ddp.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

	tosat.sat_addr.s_node = ddp->deh_dnode;
	tosat.sat_port = ddp->deh_dport;

	sock = atalk_search_socket(&tosat, atif);
	if (!sock) /* But not one of our sockets */
		goto freeit;

	/* Queue packet (standard) */
	skb->sk = sock;

	if (sock_queue_rcv_skb(sock, skb) < 0)
		goto freeit;
	goto out;
freeit:	kfree_skb(skb);
out:	return 0;
}

/*
 * Receive a LocalTalk frame. We make some demands on the caller here.
 * Caller must provide enough headroom on the packet to pull the short
 * header and append a long one.
 */
static int ltalk_rcv(struct sk_buff *skb, struct net_device *dev,
			struct packet_type *pt)
{
	struct ddpehdr *ddp;
	struct at_addr *ap;

	/* Expand any short form frames */
	if (skb->mac.raw[2] == 1) {
		/* Find our address */

		ap = atalk_find_dev_addr(dev);
		if (!ap || skb->len < sizeof(struct ddpshdr)) {
			kfree_skb(skb);
			return 0;
		}

		/*
		 * The push leaves us with a ddephdr not an shdr, and
		 * handily the port bytes in the right place preset.
		 */

		skb_push(skb, sizeof(*ddp) - 4);
		ddp = (struct ddpehdr *)skb->data;

		/* Now fill in the long header */

	 	/*
	 	 * These two first. The mac overlays the new source/dest
	 	 * network information so we MUST copy these before
	 	 * we write the network numbers !
	 	 */

		ddp->deh_dnode = skb->mac.raw[0];     /* From physical header */
		ddp->deh_snode = skb->mac.raw[1];     /* From physical header */

		ddp->deh_dnet  = ap->s_net;	/* Network number */
		ddp->deh_snet  = ap->s_net;
		ddp->deh_sum   = 0;		/* No checksum */
		/*
		 * Not sure about this bit...
		 */
		ddp->deh_len   = skb->len;
		ddp->deh_hops  = DDP_MAXHOPS;	/* Non routable, so force a drop
						   if we slip up later */
		/* Mend the byte order */
		*((__u16 *)ddp) = htons(*((__u16 *)ddp));
	}
	skb->h.raw = skb->data;

	return atalk_rcv(skb, dev, pt);
}

static int atalk_sendmsg(struct socket *sock, struct msghdr *msg, int len,
				struct scm_cookie *scm)
{
	struct sock *sk = sock->sk;
	struct sockaddr_at *usat = (struct sockaddr_at *)msg->msg_name;
	int flags = msg->msg_flags;
	int loopback = 0;
	struct sockaddr_at local_satalk, gsat;
	struct sk_buff *skb;
	struct net_device *dev;
	struct ddpehdr *ddp;
	int size;
	struct atalk_route *rt;
	int err;

	if (flags & ~MSG_DONTWAIT)
		return -EINVAL;

	if (len > DDP_MAXSZ)
		return -EMSGSIZE;

	if (usat) {
		if (sk->zapped)
			if (atalk_autobind(sk) < 0)
				return -EBUSY;

		if (msg->msg_namelen < sizeof(*usat) ||
		    usat->sat_family != AF_APPLETALK)
			return -EINVAL;

		/* netatalk doesn't implement this check */
		if (usat->sat_addr.s_node == ATADDR_BCAST && !sk->broadcast) {
			printk(KERN_INFO "SO_BROADCAST: Fix your netatalk as "
					 "it will break before 2.2\n");
#if 0
			return -EPERM;
#endif
		}
	} else {
		if (sk->state != TCP_ESTABLISHED)
			return -ENOTCONN;
		usat = &local_satalk;
		usat->sat_family = AF_APPLETALK;
		usat->sat_port   = sk->protinfo.af_at.dest_port;
		usat->sat_addr.s_node = sk->protinfo.af_at.dest_node;
		usat->sat_addr.s_net  = sk->protinfo.af_at.dest_net;
	}

	/* Build a packet */
	SOCK_DEBUG(sk, "SK %p: Got address.\n", sk);

	/* For headers */
	size = sizeof(struct ddpehdr) + len + ddp_dl->header_length;

	if (usat->sat_addr.s_net || usat->sat_addr.s_node == ATADDR_ANYNODE) {
		rt = atrtr_find(&usat->sat_addr);
		if (!rt)
			return -ENETUNREACH;

		dev = rt->dev;
	} else {
		struct at_addr at_hint;

		at_hint.s_node = 0;
		at_hint.s_net  = sk->protinfo.af_at.src_net;

		rt = atrtr_find(&at_hint);
		if (!rt)
			return -ENETUNREACH;

		dev = rt->dev;
	}

	SOCK_DEBUG(sk, "SK %p: Size needed %d, device %s\n",
			sk, size, dev->name);

	size += dev->hard_header_len;
	skb = sock_alloc_send_skb(sk, size, (flags & MSG_DONTWAIT), &err);
	if (!skb)
		return err;
	
	skb->sk = sk;
	skb_reserve(skb, ddp_dl->header_length);
	skb_reserve(skb, dev->hard_header_len);
	skb->dev = dev;

	SOCK_DEBUG(sk, "SK %p: Begin build.\n", sk);

	ddp = (struct ddpehdr *)skb_put(skb, sizeof(struct ddpehdr));
	ddp->deh_pad  = 0;
	ddp->deh_hops = 0;
	ddp->deh_len  = len + sizeof(*ddp);
	/*
	 * Fix up the length field [Ok this is horrible but otherwise
	 * I end up with unions of bit fields and messy bit field order
	 * compiler/endian dependencies..
	 */
	*((__u16 *)ddp) = ntohs(*((__u16 *)ddp));

	ddp->deh_dnet  = usat->sat_addr.s_net;
	ddp->deh_snet  = sk->protinfo.af_at.src_net;
	ddp->deh_dnode = usat->sat_addr.s_node;
	ddp->deh_snode = sk->protinfo.af_at.src_node;
	ddp->deh_dport = usat->sat_port;
	ddp->deh_sport = sk->protinfo.af_at.src_port;

	SOCK_DEBUG(sk, "SK %p: Copy user data (%d bytes).\n", sk, len);

	err = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
	if (err) {
		kfree_skb(skb);
		return -EFAULT;
	}

	if (sk->no_check == 1)
		ddp->deh_sum = 0;
	else
		ddp->deh_sum = atalk_checksum(ddp, len + sizeof(*ddp));

	/*
	 * Loopback broadcast packets to non gateway targets (ie routes
	 * to group we are in)
	 */
	if (ddp->deh_dnode == ATADDR_BCAST &&
	    !(rt->flags & RTF_GATEWAY) && !(dev->flags & IFF_LOOPBACK)) {
		struct sk_buff *skb2 = skb_copy(skb, GFP_KERNEL);

		if (skb2) {
			loopback = 1;
			SOCK_DEBUG(sk, "SK %p: send out(copy).\n", sk);
			if (aarp_send_ddp(dev, skb2,
					  &usat->sat_addr, NULL) == -1)
				kfree_skb(skb2);
				/* else queued/sent above in the aarp queue */
		}
	}

	if (dev->flags & IFF_LOOPBACK || loopback) {
		SOCK_DEBUG(sk, "SK %p: Loop back.\n", sk);
		/* loop back */
		skb_orphan(skb);
		ddp_dl->datalink_header(ddp_dl, skb, dev->dev_addr);
		skb->mac.raw = skb->data;
		skb->h.raw   = skb->data + ddp_dl->header_length +
				dev->hard_header_len;
		skb_pull(skb, dev->hard_header_len);
		skb_pull(skb, ddp_dl->header_length);
		atalk_rcv(skb, dev, NULL);
	} else {
		SOCK_DEBUG(sk, "SK %p: send out.\n", sk);
		if (rt->flags & RTF_GATEWAY) {
		    gsat.sat_addr = rt->gateway;
		    usat = &gsat;
		}

		if (aarp_send_ddp(dev, skb, &usat->sat_addr, NULL) == -1)
			kfree_skb(skb);
		/* else queued/sent above in the aarp queue */
	}
	SOCK_DEBUG(sk, "SK %p: Done write (%d).\n", sk, len);

