rfc1201.c

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

#define VERSION "arcnet: RFC1201 \"standard\" (`a') encapsulation support loaded.\n"


static unsigned short 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, 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);

struct ArcProto rfc1201_proto =
{
	'a',
	1500,			/* could be more, but some receivers can't handle it... */
	rx,
	build_header,
	prepare_tx,
	continue_tx
};


void __init arcnet_rfc1201_init(void)
{
	arc_proto_map[ARC_P_IP]
	    = 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;
}


#ifdef MODULE

int __init init_module(void)
{
	printk(VERSION);
	arcnet_rfc1201_init();
	return 0;
}

void cleanup_module(void)
{
	arcnet_unregister_proto(&rfc1201_proto);
}

#endif				/* MODULE */


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

	/* Pull off the arcnet header. */
	skb->mac.raw = skb->data;
	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_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:
		lp->stats.rx_errors++;
		lp->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 = (struct arcnet_local *) dev->priv;
	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];

	BUGMSG(D_DURING, "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)
			BUGMSG(D_DURING, "compensating for exception packet\n");
		else {
			BUGMSG(D_EXTRA, "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 */
		BUGMSG(D_RX, "incoming is not split (splitflag=%d)\n",
		       soft->split_flag);

		if (in->skb) {	/* already assembling one! */
			BUGMSG(D_EXTRA, "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);
			lp->stats.rx_errors++;
			lp->stats.rx_missed_errors++;
			in->skb = NULL;
		}
		in->sequence = soft->sequence;

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

		skb->protocol = type_trans(skb, dev);
		netif_rx(skb);
		dev->last_rx = jiffies;
	} 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.
		 */

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

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