net: move tap_probe_vnet_hdr() to tap-linux.c

Only Linux has support for IFF_VNET_HDR

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/net/tap-linux.c b/net/tap-linux.c
index 6c3b6e311b..0059404069 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -99,3 +99,15 @@ int tap_set_sndbuf(int fd, QemuOpts *opts)
     }
     return 0;
 }
+
+int tap_probe_vnet_hdr(int fd)
+{
+    struct ifreq ifr;
+
+    if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
+        qemu_error("TUNGETIFF ioctl() failed: %s\n", strerror(errno));
+        return 0;
+    }
+
+    return ifr.ifr_flags & IFF_VNET_HDR;
+}