#ifndef _LINUX_VIRTIO_NET_H
  #define _LINUX_VIRTIO_NET_H

  /* This header is BSD licensed so anyone can use the definitions to implement

   * compatible drivers/servers.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of IBM nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE. */

  #include <linux/types.h>

  #include <linux/virtio_ids.h>

  #include <linux/virtio_config.h>

  #include <linux/if_ether.h>

  /* The feature bitmap for virtio net */

  #define VIRTIO_NET_F_CSUM	0	/* Host handles pkts w/ partial csum */
  #define VIRTIO_NET_F_GUEST_CSUM	1	/* Guest handles pkts w/ partial csum */

  #define VIRTIO_NET_F_MAC	5	/* Host has given MAC address. */

  #define VIRTIO_NET_F_GSO	6	/* Host handles pkts w/ any GSO type */
  #define VIRTIO_NET_F_GUEST_TSO4	7	/* Guest can handle TSOv4 in. */
  #define VIRTIO_NET_F_GUEST_TSO6	8	/* Guest can handle TSOv6 in. */
  #define VIRTIO_NET_F_GUEST_ECN	9	/* Guest can handle TSO[6] w/ ECN in. */
  #define VIRTIO_NET_F_GUEST_UFO	10	/* Guest can handle UFO in. */
  #define VIRTIO_NET_F_HOST_TSO4	11	/* Host can handle TSOv4 in. */
  #define VIRTIO_NET_F_HOST_TSO6	12	/* Host can handle TSOv6 in. */
  #define VIRTIO_NET_F_HOST_ECN	13	/* Host can handle TSO[6] w/ ECN in. */
  #define VIRTIO_NET_F_HOST_UFO	14	/* Host can handle UFO in. */

  #define VIRTIO_NET_F_MRG_RXBUF	15	/* Host can merge receive buffers. */

  #define VIRTIO_NET_F_STATUS	16	/* virtio_net_config.status available */

  #define VIRTIO_NET_F_CTRL_VQ	17	/* Control channel available */

  #define VIRTIO_NET_F_CTRL_RX	18	/* Control channel RX mode support */

  #define VIRTIO_NET_F_CTRL_VLAN	19	/* Control channel VLAN filtering */

  #define VIRTIO_NET_F_CTRL_RX_EXTRA 20	/* Extra RX mode control support */

  
  #define VIRTIO_NET_S_LINK_UP	1	/* Link is up */

  struct virtio_net_config {

  	/* The config defining mac address (if VIRTIO_NET_F_MAC) */
  	__u8 mac[6];

  	/* See VIRTIO_NET_F_STATUS and VIRTIO_NET_S_* above */
  	__u16 status;

  } __attribute__((packed));

  
  /* This is the first element of the scatter-gather list.  If you don't
   * specify GSO or CSUM features, you can simply ignore the header. */

  struct virtio_net_hdr {

  #define VIRTIO_NET_HDR_F_NEEDS_CSUM	1	// Use csum_start, csum_offset

  #define VIRTIO_NET_HDR_F_DATA_VALID	2	// Csum is valid

  	__u8 flags;

  #define VIRTIO_NET_HDR_GSO_NONE		0	// Not a GSO frame
  #define VIRTIO_NET_HDR_GSO_TCPV4	1	// GSO frame, IPv4 TCP (TSO)

  #define VIRTIO_NET_HDR_GSO_UDP		3	// GSO frame, IPv4 UDP (UFO)
  #define VIRTIO_NET_HDR_GSO_TCPV6	4	// GSO frame, IPv6 TCP

  #define VIRTIO_NET_HDR_GSO_ECN		0x80	// TCP has ECN set

  	__u8 gso_type;
  	__u16 hdr_len;		/* Ethernet + IP + tcp/udp hdrs */

  	__u16 gso_size;		/* Bytes to append to hdr_len per frame */

  	__u16 csum_start;	/* Position to start checksumming from */
  	__u16 csum_offset;	/* Offset after that to place checksum */

  };

  
  /* This is the version of the header to use when the MRG_RXBUF
   * feature has been negotiated. */
  struct virtio_net_hdr_mrg_rxbuf {
  	struct virtio_net_hdr hdr;
  	__u16 num_buffers;	/* Number of merged rx buffers */
  };

  /*
   * Control virtqueue data structures
   *
   * The control virtqueue expects a header in the first sg entry
   * and an ack/status response in the last entry.  Data for the
   * command goes in between.
   */
  struct virtio_net_ctrl_hdr {
  	__u8 class;
  	__u8 cmd;
  } __attribute__((packed));
  
  typedef __u8 virtio_net_ctrl_ack;
  
  #define VIRTIO_NET_OK     0
  #define VIRTIO_NET_ERR    1

  /*

   * Control the RX mode, ie. promisucous, allmulti, etc...
   * All commands require an "out" sg entry containing a 1 byte
   * state value, zero = disable, non-zero = enable.  Commands
   * 0 and 1 are supported with the VIRTIO_NET_F_CTRL_RX feature.
   * Commands 2-5 are added with VIRTIO_NET_F_CTRL_RX_EXTRA.

   */
  #define VIRTIO_NET_CTRL_RX    0
   #define VIRTIO_NET_CTRL_RX_PROMISC      0
   #define VIRTIO_NET_CTRL_RX_ALLMULTI     1

   #define VIRTIO_NET_CTRL_RX_ALLUNI       2
   #define VIRTIO_NET_CTRL_RX_NOMULTI      3
   #define VIRTIO_NET_CTRL_RX_NOUNI        4
   #define VIRTIO_NET_CTRL_RX_NOBCAST      5

  /*
   * Control the MAC filter table.
   *
   * The MAC filter table is managed by the hypervisor, the guest should
   * assume the size is infinite.  Filtering should be considered
   * non-perfect, ie. based on hypervisor resources, the guest may
   * received packets from sources not specified in the filter list.
   *
   * In addition to the class/cmd header, the TABLE_SET command requires
   * two out scatterlists.  Each contains a 4 byte count of entries followed
   * by a concatenated byte stream of the ETH_ALEN MAC addresses.  The
   * first sg list contains unicast addresses, the second is for multicast.
   * This functionality is present if the VIRTIO_NET_F_CTRL_RX feature
   * is available.
   */
  struct virtio_net_ctrl_mac {
  	__u32 entries;
  	__u8 macs[][ETH_ALEN];
  } __attribute__((packed));
  
  #define VIRTIO_NET_CTRL_MAC    1
   #define VIRTIO_NET_CTRL_MAC_TABLE_SET        0

  /*
   * Control VLAN filtering
   *
   * The VLAN filter table is controlled via a simple ADD/DEL interface.
   * VLAN IDs not added may be filterd by the hypervisor.  Del is the
   * opposite of add.  Both commands expect an out entry containing a 2
   * byte VLAN ID.  VLAN filterting is available with the
   * VIRTIO_NET_F_CTRL_VLAN feature bit.
   */
  #define VIRTIO_NET_CTRL_VLAN       2
   #define VIRTIO_NET_CTRL_VLAN_ADD             0
   #define VIRTIO_NET_CTRL_VLAN_DEL             1

  #endif /* _LINUX_VIRTIO_NET_H */