drivers/net/arcnet/rfc1201.c - kernel/bruno - Git at Google

 /*
  * Linux ARCnet driver - RFC1201 (standard) packet encapsulation
  *
  * Written 1994-1999 by Avery Pennarun.
  * Derived from skeleton.c by Donald Becker.
  *
  * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)
  *  for sponsoring the further development of this driver.
  *
  * **********************
  *
  * The original copyright of skeleton.c was as follows:
  *
  * skeleton.c Written 1993 by Donald Becker.
  * Copyright 1993 United States Government as represented by the
  * Director, National Security Agency.  This software may only be used
  * and distributed according to the terms of the GNU General Public License as
  * modified by SRC, incorporated herein by reference.
  *
  * **********************
  *
  * For more details, see drivers/net/arcnet.c
  *
  * **********************
  */

 #define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt

 #include <linux/gfp.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/if_arp.h>
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>

 #include "arcdevice.h"

 MODULE_LICENSE("GPL");

 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);
 static void rx(struct net_device *dev, int bufnum,
 	       struct archdr *pkthdr, int length);
 static int build_header(struct sk_buff *skb, struct net_device *dev,
 			unsigned short type, uint8_t daddr);
 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 		      int bufnum);
 static int continue_tx(struct net_device *dev, int bufnum);

 static struct ArcProto rfc1201_proto = {
 	.suffix		= 'a',
 	.mtu		= 1500,	/* could be more, but some receivers can't handle it... */
 	.is_ip          = 1,    /* This is for sending IP and ARP packages */
 	.rx		= rx,
 	.build_header	= build_header,
 	.prepare_tx	= prepare_tx,
 	.continue_tx	= continue_tx,
 	.ack_tx         = NULL
 };

 static int __init arcnet_rfc1201_init(void)
 {
 	pr_info("%s\n", "RFC1201 \"standard\" (`a') encapsulation support loaded");

 	arc_proto_map[ARC_P_IP]
 	    = arc_proto_map[ARC_P_IPV6]
 	    = arc_proto_map[ARC_P_ARP]
 	    = arc_proto_map[ARC_P_RARP]
 	    = arc_proto_map[ARC_P_IPX]
 	    = arc_proto_map[ARC_P_NOVELL_EC]
 	    = &rfc1201_proto;

 	/* if someone else already owns the broadcast, we won't take it */
 	if (arc_bcast_proto == arc_proto_default)
 		arc_bcast_proto = &rfc1201_proto;

 	return 0;
 }

 static void __exit arcnet_rfc1201_exit(void)
 {
 	arcnet_unregister_proto(&rfc1201_proto);
 }

 module_init(arcnet_rfc1201_init);
 module_exit(arcnet_rfc1201_exit);

 /* Determine a packet's protocol ID.
  *
  * With ARCnet we have to convert everything to Ethernet-style stuff.
  */
 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)
 {
 	struct archdr *pkt = (struct archdr *)skb->data;
 	struct arc_rfc1201 *soft = &pkt->soft.rfc1201;
 	int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;

 	/* Pull off the arcnet header. */
 	skb_reset_mac_header(skb);
 	skb_pull(skb, hdr_size);

 	if (pkt->hard.dest == 0) {
 		skb->pkt_type = PACKET_BROADCAST;
 	} else if (dev->flags & IFF_PROMISC) {
 		/* if we're not sending to ourselves :) */
 		if (pkt->hard.dest != dev->dev_addr[0])
 			skb->pkt_type = PACKET_OTHERHOST;
 	}
 	/* now return the protocol number */
 	switch (soft->proto) {
 	case ARC_P_IP:
 		return htons(ETH_P_IP);
 	case ARC_P_IPV6:
 		return htons(ETH_P_IPV6);
 	case ARC_P_ARP:
 		return htons(ETH_P_ARP);
 	case ARC_P_RARP:
 		return htons(ETH_P_RARP);

 	case ARC_P_IPX:
 	case ARC_P_NOVELL_EC:
 		return htons(ETH_P_802_3);
 	default:
 		dev->stats.rx_errors++;
 		dev->stats.rx_crc_errors++;
 		return 0;
 	}

 	return htons(ETH_P_IP);
 }

 /* packet receiver */
 static void rx(struct net_device *dev, int bufnum,
 	       struct archdr *pkthdr, int length)
 {
 	struct arcnet_local *lp = netdev_priv(dev);
 	struct sk_buff *skb;
 	struct archdr *pkt = pkthdr;
 	struct arc_rfc1201 *soft = &pkthdr->soft.rfc1201;
 	int saddr = pkt->hard.source, ofs;
 	struct Incoming *in = &lp->rfc1201.incoming[saddr];

 	arc_printk(D_DURING, dev, "it's an RFC1201 packet (length=%d)\n",
 		   length);

 	if (length >= MinTU)
 		ofs = 512 - length;
 	else
 		ofs = 256 - length;

 	if (soft->split_flag == 0xFF) {		/* Exception Packet */
 		if (length >= 4 + RFC1201_HDR_SIZE) {
 			arc_printk(D_DURING, dev, "compensating for exception packet\n");
 		} else {
 			arc_printk(D_EXTRA, dev, "short RFC1201 exception packet from %02Xh",
 				   saddr);
 			return;
 		}

