// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              FDDI-type device handling.
 *
 * Version:     @(#)fddi.c      1.0.0   08/12/96
 *
 * Authors:     Lawrence V. Stefani, <stefani@lkg.dec.com>
 *
 *              fddi.c is based on previous eth.c and tr.c work by
 *                      Ross Biro
 *                      Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *                      Mark Evans, <evansmp@uhura.aston.ac.uk>
 *                      Florian La Roche, <rzsfl@rz.uni-sb.de>
 *                      Alan Cox, <gw4pts@gw4pts.ampr.org>
 *
 *      Changes
 *              Alan Cox                :       New arp/rebuild header
 *              Maciej W. Rozycki       :       IPv6 support
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/fddidevice.h>
#include <linux/if_ether.h>
#include <linux/skbuff.h>
#include <linux/errno.h>
#include <net/arp.h>
#include <net/sock.h>

/*
 * Create the FDDI MAC header for an arbitrary protocol layer
 *
 * saddr=NULL   means use device source address
 * daddr=NULL   means leave destination address (eg unresolved arp)
 */

static int fddi_header(struct sk_buff *skb, struct net_device *dev,
                       unsigned short type,
                       const void *daddr, const void *saddr, unsigned int len)
{
        int hl = FDDI_K_SNAP_HLEN;
        struct fddihdr *fddi;

        if(type != ETH_P_IP && type != ETH_P_IPV6 && type != ETH_P_ARP)
                hl=FDDI_K_8022_HLEN-3;
        fddi = skb_push(skb, hl);
        fddi->fc                         = FDDI_FC_K_ASYNC_LLC_DEF;
        if(type == ETH_P_IP || type == ETH_P_IPV6 || type == ETH_P_ARP)
        {
                fddi->hdr.llc_snap.dsap          = FDDI_EXTENDED_SAP;
                fddi->hdr.llc_snap.ssap          = FDDI_EXTENDED_SAP;
                fddi->hdr.llc_snap.ctrl          = FDDI_UI_CMD;
                fddi->hdr.llc_snap.oui[0]        = 0x00;
                fddi->hdr.llc_snap.oui[1]        = 0x00;
                fddi->hdr.llc_snap.oui[2]        = 0x00;
                fddi->hdr.llc_snap.ethertype     = htons(type);
        }

        /* Set the source and destination hardware addresses */

        if (saddr != NULL)
                memcpy(fddi->saddr, saddr, dev->addr_len);
        else
                memcpy(fddi->saddr, dev->dev_addr, dev->addr_len);

        if (daddr != NULL)
        {
                memcpy(fddi->daddr, daddr, dev->addr_len);
                return hl;
        }

        return -hl;
}

/*
 * Determine the packet's protocol ID and fill in skb fields.
 * This routine is called before an incoming packet is passed
 * up.  It's used to fill in specific skb fields and to set
 * the proper pointer to the start of packet data (skb->data).
 */

__be16 fddi_type_trans(struct sk_buff *skb, struct net_device *dev)
{
        struct fddihdr *fddi = (struct fddihdr *)skb->data;
        __be16 type;

        /*
         * Set mac.raw field to point to FC byte, set data field to point
         * to start of packet data.  Assume 802.2 SNAP frames for now.
         */

        skb->dev = dev;
        skb_reset_mac_header(skb);      /* point to frame control (FC) */

        if(fddi->hdr.llc_8022_1.dsap==0xe0)
        {
                skb_pull(skb, FDDI_K_8022_HLEN-3);
                type = htons(ETH_P_802_2);
        }
        else
        {
                skb_pull(skb, FDDI_K_SNAP_HLEN);                /* adjust for 21 byte header */
                type=fddi->hdr.llc_snap.ethertype;
        }

        /* Set packet type based on destination address and flag settings */

        if (*fddi->daddr & 0x01)
        {
                if (memcmp(fddi->daddr, dev->broadcast, FDDI_K_ALEN) == 0)
                        skb->pkt_type = PACKET_BROADCAST;
                else
                        skb->pkt_type = PACKET_MULTICAST;
        }

        else if (dev->flags & IFF_PROMISC)
        {
                if (memcmp(fddi->daddr, dev->dev_addr, FDDI_K_ALEN))
                        skb->pkt_type = PACKET_OTHERHOST;
        }

        /* Assume 802.2 SNAP frames, for now */

        return type;
}

EXPORT_SYMBOL(fddi_type_trans);

static const struct header_ops fddi_header_ops = {
        .create         = fddi_header,
};


static void fddi_setup(struct net_device *dev)
{
        dev->header_ops         = &fddi_header_ops;
        dev->type               = ARPHRD_FDDI;
        dev->hard_header_len    = FDDI_K_SNAP_HLEN+3;   /* Assume 802.2 SNAP hdr len + 3 pad bytes */
        dev->mtu                = FDDI_K_SNAP_DLEN;     /* Assume max payload of 802.2 SNAP frame */
        dev->min_mtu            = FDDI_K_SNAP_HLEN;
        dev->max_mtu            = FDDI_K_SNAP_DLEN;
        dev->addr_len           = FDDI_K_ALEN;
        dev->tx_queue_len       = 100;                  /* Long queues on FDDI */
        dev->flags              = IFF_BROADCAST | IFF_MULTICAST;

        memset(dev->broadcast, 0xFF, FDDI_K_ALEN);
}

/**
 * alloc_fddidev - Register FDDI device
 * @sizeof_priv: Size of additional driver-private structure to be allocated
 *      for this FDDI device
 *
 * Fill in the fields of the device structure with FDDI-generic values.
 *
 * Constructs a new net device, complete with a private data area of
 * size @sizeof_priv.  A 32-byte (not bit) alignment is enforced for
 * this private data area.
 */
struct net_device *alloc_fddidev(int sizeof_priv)
{
        return alloc_netdev(sizeof_priv, "fddi%d", NET_NAME_UNKNOWN,
                            fddi_setup);
}
EXPORT_SYMBOL(alloc_fddidev);

MODULE_LICENSE("GPL");