udp_tap_handler() currently skips outbound packets if they have a payload
length of zero. This is not correct, since in a datagram protocol zero
length packets still have meaning.
Adjust this to correctly forward the zero-length packets by using a msghdr
with msg_iovlen == 0.
Bugzilla: https://bugs.passt.top/show_bug.cgi?id=19
Signed-off-by: David Gibson
---
udp.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/udp.c b/udp.c
index 864e7b2..0b4e134 100644
--- a/udp.c
+++ b/udp.c
@@ -1075,17 +1075,20 @@ int udp_tap_handler(struct ctx *c, int af, const void *addr,
uh_send = packet_get(p, i, 0, sizeof(*uh), &len);
if (!uh_send)
return p->count;
- if (!len)
- continue;
-
- m[i].iov_base = (char *)(uh_send + 1);
- m[i].iov_len = len;
mm[i].msg_hdr.msg_name = sa;
mm[i].msg_hdr.msg_namelen = sl;
- mm[i].msg_hdr.msg_iov = m + i;
- mm[i].msg_hdr.msg_iovlen = 1;
+ if (len) {
+ m[i].iov_base = (char *)(uh_send + 1);
+ m[i].iov_len = len;
+
+ mm[i].msg_hdr.msg_iov = m + i;
+ mm[i].msg_hdr.msg_iovlen = 1;
+ } else {
+ mm[i].msg_hdr.msg_iov = NULL;
+ mm[i].msg_hdr.msg_iovlen = 0;
+ }
mm[i].msg_hdr.msg_control = NULL;
mm[i].msg_hdr.msg_controllen = 0;
--
2.37.3