 		/* skip over 4-byte junkola */
 		length -= 4;
 		ofs += 4;
 		lp->hw.copy_from_card(dev, bufnum, 512 - length,
 				      soft, sizeof(pkt->soft));
 	}
 	if (!soft->split_flag) {	/* not split */
 		arc_printk(D_RX, dev, "incoming is not split (splitflag=%d)\n",
 			   soft->split_flag);

 		if (in->skb) {	/* already assembling one! */
 			arc_printk(D_EXTRA, dev, "aborting assembly (seq=%d) for unsplit packet (splitflag=%d, seq=%d)\n",
 				   in->sequence, soft->split_flag,
 				   soft->sequence);
 			lp->rfc1201.aborted_seq = soft->sequence;
 			dev_kfree_skb_irq(in->skb);
 			dev->stats.rx_errors++;
 			dev->stats.rx_missed_errors++;
 			in->skb = NULL;
 		}
 		in->sequence = soft->sequence;

 		skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
 		if (!skb) {
 			dev->stats.rx_dropped++;
 			return;
 		}
 		skb_put(skb, length + ARC_HDR_SIZE);
 		skb->dev = dev;

 		pkt = (struct archdr *)skb->data;
 		soft = &pkt->soft.rfc1201;

 		/* up to sizeof(pkt->soft) has already
 		 * been copied from the card
 		 */
 		memcpy(pkt, pkthdr, sizeof(struct archdr));
 		if (length > sizeof(pkt->soft))
 			lp->hw.copy_from_card(dev, bufnum,
 					      ofs + sizeof(pkt->soft),
 					      pkt->soft.raw + sizeof(pkt->soft),
 					      length - sizeof(pkt->soft));

 		/* ARP packets have problems when sent from some DOS systems:
 		 * the source address is always 0!
 		 * So we take the hardware source addr (which is impossible
 		 * to fumble) and insert it ourselves.
 		 */
 		if (soft->proto == ARC_P_ARP) {
 			struct arphdr *arp = (struct arphdr *)soft->payload;

 			/* make sure addresses are the right length */
 			if (arp->ar_hln == 1 && arp->ar_pln == 4) {
 				uint8_t *cptr = (uint8_t *)arp + sizeof(struct arphdr);

 				if (!*cptr) {	/* is saddr = 00? */
 					arc_printk(D_EXTRA, dev,
 						   "ARP source address was 00h, set to %02Xh\n",
 						   saddr);
 					dev->stats.rx_crc_errors++;
 					*cptr = saddr;
 				} else {
 					arc_printk(D_DURING, dev, "ARP source address (%Xh) is fine.\n",
 						   *cptr);
 				}
 			} else {
 				arc_printk(D_NORMAL, dev, "funny-shaped ARP packet. (%Xh, %Xh)\n",
 					   arp->ar_hln, arp->ar_pln);
 				dev->stats.rx_errors++;
 				dev->stats.rx_crc_errors++;
 			}
 		}
 		if (BUGLVL(D_SKB))
 			arcnet_dump_skb(dev, skb, "rx");

 		skb->protocol = type_trans(skb, dev);
 		netif_rx(skb);
 	} else {		/* split packet */
 		/* NOTE: MSDOS ARP packet correction should only need to
 		 * apply to unsplit packets, since ARP packets are so short.
 		 *
 		 * My interpretation of the RFC1201 document is that if a
 		 * packet is received out of order, the entire assembly
 		 * process should be aborted.
 		 *
 		 * The RFC also mentions "it is possible for successfully
 		 * received packets to be retransmitted." As of 0.40 all
 		 * previously received packets are allowed, not just the
 		 * most recent one.
 		 *
 		 * We allow multiple assembly processes, one for each
 		 * ARCnet card possible on the network.
 		 * Seems rather like a waste of memory, but there's no
 		 * other way to be reliable.
 		 */

 		arc_printk(D_RX, dev, "packet is split (splitflag=%d, seq=%d)\n",
 			   soft->split_flag, in->sequence);

 		if (in->skb && in->sequence != soft->sequence) {
 			arc_printk(D_EXTRA, dev, "wrong seq number (saddr=%d, expected=%d, seq=%d, splitflag=%d)\n",
 				   saddr, in->sequence, soft->sequence,
 				   soft->split_flag);
 			dev_kfree_skb_irq(in->skb);
 			in->skb = NULL;
 			dev->stats.rx_errors++;
 			dev->stats.rx_missed_errors++;
 			in->lastpacket = in->numpackets = 0;
 		}
 		if (soft->split_flag & 1) {	/* first packet in split */
 			arc_printk(D_RX, dev, "brand new splitpacket (splitflag=%d)\n",
 				   soft->split_flag);
 			if (in->skb) {	/* already assembling one! */
 				arc_printk(D_EXTRA, dev, "aborting previous (seq=%d) assembly (splitflag=%d, seq=%d)\n",
 					   in->sequence, soft->split_flag,
 					   soft->sequence);
 				dev->stats.rx_errors++;
 				dev->stats.rx_missed_errors++;
 				dev_kfree_skb_irq(in->skb);
 			}
 			in->sequence = soft->sequence;
 			in->numpackets = ((unsigned)soft->split_flag >> 1) + 2;
 			in->lastpacket = 1;

