[PATCH] tap: Drop frames if no client connected

[Yumei Huang <yuhuang@redhat.com>]

If no client is attached, discard outgoing frames and report them as
sent. This mimics the behavior of a physical host with its network
cable unplugged.

Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Yumei Huang <yuhuang@redhat.com>
---
 tap.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tap.c b/tap.c
index 7ba6399..e01219d 100644
--- a/tap.c
+++ b/tap.c
@@ -507,13 +507,17 @@ static size_t tap_send_frames_passt(const struct ctx *c,
  * @iov must have total length @bufs_per_frame * @nframes, with each set of
  * @bufs_per_frame contiguous buffers representing a single frame.
  *
- * Return: number of frames actually sent
+ * Return: number of frames actually sent, or accounted as sent
  */
 size_t tap_send_frames(const struct ctx *c, const struct iovec *iov,
 		       size_t bufs_per_frame, size_t nframes)
 {
 	size_t m;
 
+	if (c->fd_tap == -1)
+		/* If no client connected, account the frames have been sent */
+		return nframes;
+
 	if (!nframes)
 		return 0;
 
-- 
@@ -507,13 +507,17 @@ static size_t tap_send_frames_passt(const struct ctx *c,
  * @iov must have total length @bufs_per_frame * @nframes, with each set of
  * @bufs_per_frame contiguous buffers representing a single frame.
  *
- * Return: number of frames actually sent
+ * Return: number of frames actually sent, or accounted as sent
  */
 size_t tap_send_frames(const struct ctx *c, const struct iovec *iov,
 		       size_t bufs_per_frame, size_t nframes)
 {
 	size_t m;
 
+	if (c->fd_tap == -1)
+		/* If no client connected, account the frames have been sent */
+		return nframes;
+
 	if (!nframes)
 		return 0;
 
-- 
2.47.0