af_x25.c

之前积累的一个X25在LINUX下的协议实现代码,现在估计应该比较少见了,应该是收藏的东西

/*
 *	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
 *	2002-10-06	Arnaldo C. Melo Get rid of cli/sti, move proc stuff to
 *					x25_proc.c, using seq_file
 *	2005-04-02	Shaun Pereira	Selective sub address matching
 *					with call user data
 *	2005-04-15	Shaun Pereira	Fast select with no restriction on
 *					response
 */

#include <linux/module.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <asm/uaccess.h>
#include <linux/fcntl.h>
#include <linux/termios.h>	/* For TIOCINQ/OUTQ */
#include <linux/notifier.h>
#include <linux/init.h>
#include <linux/compat.h>

#include <net/x25.h>
#include <net/compat.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;

HLIST_HEAD(x25_list);
DEFINE_RWLOCK(x25_list_lock);

static const struct proto_ops x25_proto_ops;

static struct x25_address null_x25_address = {"               "};

#ifdef CONFIG_COMPAT
struct compat_x25_subscrip_struct {
	char device[200-sizeof(compat_ulong_t)];
	compat_ulong_t global_facil_mask;
	compat_uint_t extended;
};
#endif

int x25_addr_ntoa(unsigned char *p, struct x25_address *called_addr,
		  struct 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 = *calling = '\0';

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

int x25_addr_aton(unsigned char *p, struct x25_address *called_addr,
		  struct 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)
{
	write_lock_bh(&x25_list_lock);
	sk_del_node_init(sk);
	write_unlock_bh(&x25_list_lock);
}

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

	write_lock_bh(&x25_list_lock);

	sk_for_each(s, node, &x25_list)
		if (x25_sk(s)->neighbour && x25_sk(s)->neighbour->dev == dev)
			x25_disconnect(s, ENETUNREACH, 0, 0);

	write_unlock_bh(&x25_list_lock);
}

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

	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:
				nb = x25_get_neigh(dev);
				if (nb) {
					x25_terminate_link(nb);
					x25_neigh_put(nb);
				}
				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)
{
	write_lock_bh(&x25_list_lock);
	sk_add_node(sk, &x25_list);
	write_unlock_bh(&x25_list_lock);
}

/*
 *	Find a socket that wants to accept the Call Request we just
 *	received. Check the full list for an address/cud match.
 *	If no cuds match return the next_best thing, an address match.
 *	Note: if a listening socket has cud set it must only get calls
 *	with matching cud.
 */
static struct sock *x25_find_listener(struct x25_address *addr,
					struct sk_buff *skb)
{
	struct sock *s;
	struct sock *next_best;
	struct hlist_node *node;

	read_lock_bh(&x25_list_lock);
	next_best = NULL;

	sk_for_each(s, node, &x25_list)
		if ((!strcmp(addr->x25_addr,
			x25_sk(s)->source_addr.x25_addr) ||
				!strcmp(addr->x25_addr,
					null_x25_address.x25_addr)) &&
					s->sk_state == TCP_LISTEN) {
			/*
			 * Found a listening socket, now check the incoming
			 * call user data vs this sockets call user data
			 */
			if(skb->len > 0 && x25_sk(s)->cudmatchlength > 0) {
			 	if((memcmp(x25_sk(s)->calluserdata.cuddata,
			 		skb->data,
					x25_sk(s)->cudmatchlength)) == 0) {
					sock_hold(s);
					goto found;
				 }
			} else
				next_best = s;
		}
	if (next_best) {
		s = next_best;
		sock_hold(s);
		goto found;
	}
	s = NULL;
found:
	read_unlock_bh(&x25_list_lock);
	return s;
}

/*
 *	Find a connected X.25 socket given my LCI and neighbour.
 */
static struct sock *__x25_find_socket(unsigned int lci, struct x25_neigh *nb)
{
	struct sock *s;
	struct hlist_node *node;

	sk_for_each(s, node, &x25_list)
		if (x25_sk(s)->lci == lci && x25_sk(s)->neighbour == nb) {
			sock_hold(s);
			goto found;
		}
	s = NULL;
found:
	return s;
}

struct sock *x25_find_socket(unsigned int lci, struct x25_neigh *nb)
{
	struct sock *s;

	read_lock_bh(&x25_list_lock);
	s = __x25_find_socket(lci, nb);
	read_unlock_bh(&x25_list_lock);
	return s;
}

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

	read_lock_bh(&x25_list_lock);

	while ((sk = __x25_find_socket(lci, nb)) != NULL) {
		sock_put(sk);
		if (++lci == 4096) {
			lci = 0;
			break;
		}
	}

	read_unlock_bh(&x25_list_lock);
	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.
 *	Not static as it's used by the timer
 */
void x25_destroy_socket(struct sock *sk)
{
	struct sk_buff *skb;

	sock_hold(sk);
	lock_sock(sk);
	x25_stop_heartbeat(sk);
	x25_stop_timer(sk);

