alistair23-linux/net/802/hippi.c

// 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);