 			if (in->numpackets > 16) {
 				arc_printk(D_EXTRA, dev, "incoming packet more than 16 segments; dropping. (splitflag=%d)\n",
 					   soft->split_flag);
 				lp->rfc1201.aborted_seq = soft->sequence;
 				dev->stats.rx_errors++;
 				dev->stats.rx_length_errors++;
 				return;
 			}
 			in->skb = skb = alloc_skb(508 * in->numpackets + ARC_HDR_SIZE,
 						  GFP_ATOMIC);
 			if (!skb) {
 				arc_printk(D_NORMAL, dev, "(split) memory squeeze, dropping packet.\n");
 				lp->rfc1201.aborted_seq = soft->sequence;
 				dev->stats.rx_dropped++;
 				return;
 			}
 			skb->dev = dev;
 			pkt = (struct archdr *)skb->data;
 			soft = &pkt->soft.rfc1201;

 			memcpy(pkt, pkthdr, ARC_HDR_SIZE + RFC1201_HDR_SIZE);
 			skb_put(skb, ARC_HDR_SIZE + RFC1201_HDR_SIZE);

 			soft->split_flag = 0;	/* end result won't be split */
 		} else {	/* not first packet */
 			int packetnum = ((unsigned)soft->split_flag >> 1) + 1;

 			/* if we're not assembling, there's no point trying to
 			 * continue.
 			 */
 			if (!in->skb) {
 				if (lp->rfc1201.aborted_seq != soft->sequence) {
 					arc_printk(D_EXTRA, dev, "can't continue split without starting first! (splitflag=%d, seq=%d, aborted=%d)\n",
 						   soft->split_flag,
 						   soft->sequence,
 						   lp->rfc1201.aborted_seq);
 					dev->stats.rx_errors++;
 					dev->stats.rx_missed_errors++;
 				}
 				return;
 			}
 			in->lastpacket++;
 			/* if not the right flag */
 			if (packetnum != in->lastpacket) {
 				/* harmless duplicate? ignore. */
 				if (packetnum <= in->lastpacket - 1) {
 					arc_printk(D_EXTRA, dev, "duplicate splitpacket ignored! (splitflag=%d)\n",
 						   soft->split_flag);
 					dev->stats.rx_errors++;
 					dev->stats.rx_frame_errors++;
 					return;
 				}
 				/* "bad" duplicate, kill reassembly */
 				arc_printk(D_EXTRA, dev, "out-of-order splitpacket, reassembly (seq=%d) aborted (splitflag=%d, seq=%d)\n",
 					   in->sequence, soft->split_flag,
 					   soft->sequence);
 				lp->rfc1201.aborted_seq = soft->sequence;
 				dev_kfree_skb_irq(in->skb);
 				in->skb = NULL;
 				dev->stats.rx_errors++;
 				dev->stats.rx_missed_errors++;
 				in->lastpacket = in->numpackets = 0;
 				return;
 			}
 			pkt = (struct archdr *)in->skb->data;
 			soft = &pkt->soft.rfc1201;
 		}

 		skb = in->skb;

 		lp->hw.copy_from_card(dev, bufnum, ofs + RFC1201_HDR_SIZE,
 				      skb->data + skb->len,
 				      length - RFC1201_HDR_SIZE);
 		skb_put(skb, length - RFC1201_HDR_SIZE);

 		/* are we done? */
 		if (in->lastpacket == in->numpackets) {
 			in->skb = NULL;
 			in->lastpacket = in->numpackets = 0;

 			arc_printk(D_SKB_SIZE, dev, "skb: received %d bytes from %02X (unsplit)\n",
 				   skb->len, pkt->hard.source);
 			arc_printk(D_SKB_SIZE, dev, "skb: received %d bytes from %02X (split)\n",
 				   skb->len, pkt->hard.source);
 			if (BUGLVL(D_SKB))
 				arcnet_dump_skb(dev, skb, "rx");

 			skb->protocol = type_trans(skb, dev);
 			netif_rx(skb);
 		}
 	}
 }

 /* Create the ARCnet hard/soft headers for RFC1201. */
 static int build_header(struct sk_buff *skb, struct net_device *dev,
 			unsigned short type, uint8_t daddr)
 {
 	struct arcnet_local *lp = netdev_priv(dev);
 	int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;
 	struct archdr *pkt = (struct archdr *)skb_push(skb, hdr_size);
 	struct arc_rfc1201 *soft = &pkt->soft.rfc1201;

