1 files changed, 32 insertions, 20 deletions

diff --git a/udp_vu.c b/udp_vu.c
index 099677f..3520f89 100644
--- a/udp_vu.c
+++ b/udp_vu.c
@@ -37,17 +37,16 @@ static struct iovec     iov_vu		[VIRTQUEUE_MAX_SIZE];
 static struct vu_virtq_element	elem		[VIRTQUEUE_MAX_SIZE];
 
 /**
- * udp_vu_hdrlen() - return the size of the header in level 2 frame (UDP)
+ * udp_vu_hdrlen() - Sum size of all headers, from UDP to virtio-net
  * @v6:		Set for IPv6 packet
  *
- * Return: return the size of the header
+ * Return: total size of virtio-net, Ethernet, IP, and UDP headers
  */
 static size_t udp_vu_hdrlen(bool v6)
 {
 	size_t hdrlen;
 
-	hdrlen = sizeof(struct virtio_net_hdr_mrg_rxbuf) +
-		 sizeof(struct ethhdr) + sizeof(struct udphdr);
+	hdrlen = VNET_HLEN + sizeof(struct ethhdr) + sizeof(struct udphdr);
 
 	if (v6)
 		hdrlen += sizeof(struct ipv6hdr);
@@ -65,32 +64,40 @@ static size_t udp_vu_hdrlen(bool v6)
  * @v6:		Set for IPv6 connections
  * @dlen:	Size of received data (output)
  *
- * Return: number of iov entries used to store the datagram
+ * Return: number of iov entries used to store the datagram, 0 if the datagram
+ *         was discarded because the virtqueue is not ready, -1 on error
  */
 static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
 			    bool v6, ssize_t *dlen)
 {
 	const struct vu_dev *vdev = c->vdev;
 	int iov_cnt, idx, iov_used;
+	size_t off, hdrlen, l2len;
 	struct msghdr msg  = { 0 };
-	size_t off, hdrlen;
 
 	ASSERT(!c->no_udp);
 
+	if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) {
+		debug("Got UDP packet, but RX virtqueue not usable yet");
+
+		if (recvmsg(s, &msg, MSG_DONTWAIT) < 0)
+			debug_perror("Failed to discard datagram");
+
+		return 0;
+	}
+
 	/* compute L2 header length */
 	hdrlen = udp_vu_hdrlen(v6);
 
 	vu_init_elem(elem, iov_vu, VIRTQUEUE_MAX_SIZE);
 
 	iov_cnt = vu_collect(vdev, vq, elem, VIRTQUEUE_MAX_SIZE,
-			     IP_MAX_MTU + ETH_HLEN +
-			     sizeof(struct virtio_net_hdr_mrg_rxbuf),
-			     NULL);
+			     IP_MAX_MTU + ETH_HLEN + VNET_HLEN, NULL);
 	if (iov_cnt == 0)
-		return 0;
+		return -1;
 
 	/* reserve space for the headers */
-	ASSERT(iov_vu[0].iov_len >= hdrlen);
+	ASSERT(iov_vu[0].iov_len >= MAX(hdrlen, ETH_ZLEN + VNET_HLEN));
 	iov_vu[0].iov_base = (char *)iov_vu[0].iov_base + hdrlen;
 	iov_vu[0].iov_len -= hdrlen;
 
@@ -101,7 +108,7 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
 	*dlen = recvmsg(s, &msg, 0);
 	if (*dlen < 0) {
 		vu_queue_rewind(vq, iov_cnt);
-		return 0;
+		return -1;
 	}
 
 	/* restore the pointer to the headers address */
@@ -116,7 +123,11 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s,
 		iov_vu[idx].iov_len = off;
 	iov_used = idx + !!off;
 
-	vu_set_vnethdr(vdev, iov_vu[0].iov_base, iov_used);
+	/* pad frame to 60 bytes: first buffer is at least ETH_ZLEN long */
+	l2len = *dlen + hdrlen - VNET_HLEN;
+	vu_pad(&iov_vu[0], l2len);
+
+	vu_set_vnethdr(iov_vu[0].iov_base, iov_used);
 
 	/* release unused buffers */
 	vu_queue_rewind(vq, iov_cnt - iov_used);
@@ -212,15 +223,16 @@ void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx)
 		int iov_used;
 
 		iov_used = udp_vu_sock_recv(c, vq, s, v6, &dlen);
-		if (iov_used <= 0)
+		if (iov_used < 0)
 			break;
 
-		udp_vu_prepare(c, toside, dlen);
-		if (*c->pcap) {
-			udp_vu_csum(toside, iov_used);
-			pcap_iov(iov_vu, iov_used,
-				 sizeof(struct virtio_net_hdr_mrg_rxbuf));
+		if (iov_used > 0) {
+			udp_vu_prepare(c, toside, dlen);
+			if (*c->pcap) {
+				udp_vu_csum(toside, iov_used);
+				pcap_iov(iov_vu, iov_used, VNET_HLEN);
+			}
+			vu_flush(vdev, vq, elem, iov_used);
 		}
-		vu_flush(vdev, vq, elem, iov_used);
 	}
 }