Gesendet: Montag, 04. Juli 2016 um 09:25 Uhr
Von: "Michael Brown" <address@hidden>
An: address@hidden
Cc: "Michael Brown" <address@hidden>
Betreff: [lwip-devel] [PATCH] tcp: Avoid 3-second delay for a half-open connection
If lwIP encounters a half-open connection (e.g. due to a restarted
application reusing the same port numbers) it will correctly send a
RST but will not resend the SYN until one retransmission timeout later
(approximately three seconds). This can increase the time taken by
lpxelinux.0 to fetch its configuration file from a few milliseconds to
around 30 seconds.
Fix by immediately retransmitting the SYN whenever a half-open
connection is detected.
Signed-off-by: Michael Brown <address@hidden>
---
src/core/tcp_in.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/src/core/tcp_in.c b/src/core/tcp_in.c
index f291887..5e7f2cd 100644
--- a/src/core/tcp_in.c
+++ b/src/core/tcp_in.c
@@ -812,6 +812,9 @@ tcp_process(struct tcp_pcb *pcb)
/* send a RST to bring the other side in a non-synchronized state. */
tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(),
ip_current_src_addr(), tcphdr->dest, tcphdr->src);
+ /* Resend SYN immediately to establish connection */
+ pcb->rtime = 0;
+ tcp_rexmit_rto(pcb);
}
break;
case SYN_RCVD:
--
2.3.8
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