 	/* set the protocol ID according to RFC1201 */
 	switch (type) {
 	case ETH_P_IP:
 		soft->proto = ARC_P_IP;
 		break;
 	case ETH_P_IPV6:
 		soft->proto = ARC_P_IPV6;
 		break;
 	case ETH_P_ARP:
 		soft->proto = ARC_P_ARP;
 		break;
 	case ETH_P_RARP:
 		soft->proto = ARC_P_RARP;
 		break;
 	case ETH_P_IPX:
 	case ETH_P_802_3:
 	case ETH_P_802_2:
 		soft->proto = ARC_P_IPX;
 		break;
 	case ETH_P_ATALK:
 		soft->proto = ARC_P_ATALK;
 		break;
 	default:
 		arc_printk(D_NORMAL, dev, "RFC1201: I don't understand protocol %d (%Xh)\n",
 			   type, type);
 		dev->stats.tx_errors++;
 		dev->stats.tx_aborted_errors++;
 		return 0;
 	}

 	/* Set the source hardware address.
 	 *
 	 * This is pretty pointless for most purposes, but it can help in
 	 * debugging.  ARCnet does not allow us to change the source address
 	 * in the actual packet sent.
 	 */
 	pkt->hard.source = *dev->dev_addr;

 	soft->sequence = htons(lp->rfc1201.sequence++);
 	soft->split_flag = 0;	/* split packets are done elsewhere */

 	/* see linux/net/ethernet/eth.c to see where I got the following */

 	if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 		/* FIXME: fill in the last byte of the dest ipaddr here
 		 * to better comply with RFC1051 in "noarp" mode.
 		 * For now, always broadcasting will probably at least get
 		 * packets sent out :)
 		 */
 		pkt->hard.dest = 0;
 		return hdr_size;
 	}
 	/* otherwise, drop in the dest address */
 	pkt->hard.dest = daddr;
 	return hdr_size;
 }

 static void load_pkt(struct net_device *dev, struct arc_hardware *hard,
 		     struct arc_rfc1201 *soft, int softlen, int bufnum)
 {
 	struct arcnet_local *lp = netdev_priv(dev);
 	int ofs;

 	/* assume length <= XMTU: someone should have handled that by now. */

 	if (softlen > MinTU) {
 		hard->offset[0] = 0;
 		hard->offset[1] = ofs = 512 - softlen;
 	} else if (softlen > MTU) {	/* exception packet - add an extra header */
 		struct arc_rfc1201 excsoft;

 		excsoft.proto = soft->proto;
 		excsoft.split_flag = 0xff;
 		excsoft.sequence = htons(0xffff);

 		hard->offset[0] = 0;
 		ofs = 512 - softlen;
 		hard->offset[1] = ofs - RFC1201_HDR_SIZE;
 		lp->hw.copy_to_card(dev, bufnum, ofs - RFC1201_HDR_SIZE,
 				    &excsoft, RFC1201_HDR_SIZE);
 	} else {
 		hard->offset[0] = ofs = 256 - softlen;
 	}

 	lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 	lp->hw.copy_to_card(dev, bufnum, ofs, soft, softlen);

 	lp->lastload_dest = hard->dest;
 }

 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 		      int bufnum)
 {
 	struct arcnet_local *lp = netdev_priv(dev);
 	const int maxsegsize = XMTU - RFC1201_HDR_SIZE;
 	struct Outgoing *out;

 	arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
 		   lp->next_tx, lp->cur_tx, bufnum);

 	/* hard header is not included in packet length */
 	length -= ARC_HDR_SIZE;
 	pkt->soft.rfc1201.split_flag = 0;

 	/* need to do a split packet? */
 	if (length > XMTU) {
 		out = &lp->outgoing;

 		out->length = length - RFC1201_HDR_SIZE;
 		out->dataleft = lp->outgoing.length;
 		out->numsegs = (out->dataleft + maxsegsize - 1) / maxsegsize;
 		out->segnum = 0;

 		arc_printk(D_DURING, dev, "rfc1201 prep_tx: ready for %d-segment split (%d bytes, seq=%d)\n",
 			   out->numsegs, out->length,
 			   pkt->soft.rfc1201.sequence);

 		return 0;	/* not done */
 	}
 	/* just load the packet into the buffers and send it off */
 	load_pkt(dev, &pkt->hard, &pkt->soft.rfc1201, length, bufnum);

 	return 1;		/* done */
 }

 static int continue_tx(struct net_device *dev, int bufnum)
 {
 	struct arcnet_local *lp = netdev_priv(dev);
 	struct Outgoing *out = &lp->outgoing;
 	struct arc_hardware *hard = &out->pkt->hard;
 	struct arc_rfc1201 *soft = &out->pkt->soft.rfc1201, *newsoft;
 	int maxsegsize = XMTU - RFC1201_HDR_SIZE;
 	int seglen;

 	arc_printk(D_DURING, dev,
 		   "rfc1201 continue_tx: loading segment %d(+1) of %d (seq=%d)\n",
 		   out->segnum, out->numsegs, soft->sequence);

