From: Guus Sliepen <guus@sliepen.org>
Date: Thu, 10 Oct 2019 20:10:44 +0000 (+0200)
Subject: Correctly handle incoming retransmissions of SYN packets.
X-Git-Url: http://git.meshlink.io/?p=utcp;a=commitdiff_plain;h=25675cca79330f968b3fb106793a5265615f4df7

Correctly handle incoming retransmissions of SYN packets.
---

diff --git a/utcp.c b/utcp.c
index ac162fe..f35f965 100644
--- a/utcp.c
+++ b/utcp.c
@@ -1055,6 +1055,7 @@ ssize_t utcp_recv(struct utcp *utcp, const void *data, size_t len) {
 				c->flags = UTCP_TCP;
 			}
 
+synack:
 			// Return SYN+ACK, go to SYN_RECEIVED state
 			c->snd.wnd = hdr.wnd;
 			c->rcv.irs = hdr.seq;
@@ -1410,6 +1411,9 @@ skip_ack:
 			break;
 
 		case SYN_RECEIVED:
+			// This is a retransmit of a SYN, send back the SYNACK.
+			goto synack;
+
 		case ESTABLISHED:
 		case FIN_WAIT_1:
 		case FIN_WAIT_2: