From: Guus Sliepen <guus@meshlink.io>
Date: Mon, 8 Dec 2014 15:18:30 +0000 (+0100)
Subject: Prevent FIN bit from being sent too early.
X-Git-Url: https://git.meshlink.io/?a=commitdiff_plain;h=387d0814ba7ede1246e00f95912c5256c8d59e08;p=utcp

Prevent FIN bit from being sent too early.

Due to a logic bug in ack(), the FIN bit could be set on a too early packet,
if utcp_shutdown() was called with a full send buffer.
---

diff --git a/utcp.c b/utcp.c
index 186b63e..1d8f4b2 100644
--- a/utcp.c
+++ b/utcp.c
@@ -366,7 +366,7 @@ static void ack(struct utcp_connection *c, bool sendatleastone) {
 		c->snd.nxt += seglen;
 		left -= seglen;
 
-		if(c->state != ESTABLISHED && !left && seglen) {
+		if(c->state != ESTABLISHED && seglen && c->snd.nxt == c->snd.last) {
 			switch(c->state) {
 			case FIN_WAIT_1:
 			case CLOSING:
@@ -954,7 +954,7 @@ reset:
 }
 
 int utcp_shutdown(struct utcp_connection *c, int dir) {
-	debug("%p shutdown %d\n", c ? c->utcp : NULL, dir);
+	debug("%p shutdown %d at %u\n", c ? c->utcp : NULL, dir, c->snd.last);
 	if(!c) {
 		errno = EFAULT;
 		return -1;
@@ -967,6 +967,7 @@ int utcp_shutdown(struct utcp_connection *c, int dir) {
 	}
 
 	// TODO: handle dir
+	// TODO: check that repeated calls with the same parameters should have no effect
 
 	switch(c->state) {
 	case CLOSED: