rfc1201.c

h内核

			}
			in->sequence = soft->sequence;
			in->numpackets = ((unsigned) soft->split_flag >> 1) + 2;
			in->lastpacket = 1;

			if (in->numpackets > 16) {
				BUGMSG(D_EXTRA, "incoming packet more than 16 segments; dropping. (splitflag=%d)\n",
				       soft->split_flag);
				lp->rfc1201.aborted_seq = soft->sequence;
				lp->stats.rx_errors++;
				lp->stats.rx_length_errors++;
				return;
			}
			in->skb = skb = alloc_skb(508 * in->numpackets + ARC_HDR_SIZE,
						  GFP_ATOMIC);
			if (skb == NULL) {
				BUGMSG(D_NORMAL, "(split) memory squeeze, dropping packet.\n");
				lp->rfc1201.aborted_seq = soft->sequence;
				lp->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) {
					BUGMSG(D_EXTRA, "can't continue split without starting "
					       "first! (splitflag=%d, seq=%d, aborted=%d)\n",
					soft->split_flag, soft->sequence,
					       lp->rfc1201.aborted_seq);
					lp->stats.rx_errors++;
					lp->stats.rx_missed_errors++;
				}
				return;
			}
			in->lastpacket++;
			if (packetnum != in->lastpacket) {	/* not the right flag! */
				/* harmless duplicate? ignore. */
				if (packetnum <= in->lastpacket - 1) {
					BUGMSG(D_EXTRA, "duplicate splitpacket ignored! (splitflag=%d)\n",
					       soft->split_flag);
					lp->stats.rx_errors++;
					lp->stats.rx_frame_errors++;
					return;
				}
				/* "bad" duplicate, kill reassembly */
				BUGMSG(D_EXTRA, "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;
				lp->stats.rx_errors++;
				lp->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;

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

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


/* 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 = (struct arcnet_local *) dev->priv;
	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:
		BUGMSG(D_NORMAL, "RFC1201: I don't understand protocol %d (%Xh)\n",
		       type, type);
		lp->stats.tx_errors++;
		lp->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 = (struct arcnet_local *) dev->priv;
	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 = 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 = (struct arcnet_local *) dev->priv;
	const int maxsegsize = XMTU - RFC1201_HDR_SIZE;
	struct Outgoing *out;


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

	length -= ARC_HDR_SIZE;	/* hard header is not included in packet length */
	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;

		BUGMSG(D_DURING, "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 = (struct arcnet_local *) dev->priv;
	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;

	BUGMSG(D_DURING,
	  "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;
}