[PATCH v3 6/8] qemu:virtio-net: Enable filtering based on MAC, promisc, broadcast and allmulti

[Alex Williamson <alex.williamson@hp.com>]

Make use of the new RX_MODE control virtqueue class by dropping
packets the guest doesn't want to see.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
---

 hw/virtio-net.c |   28 ++++++++++++++++++++++++++++
 1 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 7e130f7..001169d 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -222,6 +222,31 @@ static int receive_header(VirtIONet *n, struct iovec *iov, int iovcnt,
     return offset;
 }
 
+static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
+{
+    static const uint8_t bcast[] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
+    uint8_t *ptr = (uint8_t *)buf;
+
+    if (n->promisc)
+        return 1;
+
+#ifdef TAP_VNET_HDR
+    if (tap_has_vnet_hdr(n->vc->vlan->first_client))
+        ptr += sizeof(struct virtio_net_hdr);
+#endif
+
+    if ((ptr[0] & 1) && n->allmulti)
+        return 1;
+
+    if (!memcmp(ptr, bcast, sizeof(bcast)))
+        return 1;
+
+    if (!memcmp(ptr, n->mac, ETH_ALEN))
+        return 1;
+
+    return 0;
+}
+
 static void virtio_net_receive(void *opaque, const uint8_t *buf, int size)
 {
     VirtIONet *n = opaque;
@@ -231,6 +256,9 @@ static void virtio_net_receive(void *opaque, const uint8_t *buf, int size)
     if (!do_virtio_net_can_receive(n, size))
         return;
 
+    if (!receive_filter(n, buf, size))
+        return;
+
     /* hdr_len refers to the header we supply to the guest */
     hdr_len = n->mergeable_rx_bufs ?
         sizeof(struct virtio_net_hdr_mrg_rxbuf) : sizeof(struct virtio_net_hdr);