af_econet.c

嵌入式系统设计与实验教材二源码linux内核移植与编译

/*
 *	An implementation of the Acorn Econet and AUN protocols.
 *	Philip Blundell <[e-mail]>
 *
 *	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/config.h>
#include <linux/module.h>

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/route.h>
#include <linux/inet.h>
#include <linux/etherdevice.h>
#include <linux/if_arp.h>
#include <linux/wireless.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/inet_common.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/if_ec.h>
#include <net/udp.h>
#include <net/ip.h>
#include <linux/spinlock.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/bitops.h>

static struct proto_ops econet_ops;
static struct sock *econet_sklist;

/* Since there are only 256 possible network numbers (or fewer, depends
   how you count) it makes sense to use a simple lookup table. */
static struct net_device *net2dev_map[256];

#define EC_PORT_IP	0xd2

#ifdef CONFIG_ECONET_AUNUDP
static spinlock_t aun_queue_lock;
static struct socket *udpsock;
#define AUN_PORT	0x8000


struct aunhdr
{
	unsigned char code;		/* AUN magic protocol byte */
	unsigned char port;
	unsigned char cb;
	unsigned char pad;
	unsigned long handle;
};

static unsigned long aun_seq;

/* Queue of packets waiting to be transmitted. */
static struct sk_buff_head aun_queue;
static struct timer_list ab_cleanup_timer;

#endif		/* CONFIG_ECONET_AUNUDP */

/* Per-packet information */
struct ec_cb
{
	struct sockaddr_ec sec;
	unsigned long cookie;		/* Supplied by user. */
#ifdef CONFIG_ECONET_AUNUDP
	int done;
	unsigned long seq;		/* Sequencing */
	unsigned long timeout;		/* Timeout */
	unsigned long start;		/* jiffies */
#endif
#ifdef CONFIG_ECONET_NATIVE
	void (*sent)(struct sk_buff *, int result);
#endif
};

/*
 *	Pull a packet from our receive queue and hand it to the user.
 *	If necessary we block.
 */

static int econet_recvmsg(struct socket *sock, struct msghdr *msg, int len,
			  int flags, struct scm_cookie *scm)
{
	struct sock *sk = sock->sk;
	struct sk_buff *skb;
	int copied, err;

	msg->msg_namelen = sizeof(struct sockaddr_ec);

	/*
	 *	Call the generic datagram receiver. This handles all sorts
	 *	of horrible races and re-entrancy so we can forget about it
	 *	in the protocol layers.
	 *
	 *	Now it will return ENETDOWN, if device have just gone down,
	 *	but then it will block.
	 */

	skb=skb_recv_datagram(sk,flags,flags&MSG_DONTWAIT,&err);

	/*
	 *	An error occurred so return it. Because skb_recv_datagram() 
	 *	handles the blocking we don't see and worry about blocking
	 *	retries.
	 */

	if(skb==NULL)
		goto out;

	/*
	 *	You lose any data beyond the buffer you gave. If it worries a
	 *	user program they can ask the device for its MTU anyway.
	 */

	copied = skb->len;
	if (copied > len)
	{
		copied=len;
		msg->msg_flags|=MSG_TRUNC;
	}

	/* We can't use skb_copy_datagram here */
	err = memcpy_toiovec(msg->msg_iov, skb->data, copied);
	if (err)
		goto out_free;
	sk->stamp=skb->stamp;

	if (msg->msg_name)
		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);

	/*
	 *	Free or return the buffer as appropriate. Again this
	 *	hides all the races and re-entrancy issues from us.
	 */
	err = copied;

out_free:
	skb_free_datagram(sk, skb);
out:
	return err;
}

/*
 *	Bind an Econet socket.
 */

static int econet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
	struct sockaddr_ec *sec = (struct sockaddr_ec *)uaddr;
	struct sock *sk=sock->sk;
	
	/*
	 *	Check legality
	 */
	 
	if (addr_len < sizeof(struct sockaddr_ec) ||
	    sec->sec_family != AF_ECONET)
		return -EINVAL;
	
	sk->protinfo.af_econet->cb = sec->cb;
	sk->protinfo.af_econet->port = sec->port;
	sk->protinfo.af_econet->station = sec->addr.station;
	sk->protinfo.af_econet->net = sec->addr.net;

	return 0;
}

/*
 *	Queue a transmit result for the user to be told about.
 */

static void tx_result(struct sock *sk, unsigned long cookie, int result)
{
	struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);
	struct ec_cb *eb;
	struct sockaddr_ec *sec;

	if (skb == NULL)
	{
		printk(KERN_DEBUG "ec: memory squeeze, transmit result dropped.\n");
		return;
	}

	eb = (struct ec_cb *)&skb->cb;
	sec = (struct sockaddr_ec *)&eb->sec;
	memset(sec, 0, sizeof(struct sockaddr_ec));
	sec->cookie = cookie;
	sec->type = ECTYPE_TRANSMIT_STATUS | result;
	sec->sec_family = AF_ECONET;

	if (sock_queue_rcv_skb(sk, skb) < 0)
		kfree_skb(skb);
}

#ifdef CONFIG_ECONET_NATIVE
/*
 *	Called by the Econet hardware driver when a packet transmit
 *	has completed.  Tell the user.
 */

static void ec_tx_done(struct sk_buff *skb, int result)
{
	struct ec_cb *eb = (struct ec_cb *)&skb->cb;
	tx_result(skb->sk, eb->cookie, result);
}
#endif

/*
 *	Send a packet.  We have to work out which device it's going out on
 *	and hence whether to use real Econet or the UDP emulation.
 */

static int econet_sendmsg(struct socket *sock, struct msghdr *msg, int len,
			  struct scm_cookie *scm)
{
	struct sock *sk = sock->sk;
	struct sockaddr_ec *saddr=(struct sockaddr_ec *)msg->msg_name;
	struct net_device *dev;
	struct ec_addr addr;
	int err;
	unsigned char port, cb;
	struct sk_buff *skb;
	struct ec_cb *eb;
#ifdef CONFIG_ECONET_NATIVE
	unsigned short proto = 0;
#endif
#ifdef CONFIG_ECONET_AUNUDP
	struct msghdr udpmsg;
	struct iovec iov[msg->msg_iovlen+1];
	struct aunhdr ah;
	struct sockaddr_in udpdest;
	__kernel_size_t size;
	int i;
	mm_segment_t oldfs;
#endif
		
	/*
	 *	Check the flags. 
	 */

	if (msg->msg_flags&~MSG_DONTWAIT) 
		return(-EINVAL);

	/*
	 *	Get and verify the address. 
	 */
	 
	if (saddr == NULL) {
		addr.station = sk->protinfo.af_econet->station;
		addr.net = sk->protinfo.af_econet->net;
		port = sk->protinfo.af_econet->port;
		cb = sk->protinfo.af_econet->cb;
	} else {
		if (msg->msg_namelen < sizeof(struct sockaddr_ec)) 
			return -EINVAL;
		addr.station = saddr->addr.station;
		addr.net = saddr->addr.net;
		port = saddr->port;
		cb = saddr->cb;
	}

	/* Look for a device with the right network number. */
	dev = net2dev_map[addr.net];

	/* If not directly reachable, use some default */
	if (dev == NULL)
	{
		dev = net2dev_map[0];
		/* No interfaces at all? */
		if (dev == NULL)
			return -ENETDOWN;
	}

	if (dev->type == ARPHRD_ECONET)
	{
		/* Real hardware Econet.  We're not worthy etc. */
#ifdef CONFIG_ECONET_NATIVE
		atomic_inc(&dev->refcnt);
		
		skb = sock_alloc_send_skb(sk, len+dev->hard_header_len+15, 
					  msg->msg_flags & MSG_DONTWAIT, &err);
		if (skb==NULL)
			goto out_unlock;
		
		skb_reserve(skb, (dev->hard_header_len+15)&~15);
		skb->nh.raw = skb->data;
		
		eb = (struct ec_cb *)&skb->cb;
		
		eb->cookie = saddr->cookie;
		eb->sec = *saddr;
		eb->sent = ec_tx_done;

		if (dev->hard_header) {
			int res;
			struct ec_framehdr *fh;
			err = -EINVAL;
			res = dev->hard_header(skb, dev, ntohs(proto), 
					       &addr, NULL, len);
			/* Poke in our control byte and
			   port number.  Hack, hack.  */
			fh = (struct ec_framehdr *)(skb->data);
			fh->cb = cb;
			fh->port = port;
			if (sock->type != SOCK_DGRAM) {
				skb->tail = skb->data;
				skb->len = 0;
			} else if (res < 0)
				goto out_free;
		}
		
		/* Copy the data. Returns -EFAULT on error */
		err = memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len);
		skb->protocol = proto;
		skb->dev = dev;
		skb->priority = sk->priority;
		if (err)
			goto out_free;
		
		err = -ENETDOWN;
		if (!(dev->flags & IFF_UP))
			goto out_free;
		
		/*
		 *	Now send it
		 */
		
		dev_queue_xmit(skb);
		dev_put(dev);
		return(len);

	out_free:
		kfree_skb(skb);
	out_unlock:
		if (dev)
			dev_put(dev);
#else
		err = -EPROTOTYPE;
#endif
		return err;
	}

#ifdef CONFIG_ECONET_AUNUDP
	/* AUN virtual Econet. */

	if (udpsock == NULL)
		return -ENETDOWN;		/* No socket - can't send */
	
	/* Make up a UDP datagram and hand it off to some higher intellect. */

	memset(&udpdest, 0, sizeof(udpdest));
	udpdest.sin_family = AF_INET;
	udpdest.sin_port = htons(AUN_PORT);

	/* At the moment we use the stupid Acorn scheme of Econet address
	   y.x maps to IP a.b.c.x.  This should be replaced with something
	   more flexible and more aware of subnet masks.  */
	{
		struct in_device *idev = in_dev_get(dev);
		unsigned long network = 0;
		if (idev) {
			read_lock(&idev->lock);
			if (idev->ifa_list)
				network = ntohl(idev->ifa_list->ifa_address) & 
					0xffffff00;		/* !!! */
			read_unlock(&idev->lock);
			in_dev_put(idev);
		}
		udpdest.sin_addr.s_addr = htonl(network | addr.station);
	}

	ah.port = port;
	ah.cb = cb & 0x7f;
	ah.code = 2;		/* magic */
	ah.pad = 0;

	/* tack our header on the front of the iovec */
	size = sizeof(struct aunhdr);
	iov[0].iov_base = (void *)&ah;
	iov[0].iov_len = size;
	for (i = 0; i < msg->msg_iovlen; i++) {
		void *base = msg->msg_iov[i].iov_base;
		size_t len = msg->msg_iov[i].iov_len;
		/* Check it now since we switch to KERNEL_DS later. */
		if ((err = verify_area(VERIFY_READ, base, len)) < 0)
			return err;
		iov[i+1].iov_base = base;
		iov[i+1].iov_len = len;
		size += len;
	}

	/* Get a skbuff (no data, just holds our cb information) */
	if ((skb = sock_alloc_send_skb(sk, 0, 
			     msg->msg_flags & MSG_DONTWAIT, &err)) == NULL)
		return err;

	eb = (struct ec_cb *)&skb->cb;

	eb->cookie = saddr->cookie;
	eb->timeout = (5*HZ);
	eb->start = jiffies;
	ah.handle = aun_seq;
	eb->seq = (aun_seq++);
	eb->sec = *saddr;

	skb_queue_tail(&aun_queue, skb);

	udpmsg.msg_name = (void *)&udpdest;
	udpmsg.msg_namelen = sizeof(udpdest);
	udpmsg.msg_iov = &iov[0];
	udpmsg.msg_iovlen = msg->msg_iovlen + 1;
	udpmsg.msg_control = NULL;
	udpmsg.msg_controllen = 0;
	udpmsg.msg_flags=0;

	oldfs = get_fs(); set_fs(KERNEL_DS);	/* More privs :-) */
	err = sock_sendmsg(udpsock, &udpmsg, size);
	set_fs(oldfs);
#else
	err = -EPROTOTYPE;
#endif
	return err;
}

/*
 *	Look up the address of a socket.
 */

static int econet_getname(struct socket *sock, struct sockaddr *uaddr,
			  int *uaddr_len, int peer)
{
	struct sock *sk = sock->sk;
	struct sockaddr_ec *sec = (struct sockaddr_ec *)uaddr;

	if (peer)
		return -EOPNOTSUPP;

	sec->sec_family = AF_ECONET;
	sec->port = sk->protinfo.af_econet->port;
	sec->addr.station = sk->protinfo.af_econet->station;
	sec->addr.net = sk->protinfo.af_econet->net;

	*uaddr_len = sizeof(*sec);
	return 0;
}

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

	if (!atomic_read(&sk->wmem_alloc) && !atomic_read(&sk->rmem_alloc)) {
		sk_free(sk);
		MOD_DEC_USE_COUNT;
		return;
	}

	sk->timer.expires=jiffies+10*HZ;
	add_timer(&sk->timer);
	printk(KERN_DEBUG "econet socket destroy delayed\n");
}

/*
 *	Close an econet socket.
 */

static int econet_release(struct socket *sock)
{
	struct sock *sk = sock->sk;

	if (!sk)
		return 0;

	sklist_remove_socket(&econet_sklist, sk);

	/*
	 *	Now the socket is dead. No more input will appear.
	 */

	sk->state_change(sk);	/* It is useless. Just for sanity. */

	sock->sk = NULL;
	sk->socket = NULL;
	sk->dead = 1;

	/* Purge queues */

	skb_queue_purge(&sk->receive_queue);

	if (atomic_read(&sk->rmem_alloc) || atomic_read(&sk->wmem_alloc)) {
		sk->timer.data=(unsigned long)sk;
		sk->timer.expires=jiffies+HZ;
		sk->timer.function=econet_destroy_timer;
		add_timer(&sk->timer);
		return 0;
	}

	sk_free(sk);
	MOD_DEC_USE_COUNT;
	return 0;
}

/*
 *	Create an Econet socket
 */

static int econet_create(struct socket *sock, int protocol)
{
	struct sock *sk;
	int err;

	/* Econet only provides datagram services. */
	if (sock->type != SOCK_DGRAM)
		return -ESOCKTNOSUPPORT;

	sock->state = SS_UNCONNECTED;
	MOD_INC_USE_COUNT;

	err = -ENOBUFS;
	sk = sk_alloc(PF_ECONET, GFP_KERNEL, 1);
	if (sk == NULL)
		goto out;

	sk->reuse = 1;
	sock->ops = &econet_ops;
	sock_init_data(sock,sk);

	sk->protinfo.af_econet = kmalloc(sizeof(struct econet_opt), GFP_KERNEL);
	if (sk->protinfo.af_econet == NULL)
		goto out_free;
	memset(sk->protinfo.af_econet, 0, sizeof(struct econet_opt));
	sk->zapped=0;
	sk->family = PF_ECONET;
	sk->num = protocol;

	sklist_insert_socket(&econet_sklist, sk);
	return(0);

out_free:
	sk_free(sk);
out:
	MOD_DEC_USE_COUNT;
	return err;
}

/*
 *	Handle Econet specific ioctls
 */