Linux/NetDriver/sheep_net.c

/*
 *  sheep_net.c - Linux driver for SheepShaver/Basilisk II networking (access to raw Ethernet packets)
 *
 *  sheep_net (C) 1999-2002 Mar"c" Hellwig and Christian Bauer
 *
 *  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.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/miscdevice.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <net/sock.h>
#include <asm/uaccess.h>
#include <net/arp.h>
#include <net/ip.h>
#include <linux/in.h>
#include <linux/wait.h>

MODULE_AUTHOR("Christian Bauer");
MODULE_DESCRIPTION("Pseudo ethernet device for emulators");

/* Compatibility glue */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
#define LINUX_24
#else
#define net_device device
typedef struct wait_queue *wait_queue_head_t;
#define init_waitqueue_head(x) *(x)=NULL
#endif

#define DEBUG 0

#define bug printk
#if DEBUG
#define D(x) (x);
#else
#define D(x) ;
#endif


/* Constants */
#define SHEEP_NET_MINOR 198             /* Driver minor number */
#define MAX_QUEUE 32                    /* Maximum number of packets in queue */
#define PROT_MAGIC 1520                 /* Our "magic" protocol type */

#define ETH_ADDR_MULTICAST 0x1
#define ETH_ADDR_LOCALLY_DEFINED 0x02

#define SIOC_MOL_GET_IPFILTER SIOCDEVPRIVATE
#define SIOC_MOL_SET_IPFILTER (SIOCDEVPRIVATE + 1)

/* Prototypes */
static int sheep_net_open(struct inode *inode, struct file *f);
static int sheep_net_release(struct inode *inode, struct file *f);
static ssize_t sheep_net_read(struct file *f, char *buf, size_t count, loff_t *off);
static ssize_t sheep_net_write(struct file *f, const char *buf, size_t count, loff_t *off);
static unsigned int sheep_net_poll(struct file *f, struct poll_table_struct *wait);
static int sheep_net_ioctl(struct inode *inode, struct file *f, unsigned int code, unsigned long arg);
static int sheep_net_receiver(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt);


/*
 *  Driver private variables
 */

struct SheepVars {
        struct net_device *ether;       /* The Ethernet device we're attached to */
        struct sock *skt;                       /* Socket for communication with Ethernet card */
        struct sk_buff_head queue;      /* Receiver packet queue */
        struct packet_type pt;          /* Receiver packet type */
        wait_queue_head_t wait;         /* Wait queue for blocking read operations */
        u32 ipfilter;                           /* Only receive IP packets destined for this address (host byte order) */
        char eth_addr[6];                       /* Hardware address of the Ethernet card */
        char fake_addr[6];                      /* Local faked hardware address (what SheepShaver sees) */
};


/*
 *  file_operations structure - has function pointers to the
 *  various entry points for device operations
 */

static struct file_operations sheep_net_fops = {
        read:           sheep_net_read,
        write:          sheep_net_write,
        poll:           sheep_net_poll,
        ioctl:          sheep_net_ioctl,
        open:           sheep_net_open,
        release:        sheep_net_release,
};


/*
 *  miscdevice structure for driver initialization
 */

static struct miscdevice sheep_net_device = {
        SHEEP_NET_MINOR,        /* minor number */
        "sheep_net",            /* name */
        &sheep_net_fops,
        NULL,
        NULL
};


/*
 *  Initialize module
 */

int init_module(void)
{
        int ret;

        /* Register driver */
        ret = misc_register(&sheep_net_device);
        D(bug("Sheep net driver installed\n"));
        return ret;
}


/*
 *  Deinitialize module
 */

int cleanup_module(void)
{
        int ret;

        /* Unregister driver */
        ret = misc_deregister(&sheep_net_device);
        D(bug("Sheep net driver removed\n"));
        return ret;
}


/*
 *  Driver open() function
 */

static int sheep_net_open(struct inode *inode, struct file *f)
{
        struct SheepVars *v;
        D(bug("sheep_net: open\n"));

        /* Must be opened with read permissions */
        if ((f->f_flags & O_ACCMODE) == O_WRONLY)
                return -EPERM;

        /* Allocate private variables */
        v = (struct SheepVars *)f->private_data = kmalloc(sizeof(struct SheepVars), GFP_USER);
        if (v == NULL)
                return -ENOMEM;
        memset(v, 0, sizeof(struct SheepVars));
        skb_queue_head_init(&v->queue);
        init_waitqueue_head(&v->wait);
        v->fake_addr[0] = 0xfe;
        v->fake_addr[1] = 0xfd;
        v->fake_addr[2] = 0xde;
        v->fake_addr[3] = 0xad;
        v->fake_addr[4] = 0xbe;
        v->fake_addr[5] = 0xef;

        /* Yes, we're open */
        MOD_INC_USE_COUNT;
        return 0;
}


/*
 *  Driver release() function
 */

static int sheep_net_release(struct inode *inode, struct file *f)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        struct sk_buff *skb;
        D(bug("sheep_net: close\n"));

        /* Detach from Ethernet card */
        if (v->ether) {
                dev_remove_pack(&v->pt);
                sk_free(v->skt);
                v->skt = NULL;
#ifdef LINUX_24
                dev_put( v->ether );
#endif
                v->ether = NULL;
        }

        /* Empty packet queue */
        while ((skb = skb_dequeue(&v->queue)) != NULL)
                dev_kfree_skb(skb);

        /* Free private variables */
        kfree(v);

        /* Sorry, we're closed */
        MOD_DEC_USE_COUNT;
        return 0;
}


/*
 *  Check whether an Ethernet address is the local (attached) one or
 *  the fake one
 */

static inline int is_local_addr(struct SheepVars *v, void *a)
{
        return memcmp(a, v->eth_addr, 6) == 0;
}

static inline int is_fake_addr(struct SheepVars *v, void *a)
{
        return memcmp(a, v->fake_addr, 6) == 0;
}


/* 
 * Outgoing packet. Replace the fake enet addr with the real local one.
 */

static inline void do_demasq(struct SheepVars *v, u8 *p)
{
        memcpy(p, v->eth_addr, 6);
}

static void demasquerade(struct SheepVars *v, struct sk_buff *skb)
{
        u8 *p = skb->mac.raw;
        int proto = (p[12] << 8) | p[13];
        
        do_demasq(v, p + 6); /* source address */

        /* Need to fix ARP packets */
        if (proto == ETH_P_ARP) {
                if (is_fake_addr(v, p + 14 + 8)) /* sender HW-addr */
                        do_demasq(v, p + 14 + 8);
        }

        /* ...and AARPs (snap code: 0x00,0x00,0x00,0x80,0xF3) */
        if (p[17] == 0 && p[18] == 0 && p[19] == 0 && p[20] == 0x80 && p[21] == 0xf3) {
                /* XXX: we should perhaps look for the 802 frame too */
                if (is_fake_addr(v, p + 30))
                        do_demasq(v, p + 30); /* sender HW-addr */
        }
}


/*
 * Incoming packet. Replace the local enet addr with the fake one.
 */

static inline void do_masq(struct SheepVars *v, u8 *p)
{
        memcpy(p, v->fake_addr, 6);
}

static void masquerade(struct SheepVars *v, struct sk_buff *skb)
{
        u8 *p = skb->mac.raw;
        if (!(p[0] & ETH_ADDR_MULTICAST))
                do_masq(v, p); /* destination address */

        /* XXX: reverse ARP might need to be fixed */
}


/*
 *  Driver read() function
 */

static ssize_t sheep_net_read(struct file *f, char *buf, size_t count, loff_t *off)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        struct sk_buff *skb;

        D(bug("sheep_net: read\n"));

        for (;;) {

                /* Get next packet from queue */
                skb = skb_dequeue(&v->queue);
                if (skb != NULL || (f->f_flags & O_NONBLOCK))
                        break;

                /* No packet in queue and in blocking mode, so block */
                interruptible_sleep_on(&v->wait);

                /* Signal received? Then bail out */
                if (signal_pending(current))
                        return -EINTR;
        }
        if (skb == NULL)
                return -EAGAIN;

        /* Pass packet to caller */
        if (count > skb->len)
                count = skb->len;
        if (copy_to_user(buf, skb->data, count))
                count = -EFAULT;
        dev_kfree_skb(skb);
        return count;
}


/*
 *  Driver write() function
 */

static ssize_t sheep_net_write(struct file *f, const char *buf, size_t count, loff_t *off)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        struct sk_buff *skb;
        char *p;
        D(bug("sheep_net: write\n"));

        /* Check packet size */
        if (count < sizeof(struct ethhdr))
                return -EINVAL;
        if (count > 1514) {
                printk("sheep_net_write: packet size > 1514\n");
                count = 1514;
        }

        /* Interface active? */
        if (v->ether == NULL)
                return count;

        /* Allocate buffer for packet */
        skb = dev_alloc_skb(count);
        if (skb == NULL)
                return -ENOBUFS;

        /* Stuff packet in buffer */
        p = skb_put(skb, count);
        if (copy_from_user(p, buf, count)) {
                kfree_skb(skb);
                return -EFAULT;
        }

        /* Transmit packet */
        atomic_add(skb->truesize, &v->skt->wmem_alloc);
        skb->sk = v->skt;
        skb->dev = v->ether;
        skb->priority = 0;
        skb->nh.raw = skb->h.raw = skb->data + v->ether->hard_header_len;
        skb->mac.raw = skb->data;

