af_ipx.c

讲述linux的初始化过程

#else

static int ipxitf_demux_socket(ipx_interface *intrfc, struct sk_buff *skb, int copy)
{
	struct ipxhdr *ipx = skb->nh.ipxh;
	struct sock *sock1 = NULL, *sock2 = NULL;
	struct sk_buff *skb1 = NULL, *skb2 = NULL;
	int ret;

	if (intrfc == ipx_primary_net && ntohs(ipx->ipx_dest.sock) == 0x451) 
	{
		/* 
	 	 * The packet's target is a NCP connection handler. We want to
	 	 * hand it to the correct socket directly within the kernel,
	 	 * so that the mars_nwe packet distribution process
	 	 * does not have to do it. Here we only care about NCP and
	 	 * BURST packets.
	 	 * You might call this a hack, but believe me, you do not
	 	 * want a complete NCP layer in the kernel, and this is
	 	 * VERY fast as well.
	 	 */
	 	int connection = 0;

	 	if (*((char*)(ipx+1)) == 0x22 &&  *((char*)(ipx+1)+1) == 0x22) 
		{
	  		/*
			 * The packet is a NCP request
			 */
			connection = ( ((int) *((char*)(ipx+1)+5)) << 8 )
		 	       | (int) *((char*)(ipx+1)+3);
		} 
		else if (*((char*)(ipx+1))== 0x77 &&  *((char*)(ipx+1)+1) == 0x77) 
		{
			/*
			 * The packet is a BURST packet
			 */
			connection = ( ((int) *((char*)(ipx+1)+9)) << 8 )
		 	       | (int) *((char*)(ipx+1)+8);
		}

        	if (connection) 
		{
			/*
			 * Now we have to look for a special NCP connection handling
			 * socket. Only these sockets have ipx_ncp_conn != 0, set
			 * by SIOCIPXNCPCONN.
			 */
			spin_lock_bh(&intrfc->if_sklist_lock);
			for (sock1=intrfc->if_sklist;
				(sock1 != NULL) &&
				(sock1->protinfo.af_ipx.ipx_ncp_conn != connection);
					sock1=sock1->next);
			if (sock1)
				sock_hold(sock1);
			spin_unlock_bh(&intrfc->if_sklist_lock);
		}
        }
        if (sock1 == NULL) 
	{
		/* No special socket found, forward the packet the
		 * normal way.
		 */
		sock1 = ipxitf_find_socket(intrfc, ipx->ipx_dest.sock);
	}

	/*
	 * We need to check if there is a primary net and if
	 * this is addressed to one of the *SPECIAL* sockets because
	 * these need to be propagated to the primary net.
	 * The *SPECIAL* socket list contains: 0x452(SAP), 0x453(RIP) and
	 * 0x456(Diagnostic).
	 */

	if(ipx_primary_net && (intrfc != ipx_primary_net))
	{
		switch(ntohs(ipx->ipx_dest.sock))
		{
			case 0x452:
			case 0x453:
			case 0x456:
				/*
				 * The appropriate thing to do here is to
				 * dup the packet and route to the primary net
				 * interface via ipxitf_send; however, we'll 
				 * cheat and just demux it here.
				 */
				sock2 = ipxitf_find_socket(ipx_primary_net,
					ipx->ipx_dest.sock);
				break;
			default:
				break;
		}
	}

	/*
	 * If there is nothing to do return. The kfree will cancel any charging.
	 */
	if(sock1 == NULL && sock2 == NULL)
	{
		if(!copy)
			kfree_skb(skb);
		return (0);
	}

	/*
	 * This next segment of code is a little awkward, but it sets it up
	 * so that the appropriate number of copies of the SKB are made and
	 * that skb1 and skb2 point to it (them) so that it (they) can be
	 * demuxed to sock1 and/or sock2.  If we are unable to make enough
	 * copies, we do as much as is possible.
	 */

	if(copy)
		skb1 = skb_clone(skb, GFP_ATOMIC);
	else
		skb1 = skb;

	ret = -ENOMEM;
	if(skb1 == NULL)
		goto out;

	/* Do we need 2 SKBs? */
	if(sock1 && sock2)
		skb2 = skb_clone(skb1, GFP_ATOMIC);
	else
		skb2 = skb1;

	if(sock1)
		(void) ipxitf_def_skb_handler(sock1, skb1);

	ret = -ENOMEM;
	if(skb2 == NULL)
		goto out;

	if(sock2)
		(void) ipxitf_def_skb_handler(sock2, skb2);

	ret = 0;
out:	if (sock1)
		sock_put(sock1);
	if (sock2)
		sock_put(sock2);
	return ret;
}
#endif	/* CONFIG_IPX_INTERN */

static struct sk_buff *ipxitf_adjust_skbuff(ipx_interface *intrfc, struct sk_buff *skb)
{
	struct sk_buff *skb2;
	int in_offset = skb->h.raw - skb->head;
	int out_offset = intrfc->if_ipx_offset;
	int len;

	/* Hopefully, most cases */
	if(in_offset >= out_offset)
		return (skb);

	/* Need new SKB */
	len  = skb->len + out_offset;
	skb2 = alloc_skb(len, GFP_ATOMIC);
	if(skb2 != NULL)
	{
		skb_reserve(skb2, out_offset);
		skb2->nh.raw =
		skb2->h.raw = skb_put(skb2,skb->len);
		memcpy(skb2->h.raw, skb->h.raw, skb->len);
	}
	kfree_skb(skb);
	return (skb2);
}

/* caller must hold a reference to intrfc */

static int ipxitf_send(ipx_interface *intrfc, struct sk_buff *skb, char *node)
{
	struct ipxhdr *ipx = skb->nh.ipxh;
	struct net_device *dev = intrfc->if_dev;
	struct datalink_proto *dl = intrfc->if_dlink;
	char dest_node[IPX_NODE_LEN];
	int send_to_wire = 1;
	int addr_len;
	
	/* 
	 * We need to know how many skbuffs it will take to send out this
	 * packet to avoid unnecessary copies.
	 */
	 
	if((dl == NULL) || (dev == NULL) || (dev->flags & IFF_LOOPBACK)) 
		send_to_wire = 0;	/* No non looped */

	/*
	 * See if this should be demuxed to sockets on this interface 
	 *
	 * We want to ensure the original was eaten or that we only use
	 * up clones.
	 */
	 
	if(ipx->ipx_dest.net == intrfc->if_netnum) 
	{
		/*
		 * To our own node, loop and free the original.
		 * The internal net will receive on all node address.
		 */
		if((intrfc == ipx_internal_net)
		    || memcmp(intrfc->if_node, node, IPX_NODE_LEN) == 0) 
		{
			/* Don't charge sender */
			skb_orphan(skb);

			/* Will charge receiver */
			return (ipxitf_demux_socket(intrfc, skb, 0));
		}

		/* Broadcast, loop and possibly keep to send on. */
		if(memcmp(ipx_broadcast_node, node, IPX_NODE_LEN) == 0)
		{
			if(!send_to_wire)
				skb_orphan(skb);
			ipxitf_demux_socket(intrfc, skb, send_to_wire);
			if(!send_to_wire)
				return (0);
		}
	}

	/*
	 * If the originating net is not equal to our net; this is routed
	 * We are still charging the sender. Which is right - the driver
	 * free will handle this fairly.
	 */
	if(ipx->ipx_source.net != intrfc->if_netnum)
	{
		/*
		 * Unshare the buffer before modifying the count in
		 * case its a flood or tcpdump
		 */
		skb = skb_unshare(skb, GFP_ATOMIC);
		if(!skb)
			return (0);
		if(++(ipx->ipx_tctrl) > ipxcfg_max_hops)
			send_to_wire = 0;
	}

	if(!send_to_wire)
	{
		kfree_skb(skb);
		return (0);
	}

	/* Determine the appropriate hardware address */
	addr_len = dev->addr_len;
	if(memcmp(ipx_broadcast_node, node, IPX_NODE_LEN) == 0)
		memcpy(dest_node, dev->broadcast, addr_len);
	else
		memcpy(dest_node, &(node[IPX_NODE_LEN-addr_len]), addr_len);

	/* Make any compensation for differing physical/data link size */
	skb = ipxitf_adjust_skbuff(intrfc, skb);
	if(skb == NULL)
		return (0);

	/* set up data link and physical headers */
	skb->dev = dev;
	skb->protocol = htons(ETH_P_IPX);
	dl->datalink_header(dl, skb, dest_node);

	/* Send it out */
	dev_queue_xmit(skb);

	return (0);
}

static int ipxrtr_add_route(__u32, ipx_interface *, unsigned char *);

static int ipxitf_add_local_route(ipx_interface *intrfc)
{
	return (ipxrtr_add_route(intrfc->if_netnum, intrfc, NULL));
}

static const char * ipx_frame_name(unsigned short);
static const char * ipx_device_name(ipx_interface *);

static int ipxitf_rcv(ipx_interface *intrfc, struct sk_buff *skb)
{
	struct ipxhdr	*ipx = skb->nh.ipxh;
	ipx_interface	*i;
	int ret = 0;

	ipxitf_hold(intrfc);

	/* See if we should update our network number */
	if(!intrfc->if_netnum  /* net number of intrfc not known yet (== 0) */
		&& (ipx->ipx_source.net == ipx->ipx_dest.net) /* intra packet */
		&& ipx->ipx_source.net)  /* source net number of packet != 0 */
	{
		/* NB: NetWare servers lie about their hop count so we
		 * dropped the test based on it.  This is the best way
		 * to determine this is a 0 hop count packet.
		 */
		if((i=ipxitf_find_using_net(ipx->ipx_source.net)) == NULL)
		{
			intrfc->if_netnum = ipx->ipx_source.net;
			(void) ipxitf_add_local_route(intrfc);
		}
		else
		{
			printk(KERN_WARNING "IPX: Network number collision %lx\n        %s %s and %s %s\n",
				(long unsigned int) htonl(ipx->ipx_source.net),
				ipx_device_name(i),
				ipx_frame_name(i->if_dlink_type),
				ipx_device_name(intrfc),
				ipx_frame_name(intrfc->if_dlink_type));
			ipxitf_put(i);
		}
	}

	if(ipx->ipx_type == IPX_TYPE_PPROP
		&& ipx->ipx_tctrl < 8 
		&& skb->pkt_type != PACKET_OTHERHOST
		   /* header + 8 network numbers */ 
		&& ntohs(ipx->ipx_pktsize) >= sizeof(struct ipxhdr) + 8 * 4) 
	{
		int i;
        	ipx_interface *ifcs;
		struct sk_buff *skb2;
  		__u32 *l;
		char *c;
		
		c = (char *) skb->data;
		c += sizeof(struct ipxhdr);
		l = (__u32 *) c;

		i = 0;

		/* Dump packet if already seen this net */
		for( ; i < ipx->ipx_tctrl; i++)
			if(*l++ == intrfc->if_netnum)
				break;

		if(i == ipx->ipx_tctrl) 
		{ 
			/* < 8 hops && input itfc not in list */
			*l = intrfc->if_netnum; /* insert recvd netnum into list */
			ipx->ipx_tctrl++;
			/* xmit on all other interfaces... */
			spin_lock_bh(&ipx_interfaces_lock);
			for(ifcs = ipx_interfaces; ifcs != NULL; ifcs = ifcs->if_next) 
			{
				/* Except unconfigured interfaces */
				if(ifcs->if_netnum == 0)
					continue;
					
				/* That aren't in the list */
				l = (__u32 *) c;
				for(i = 0; i <= ipx->ipx_tctrl; i++)
					if(ifcs->if_netnum == *l++)
						break;
				if(i - 1 == ipx->ipx_tctrl) 
				{
					ipx->ipx_dest.net = ifcs->if_netnum;
					skb2=skb_clone(skb, GFP_ATOMIC);
					if (skb2)
						ipxrtr_route_skb(skb2);
				}
			}
			spin_unlock_bh(&ipx_interfaces_lock);

			/* Reset network number in packet */
			ipx->ipx_dest.net = intrfc->if_netnum;
		}
	}

	if(!ipx->ipx_dest.net)
		ipx->ipx_dest.net = intrfc->if_netnum;
	if(!ipx->ipx_source.net)
		ipx->ipx_source.net = intrfc->if_netnum;

	if(intrfc->if_netnum != ipx->ipx_dest.net)
	{
		/* We only route point-to-point packets. */
		if(skb->pkt_type == PACKET_HOST)
		{
			skb=skb_unshare(skb, GFP_ATOMIC);
			if(skb)
				ret = ipxrtr_route_skb(skb);
			goto out_intrfc;
		}

		goto out_free_skb;
	}

	/* see if we should keep it */
	if((memcmp(ipx_broadcast_node, ipx->ipx_dest.node, IPX_NODE_LEN) == 0)
		|| (memcmp(intrfc->if_node, ipx->ipx_dest.node, IPX_NODE_LEN) == 0))
	{
		ret = ipxitf_demux_socket(intrfc, skb, 0);
		goto out_intrfc;
	}

