cli: fix data output miss-ordering

In tcp and telnet backends, the first buffer been queued is directly
pointed to by cln->xmit_buf. It's not added to cln->xmit_queue.
Therefore testing if ->xmit_queue is empty doesn't reliably tells
if data has already been queued.

We should test if ->xmit_buf is non-NULL instead. This is reliable
because ->xmit_buf is re-filled with the first buffer from ->xmit_queue
after every successful write().

Failure to properly check if data has already been queued can lead to
message miss-ordering because cli_client_send() or telnet_send() will
try to directly write() their input buffer, effectively bypassing the
one previously queued up in ->xmit_buf.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>

1 files changed, 1 insertions, 1 deletions

diff --git a/accel-pppd/cli/telnet.c b/accel-pppd/cli/telnet.c
index b8ca8231..6c41769e 100644
--- a/accel-pppd/cli/telnet.c
+++ b/accel-pppd/cli/telnet.c
@@ -143,7 +143,7 @@ static int telnet_send(struct telnet_client_t *cln, const void *_buf, int size)
 	if (cln->disconnect)
 		return -1;
 
-	if (!list_empty(&cln->xmit_queue)) {
+	if (cln->xmit_buf) {
 		b = _malloc(sizeof(*b) + size);
 		b->size = size;
 		memcpy(b->buf, buf, size);