	return len;
}

static int atalk_recvmsg(struct socket *sock, struct msghdr *msg, int size,
			 int flags, struct scm_cookie *scm)
{
	struct sock *sk = sock->sk;
	struct sockaddr_at *sat = (struct sockaddr_at *)msg->msg_name;
	struct ddpehdr *ddp = NULL;
	int copied = 0;
	int err = 0;
        struct ddpebits ddphv;
	struct sk_buff *skb;

	skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT,
				flags & MSG_DONTWAIT, &err);
	if (!skb)
		return err;

	ddp = (struct ddpehdr *)(skb->h.raw);
	*((__u16 *)&ddphv) = ntohs(*((__u16 *)ddp));

	if (sk->type == SOCK_RAW) {
		copied = ddphv.deh_len;
		if (copied > size) {
			copied = size;
			msg->msg_flags |= MSG_TRUNC;
		}

		err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
	} else {
		copied = ddphv.deh_len - sizeof(*ddp);
		if (copied > size) {
			copied = size;
			msg->msg_flags |= MSG_TRUNC;
		}
		err = skb_copy_datagram_iovec(skb, sizeof(*ddp),
						msg->msg_iov, copied);
	}

	if (!err) {
		if (sat) {
			sat->sat_family      = AF_APPLETALK;
			sat->sat_port        = ddp->deh_sport;
			sat->sat_addr.s_node = ddp->deh_snode;
			sat->sat_addr.s_net  = ddp->deh_snet;
		}
		msg->msg_namelen = sizeof(*sat);
	}

	skb_free_datagram(sk, skb);	/* Free the datagram. */
	return err ? err : copied;
}


/*
 * AppleTalk ioctl calls.
 */
static int atalk_ioctl(struct socket *sock,unsigned int cmd, unsigned long arg)
{
	long amount = 0;
	struct sock *sk = sock->sk;

	switch (cmd) {
		/* Protocol layer */
		case TIOCOUTQ:
			amount = sk->sndbuf - atomic_read(&sk->wmem_alloc);
			if (amount < 0)
				amount = 0;
			break;
		case TIOCINQ:
		{
			/* These two are safe on a single CPU system as only
			 * user tasks fiddle here */
			struct sk_buff *skb = skb_peek(&sk->receive_queue);

			if (skb)
				amount = skb->len-sizeof(struct ddpehdr);
			break;
		}
		case SIOCGSTAMP:
			if (!sk)
				return -EINVAL;
			if (!sk->stamp.tv_sec)
				return -ENOENT;
			return copy_to_user((void *)arg, &sk->stamp,
					sizeof(struct timeval)) ? -EFAULT : 0;
		/* Routing */
		case SIOCADDRT:
		case SIOCDELRT:
			if (!capable(CAP_NET_ADMIN))
				return -EPERM;
			return atrtr_ioctl(cmd, (void *)arg);
		/* Interface */
		case SIOCGIFADDR:
		case SIOCSIFADDR:
		case SIOCGIFBRDADDR:
		case SIOCATALKDIFADDR:
		case SIOCDIFADDR:
		case SIOCSARP:	/* proxy AARP */
		case SIOCDARP:	/* proxy AARP */
		{
			int ret;

			rtnl_lock();
			ret = atif_ioctl(cmd, (void *)arg);
			rtnl_unlock();

			return ret;
		}
		/* Physical layer ioctl calls */
		case SIOCSIFLINK:
		case SIOCGIFHWADDR:
		case SIOCSIFHWADDR:
		case SIOCGIFFLAGS:
		case SIOCSIFFLAGS:
		case SIOCGIFMTU:
		case SIOCGIFCONF:
		case SIOCADDMULTI:
		case SIOCDELMULTI:
		case SIOCGIFCOUNT:
		case SIOCGIFINDEX:
		case SIOCGIFNAME:
			return dev_ioctl(cmd,(void *) arg);
		case SIOCSIFMETRIC:
		case SIOCSIFBRDADDR:
		case SIOCGIFNETMASK:
		case SIOCSIFNETMASK:
		case SIOCGIFMEM:
		case SIOCSIFMEM:
		case SIOCGIFDSTADDR:
		case SIOCSIFDSTADDR:
			return -EINVAL;
		default:
			return -EINVAL;
	}

	return put_user(amount, (int *)arg);
}

static struct net_proto_family atalk_family_ops =
{
	PF_APPLETALK,
	atalk_create
};