 	/* the "new" soft header comes right before the data chunk */
 	newsoft = (struct arc_rfc1201 *)
 	    (out->pkt->soft.raw + out->length - out->dataleft);

 	if (!out->segnum)	/* first packet; newsoft == soft */
 		newsoft->split_flag = ((out->numsegs - 2) << 1) | 1;
 	else {
 		newsoft->split_flag = out->segnum << 1;
 		newsoft->proto = soft->proto;
 		newsoft->sequence = soft->sequence;
 	}

 	seglen = maxsegsize;
 	if (seglen > out->dataleft)
 		seglen = out->dataleft;
 	out->dataleft -= seglen;

 	load_pkt(dev, hard, newsoft, seglen + RFC1201_HDR_SIZE, bufnum);

 	out->segnum++;
 	if (out->segnum >= out->numsegs)
 		return 1;
 	else
 		return 0;
 }
	/*
	* Linux ARCnet driver - RFC1201 (standard) packet encapsulation
	*
	* Written 1994-1999 by Avery Pennarun.
	* Derived from skeleton.c by Donald Becker.
	*
	* Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)
	* for sponsoring the further development of this driver.
	*
	* **********************
	*
	* The original copyright of skeleton.c was as follows:
	*
	* skeleton.c Written 1993 by Donald Becker.
	* Copyright 1993 United States Government as represented by the
	* Director, National Security Agency. This software may only be used
	* and distributed according to the terms of the GNU General Public License as
	* modified by SRC, incorporated herein by reference.
	*
	* **********************
	*
	* For more details, see drivers/net/arcnet.c
	*
	* **********************
	*/

	#define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt

	#include <linux/gfp.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/if_arp.h>
	#include <linux/netdevice.h>
	#include <linux/skbuff.h>

	#include "arcdevice.h"

	MODULE_LICENSE("GPL");

	static __be16 type_trans(struct sk_buff skb, struct net_device dev);
	static void rx(struct net_device *dev, int bufnum,
	struct archdr *pkthdr, int length);
	static int build_header(struct sk_buff skb, struct net_device dev,
	unsigned short type, uint8_t daddr);
	static int prepare_tx(struct net_device dev, struct archdr pkt, int length,
	int bufnum);
	static int continue_tx(struct net_device *dev, int bufnum);

	static struct ArcProto rfc1201_proto = {
	.suffix = 'a',
	.mtu = 1500, /* could be more, but some receivers can't handle it... */
	.is_ip = 1, /* This is for sending IP and ARP packages */
	.rx = rx,
	.build_header = build_header,
	.prepare_tx = prepare_tx,
	.continue_tx = continue_tx,
	.ack_tx = NULL
	};

	static int __init arcnet_rfc1201_init(void)
	{
	pr_info("%s\n", "RFC1201 \"standard\" (`a') encapsulation support loaded");

	arc_proto_map[ARC_P_IP]
	= arc_proto_map[ARC_P_IPV6]
	= arc_proto_map[ARC_P_ARP]
	= arc_proto_map[ARC_P_RARP]
	= arc_proto_map[ARC_P_IPX]
	= arc_proto_map[ARC_P_NOVELL_EC]
	= &rfc1201_proto;

	/* if someone else already owns the broadcast, we won't take it */
	if (arc_bcast_proto == arc_proto_default)
	arc_bcast_proto = &rfc1201_proto;

	return 0;
	}

	static void __exit arcnet_rfc1201_exit(void)
	{
	arcnet_unregister_proto(&rfc1201_proto);
	}

	module_init(arcnet_rfc1201_init);
	module_exit(arcnet_rfc1201_exit);

	/* Determine a packet's protocol ID.
	*
	* With ARCnet we have to convert everything to Ethernet-style stuff.
	*/
	static __be16 type_trans(struct sk_buff skb, struct net_device dev)
	{
	struct archdr pkt = (struct archdr )skb->data;
	struct arc_rfc1201 *soft = &pkt->soft.rfc1201;
	int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;

	/* Pull off the arcnet header. */
	skb_reset_mac_header(skb);
	skb_pull(skb, hdr_size);

	if (pkt->hard.dest == 0) {
	skb->pkt_type = PACKET_BROADCAST;
	} else if (dev->flags & IFF_PROMISC) {
	/* if we're not sending to ourselves :) */
	if (pkt->hard.dest != dev->dev_addr[0])
	skb->pkt_type = PACKET_OTHERHOST;
	}
	/* now return the protocol number */
	switch (soft->proto) {
	case ARC_P_IP:
	return htons(ETH_P_IP);
	case ARC_P_IPV6:
	return htons(ETH_P_IPV6);
	case ARC_P_ARP:
	return htons(ETH_P_ARP);
	case ARC_P_RARP:
	return htons(ETH_P_RARP);

	case ARC_P_IPX:
	case ARC_P_NOVELL_EC:
	return htons(ETH_P_802_3);
	default:
	dev->stats.rx_errors++;
	dev->stats.rx_crc_errors++;
	return 0;
	}

	return htons(ETH_P_IP);
	}

	/* packet receiver */
	static void rx(struct net_device *dev, int bufnum,
	struct archdr *pkthdr, int length)
	{
	struct arcnet_local *lp = netdev_priv(dev);
	struct sk_buff *skb;
	struct archdr *pkt = pkthdr;
	struct arc_rfc1201 *soft = &pkthdr->soft.rfc1201;
	int saddr = pkt->hard.source, ofs;
	struct Incoming *in = &lp->rfc1201.incoming[saddr];

	arc_printk(D_DURING, dev, "it's an RFC1201 packet (length=%d)\n",
	length);

	if (length >= MinTU)
	ofs = 512 - length;
	else
	ofs = 256 - length;

	if (soft->split_flag == 0xFF) { /* Exception Packet */
	if (length >= 4 + RFC1201_HDR_SIZE) {
	arc_printk(D_DURING, dev, "compensating for exception packet\n");
	} else {
	arc_printk(D_EXTRA, dev, "short RFC1201 exception packet from %02Xh",
	saddr);
	return;
	}