        /* Base the IP-filtering on the IP address in any outgoing ARP packets */
        if (skb->mac.ethernet->h_proto == htons(ETH_P_ARP)) {
                u8 *p = &skb->data[14+14];      /* source IP address */
                u32 ip = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
                if (ip != v->ipfilter) {
                        v->ipfilter = ip;
                        printk("sheep_net: ipfilter set to %d.%d.%d.%d\n", (ip >> 24) & 0xff, (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
                }
        }

        /* Is this packet addressed solely to the local host? */
        if (is_local_addr(v, skb->data) && !(skb->data[0] & ETH_ADDR_MULTICAST)) {
                skb->protocol = eth_type_trans(skb, v->ether);
                netif_rx(skb);
                return count;
        }
        if (skb->data[0] & ETH_ADDR_MULTICAST) {
                /* We can't clone the skb since we will manipulate the data below */
                struct sk_buff *lskb = skb_copy(skb, GFP_ATOMIC);
                if (lskb) {
                        lskb->protocol = eth_type_trans(lskb, v->ether);
                        netif_rx(lskb);
                }
        }

        /* Outgoing packet (will be on the net) */
        demasquerade(v, skb);

        skb->protocol = PROT_MAGIC;     /* Magic value (we can recognize the packet in sheep_net_receiver) */
        dev_queue_xmit(skb);
        return count;
}


/*
 *  Driver poll() function
 */

static unsigned int sheep_net_poll(struct file *f, struct poll_table_struct *wait)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        D(bug("sheep_net: poll\n"));

        /* Packets in queue? Then return */
        if (!skb_queue_empty(&v->queue))
                return POLLIN | POLLRDNORM;

        /* Otherwise wait for packet */
        poll_wait(f, &v->wait, wait);
        if (!skb_queue_empty(&v->queue))
                return POLLIN | POLLRDNORM;
        else
                return 0;
}


/*
 *  Driver ioctl() function
 */

static int sheep_net_ioctl(struct inode *inode, struct file *f, unsigned int code, unsigned long arg)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        D(bug("sheep_net: ioctl %04x\n", code));

        switch (code) {

                /* Attach to Ethernet card
                   arg: pointer to name of Ethernet device (char[20]) */
                case SIOCSIFLINK: {
                        char name[20];
                        int err;

                        /* Already attached? */
                        if (v->ether)
                                return -EBUSY;

                        /* Get Ethernet card name */
                        if (copy_from_user(name, (void *)arg, 20))
                                return -EFAULT;
                        name[19] = 0;

                        /* Find card */
#ifdef LINUX_24
                        v->ether = dev_get_by_name(name);
#else
                        dev_lock_list();
                        v->ether = dev_get(name);
#endif
                        if (v->ether == NULL) {
                                err = -ENODEV;
                                goto error;
                        }

                        /* Is it Ethernet? */
                        if (v->ether->type != ARPHRD_ETHER) {
                                err = -EINVAL;
                                goto error;
                        }

                        /* Remember the card's hardware address */
                        memcpy(v->eth_addr, v->ether->dev_addr, 6);

                        /* Allocate socket */
                        v->skt = sk_alloc(0, GFP_USER, 1);
                        if (v->skt == NULL) {
                                err = -ENOMEM;
                                goto error;
                        }
                        v->skt->dead = 1;

                        /* Attach packet handler */
                        v->pt.type = htons(ETH_P_ALL);
                        v->pt.dev = v->ether;
                        v->pt.func = sheep_net_receiver;
                        v->pt.data = v;
                        dev_add_pack(&v->pt);
#ifndef LINUX_24
                        dev_unlock_list();
#endif
                        return 0;

error:
#ifdef LINUX_24
                        if (v->ether)
                                dev_put(v->ether);
#else
                        dev_unlock_list();
#endif
                        v->ether = NULL;
                        return err;
                }

                /* Get hardware address of the sheep_net module
                   arg: pointer to buffer (6 bytes) to store address */
                case SIOCGIFADDR:
                        if (copy_to_user((void *)arg, v->fake_addr, 6))
                                return -EFAULT;
                        return 0;

                /* Set the hardware address of the sheep_net module
                   arg: pointer to new address (6 bytes) */
                case SIOCSIFADDR:
                        if (copy_from_user(v->fake_addr, (void*)arg, 6))
                                return -EFAULT;
                        return 0;

                /* Add multicast address
                   arg: pointer to address (6 bytes) */
                case SIOCADDMULTI: {
                        char addr[6];
                        if (v->ether == NULL)
                                return -ENODEV;
                        if (copy_from_user(addr, (void *)arg, 6))
                                return -EFAULT;
                        return dev_mc_add(v->ether, addr, 6, 0);
                }

                /* Remove multicast address
                   arg: pointer to address (6 bytes) */
                case SIOCDELMULTI: {
                        char addr[6];
                        if (v->ether == NULL)
                                return -ENODEV;
                        if (copy_from_user(addr, (void *)arg, 6))
                                return -EFAULT;
                        return dev_mc_delete(v->ether, addr, 6, 0);
                }

                /* Return size of first packet in queue */
                case FIONREAD: {
                        int count = 0;
                        struct sk_buff *skb;
#ifdef LINUX_24
                        long flags;
                        spin_lock_irqsave(&v->queue.lock, flags);
#else
                        cli();
#endif
                        skb = skb_peek(&v->queue);
                        if (skb)
                                count = skb->len;
#ifdef LINUX_24
                        spin_unlock_irqrestore(&v->queue.lock, flags);
#else
                        sti();
#endif
                        return put_user(count, (int *)arg);
                }

                case SIOC_MOL_GET_IPFILTER:
                        return put_user(v->ipfilter, (int *)arg);

                case SIOC_MOL_SET_IPFILTER:
                        v->ipfilter = arg;
                        return 0;

                default:
                        return -ENOIOCTLCMD;
        }
}


/*
 *  Packet receiver function
 */

static int sheep_net_receiver(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
{
        struct SheepVars *v = (struct SheepVars *)pt->data;
        struct sk_buff *skb2;
        int fake;
        int multicast;
        D(bug("sheep_net: packet received\n"));

        multicast = (skb->mac.ethernet->h_dest[0] & ETH_ADDR_MULTICAST);
        fake = is_fake_addr(v, &skb->mac.ethernet->h_dest);

        /* Packet sent by us? Then discard */
        if (is_fake_addr(v, &skb->mac.ethernet->h_source) || skb->protocol == PROT_MAGIC)
                goto drop;

        /* If the packet is not meant for this host, discard it */
        if (!is_local_addr(v, &skb->mac.ethernet->h_dest) && !multicast && !fake)
                goto drop;

        /* Discard packets if queue gets too full */
        if (skb_queue_len(&v->queue) > MAX_QUEUE)
                goto drop;

        /* Apply any filters here (if fake is true, then we *know* we want this packet) */
        if (!fake) {
                if ((skb->protocol == htons(ETH_P_IP))
                 && (!v->ipfilter || (ntohl(skb->h.ipiph->daddr) != v->ipfilter && !multicast)))
                        goto drop;
        }

        /* Masquerade (we are typically a clone - best to make a real copy) */
        skb2 = skb_copy(skb, GFP_ATOMIC);
        if (!skb2)
                goto drop;
        kfree_skb(skb);
        skb = skb2;
        masquerade(v, skb);

        /* We also want the Ethernet header */
        skb_push(skb, skb->data - skb->mac.raw);

        /* Enqueue packet */
        skb_queue_tail(&v->queue, skb);

        /* Unblock blocked read */
        wake_up(&v->wait);
        return 0;

drop:
        kfree_skb(skb);
        return 0;
}
Revision:	1.8
Committed:	2002-01-15T14:58:39Z (22 years, 5 months ago) by cebix
Content type:	text/plain
Branch:	MAIN
CVS Tags:	snapshot-15012002
Changes since 1.7:	+1 -1 lines
Log Message:	- documentation updates - 2001 -> 2002 - version 0.9 -> 1.0
#	User	Rev	Content
1	cebix	1.1	/*
2			* sheep_net.c - Linux driver for SheepShaver/Basilisk II networking (access to raw Ethernet packets)
3			*
4	cebix	1.8	* sheep_net (C) 1999-2002 Mar"c" Hellwig and Christian Bauer
5	cebix	1.1	*
6			* This program is free software; you can redistribute it and/or modify
7			* it under the terms of the GNU General Public License as published by
8			* the Free Software Foundation; either version 2 of the License, or
9			* (at your option) any later version.
10			*
11			* This program is distributed in the hope that it will be useful,
12			* but WITHOUT ANY WARRANTY; without even the implied warranty of
13			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14			* GNU General Public License for more details.
15			*
16			* You should have received a copy of the GNU General Public License
17			* along with this program; if not, write to the Free Software
18			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19			*/
20
21	cebix	1.7	#include <linux/kernel.h>
22	cebix	1.1	#include <linux/module.h>
23			#include <linux/version.h>
24			#include <linux/miscdevice.h>
25			#include <linux/netdevice.h>
26			#include <linux/etherdevice.h>
27			#include <linux/if_ether.h>
28			#include <linux/if_arp.h>
29	cebix	1.7	#include <linux/fs.h>
30	cebix	1.1	#include <linux/poll.h>
31			#include <linux/init.h>
32			#include <net/sock.h>
33	cebix	1.7	#include <asm/uaccess.h>
34	cebix	1.4	#include <net/arp.h>
35			#include <net/ip.h>
36	cebix	1.7	#include <linux/in.h>
37			#include <linux/wait.h>
38	cebix	1.1
39	cebix	1.5	MODULE_AUTHOR("Christian Bauer");
40			MODULE_DESCRIPTION("Pseudo ethernet device for emulators");
41
42	cebix	1.4	/* Compatibility glue */
43			#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
44			#define LINUX_24
45			#else
46			#define net_device device
47			typedef struct wait_queue *wait_queue_head_t;
48			#define init_waitqueue_head(x) *(x)=NULL
49			#endif
50
51	cebix	1.1	#define DEBUG 0
52
53			#define bug printk
54			#if DEBUG
55			#define D(x) (x);
56			#else
57			#define D(x) ;
58			#endif
59
60
61	cebix	1.4	/* Constants */
62			#define SHEEP_NET_MINOR 198 /* Driver minor number */
63			#define MAX_QUEUE 32 /* Maximum number of packets in queue */
64			#define PROT_MAGIC 1520 /* Our "magic" protocol type */
65	cebix	1.1
66	cebix	1.4	#define ETH_ADDR_MULTICAST 0x1
67	cebix	1.7	#define ETH_ADDR_LOCALLY_DEFINED 0x02
68	cebix	1.4
69			#define SIOC_MOL_GET_IPFILTER SIOCDEVPRIVATE
70			#define SIOC_MOL_SET_IPFILTER (SIOCDEVPRIVATE + 1)
71
72			/* Prototypes */
73	cebix	1.1	static int sheep_net_open(struct inode inode, struct file f);
74			static int sheep_net_release(struct inode inode, struct file f);
75			static ssize_t sheep_net_read(struct file f, char buf, size_t count, loff_t *off);
76			static ssize_t sheep_net_write(struct file f, const char buf, size_t count, loff_t *off);
77			static unsigned int sheep_net_poll(struct file f, struct poll_table_struct wait);
78			static int sheep_net_ioctl(struct inode inode, struct file f, unsigned int code, unsigned long arg);
79	cebix	1.4	static int sheep_net_receiver(struct sk_buff skb, struct net_device dev, struct packet_type *pt);
80	cebix	1.1
81
82			/*
83			* Driver private variables
84			*/
85
86			struct SheepVars {
87	cebix	1.4	struct net_device ether; / The Ethernet device we're attached to */
88			struct sock skt; / Socket for communication with Ethernet card */
89			struct sk_buff_head queue; /* Receiver packet queue */
90			struct packet_type pt; /* Receiver packet type */
91			wait_queue_head_t wait; /* Wait queue for blocking read operations */
92			u32 ipfilter; /* Only receive IP packets destined for this address (host byte order) */
93			char eth_addr[6]; /* Hardware address of the Ethernet card */
94			char fake_addr[6]; /* Local faked hardware address (what SheepShaver sees) */
95	cebix	1.1	};
96
97
98			/*
99			* file_operations structure - has function pointers to the
100			* various entry points for device operations
101			*/
102
103			static struct file_operations sheep_net_fops = {
104	cebix	1.4	read: sheep_net_read,
105			write: sheep_net_write,
106			poll: sheep_net_poll,
107			ioctl: sheep_net_ioctl,
108			open: sheep_net_open,
109			release: sheep_net_release,
110	cebix	1.1	};
111
112
113			/*
114			* miscdevice structure for driver initialization
115			*/
116
117			static struct miscdevice sheep_net_device = {
118	cebix	1.4	SHEEP_NET_MINOR, /* minor number */
119			"sheep_net", /* name */
120	cebix	1.1	&sheep_net_fops,
121			NULL,
122			NULL
123			};
124
125
126			/*
127			* Initialize module
128			*/
129
130			int init_module(void)
131			{
132			int ret;
133
134	cebix	1.4	/* Register driver */
135	cebix	1.1	ret = misc_register(&sheep_net_device);
136			D(bug("Sheep net driver installed\n"));
137			return ret;
138			}
139
140
141			/*
142			* Deinitialize module
143			*/
144
145	cebix	1.7	int cleanup_module(void)
146	cebix	1.1	{
147	cebix	1.7	int ret;
148
149	cebix	1.4	/* Unregister driver */
150	cebix	1.7	ret = misc_deregister(&sheep_net_device);
151	cebix	1.1	D(bug("Sheep net driver removed\n"));
152	cebix	1.7	return ret;
153	cebix	1.1	}
154
155
156			/*
157			* Driver open() function
158			*/
159
160			static int sheep_net_open(struct inode inode, struct file f)
161			{
162			struct SheepVars *v;
163			D(bug("sheep_net: open\n"));
164
165	cebix	1.4	/* Must be opened with read permissions */
166	cebix	1.1	if ((f->f_flags & O_ACCMODE) == O_WRONLY)
167			return -EPERM;
168
169	cebix	1.4	/* Allocate private variables */
170	cebix	1.1	v = (struct SheepVars *)f->private_data = kmalloc(sizeof(struct SheepVars), GFP_USER);
171			if (v == NULL)
172			return -ENOMEM;
173			memset(v, 0, sizeof(struct SheepVars));
174			skb_queue_head_init(&v->queue);
175	cebix	1.4	init_waitqueue_head(&v->wait);
176			v->fake_addr[0] = 0xfe;
177			v->fake_addr[1] = 0xfd;
178			v->fake_addr[2] = 0xde;
179			v->fake_addr[3] = 0xad;
180			v->fake_addr[4] = 0xbe;
181			v->fake_addr[5] = 0xef;
182	cebix	1.1
183	cebix	1.4	/* Yes, we're open */
184	cebix	1.1	MOD_INC_USE_COUNT;
185			return 0;
186			}
187
188
189			/*
190			* Driver release() function
191			*/
192
193			static int sheep_net_release(struct inode inode, struct file f)
194			{
195			struct SheepVars v = (struct SheepVars )f->private_data;
196			struct sk_buff *skb;
197			D(bug("sheep_net: close\n"));
198
199	cebix	1.4	/* Detach from Ethernet card */
200	cebix	1.1	if (v->ether) {
201			dev_remove_pack(&v->pt);
202			sk_free(v->skt);
203			v->skt = NULL;
204	cebix	1.4	#ifdef LINUX_24
205			dev_put( v->ether );
206			#endif
207	cebix	1.1	v->ether = NULL;
208			}
209
210	cebix	1.4	/* Empty packet queue */
211	cebix	1.1	while ((skb = skb_dequeue(&v->queue)) != NULL)
212			dev_kfree_skb(skb);
213
214	cebix	1.4	/* Free private variables */
215	cebix	1.1	kfree(v);
216
217	cebix	1.4	/* Sorry, we're closed */
218	cebix	1.1	MOD_DEC_USE_COUNT;
219			return 0;
220			}
221
222
223			/*
224	cebix	1.4	* Check whether an Ethernet address is the local (attached) one or
225			* the fake one
226			*/
227
228			static inline int is_local_addr(struct SheepVars v, void a)
229			{
230			return memcmp(a, v->eth_addr, 6) == 0;
231			}
232
233			static inline int is_fake_addr(struct SheepVars v, void a)
234			{
235			return memcmp(a, v->fake_addr, 6) == 0;
236			}
237
238
239			/*
240			* Outgoing packet. Replace the fake enet addr with the real local one.
241			*/
242
243			static inline void do_demasq(struct SheepVars v, u8 p)
244			{
245			memcpy(p, v->eth_addr, 6);
246			}
247
248			static void demasquerade(struct SheepVars v, struct sk_buff skb)
249			{
250			u8 *p = skb->mac.raw;
251			int proto = (p[12] << 8) \| p[13];
252
253			do_demasq(v, p + 6); /* source address */
254
255			/* Need to fix ARP packets */
256			if (proto == ETH_P_ARP) {
257			if (is_fake_addr(v, p + 14 + 8)) /* sender HW-addr */
258			do_demasq(v, p + 14 + 8);
259			}
260
261			/* ...and AARPs (snap code: 0x00,0x00,0x00,0x80,0xF3) */
262			if (p[17] == 0 && p[18] == 0 && p[19] == 0 && p[20] == 0x80 && p[21] == 0xf3) {
263			/* XXX: we should perhaps look for the 802 frame too */
264			if (is_fake_addr(v, p + 30))
265			do_demasq(v, p + 30); /* sender HW-addr */
266			}
267			}
268
269
270			/*
271			* Incoming packet. Replace the local enet addr with the fake one.
272			*/
273
274			static inline void do_masq(struct SheepVars v, u8 p)
275			{
276			memcpy(p, v->fake_addr, 6);
277			}
278
279			static void masquerade(struct SheepVars v, struct sk_buff skb)
280			{
281			u8 *p = skb->mac.raw;
282			if (!(p[0] & ETH_ADDR_MULTICAST))
283			do_masq(v, p); /* destination address */
284
285			/* XXX: reverse ARP might need to be fixed */
286			}
287
288
289			/*
290	cebix	1.1	* Driver read() function
291			*/
292
293			static ssize_t sheep_net_read(struct file f, char buf, size_t count, loff_t *off)
294			{
295			struct SheepVars v = (struct SheepVars )f->private_data;
296			struct sk_buff *skb;
297	cebix	1.4
298	cebix	1.1	D(bug("sheep_net: read\n"));
299
300			for (;;) {
301
302	cebix	1.4	/* Get next packet from queue */
303	cebix	1.1	skb = skb_dequeue(&v->queue);
304			if (skb != NULL \|\| (f->f_flags & O_NONBLOCK))
305			break;
306
307	cebix	1.4	/* No packet in queue and in blocking mode, so block */
308	cebix	1.1	interruptible_sleep_on(&v->wait);
309
310	cebix	1.4	/* Signal received? Then bail out */
311			if (signal_pending(current))
312			return -EINTR;
313	cebix	1.1	}
314			if (skb == NULL)
315			return -EAGAIN;
316
317	cebix	1.4	/* Pass packet to caller */
318	cebix	1.1	if (count > skb->len)
319			count = skb->len;
320			if (copy_to_user(buf, skb->data, count))
321			count = -EFAULT;
322			dev_kfree_skb(skb);
323			return count;
324			}
325
326
327			/*
328			* Driver write() function
329			*/
330
331			static ssize_t sheep_net_write(struct file f, const char buf, size_t count, loff_t *off)
332			{
333			struct SheepVars v = (struct SheepVars )f->private_data;
334			struct sk_buff *skb;
335			char *p;
336			D(bug("sheep_net: write\n"));
337
338	cebix	1.4	/* Check packet size */
339	cebix	1.1	if (count < sizeof(struct ethhdr))
340			return -EINVAL;
341	cebix	1.7	if (count > 1514) {
342			printk("sheep_net_write: packet size > 1514\n");
343	cebix	1.1	count = 1514;
344	cebix	1.7	}
345	cebix	1.1
346	cebix	1.4	/* Interface active? */
347	cebix	1.1	if (v->ether == NULL)
348			return count;
349
350	cebix	1.4	/* Allocate buffer for packet */
351	cebix	1.1	skb = dev_alloc_skb(count);
352			if (skb == NULL)
353			return -ENOBUFS;
354
355	cebix	1.4	/* Stuff packet in buffer */
356	cebix	1.1	p = skb_put(skb, count);
357			if (copy_from_user(p, buf, count)) {
358			kfree_skb(skb);
359			return -EFAULT;
360			}
361
362	cebix	1.4	/* Transmit packet */
363	cebix	1.1	atomic_add(skb->truesize, &v->skt->wmem_alloc);
364			skb->sk = v->skt;
365			skb->dev = v->ether;
366			skb->priority = 0;
367			skb->nh.raw = skb->h.raw = skb->data + v->ether->hard_header_len;
368	cebix	1.4	skb->mac.raw = skb->data;
369
370			/* Base the IP-filtering on the IP address in any outgoing ARP packets */
371			if (skb->mac.ethernet->h_proto == htons(ETH_P_ARP)) {
372			u8 p = &skb->data[14+14]; / source IP address */
373			u32 ip = (p[0] << 24) \| (p[1] << 16) \| (p[2] << 8) \| p[3];
374			if (ip != v->ipfilter) {
375			v->ipfilter = ip;
376			printk("sheep_net: ipfilter set to %d.%d.%d.%d\n", (ip >> 24) & 0xff, (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
377			}
378			}
379
380			/* Is this packet addressed solely to the local host? */
381			if (is_local_addr(v, skb->data) && !(skb->data[0] & ETH_ADDR_MULTICAST)) {
382			skb->protocol = eth_type_trans(skb, v->ether);
383			netif_rx(skb);
384			return count;
385			}
386			if (skb->data[0] & ETH_ADDR_MULTICAST) {
387			/* We can't clone the skb since we will manipulate the data below */
388			struct sk_buff *lskb = skb_copy(skb, GFP_ATOMIC);
389			if (lskb) {
390			lskb->protocol = eth_type_trans(lskb, v->ether);
391			netif_rx(lskb);
392			}
393			}
394
395			/* Outgoing packet (will be on the net) */
396			demasquerade(v, skb);
397
398			skb->protocol = PROT_MAGIC; /* Magic value (we can recognize the packet in sheep_net_receiver) */
