// 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.
 *
 *              HIPPI-type device handling.
 *
 * Version:     @(#)hippi.c     1.0.0   05/29/97
 *
 * Authors:     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>
 *              Jes Sorensen, <Jes.Sorensen@cern.ch>
 */

#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/hippidevice.h>
#include <linux/skbuff.h>
#include <linux/errno.h>
#include <net/arp.h>
#include <net/sock.h>
#include <linux/uaccess.h>

/*
 * Create the HIPPI 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 hippi_header(struct sk_buff *skb, struct net_device *dev,
                        unsigned short type,
                        const void *daddr, const void *saddr, unsigned int len)
{
        struct hippi_hdr *hip = skb_push(skb, HIPPI_HLEN);
        struct hippi_cb *hcb = (struct hippi_cb *) skb->cb;

        if (!len){
                len = skb->len - HIPPI_HLEN;
                printk("hippi_header(): length not supplied\n");
        }

        /*
         * Due to the stupidity of the little endian byte-order we
         * have to set the fp field this way.
         */
        hip->fp.fixed           = htonl(0x04800018);
        hip->fp.d2_size         = htonl(len + 8);
        hip->le.fc              = 0;
        hip->le.double_wide     = 0;    /* only HIPPI 800 for the time being */
        hip->le.message_type    = 0;    /* Data PDU */

        hip->le.dest_addr_type  = 2;    /* 12 bit SC address */
        hip->le.src_addr_type   = 2;    /* 12 bit SC address */

        memcpy(hip->le.src_switch_addr, dev->dev_addr + 3, 3);
        memset(&hip->le.reserved, 0, 16);

        hip->snap.dsap          = HIPPI_EXTENDED_SAP;
        hip->snap.ssap          = HIPPI_EXTENDED_SAP;
        hip->snap.ctrl          = HIPPI_UI_CMD;
        hip->snap.oui[0]        = 0x00;
        hip->snap.oui[1]        = 0x00;
        hip->snap.oui[2]        = 0x00;
        hip->snap.ethertype     = htons(type);

        if (daddr)
        {
                memcpy(hip->le.dest_switch_addr, daddr + 3, 3);
                memcpy(&hcb->ifield, daddr + 2, 4);
                return HIPPI_HLEN;
        }
        hcb->ifield = 0;
        return -((int)HIPPI_HLEN);
}


/*
 *      Determine the packet's protocol ID.
 */

__be16 hippi_type_trans(struct sk_buff *skb, struct net_device *dev)
{
        struct hippi_hdr *hip;

        /*
         * This is actually wrong ... question is if we really should
         * set the raw address here.
         */
        skb->dev = dev;
        skb_reset_mac_header(skb);
        hip = (struct hippi_hdr *)skb_mac_header(skb);
        skb_pull(skb, HIPPI_HLEN);

        /*
         * No fancy promisc stuff here now.
         */

        return hip->snap.ethertype;
}

EXPORT_SYMBOL(hippi_type_trans);

/*
 * For HIPPI we will actually use the lower 4 bytes of the hardware
 * address as the I-FIELD rather than the actual hardware address.
 */
int hippi_mac_addr(struct net_device *dev, void *p)
{
        struct sockaddr *addr = p;
        if (netif_running(dev))
                return -EBUSY;
        memcpy(dev->dev_addr, addr->sa_data, dev->addr_len);
        return 0;
}
EXPORT_SYMBOL(hippi_mac_addr);

int hippi_neigh_setup_dev(struct net_device *dev, struct neigh_parms *p)
{
        /* Never send broadcast/multicast ARP messages */
        NEIGH_VAR_INIT(p, MCAST_PROBES, 0);

        /* In IPv6 unicast probes are valid even on NBMA,
        * because they are encapsulated in normal IPv6 protocol.
        * Should be a generic flag.
        */
        if (p->tbl->family != AF_INET6)
                NEIGH_VAR_INIT(p, UCAST_PROBES, 0);
        return 0;
}
EXPORT_SYMBOL(hippi_neigh_setup_dev);

static const struct header_ops hippi_header_ops = {
        .create         = hippi_header,
};


static void hippi_setup(struct net_device *dev)
{
        dev->header_ops                 = &hippi_header_ops;

        /*
         * We don't support HIPPI `ARP' for the time being, and probably
         * never will unless someone else implements it. However we
         * still need a fake ARPHRD to make ifconfig and friends play ball.
         */
        dev->type               = ARPHRD_HIPPI;
        dev->hard_header_len    = HIPPI_HLEN;
        dev->mtu                = 65280;
        dev->min_mtu            = 68;
        dev->max_mtu            = 65280;
        dev->addr_len           = HIPPI_ALEN;
        dev->tx_queue_len       = 25 /* 5 */;
        memset(dev->broadcast, 0xFF, HIPPI_ALEN);


        /*
         * HIPPI doesn't support broadcast+multicast and we only use
         * static ARP tables. ARP is disabled by hippi_neigh_setup_dev.
         */
        dev->flags = 0;
}

/**
 * alloc_hippi_dev - Register HIPPI device
 * @sizeof_priv: Size of additional driver-private structure to be allocated
 *      for this HIPPI device
 *
 * Fill in the fields of the device structure with HIPPI-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_hippi_dev(int sizeof_priv)
{
        return alloc_netdev(sizeof_priv, "hip%d", NET_NAME_UNKNOWN,
                            hippi_setup);
}

EXPORT_SYMBOL(alloc_hippi_dev);