l4p/tcp: few fixes for sending RST packet logic

- for RST on RTO use SND.NXT instead of SND.UNA
- for RST on invalid SEQSEG.ACK in SYN-SENT state:
  - use SEG.ACK
  - don't terminate the connection

Change-Id: I9943f6fdfb89493af4b0437c5a81af34c450c630
Signed-off-by: Jielong Zhou <jielong.zjl@antfin.com>
Signed-off-by: Jianfeng Tan <henry.tjf@antfin.com>
Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

1 files changed, 10 insertions, 7 deletions

diff --git a/lib/libtle_l4p/tcp_rxtx.c b/lib/libtle_l4p/tcp_rxtx.c
index c0a0dd1..e785b9a 100644
--- a/lib/libtle_l4p/tcp_rxtx.c
+++ b/lib/libtle_l4p/tcp_rxtx.c
@@ -1554,9 +1554,15 @@ rx_synack(struct tle_tcp_stream *s, uint32_t ts, uint32_t state,
 	if (state != TCP_ST_SYN_SENT)
 		return -EINVAL;
 
-	/* invalid SEG.SEQ */
+	/*
+	 * RFC 793 3.9: in the SYN-SENT state
+	 * If SEG.ACK =< ISS, or SEG.ACK > SND.NXT, send a reset
+	 * <SEQ=SEG.ACK><CTL=RST>
+	 * and discard the segment.
+	 * The connection remains in the same state.
+	 */
 	if (si->ack != (uint32_t)s->tcb.snd.nxt) {
-		rsp->flags = TCP_FLAG_RST;
+		send_rst(s, si->ack);
 		return 0;
 	}
 
@@ -1711,10 +1717,7 @@ rx_stream(struct tle_tcp_stream *s, uint32_t ts,
 		i = 0;
 
 	/* we have a response packet to send. */
-	if (rsp.flags == TCP_FLAG_RST) {
-		send_rst(s, si[i].ack);
-		stream_term(s);
-	} else if (rsp.flags != 0) {
+	if (rsp.flags != 0) {
 		send_ack(s, ts, rsp.flags);
 
 		/* start the timer for FIN packet */
@@ -2590,7 +2593,7 @@ rto_stream(struct tle_tcp_stream *s, uint32_t tms)
 		timer_restart(s);
 
 	} else {
-		send_rst(s, s->tcb.snd.una);
+		send_rst(s, s->tcb.snd.nxt);
 		stream_term(s);
 	}
 }