	/* skip over 4-byte junkola */
	length -= 4;
	ofs += 4;
	lp->hw.copy_from_card(dev, bufnum, 512 - length,
	soft, sizeof(pkt->soft));
	}
	if (!soft->split_flag) { /* not split */
	arc_printk(D_RX, dev, "incoming is not split (splitflag=%d)\n",
	soft->split_flag);

	if (in->skb) { /* already assembling one! */
	arc_printk(D_EXTRA, dev, "aborting assembly (seq=%d) for unsplit packet (splitflag=%d, seq=%d)\n",
	in->sequence, soft->split_flag,
	soft->sequence);
	lp->rfc1201.aborted_seq = soft->sequence;
	dev_kfree_skb_irq(in->skb);
	dev->stats.rx_errors++;
	dev->stats.rx_missed_errors++;
	in->skb = NULL;
	}
	in->sequence = soft->sequence;

	skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
	if (!skb) {
	dev->stats.rx_dropped++;
	return;
	}
	skb_put(skb, length + ARC_HDR_SIZE);
	skb->dev = dev;

	pkt = (struct archdr *)skb->data;
	soft = &pkt->soft.rfc1201;

	/* up to sizeof(pkt->soft) has already
	* been copied from the card
	*/
	memcpy(pkt, pkthdr, sizeof(struct archdr));
	if (length > sizeof(pkt->soft))
	lp->hw.copy_from_card(dev, bufnum,
	ofs + sizeof(pkt->soft),
	pkt->soft.raw + sizeof(pkt->soft),
	length - sizeof(pkt->soft));

	/* ARP packets have problems when sent from some DOS systems:
	* the source address is always 0!
	* So we take the hardware source addr (which is impossible
	* to fumble) and insert it ourselves.
	*/
	if (soft->proto == ARC_P_ARP) {
	struct arphdr arp = (struct arphdr )soft->payload;

	/* make sure addresses are the right length */
	if (arp->ar_hln == 1 && arp->ar_pln == 4) {
	uint8_t cptr = (uint8_t )arp + sizeof(struct arphdr);

	if (!cptr) { / is saddr = 00? */
	arc_printk(D_EXTRA, dev,
	"ARP source address was 00h, set to %02Xh\n",
	saddr);
	dev->stats.rx_crc_errors++;
	*cptr = saddr;
	} else {
	arc_printk(D_DURING, dev, "ARP source address (%Xh) is fine.\n",
	*cptr);
	}
	} else {
	arc_printk(D_NORMAL, dev, "funny-shaped ARP packet. (%Xh, %Xh)\n",
	arp->ar_hln, arp->ar_pln);
	dev->stats.rx_errors++;
	dev->stats.rx_crc_errors++;
	}
	}
	if (BUGLVL(D_SKB))
	arcnet_dump_skb(dev, skb, "rx");

	skb->protocol = type_trans(skb, dev);
	netif_rx(skb);
	} else { /* split packet */
	/* NOTE: MSDOS ARP packet correction should only need to
	* apply to unsplit packets, since ARP packets are so short.
	*
	* My interpretation of the RFC1201 document is that if a
	* packet is received out of order, the entire assembly
	* process should be aborted.
	*
	* The RFC also mentions "it is possible for successfully
	* received packets to be retransmitted." As of 0.40 all
	* previously received packets are allowed, not just the
	* most recent one.
	*
	* We allow multiple assembly processes, one for each
	* ARCnet card possible on the network.
	* Seems rather like a waste of memory, but there's no
	* other way to be reliable.
	*/

	arc_printk(D_RX, dev, "packet is split (splitflag=%d, seq=%d)\n",
	soft->split_flag, in->sequence);

	if (in->skb && in->sequence != soft->sequence) {
	arc_printk(D_EXTRA, dev, "wrong seq number (saddr=%d, expected=%d, seq=%d, splitflag=%d)\n",
	saddr, in->sequence, soft->sequence,
	soft->split_flag);
	dev_kfree_skb_irq(in->skb);
	in->skb = NULL;
	dev->stats.rx_errors++;
	dev->stats.rx_missed_errors++;
	in->lastpacket = in->numpackets = 0;
	}
	if (soft->split_flag & 1) { /* first packet in split */
	arc_printk(D_RX, dev, "brand new splitpacket (splitflag=%d)\n",
	soft->split_flag);
	if (in->skb) { /* already assembling one! */
	arc_printk(D_EXTRA, dev, "aborting previous (seq=%d) assembly (splitflag=%d, seq=%d)\n",
	in->sequence, soft->split_flag,
	soft->sequence);
	dev->stats.rx_errors++;
	dev->stats.rx_missed_errors++;
	dev_kfree_skb_irq(in->skb);
	}
	in->sequence = soft->sequence;
	in->numpackets = ((unsigned)soft->split_flag >> 1) + 2;
	in->lastpacket = 1;

