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authorFlorin Coras <fcoras@cisco.com>2017-04-26 00:08:42 -0700
committerFlorin Coras <fcoras@cisco.com>2017-05-01 10:41:44 -0700
commitc28764fd356632763614ea579f678d8f55eca4c7 (patch)
tree2c46999bc9474a5604f057812e6c25a821621b2c /src/vnet/tcp/tcp_input.c
parent63c7e14f2e62caa1246349cfe341a93176ec4a43 (diff)
TCP ooo reception fixes
- Improve svm fifo handling of out-of-order segments - Ensure tsval_recent is updated only if rcv_las falls withing the segments's sequence space - Avoid directly dropping old ACKs - Improve debugging Change-Id: I88dbe2394a0ad7eb389a4cc12d013a13733953aa 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.c81
1 files changed, 55 insertions, 26 deletions
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 3c65a5ea73d..0030cfe24ab 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -208,6 +208,15 @@ tcp_options_parse (tcp_header_t * th, tcp_options_t * to)
}
}
+/**
+ * RFC1323: Check against wrapped sequence numbers (PAWS). If we have
+ * timestamp to echo and it's less than tsval_recent, drop segment
+ * but still send an ACK in order to retain TCP's mechanism for detecting
+ * and recovering from half-open connections
+ *
+ * Or at least that's what the theory says. It seems that this might not work
+ * very well with packet reordering and fast retransmit. XXX
+ */
always_inline int
tcp_segment_check_paws (tcp_connection_t * tc)
{
@@ -216,6 +225,27 @@ tcp_segment_check_paws (tcp_connection_t * tc)
}
/**
+ * Update tsval recent
+ */
+always_inline void
+tcp_update_timestamp (tcp_connection_t * tc, u32 seq, u32 seq_end)
+{
+ /*
+ * RFC1323: If Last.ACK.sent falls within the range of sequence numbers
+ * of an incoming segment:
+ * SEG.SEQ <= Last.ACK.sent < SEG.SEQ + SEG.LEN
+ * then the TSval from the segment is copied to TS.Recent;
+ * otherwise, the TSval is ignored.
+ */
+ if (tcp_opts_tstamp (&tc->opt) && tc->tsval_recent
+ && seq_leq (seq, tc->rcv_las) && seq_leq (tc->rcv_las, seq_end))
+ {
+ tc->tsval_recent = tc->opt.tsval;
+ tc->tsval_recent_age = tcp_time_now ();
+ }
+}
+
+/**
* Validate incoming segment as per RFC793 p. 69 and RFC1323 p. 19
*
* It first verifies if segment has a wrapped sequence number (PAWS) and then
@@ -228,21 +258,16 @@ static int
tcp_segment_validate (vlib_main_t * vm, tcp_connection_t * tc0,
vlib_buffer_t * b0, tcp_header_t * th0, u32 * next0)
{
- u8 paws_failed;
-
if (PREDICT_FALSE (!tcp_ack (th0) && !tcp_rst (th0) && !tcp_syn (th0)))
return -1;
tcp_options_parse (th0, &tc0->opt);
- /* RFC1323: Check against wrapped sequence numbers (PAWS). If we have
- * timestamp to echo and it's less than tsval_recent, drop segment
- * but still send an ACK in order to retain TCP's mechanism for detecting
- * and recovering from half-open connections */
- paws_failed = tcp_segment_check_paws (tc0);
- if (paws_failed)
+ if (tcp_segment_check_paws (tc0))
{
clib_warning ("paws failed");
+ TCP_EVT_DBG (TCP_EVT_PAWS_FAIL, tc0, vnet_buffer (b0)->tcp.seq_number,
+ vnet_buffer (b0)->tcp.seq_end);
/* If it just so happens that a segment updates tsval_recent for a
* segment over 24 days old, invalidate tsval_recent. */
@@ -251,6 +276,7 @@ tcp_segment_validate (vlib_main_t * vm, tcp_connection_t * tc0,
{
/* Age isn't reset until we get a valid tsval (bsd inspired) */
tc0->tsval_recent = 0;