	/* we couldn't pawn it off so unload it */
out_free_skb:
	kfree_skb(skb);
out_intrfc:
	ipxitf_put(intrfc);
	return ret;
}

static void ipxitf_insert(ipx_interface *intrfc)
{
	ipx_interface *i;

	intrfc->if_next = NULL;
	spin_lock_bh(&ipx_interfaces_lock);
	if(ipx_interfaces == NULL)
		ipx_interfaces = intrfc;
	else
	{
		for(i = ipx_interfaces; i->if_next != NULL; i = i->if_next)
			;
		i->if_next = intrfc;
	}
	spin_unlock_bh(&ipx_interfaces_lock);

	if(ipxcfg_auto_select_primary && (ipx_primary_net == NULL))
		ipx_primary_net = intrfc;

	return;
}

static int ipxitf_create_internal(ipx_interface_definition *idef)
{
	ipx_interface *intrfc;
	int ret;

	/* Only one primary network allowed */
	if(ipx_primary_net != NULL)
		return (-EEXIST);

	/* Must have a valid network number */
	if(!idef->ipx_network)
		return (-EADDRNOTAVAIL);
	intrfc = ipxitf_find_using_net(idef->ipx_network);
	if(intrfc != NULL) {
		ipxitf_put(intrfc);
		return (-EADDRINUSE);
	}

	intrfc = (ipx_interface *)kmalloc(sizeof(ipx_interface),GFP_ATOMIC);
	if(intrfc == NULL)
		return (-EAGAIN);
	intrfc->if_dev		= NULL;
	intrfc->if_netnum	= idef->ipx_network;
	intrfc->if_dlink_type 	= 0;
	intrfc->if_dlink 	= NULL;
	intrfc->if_sklist 	= NULL;
	intrfc->if_internal 	= 1;
	intrfc->if_ipx_offset 	= 0;
	intrfc->if_sknum 	= IPX_MIN_EPHEMERAL_SOCKET;
	memcpy((char *)&(intrfc->if_node), idef->ipx_node, IPX_NODE_LEN);
	ipx_internal_net 	= intrfc;
	ipx_primary_net 	= intrfc;
	spin_lock_init(&intrfc->if_sklist_lock);
	atomic_set(&intrfc->refcnt, 1);
	MOD_INC_USE_COUNT;
	ipxitf_hold(intrfc);
	ipxitf_insert(intrfc);

	ret = ipxitf_add_local_route(intrfc);
	ipxitf_put(intrfc);
	return ret;
}

static int ipx_map_frame_type(unsigned char type)
{
	switch(type) 
	{
		case IPX_FRAME_ETHERII:
			return (htons(ETH_P_IPX));

		case IPX_FRAME_8022:
			return (htons(ETH_P_802_2));

		case IPX_FRAME_SNAP:
			return (htons(ETH_P_SNAP));

		case IPX_FRAME_8023:
			return (htons(ETH_P_802_3));
	}

	return (0);
}

static int ipxitf_create(ipx_interface_definition *idef)
{
	struct net_device *dev;
	unsigned short dlink_type = 0;
	struct datalink_proto *datalink = NULL;
	ipx_interface *intrfc;
	int err;

	if(idef->ipx_special == IPX_INTERNAL)
		return (ipxitf_create_internal(idef));

	if((idef->ipx_special == IPX_PRIMARY) && (ipx_primary_net != NULL))
		return (-EEXIST);

	intrfc = ipxitf_find_using_net(idef->ipx_network);
	if(idef->ipx_network && intrfc != NULL) {
		ipxitf_put(intrfc);
		return (-EADDRINUSE);
	}

	if (intrfc)
		ipxitf_put(intrfc);

	dev = dev_get_by_name(idef->ipx_device);
	if(dev == NULL)
		return (-ENODEV);

	switch(idef->ipx_dlink_type) 
	{
		case IPX_FRAME_TR_8022:
			printk("IPX frame type 802.2TR is obsolete. Use 802.2 instead.\n");
			/* fall through */

		case IPX_FRAME_8022:
			dlink_type 	= htons(ETH_P_802_2);
			datalink 	= p8022_datalink;
			break;

		case IPX_FRAME_ETHERII:
			if (dev->type != ARPHRD_IEEE802)
			{
				dlink_type 	= htons(ETH_P_IPX);
				datalink 	= pEII_datalink;
				break;
			}
			else 
				printk("IPX frame type EtherII over token-ring is obsolete. Use SNAP instead.\n");
			/* fall through */

		case IPX_FRAME_SNAP:
			dlink_type 	= htons(ETH_P_SNAP);