Use an exponential backoff timeout with the initial timeout 1s
and total timeout 60s.
Signed-off-by: Yumei Huang
---
tcp.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)
diff --git a/tcp.c b/tcp.c
index 85bbdac..0db7f30 100644
--- a/tcp.c
+++ b/tcp.c
@@ -185,10 +185,15 @@
* for more than TCP_MAX_RETRIES or (tcp_syn_retries +
* tcp_syn_linear_timeouts) times in a row, reset the connection
*
- * - ACK_TIMEOUT: if no ACK segment was received from tap/guest, after sending
- * data (flag ACK_FROM_TAP_DUE with ESTABLISHED event), re-send data from the
- * socket and reset sequence to what was acknowledged. If this persists for
- * more than TCP_MAX_RETRIES times in a row, reset the connection
+ * - ACK_TIMEOUT_INIT: if no ACK segment was received from tap/guest, after
+ * sending data (flag ACK_FROM_TAP_DUE with ESTABLISHED event), re-send data
+ * from the socket and reset sequence to what was acknowledged. It's the
+ * starting timeout for the first retransmission. If this persists for more
+ * than TCP_MAX_RETRIES times in a row, reset the connection
+ *
+ * - ACK_TIMEOUT_TOTAL: if no ACK segment was received from tap/guest after
+ * retransmitting data repeatedly from the socket within this time, reset
+ * the connection
*
* - FIN_TIMEOUT: if a FIN segment was sent to tap/guest (flag ACK_FROM_TAP_DUE
* with TAP_FIN_SENT event), and no ACK is received within this time, reset
@@ -344,7 +349,8 @@ enum {
#define ACK_INTERVAL 10 /* ms */
#define SYN_TIMEOUT_INIT 1 /* s */
-#define ACK_TIMEOUT 2
+#define ACK_TIMEOUT_INIT 1
+#define ACK_TIMEOUT_TOTAL 60
#define FIN_TIMEOUT 60
#define ACT_TIMEOUT 7200
@@ -358,6 +364,9 @@ enum {
((conn)->events & (SOCK_FIN_RCVD | TAP_FIN_RCVD)))
#define CONN_HAS(conn, set) (((conn)->events & (set)) == (set))
+#define RETRY_ELAPSED(timeout_init, retries) \
+ ((timeout_init) * ((1 << ((retries) + 1)) - 2))
+
/* Buffers to migrate pending data from send and receive queues. No, they don't
* use memory if we don't use them. And we're going away after this, so splurge.
*/
@@ -596,7 +605,7 @@ static void tcp_timer_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
(conn->retries - c->tcp.syn_linear_timeouts);
}
else
- it.it_value.tv_sec = ACK_TIMEOUT;
+ it.it_value.tv_sec = ACK_TIMEOUT_INIT << conn->retries;
} else if (CONN_HAS(conn, SOCK_FIN_SENT | TAP_FIN_ACKED)) {
it.it_value.tv_sec = FIN_TIMEOUT;
} else {
@@ -2438,6 +2447,10 @@ void tcp_timer_handler(const struct ctx *c, union epoll_ref ref)
} else if (conn->retries == TCP_MAX_RETRIES) {
flow_dbg(conn, "retransmissions count exceeded");
tcp_rst(c, conn);
+ } else if(RETRY_ELAPSED(ACK_TIMEOUT_INIT, conn->retries) >=
+ ACK_TIMEOUT_TOTAL) {
+ flow_dbg(conn, "retransmissions timeout exceeded");
+ tcp_rst(c, conn);
} else {
flow_dbg(conn, "ACK timeout, retry");
--
2.47.0