+ clib_warning ("paws failed - really old segment. REALLY?");
}
else
{
@@ -305,12 +331,9 @@ tcp_segment_validate (vlib_main_t * vm, tcp_connection_t * tc0,
return -1;
}
- /* If PAWS passed and segment in window, save timestamp */
- if (!paws_failed)
- {
- tc0->tsval_recent = tc0->opt.tsval;
- tc0->tsval_recent_age = tcp_time_now ();
- }
+ /* If segment in window, save timestamp */
+ tcp_update_timestamp (tc0, vnet_buffer (b0)->tcp.seq_number,
+ vnet_buffer (b0)->tcp.seq_end);
return 0;
}
@@ -835,7 +858,8 @@ tcp_rcv_ack (tcp_connection_t * tc, vlib_buffer_t * b,
TCP_EVT_DBG (TCP_EVT_DUPACK_RCVD, tc);
tcp_cc_rcv_dupack (tc, vnet_buffer (b)->tcp.ack_number);
}
- return -1;
+ /* Don't drop yet */
+ return 0;
}
if (tcp_opts_sack_permitted (&tc->opt))
@@ -932,10 +956,6 @@ tcp_update_sack_list (tcp_connection_t * tc, u32 start, u32 end)
{
vec_add1 (new_list, tc->snd_sacks[i]);
}
- else
- {
- clib_warning ("dropped sack blocks");
- }
}
ASSERT (vec_len (new_list) <= TCP_MAX_SACK_BLOCKS);
@@ -1011,7 +1031,6 @@ tcp_session_enqueue_ooo (tcp_connection_t * tc, vlib_buffer_t * b,
u16 data_len)
{
stream_session_t *s0;
- u32 offset;
int rv;
/* Pure ACK. Do nothing */
@@ -1021,12 +1040,11 @@ tcp_session_enqueue_ooo (tcp_connection_t * tc, vlib_buffer_t * b,
}
s0 = stream_session_get (tc->c_s_index, tc->c_thread_index);
- offset = vnet_buffer (b)->tcp.seq_number - tc->irs;
- clib_warning ("ooo: offset %d len %d", offset, data_len);
-
- rv = svm_fifo_enqueue_with_offset (s0->server_rx_fifo, offset, data_len,
- vlib_buffer_get_current (b));
+ /* 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));
/* Nothing written */
if (rv)
@@ -1542,6 +1560,9 @@ tcp46_syn_sent_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
/* Notify app that we have connection */
stream_session_connect_notify (&new_tc0->connection, sst, 0);
+ stream_session_init_fifos_pointers (&new_tc0->connection,
+ new_tc0->irs + 1,
+ new_tc0->iss + 1);
/* Make sure after data segment processing ACK is sent */
new_tc0->flags |= TCP_CONN_SNDACK;
}
@@ -1552,7 +1573,9 @@ tcp46_syn_sent_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
/* Notify app that we have connection */
stream_session_connect_notify (&new_tc0->connection, sst, 0);
-
+ stream_session_init_fifos_pointers (&new_tc0->connection,
+ new_tc0->irs + 1,
+ new_tc0->iss + 1);
tcp_make_synack (new_tc0, b0);
next0 = tcp_next_output (is_ip4);
@@ -2139,6 +2162,10 @@ tcp46_listen_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
tcp_make_synack (child0, b0);
next0 = tcp_next_output (is_ip4);
+ /* Init fifo pointers after we have iss */
+ stream_session_init_fifos_pointers (&child0->connection,
+ child0->irs + 1,
+ child0->iss + 1);
drop:
if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
{
@@ -2474,6 +2501,7 @@ do { \
_(LISTEN, TCP_FLAG_SYN, TCP_INPUT_NEXT_LISTEN, TCP_ERROR_NONE);
/* ACK for for a SYN-ACK -> tcp-rcv-process. */
_(SYN_RCVD, TCP_FLAG_ACK, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
+ _(SYN_RCVD, TCP_FLAG_RST, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
/* SYN-ACK for a SYN */
_(SYN_SENT, TCP_FLAG_SYN | TCP_FLAG_ACK, TCP_INPUT_NEXT_SYN_SENT,
TCP_ERROR_NONE);
@@ -2499,6 +2527,7 @@ do { \
_(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);
+ _(CLOSED, TCP_FLAG_ACK, TCP_INPUT_NEXT_DROP, TCP_ERROR_CONNECTION_CLOSED);
#undef _
}