ddp.c

linux 内核源代码

/*
 *	DDP:	An implementation of the AppleTalk DDP protocol for
 *		Ethernet 'ELAP'.
 *
 *		Alan Cox  <[e-mail]>
 *
 *		With more than a little assistance from
 *
 *		Wesley Craig <[e-mail]>
 *
 *	Fixes:
 *		Neil Horman		:	Added missing device ioctls
 *		Michael Callahan	:	Made routing work
 *		Wesley Craig		:	Fix probing to listen to a
 *						passed node id.
 *		Alan Cox		:	Added send/recvmsg support
 *		Alan Cox		:	Moved at. to protinfo in
 *						socket.
 *		Alan Cox		:	Added firewall hooks.
 *		Alan Cox		:	Supports new ARPHRD_LOOPBACK
 *		Christer Weinigel	: 	Routing and /proc fixes.
 *		Bradford Johnson	:	LocalTalk.
 *		Tom Dyas		:	Module support.
 *		Alan Cox		:	Hooks for PPP (based on the
 *						LocalTalk hook).
 *		Alan Cox		:	Posix bits
 *		Alan Cox/Mike Freeman	:	Possible fix to NBP problems
 *		Bradford Johnson	:	IP-over-DDP (experimental)
 *		Jay Schulist		:	Moved IP-over-DDP to its own
 *						driver file. (ipddp.c & ipddp.h)
 *		Jay Schulist		:	Made work as module with
 *						AppleTalk drivers, cleaned it.
 *		Rob Newberry		:	Added proxy AARP and AARP
 *						procfs, moved probing to AARP
 *						module.
 *              Adrian Sun/
 *              Michael Zuelsdorff      :       fix for net.0 packets. don't
 *                                              allow illegal ether/tokentalk
 *                                              port assignment. we lose a
 *                                              valid localtalk port as a
 *                                              result.
 *		Arnaldo C. de Melo	:	Cleanup, in preparation for
 *						shared skb support 8)
 *		Arnaldo C. de Melo	:	Move proc stuff to atalk_proc.c,
 *						use seq_file
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 */

#include <linux/capability.h>
#include <linux/module.h>
#include <linux/if_arp.h>
#include <linux/termios.h>	/* For TIOCOUTQ/INQ */
#include <net/datalink.h>
#include <net/psnap.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/route.h>
#include <linux/atalk.h>
#include "../core/kmap_skb.h"

struct datalink_proto *ddp_dl, *aarp_dl;
static const struct proto_ops atalk_dgram_ops;

/**************************************************************************\
*                                                                          *
* Handlers for the socket list.                                            *
*                                                                          *
\**************************************************************************/

HLIST_HEAD(atalk_sockets);
DEFINE_RWLOCK(atalk_sockets_lock);

static inline void __atalk_insert_socket(struct sock *sk)
{
	sk_add_node(sk, &atalk_sockets);
}

static inline void atalk_remove_socket(struct sock *sk)
{
	write_lock_bh(&atalk_sockets_lock);
	sk_del_node_init(sk);
	write_unlock_bh(&atalk_sockets_lock);
}

static struct sock *atalk_search_socket(struct sockaddr_at *to,
					struct atalk_iface *atif)
{
	struct sock *s;
	struct hlist_node *node;

	read_lock_bh(&atalk_sockets_lock);
	sk_for_each(s, node, &atalk_sockets) {
		struct atalk_sock *at = at_sk(s);

		if (to->sat_port != at->src_port)
			continue;

		if (to->sat_addr.s_net == ATADDR_ANYNET &&
		    to->sat_addr.s_node == ATADDR_BCAST)
			goto found;

		if (to->sat_addr.s_net == at->src_net &&
		    (to->sat_addr.s_node == at->src_node ||
		     to->sat_addr.s_node == ATADDR_BCAST ||
		     to->sat_addr.s_node == ATADDR_ANYNODE))
			goto found;

		/* XXXX.0 -- we got a request for this router. make sure
		 * that the node is appropriately set. */
		if (to->sat_addr.s_node == ATADDR_ANYNODE &&
		    to->sat_addr.s_net != ATADDR_ANYNET &&
		    atif->address.s_node == at->src_node) {
			to->sat_addr.s_node = atif->address.s_node;
			goto found;
		}
	}
	s = NULL;
found:
	read_unlock_bh(&atalk_sockets_lock);
	return s;
}

/**
 * atalk_find_or_insert_socket - Try to find a socket matching ADDR
 * @sk - socket to insert in the list if it is not there already
 * @sat - address to search for
 *
 * Try to find a socket matching ADDR in the socket list, if found then return
 * it. If not, insert SK into the socket list.
 *
 * This entire operation must execute atomically.
 */
static struct sock *atalk_find_or_insert_socket(struct sock *sk,
						struct sockaddr_at *sat)
{
	struct sock *s;
	struct hlist_node *node;
	struct atalk_sock *at;

	write_lock_bh(&atalk_sockets_lock);
	sk_for_each(s, node, &atalk_sockets) {
		at = at_sk(s);

		if (at->src_net == sat->sat_addr.s_net &&
		    at->src_node == sat->sat_addr.s_node &&
		    at->src_port == sat->sat_port)
			goto found;
	}
	s = NULL;
	__atalk_insert_socket(sk); /* Wheee, it's free, assign and insert. */
found:
	write_unlock_bh(&atalk_sockets_lock);
	return s;
}

static void atalk_destroy_timer(unsigned long data)
{
	struct sock *sk = (struct sock *)data;

	if (atomic_read(&sk->sk_wmem_alloc) ||
	    atomic_read(&sk->sk_rmem_alloc)) {
		sk->sk_timer.expires = jiffies + SOCK_DESTROY_TIME;
		add_timer(&sk->sk_timer);
	} else
		sock_put(sk);
}

static inline void atalk_destroy_socket(struct sock *sk)
{
	atalk_remove_socket(sk);
	skb_queue_purge(&sk->sk_receive_queue);

	if (atomic_read(&sk->sk_wmem_alloc) ||
	    atomic_read(&sk->sk_rmem_alloc)) {
		init_timer(&sk->sk_timer);
		sk->sk_timer.expires	= jiffies + SOCK_DESTROY_TIME;
		sk->sk_timer.function	= atalk_destroy_timer;
		sk->sk_timer.data	= (unsigned long)sk;
		add_timer(&sk->sk_timer);
	} else
		sock_put(sk);
}

/**************************************************************************\
*                                                                          *
* Routing tables for the AppleTalk socket layer.                           *
*                                                                          *
\**************************************************************************/

/* Anti-deadlock ordering is atalk_routes_lock --> iface_lock -DaveM */
struct atalk_route *atalk_routes;
DEFINE_RWLOCK(atalk_routes_lock);

struct atalk_iface *atalk_interfaces;
DEFINE_RWLOCK(atalk_interfaces_lock);

/* For probing devices or in a routerless network */
struct atalk_route atrtr_default;

/* AppleTalk interface control */
/*
 * Drop a device. Doesn't drop any of its routes - that is the caller's
 * problem. Called when we down the interface or delete the address.
 */
static void atif_drop_device(struct net_device *dev)
{
	struct atalk_iface **iface = &atalk_interfaces;
	struct atalk_iface *tmp;

	write_lock_bh(&atalk_interfaces_lock);
	while ((tmp = *iface) != NULL) {
		if (tmp->dev == dev) {
			*iface = tmp->next;
			dev_put(dev);
			kfree(tmp);
			dev->atalk_ptr = NULL;
		} else
			iface = &tmp->next;
	}
	write_unlock_bh(&atalk_interfaces_lock);
}

static struct atalk_iface *atif_add_device(struct net_device *dev,
					   struct atalk_addr *sa)
{
	struct atalk_iface *iface = kzalloc(sizeof(*iface), GFP_KERNEL);

	if (!iface)
		goto out;

	dev_hold(dev);
	iface->dev = dev;
	dev->atalk_ptr = iface;
	iface->address = *sa;
	iface->status = 0;

	write_lock_bh(&atalk_interfaces_lock);
	iface->next = atalk_interfaces;
	atalk_interfaces = iface;
	write_unlock_bh(&atalk_interfaces_lock);
out:
	return iface;
}

/* Perform phase 2 AARP probing on our tentative address */
static int atif_probe_device(struct atalk_iface *atif)
{
	int netrange = ntohs(atif->nets.nr_lastnet) -
			ntohs(atif->nets.nr_firstnet) + 1;
	int probe_net = ntohs(atif->address.s_net);
	int probe_node = atif->address.s_node;
	int netct, nodect;

	/* Offset the network we start probing with */
	if (probe_net == ATADDR_ANYNET) {
		probe_net = ntohs(atif->nets.nr_firstnet);
		if (netrange)
			probe_net += jiffies % netrange;
	}
	if (probe_node == ATADDR_ANYNODE)
		probe_node = jiffies & 0xFF;

	/* Scan the networks */
	atif->status |= ATIF_PROBE;
	for (netct = 0; netct <= netrange; netct++) {
		/* Sweep the available nodes from a given start */
		atif->address.s_net = htons(probe_net);
		for (nodect = 0; nodect < 256; nodect++) {
			atif->address.s_node = (nodect + probe_node) & 0xFF;
			if (atif->address.s_node > 0 &&
			    atif->address.s_node < 254) {
				/* Probe a proposed address */
				aarp_probe_network(atif);

				if (!(atif->status & ATIF_PROBE_FAIL)) {
					atif->status &= ~ATIF_PROBE;
					return 0;
				}
			}
			atif->status &= ~ATIF_PROBE_FAIL;
		}
		probe_net++;
		if (probe_net > ntohs(atif->nets.nr_lastnet))
			probe_net = ntohs(atif->nets.nr_firstnet);
	}
	atif->status &= ~ATIF_PROBE;

	return -EADDRINUSE;	/* Network is full... */
}


/* Perform AARP probing for a proxy address */
static int atif_proxy_probe_device(struct atalk_iface *atif,
				   struct atalk_addr* proxy_addr)
{
	int netrange = ntohs(atif->nets.nr_lastnet) -
			ntohs(atif->nets.nr_firstnet) + 1;
	/* we probe the interface's network */
	int probe_net = ntohs(atif->address.s_net);
	int probe_node = ATADDR_ANYNODE;	    /* we'll take anything */
	int netct, nodect;

	/* Offset the network we start probing with */
	if (probe_net == ATADDR_ANYNET) {
		probe_net = ntohs(atif->nets.nr_firstnet);
		if (netrange)
			probe_net += jiffies % netrange;
	}

	if (probe_node == ATADDR_ANYNODE)
		probe_node = jiffies & 0xFF;

	/* Scan the networks */
	for (netct = 0; netct <= netrange; netct++) {
		/* Sweep the available nodes from a given start */
		proxy_addr->s_net = htons(probe_net);
		for (nodect = 0; nodect < 256; nodect++) {
			proxy_addr->s_node = (nodect + probe_node) & 0xFF;
			if (proxy_addr->s_node > 0 &&
			    proxy_addr->s_node < 254) {
				/* Tell AARP to probe a proposed address */
				int ret = aarp_proxy_probe_network(atif,
								    proxy_addr);

				if (ret != -EADDRINUSE)
					return ret;
			}
		}
		probe_net++;
		if (probe_net > ntohs(atif->nets.nr_lastnet))
			probe_net = ntohs(atif->nets.nr_firstnet);
	}

	return -EADDRINUSE;	/* Network is full... */
}


struct atalk_addr *atalk_find_dev_addr(struct net_device *dev)
{
	struct atalk_iface *iface = dev->atalk_ptr;
	return iface ? &iface->address : NULL;
}

static struct atalk_addr *atalk_find_primary(void)
{
	struct atalk_iface *fiface = NULL;
	struct atalk_addr *retval;
	struct atalk_iface *iface;