	if (in->numpackets > 16) {
	arc_printk(D_EXTRA, dev, "incoming packet more than 16 segments; dropping. (splitflag=%d)\n",
	soft->split_flag);
	lp->rfc1201.aborted_seq = soft->sequence;
	dev->stats.rx_errors++;
	dev->stats.rx_length_errors++;
	return;
	}
	in->skb = skb = alloc_skb(508 * in->numpackets + ARC_HDR_SIZE,
	GFP_ATOMIC);
	if (!skb) {
	arc_printk(D_NORMAL, dev, "(split) memory squeeze, dropping packet.\n");
	lp->rfc1201.aborted_seq = soft->sequence;
	dev->stats.rx_dropped++;
	return;
	}
	skb->dev = dev;
	pkt = (struct archdr *)skb->data;
	soft = &pkt->soft.rfc1201;

	memcpy(pkt, pkthdr, ARC_HDR_SIZE + RFC1201_HDR_SIZE);
	skb_put(skb, ARC_HDR_SIZE + RFC1201_HDR_SIZE);

	soft->split_flag = 0; /* end result won't be split */
	} else { /* not first packet */
	int packetnum = ((unsigned)soft->split_flag >> 1) + 1;

	/* if we're not assembling, there's no point trying to
	* continue.
	*/
	if (!in->skb) {
	if (lp->rfc1201.aborted_seq != soft->sequence) {
	arc_printk(D_EXTRA, dev, "can't continue split without starting first! (splitflag=%d, seq=%d, aborted=%d)\n",
	soft->split_flag,
	soft->sequence,
	lp->rfc1201.aborted_seq);
	dev->stats.rx_errors++;
	dev->stats.rx_missed_errors++;
	}
	return;
	}
	in->lastpacket++;
	/* if not the right flag */
	if (packetnum != in->lastpacket) {
	/* harmless duplicate? ignore. */
	if (packetnum <= in->lastpacket - 1) {
	arc_printk(D_EXTRA, dev, "duplicate splitpacket ignored! (splitflag=%d)\n",
	soft->split_flag);
	dev->stats.rx_errors++;
	dev->stats.rx_frame_errors++;
	return;
	}
	/* "bad" duplicate, kill reassembly */
	arc_printk(D_EXTRA, dev, "out-of-order splitpacket, reassembly (seq=%d) aborted (splitflag=%d, seq=%d)\n",
	in->sequence, soft->split_flag,
	soft->sequence);
	lp->rfc1201.aborted_seq = soft->sequence;
	dev_kfree_skb_irq(in->skb);
	in->skb = NULL;
	dev->stats.rx_errors++;
	dev->stats.rx_missed_errors++;
	in->lastpacket = in->numpackets = 0;
	return;
	}
	pkt = (struct archdr *)in->skb->data;
	soft = &pkt->soft.rfc1201;
	}

	skb = in->skb;

	lp->hw.copy_from_card(dev, bufnum, ofs + RFC1201_HDR_SIZE,
	skb->data + skb->len,
	length - RFC1201_HDR_SIZE);
	skb_put(skb, length - RFC1201_HDR_SIZE);

	/* are we done? */
	if (in->lastpacket == in->numpackets) {
	in->skb = NULL;
	in->lastpacket = in->numpackets = 0;

	arc_printk(D_SKB_SIZE, dev, "skb: received %d bytes from %02X (unsplit)\n",
	skb->len, pkt->hard.source);
	arc_printk(D_SKB_SIZE, dev, "skb: received %d bytes from %02X (split)\n",
	skb->len, pkt->hard.source);
	if (BUGLVL(D_SKB))
	arcnet_dump_skb(dev, skb, "rx");

	skb->protocol = type_trans(skb, dev);
	netif_rx(skb);
	}
	}
	}

	/* Create the ARCnet hard/soft headers for RFC1201. */
	static int build_header(struct sk_buff skb, struct net_device dev,
	unsigned short type, uint8_t daddr)
	{
	struct arcnet_local *lp = netdev_priv(dev);
	int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;
	struct archdr pkt = (struct archdr )skb_push(skb, hdr_size);
	struct arc_rfc1201 *soft = &pkt->soft.rfc1201;

	/* set the protocol ID according to RFC1201 */
	switch (type) {
	case ETH_P_IP:
	soft->proto = ARC_P_IP;
	break;
	case ETH_P_IPV6:
	soft->proto = ARC_P_IPV6;
	break;
	case ETH_P_ARP:
	soft->proto = ARC_P_ARP;
	break;
	case ETH_P_RARP:
	soft->proto = ARC_P_RARP;
	break;
	case ETH_P_IPX:
	case ETH_P_802_3:
	case ETH_P_802_2:
	soft->proto = ARC_P_IPX;
	break;
	case ETH_P_ATALK:
	soft->proto = ARC_P_ATALK;
	break;
	default:
	arc_printk(D_NORMAL, dev, "RFC1201: I don't understand protocol %d (%Xh)\n",
	type, type);
	dev->stats.tx_errors++;
	dev->stats.tx_aborted_errors++;
	return 0;
	}

