_inc_err_counter (err_counters, error0);
- TCP_EVT_DBG (TCP_EVT_SEG_INVALID, tc0,
- vnet_buffer (b0)->tcp.seq_number,
- vnet_buffer (b0)->tcp.seq_end);
+ TCP_EVT_DBG (TCP_EVT_SEG_INVALID, tc0, vnet_buffer (b0)->tcp);
goto done;
}