af_x25.c

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/*
 *	X.25 Packet Layer release 002
 *
 *	This is ALPHA test software. This code may break your machine, randomly fail to work with new 
 *	releases, misbehave and/or generally screw up. It might even work. 
 *
 *	This code REQUIRES 2.1.15 or higher
 *
 *	This module:
 *		This module 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.
 *
 *	History
 *	X.25 001	Jonathan Naylor	Started coding.
 *	X.25 002	Jonathan Naylor	Centralised disconnect handling.
 *					New timer architecture.
 *	2000-03-11	Henner Eisen	MSG_EOR handling more POSIX compliant.
 *	2000-03-22	Daniela Squassoni Allowed disabling/enabling of 
 *					  facilities negotiation and increased 
 *					  the throughput upper limit.
 *	2000-08-27	Arnaldo C. Melo s/suser/capable/ + micro cleanups
 *	2000-09-04	Henner Eisen	Set sock->state in x25_accept(). 
 *					Fixed x25_output() related skb leakage.
 *	2000-10-02	Henner Eisen	Made x25_kick() single threaded per socket.
 *	2000-10-27	Henner Eisen    MSG_DONTWAIT for fragment allocation.
 *	2000-11-14	Henner Eisen    Closing datalink from NETDEV_GOING_DOWN
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/stat.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <asm/segment.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/fcntl.h>
#include <linux/termios.h>	/* For TIOCINQ/OUTQ */
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <net/x25.h>

int sysctl_x25_restart_request_timeout = X25_DEFAULT_T20;
int sysctl_x25_call_request_timeout    = X25_DEFAULT_T21;
int sysctl_x25_reset_request_timeout   = X25_DEFAULT_T22;
int sysctl_x25_clear_request_timeout   = X25_DEFAULT_T23;
int sysctl_x25_ack_holdback_timeout    = X25_DEFAULT_T2;

static struct sock *volatile x25_list /* = NULL initially */;

static struct proto_ops x25_proto_ops;

static x25_address null_x25_address = {"               "};

int x25_addr_ntoa(unsigned char *p, x25_address *called_addr, x25_address *calling_addr)
{
	int called_len, calling_len;
	char *called, *calling;
	int i;

	called_len  = (*p >> 0) & 0x0F;
	calling_len = (*p >> 4) & 0x0F;

	called  = called_addr->x25_addr;
	calling = calling_addr->x25_addr;
	p++;

	for (i = 0; i < (called_len + calling_len); i++) {
		if (i < called_len) {
			if (i % 2 != 0) {
				*called++ = ((*p >> 0) & 0x0F) + '0';
				p++;
			} else {
				*called++ = ((*p >> 4) & 0x0F) + '0';
			}
		} else {
			if (i % 2 != 0) {
				*calling++ = ((*p >> 0) & 0x0F) + '0';
				p++;
			} else {
				*calling++ = ((*p >> 4) & 0x0F) + '0';
			}
		}
	}

	*called  = '\0';
	*calling = '\0';

	return 1 + (called_len + calling_len + 1) / 2;
}

int x25_addr_aton(unsigned char *p, x25_address *called_addr, x25_address *calling_addr)
{
	unsigned int called_len, calling_len;
	char *called, *calling;
	int i;

	called  = called_addr->x25_addr;
	calling = calling_addr->x25_addr;

	called_len  = strlen(called);
	calling_len = strlen(calling);

	*p++ = (calling_len << 4) | (called_len << 0);

	for (i = 0; i < (called_len + calling_len); i++) {
		if (i < called_len) {
			if (i % 2 != 0) {
				*p |= (*called++ - '0') << 0;
				p++;
			} else {
				*p = 0x00;
				*p |= (*called++ - '0') << 4;
			}
		} else {
			if (i % 2 != 0) {
				*p |= (*calling++ - '0') << 0;
				p++;
			} else {
				*p = 0x00;
				*p |= (*calling++ - '0') << 4;
			}
		}
	}

	return 1 + (called_len + calling_len + 1) / 2;
}

/*
 *	Socket removal during an interrupt is now safe.
 */
static void x25_remove_socket(struct sock *sk)
{
	struct sock *s;
	unsigned long flags;

	save_flags(flags);
	cli();

	if ((s = x25_list) == sk) {
		x25_list = s->next;
		restore_flags(flags);
		return;
	}

	while (s != NULL && s->next != NULL) {
		if (s->next == sk) {
			s->next = sk->next;
			restore_flags(flags);
			return;
		}

		s = s->next;
	}

	restore_flags(flags);
}

/*
 *	Kill all bound sockets on a dropped device.
 */
static void x25_kill_by_device(struct net_device *dev)
{
	struct sock *s;

	for (s = x25_list; s != NULL; s = s->next)
		if (s->protinfo.x25->neighbour &&
		    s->protinfo.x25->neighbour->dev == dev)
			x25_disconnect(s, ENETUNREACH, 0, 0);
}

/*
 *	Handle device status changes.
 */
static int x25_device_event(struct notifier_block *this, unsigned long event, void *ptr)
{
	struct net_device *dev = (struct net_device *)ptr;
	struct x25_neigh *neigh;

	if (dev->type == ARPHRD_X25
#if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
	 || dev->type == ARPHRD_ETHER
#endif
	 ) {
		switch (event) {
			case NETDEV_UP:
				x25_link_device_up(dev);
				break;
			case NETDEV_GOING_DOWN:
				if ((neigh = x25_get_neigh(dev)))
					x25_terminate_link(neigh);
				break;
			case NETDEV_DOWN:
				x25_kill_by_device(dev);
				x25_route_device_down(dev);
				x25_link_device_down(dev);
				break;
		}
	}

	return NOTIFY_DONE;
}

/*
 *	Add a socket to the bound sockets list.
 */
static void x25_insert_socket(struct sock *sk)
{
	unsigned long flags;

	save_flags(flags);
	cli();

	sk->next = x25_list;
	x25_list = sk;

	restore_flags(flags);
}

/*
 *	Find a socket that wants to accept the Call Request we just
 *	received.
 */
static struct sock *x25_find_listener(x25_address *addr)
{
	unsigned long flags;
	struct sock *s;

	save_flags(flags);
	cli();

	for (s = x25_list; s != NULL; s = s->next) {
		if ((strcmp(addr->x25_addr, s->protinfo.x25->source_addr.x25_addr) == 0 ||
		     strcmp(addr->x25_addr, null_x25_address.x25_addr) == 0) &&
		     s->state == TCP_LISTEN) {
			restore_flags(flags);
			return s;
		}
	}

	restore_flags(flags);
	return NULL;
}

/*
 *	Find a connected X.25 socket given my LCI and neighbour.
 */
struct sock *x25_find_socket(unsigned int lci, struct x25_neigh *neigh)
{
	struct sock *s;
	unsigned long flags;

	save_flags(flags);
	cli();

	for (s = x25_list; s != NULL; s = s->next) {
		if (s->protinfo.x25->lci == lci && s->protinfo.x25->neighbour == neigh) {
			restore_flags(flags);
			return s;
		}
	}

	restore_flags(flags);
	return NULL;
}

/*
 *	Find a unique LCI for a given device.
 */
unsigned int x25_new_lci(struct x25_neigh *neigh)
{
	unsigned int lci = 1;

	while (x25_find_socket(lci, neigh) != NULL) {
		lci++;
		if (lci == 4096) return 0;
	}

	return lci;
}

/*
 *	Deferred destroy.
 */
void x25_destroy_socket(struct sock *);

/*
 *	handler for deferred kills.
 */
static void x25_destroy_timer(unsigned long data)
{
	x25_destroy_socket((struct sock *)data);
}

/*
 *	This is called from user mode and the timers. Thus it protects itself against
 *	interrupt users but doesn't worry about being called during work.
 *	Once it is removed from the queue no interrupt or bottom half will
 *	touch it and we are (fairly 8-) ) safe.
 */
void x25_destroy_socket(struct sock *sk)	/* Not static as it's used by the timer */
{
	struct sk_buff *skb;
	unsigned long flags;

	save_flags(flags);
	cli();

	x25_stop_heartbeat(sk);
	x25_stop_timer(sk);

	x25_remove_socket(sk);
	x25_clear_queues(sk);		/* Flush the queues */

	while ((skb = skb_dequeue(&sk->receive_queue)) != NULL) {
		if (skb->sk != sk) {		/* A pending connection */
			skb->sk->dead = 1;	/* Queue the unaccepted socket for death */
			x25_start_heartbeat(skb->sk);
			skb->sk->protinfo.x25->state = X25_STATE_0;
		}

		kfree_skb(skb);
	}

	if (atomic_read(&sk->wmem_alloc) != 0 || atomic_read(&sk->rmem_alloc) != 0) {
		/* Defer: outstanding buffers */
		init_timer(&sk->timer);
		sk->timer.expires  = jiffies + 10 * HZ;
		sk->timer.function = x25_destroy_timer;
		sk->timer.data     = (unsigned long)sk;
		add_timer(&sk->timer);
	} else {
		sk_free(sk);
		MOD_DEC_USE_COUNT;
	}

	restore_flags(flags);
}

/*
 *	Handling for system calls applied via the various interfaces to a
 *	X.25 socket object.
 */

static int x25_setsockopt(struct socket *sock, int level, int optname,
	char *optval, int optlen)
{
	struct sock *sk = sock->sk;
	int opt;

	if (level != SOL_X25)
		return -ENOPROTOOPT;

	if (optlen < sizeof(int))
		return-EINVAL;

	if (get_user(opt, (int *)optval))
		return -EFAULT;

	switch (optname) {
		case X25_QBITINCL:
			sk->protinfo.x25->qbitincl = opt ? 1 : 0;
			return 0;

		default:
			return -ENOPROTOOPT;
	}
}

static int x25_getsockopt(struct socket *sock, int level, int optname,
	char *optval, int *optlen)
{
	struct sock *sk = sock->sk;
	int val = 0;
	int len; 
	
	if (level != SOL_X25)
		return -ENOPROTOOPT;

	if (get_user(len, optlen))
		return -EFAULT;

	switch (optname) {
		case X25_QBITINCL:
			val = sk->protinfo.x25->qbitincl;
			break;

		default:
			return -ENOPROTOOPT;
	}

	len = min(len, sizeof(int));

	if (put_user(len, optlen))
		return -EFAULT;

	return copy_to_user(optval, &val, len) ? -EFAULT : 0;
}

static int x25_listen(struct socket *sock, int backlog)
{
	struct sock *sk = sock->sk;

	if (sk->state != TCP_LISTEN) {
		memset(&sk->protinfo.x25->dest_addr, '\0', X25_ADDR_LEN);
		sk->max_ack_backlog = backlog;
		sk->state           = TCP_LISTEN;
		return 0;
	}

	return -EOPNOTSUPP;
}

static struct sock *x25_alloc_socket(void)
{
	struct sock *sk;
	x25_cb *x25;

	if ((sk = sk_alloc(AF_X25, GFP_ATOMIC, 1)) == NULL)
		return NULL;

	if ((x25 = kmalloc(sizeof(*x25), GFP_ATOMIC)) == NULL) {
		sk_free(sk);
		return NULL;
	}

	memset(x25, 0x00, sizeof(*x25));

	x25->sk          = sk;
	sk->protinfo.x25 = x25;

	MOD_INC_USE_COUNT;

	sock_init_data(NULL, sk);

	skb_queue_head_init(&x25->ack_queue);
	skb_queue_head_init(&x25->fragment_queue);
	skb_queue_head_init(&x25->interrupt_in_queue);
	skb_queue_head_init(&x25->interrupt_out_queue);

	return sk;
}