	/* Set the source hardware address.
	*
	* This is pretty pointless for most purposes, but it can help in
	* debugging. ARCnet does not allow us to change the source address
	* in the actual packet sent.
	*/
	pkt->hard.source = *dev->dev_addr;

	soft->sequence = htons(lp->rfc1201.sequence++);
	soft->split_flag = 0; /* split packets are done elsewhere */

	/* see linux/net/ethernet/eth.c to see where I got the following */

	if (dev->flags & (IFF_LOOPBACK \| IFF_NOARP)) {
	/* FIXME: fill in the last byte of the dest ipaddr here
	* to better comply with RFC1051 in "noarp" mode.
	* For now, always broadcasting will probably at least get
	* packets sent out :)
	*/
	pkt->hard.dest = 0;
	return hdr_size;
	}
	/* otherwise, drop in the dest address */
	pkt->hard.dest = daddr;
	return hdr_size;
	}

	static void load_pkt(struct net_device dev, struct arc_hardware hard,
	struct arc_rfc1201 *soft, int softlen, int bufnum)
	{
	struct arcnet_local *lp = netdev_priv(dev);
	int ofs;

	/* assume length <= XMTU: someone should have handled that by now. */

	if (softlen > MinTU) {
	hard->offset[0] = 0;
	hard->offset[1] = ofs = 512 - softlen;
	} else if (softlen > MTU) { /* exception packet - add an extra header */
	struct arc_rfc1201 excsoft;

	excsoft.proto = soft->proto;
	excsoft.split_flag = 0xff;
	excsoft.sequence = htons(0xffff);

	hard->offset[0] = 0;
	ofs = 512 - softlen;
	hard->offset[1] = ofs - RFC1201_HDR_SIZE;
	lp->hw.copy_to_card(dev, bufnum, ofs - RFC1201_HDR_SIZE,
	&excsoft, RFC1201_HDR_SIZE);
	} else {
	hard->offset[0] = ofs = 256 - softlen;
	}

	lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
	lp->hw.copy_to_card(dev, bufnum, ofs, soft, softlen);

	lp->lastload_dest = hard->dest;
	}

	static int prepare_tx(struct net_device dev, struct archdr pkt, int length,
	int bufnum)
	{
	struct arcnet_local *lp = netdev_priv(dev);
	const int maxsegsize = XMTU - RFC1201_HDR_SIZE;
	struct Outgoing *out;

	arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
	lp->next_tx, lp->cur_tx, bufnum);

	/* hard header is not included in packet length */
	length -= ARC_HDR_SIZE;
	pkt->soft.rfc1201.split_flag = 0;

	/* need to do a split packet? */
	if (length > XMTU) {
	out = &lp->outgoing;

	out->length = length - RFC1201_HDR_SIZE;
	out->dataleft = lp->outgoing.length;
	out->numsegs = (out->dataleft + maxsegsize - 1) / maxsegsize;
	out->segnum = 0;

	arc_printk(D_DURING, dev, "rfc1201 prep_tx: ready for %d-segment split (%d bytes, seq=%d)\n",
	out->numsegs, out->length,
	pkt->soft.rfc1201.sequence);

	return 0; /* not done */
	}
	/* just load the packet into the buffers and send it off */
	load_pkt(dev, &pkt->hard, &pkt->soft.rfc1201, length, bufnum);

	return 1; /* done */
	}

	static int continue_tx(struct net_device *dev, int bufnum)
	{
	struct arcnet_local *lp = netdev_priv(dev);
	struct Outgoing *out = &lp->outgoing;
	struct arc_hardware *hard = &out->pkt->hard;
	struct arc_rfc1201 soft = &out->pkt->soft.rfc1201, newsoft;
	int maxsegsize = XMTU - RFC1201_HDR_SIZE;
	int seglen;

	arc_printk(D_DURING, dev,
	"rfc1201 continue_tx: loading segment %d(+1) of %d (seq=%d)\n",
	out->segnum, out->numsegs, soft->sequence);

	/* the "new" soft header comes right before the data chunk */
	newsoft = (struct arc_rfc1201 *)
	(out->pkt->soft.raw + out->length - out->dataleft);

	if (!out->segnum) /* first packet; newsoft == soft */
	newsoft->split_flag = ((out->numsegs - 2) << 1) \| 1;
	else {
	newsoft->split_flag = out->segnum << 1;
	newsoft->proto = soft->proto;
	newsoft->sequence = soft->sequence;
	}

	seglen = maxsegsize;
	if (seglen > out->dataleft)
	seglen = out->dataleft;
	out->dataleft -= seglen;

	load_pkt(dev, hard, newsoft, seglen + RFC1201_HDR_SIZE, bufnum);

	out->segnum++;
	if (out->segnum >= out->numsegs)
	return 1;
	else
	return 0;
	}