	/*
	 * Return a point-to-point interface only if
	 * there is no non-ptp interface available.
	 */
	read_lock_bh(&atalk_interfaces_lock);
	for (iface = atalk_interfaces; iface; iface = iface->next) {
		if (!fiface && !(iface->dev->flags & IFF_LOOPBACK))
			fiface = iface;
		if (!(iface->dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))) {
			retval = &iface->address;
			goto out;
		}
	}

	if (fiface)
		retval = &fiface->address;
	else if (atalk_interfaces)
		retval = &atalk_interfaces->address;
	else
		retval = NULL;
out:
	read_unlock_bh(&atalk_interfaces_lock);
	return retval;
}

/*
 * Find a match for 'any network' - ie any of our interfaces with that
 * node number will do just nicely.
 */
static struct atalk_iface *atalk_find_anynet(int node, struct net_device *dev)
{
	struct atalk_iface *iface = dev->atalk_ptr;

	if (!iface || iface->status & ATIF_PROBE)
		goto out_err;

	if (node != ATADDR_BCAST &&
	    iface->address.s_node != node &&
	    node != ATADDR_ANYNODE)
		goto out_err;
out:
	return iface;
out_err:
	iface = NULL;
	goto out;
}

/* Find a match for a specific network:node pair */
static struct atalk_iface *atalk_find_interface(__be16 net, int node)
{
	struct atalk_iface *iface;

	read_lock_bh(&atalk_interfaces_lock);
	for (iface = atalk_interfaces; iface; iface = iface->next) {
		if ((node == ATADDR_BCAST ||
		     node == ATADDR_ANYNODE ||
		     iface->address.s_node == node) &&
		    iface->address.s_net == net &&
		    !(iface->status & ATIF_PROBE))
			break;

		/* XXXX.0 -- net.0 returns the iface associated with net */
		if (node == ATADDR_ANYNODE && net != ATADDR_ANYNET &&
		    ntohs(iface->nets.nr_firstnet) <= ntohs(net) &&
		    ntohs(net) <= ntohs(iface->nets.nr_lastnet))
			break;
	}
	read_unlock_bh(&atalk_interfaces_lock);
	return iface;
}


/*
 * Find a route for an AppleTalk packet. This ought to get cached in
 * the socket (later on...). We know about host routes and the fact
 * that a route must be direct to broadcast.
 */
static struct atalk_route *atrtr_find(struct atalk_addr *target)
{
	/*
	 * we must search through all routes unless we find a
	 * host route, because some host routes might overlap
	 * network routes
	 */
	struct atalk_route *net_route = NULL;
	struct atalk_route *r;

	read_lock_bh(&atalk_routes_lock);
	for (r = atalk_routes; r; r = r->next) {
		if (!(r->flags & RTF_UP))
			continue;

		if (r->target.s_net == target->s_net) {
			if (r->flags & RTF_HOST) {
				/*
				 * if this host route is for the target,
				 * the we're done
				 */
				if (r->target.s_node == target->s_node)
					goto out;
			} else
				/*
				 * this route will work if there isn't a
				 * direct host route, so cache it
				 */
				net_route = r;
		}
	}

	/*
	 * if we found a network route but not a direct host
	 * route, then return it
	 */
	if (net_route)
		r = net_route;
	else if (atrtr_default.dev)
		r = &atrtr_default;
	else /* No route can be found */
		r = NULL;
out:
	read_unlock_bh(&atalk_routes_lock);
	return r;
}


/*
 * Given an AppleTalk network, find the device to use. This can be
 * a simple lookup.
 */
struct net_device *atrtr_get_dev(struct atalk_addr *sa)
{
	struct atalk_route *atr = atrtr_find(sa);