static struct proto_ops SOCKOPS_WRAPPED(atalk_dgram_ops)=
{
	family:		PF_APPLETALK,

	release:	atalk_release,
	bind:		atalk_bind,
	connect:	atalk_connect,
	socketpair:	sock_no_socketpair,
	accept:		sock_no_accept,
	getname:	atalk_getname,
	poll:		datagram_poll,
	ioctl:		atalk_ioctl,
	listen:		sock_no_listen,
	shutdown:	sock_no_shutdown,
	setsockopt:	sock_no_setsockopt,
	getsockopt:	sock_no_getsockopt,
	sendmsg:	atalk_sendmsg,
	recvmsg:	atalk_recvmsg,
	mmap:		sock_no_mmap,
	sendpage:	sock_no_sendpage,
};

#include <linux/smp_lock.h>
SOCKOPS_WRAP(atalk_dgram, PF_APPLETALK);

static struct notifier_block ddp_notifier=
{
	ddp_device_event,
	NULL,
	0
};

struct packet_type ltalk_packet_type=
{
	0,
	NULL,
	ltalk_rcv,
	NULL,
	NULL
};

struct packet_type ppptalk_packet_type=
{
	0,
	NULL,
	atalk_rcv,
	NULL,
	NULL
};

static char ddp_snap_id[] = {0x08, 0x00, 0x07, 0x80, 0x9B};

/* Export symbols for use by drivers when AppleTalk is a module */
EXPORT_SYMBOL(aarp_send_ddp);
EXPORT_SYMBOL(atrtr_get_dev);
EXPORT_SYMBOL(atalk_find_dev_addr);

/* Called by proto.c on kernel start up */
static int __init atalk_init(void)
{
	(void) sock_register(&atalk_family_ops);
	ddp_dl = register_snap_client(ddp_snap_id, atalk_rcv);
	if (!ddp_dl)
		printk(KERN_CRIT "Unable to register DDP with SNAP.\n");

	ltalk_packet_type.type = htons(ETH_P_LOCALTALK);
	dev_add_pack(&ltalk_packet_type);

	ppptalk_packet_type.type = htons(ETH_P_PPPTALK);
	dev_add_pack(&ppptalk_packet_type);

	register_netdevice_notifier(&ddp_notifier);
	aarp_proto_init();

	proc_net_create("appletalk", 0, atalk_get_info);
	proc_net_create("atalk_route", 0, atalk_rt_get_info);
	proc_net_create("atalk_iface", 0, atalk_if_get_info);
#ifdef CONFIG_PROC_FS
	aarp_register_proc_fs();
#endif /* CONFIG_PROC_FS */
#ifdef CONFIG_SYSCTL
	atalk_register_sysctl();
#endif /* CONFIG_SYSCTL */
	printk(KERN_INFO "NET4: AppleTalk 0.18a for Linux NET4.0\n");
	return 0;
}
module_init(atalk_init);

#ifdef MODULE
/*
 * Note on MOD_{INC,DEC}_USE_COUNT:
 *
 * Use counts are incremented/decremented when
 * sockets are created/deleted.
 *
 * AppleTalk interfaces are not incremented until atalkd is run
 * and are only decremented when they are downed.
 *
 * Ergo, before the AppleTalk module can be removed, all AppleTalk
 * sockets be closed from user space.
 */
static void __exit atalk_exit(void)
{
#ifdef CONFIG_SYSCTL
	atalk_unregister_sysctl();
#endif /* CONFIG_SYSCTL */
	proc_net_remove("appletalk");
	proc_net_remove("atalk_route");
	proc_net_remove("atalk_iface");
#ifdef CONFIG_PROC_FS
	aarp_unregister_proc_fs();
#endif /* CONFIG_PROC_FS */
	aarp_cleanup_module();	/* General aarp clean-up. */
	unregister_netdevice_notifier(&ddp_notifier);
	dev_remove_pack(&ltalk_packet_type);
	dev_remove_pack(&ppptalk_packet_type);
	unregister_snap_client(ddp_snap_id);
	sock_unregister(PF_APPLETALK);
}
module_exit(atalk_exit);
#endif  /* MODULE */
#endif  /* CONFIG_ATALK || CONFIG_ATALK_MODULE */