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

	while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
		if (skb->sk != sk) {		/* A pending connection */
			/*
			 * Queue the unaccepted socket for death
			 */
			sock_set_flag(skb->sk, SOCK_DEAD);
			x25_start_heartbeat(skb->sk);
			x25_sk(skb->sk)->state = X25_STATE_0;
		}

		kfree_skb(skb);
	}

	if (atomic_read(&sk->sk_wmem_alloc) ||
	    atomic_read(&sk->sk_rmem_alloc)) {
		/* Defer: outstanding buffers */
		sk->sk_timer.expires  = jiffies + 10 * HZ;
		sk->sk_timer.function = x25_destroy_timer;
		sk->sk_timer.data = (unsigned long)sk;
		add_timer(&sk->sk_timer);
	} else {
		/* drop last reference so sock_put will free */
		__sock_put(sk);
	}

	release_sock(sk);
	sock_put(sk);
}

/*
 *	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 __user *optval, int optlen)
{
	int opt;
	struct sock *sk = sock->sk;
	int rc = -ENOPROTOOPT;

	if (level != SOL_X25 || optname != X25_QBITINCL)
		goto out;

	rc = -EINVAL;
	if (optlen < sizeof(int))
		goto out;

	rc = -EFAULT;
	if (get_user(opt, (int __user *)optval))
		goto out;

	x25_sk(sk)->qbitincl = !!opt;
	rc = 0;
out:
	return rc;
}

static int x25_getsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, int __user *optlen)
{
	struct sock *sk = sock->sk;
	int val, len, rc = -ENOPROTOOPT;
	
	if (level != SOL_X25 || optname != X25_QBITINCL)
		goto out;

	rc = -EFAULT;
	if (get_user(len, optlen))
		goto out;

	len = min_t(unsigned int, len, sizeof(int));

	rc = -EINVAL;
	if (len < 0)
		goto out;
		
	rc = -EFAULT;
	if (put_user(len, optlen))
		goto out;

	val = x25_sk(sk)->qbitincl;
	rc = copy_to_user(optval, &val, len) ? -EFAULT : 0;
out:
	return rc;
}

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

	if (sk->sk_state != TCP_LISTEN) {
		memset(&x25_sk(sk)->dest_addr, 0, X25_ADDR_LEN);
		sk->sk_max_ack_backlog = backlog;
		sk->sk_state           = TCP_LISTEN;
		rc = 0;
	}

	return rc;
}

static struct proto x25_proto = {
	.name	  = "X25",
	.owner	  = THIS_MODULE,
	.obj_size = sizeof(struct x25_sock),
};

static struct sock *x25_alloc_socket(void)
{
	struct x25_sock *x25;
	struct sock *sk = sk_alloc(AF_X25, GFP_ATOMIC, &x25_proto, 1);

	if (!sk)
		goto out;

	sock_init_data(NULL, sk);

	x25 = x25_sk(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);
out:
	return sk;
}

void x25_init_timers(struct sock *sk);

static int x25_create(struct socket *sock, int protocol)
{
	struct sock *sk;
	struct x25_sock *x25;
	int rc = -ESOCKTNOSUPPORT;

	if (sock->type != SOCK_SEQPACKET || protocol)
		goto out;

	rc = -ENOMEM;
	if ((sk = x25_alloc_socket()) == NULL)
		goto out;

	x25 = x25_sk(sk);

	sock_init_data(sock, sk);

	x25_init_timers(sk);

	sock->ops    = &x25_proto_ops;
	sk->sk_protocol = protocol;
	sk->sk_backlog_rcv = x25_backlog_rcv;

	x25->t21   = sysctl_x25_call_request_timeout;
	x25->t22   = sysctl_x25_reset_request_timeout;
	x25->t23   = sysctl_x25_clear_request_timeout;
	x25->t2    = sysctl_x25_ack_holdback_timeout;
	x25->state = X25_STATE_0;
	x25->cudmatchlength = 0;
	x25->accptapprv = X25_DENY_ACCPT_APPRV;		/* normally no cud  */
							/* on call accept   */

	x25->facilities.winsize_in  = X25_DEFAULT_WINDOW_SIZE;
	x25->facilities.winsize_out = X25_DEFAULT_WINDOW_SIZE;
	x25->facilities.pacsize_in  = X25_DEFAULT_PACKET_SIZE;
	x25->facilities.pacsize_out = X25_DEFAULT_PACKET_SIZE;
	x25->facilities.throughput  = X25_DEFAULT_THROUGHPUT;
	x25->facilities.reverse     = X25_DEFAULT_REVERSE;
 	x25->dte_facilities.calling_len = 0;
 	x25->dte_facilities.called_len = 0;
 	memset(x25->dte_facilities.called_ae, '\0',
		 	sizeof(x25->dte_facilities.called_ae));
 	memset(x25->dte_facilities.calling_ae, '\0',
		 	sizeof(x25->dte_facilities.calling_ae));

	rc = 0;
out:
	return rc;
}

static struct sock *x25_make_new(struct sock *osk)
{
	struct sock *sk = NULL;
	struct x25_sock *x25, *ox25;

	if (osk->sk_type != SOCK_SEQPACKET)
		goto out;

	if ((sk = x25_alloc_socket()) == NULL)
		goto out;

	x25 = x25_sk(sk);