399	cebix	1.1	dev_queue_xmit(skb);
400			return count;
401			}
402
403
404			/*
405			* Driver poll() function
406			*/
407
408			static unsigned int sheep_net_poll(struct file f, struct poll_table_struct wait)
409			{
410			struct SheepVars v = (struct SheepVars )f->private_data;
411			D(bug("sheep_net: poll\n"));
412
413	cebix	1.4	/* Packets in queue? Then return */
414			if (!skb_queue_empty(&v->queue))
415	cebix	1.1	return POLLIN \| POLLRDNORM;
416
417	cebix	1.4	/* Otherwise wait for packet */
418	cebix	1.1	poll_wait(f, &v->wait, wait);
419	cebix	1.4	if (!skb_queue_empty(&v->queue))
420	cebix	1.1	return POLLIN \| POLLRDNORM;
421	cebix	1.4	else
422	cebix	1.1	return 0;
423			}
424
425
426			/*
427			* Driver ioctl() function
428			*/
429
430			static int sheep_net_ioctl(struct inode inode, struct file f, unsigned int code, unsigned long arg)
431			{
432			struct SheepVars v = (struct SheepVars )f->private_data;
433			D(bug("sheep_net: ioctl %04x\n", code));
434
435			switch (code) {
436
437	cebix	1.4	/* Attach to Ethernet card
438	cebix	1.7	arg: pointer to name of Ethernet device (char[20]) */
439	cebix	1.1	case SIOCSIFLINK: {
440	cebix	1.7	char name[20];
441	cebix	1.4	int err;
442	cebix	1.1
443	cebix	1.4	/* Already attached? */
444	cebix	1.1	if (v->ether)
445			return -EBUSY;
446
447	cebix	1.4	/* Get Ethernet card name */
448	cebix	1.7	if (copy_from_user(name, (void *)arg, 20))
449	cebix	1.1	return -EFAULT;
450	cebix	1.7	name[19] = 0;
451	cebix	1.1
452	cebix	1.4	/* Find card */
453			#ifdef LINUX_24
454			v->ether = dev_get_by_name(name);
455			#else
456	cebix	1.1	dev_lock_list();
457			v->ether = dev_get(name);
458	cebix	1.4	#endif
459	cebix	1.1	if (v->ether == NULL) {
460	cebix	1.4	err = -ENODEV;
461			goto error;
462	cebix	1.1	}
463
464	cebix	1.4	/* Is it Ethernet? */
465	cebix	1.1	if (v->ether->type != ARPHRD_ETHER) {
466	cebix	1.4	err = -EINVAL;
467			goto error;
468	cebix	1.1	}
469
470	cebix	1.4	/* Remember the card's hardware address */
471			memcpy(v->eth_addr, v->ether->dev_addr, 6);
472
473			/* Allocate socket */
474	cebix	1.1	v->skt = sk_alloc(0, GFP_USER, 1);
475			if (v->skt == NULL) {
476	cebix	1.4	err = -ENOMEM;
477			goto error;
478	cebix	1.1	}
479			v->skt->dead = 1;
480
481	cebix	1.4	/* Attach packet handler */
482	cebix	1.1	v->pt.type = htons(ETH_P_ALL);
483			v->pt.dev = v->ether;
484			v->pt.func = sheep_net_receiver;
485			v->pt.data = v;
486			dev_add_pack(&v->pt);
487	cebix	1.4	#ifndef LINUX_24
488	cebix	1.1	dev_unlock_list();
489	cebix	1.4	#endif
490	cebix	1.1	return 0;
491	cebix	1.4
492			error:
493			#ifdef LINUX_24
494			if (v->ether)
495			dev_put(v->ether);
496			#else
497			dev_unlock_list();
498			#endif
499			v->ether = NULL;
500			return err;
501	cebix	1.1	}
502
503	cebix	1.4	/* Get hardware address of the sheep_net module
504			arg: pointer to buffer (6 bytes) to store address */
505	cebix	1.1	case SIOCGIFADDR:
506	cebix	1.4	if (copy_to_user((void *)arg, v->fake_addr, 6))
507			return -EFAULT;
508			return 0;
509
510			/* Set the hardware address of the sheep_net module
511			arg: pointer to new address (6 bytes) */
512			case SIOCSIFADDR:
513			if (copy_from_user(v->fake_addr, (void*)arg, 6))
514	cebix	1.1	return -EFAULT;
515			return 0;
516
517	cebix	1.4	/* Add multicast address
518			arg: pointer to address (6 bytes) */
519	cebix	1.1	case SIOCADDMULTI: {
520			char addr[6];
521			if (v->ether == NULL)
522			return -ENODEV;
523			if (copy_from_user(addr, (void *)arg, 6))
524			return -EFAULT;
525			return dev_mc_add(v->ether, addr, 6, 0);
526			}
527
528	cebix	1.4	/* Remove multicast address
529			arg: pointer to address (6 bytes) */
530	cebix	1.1	case SIOCDELMULTI: {
531			char addr[6];
532			if (v->ether == NULL)
533			return -ENODEV;
534			if (copy_from_user(addr, (void *)arg, 6))
535			return -EFAULT;
536			return dev_mc_delete(v->ether, addr, 6, 0);
537			}
538
539	cebix	1.4	/* Return size of first packet in queue */
540	cebix	1.1	case FIONREAD: {
541			int count = 0;
542			struct sk_buff *skb;
543	cebix	1.4	#ifdef LINUX_24
544			long flags;
545			spin_lock_irqsave(&v->queue.lock, flags);
546			#else
547			cli();
548			#endif
549	cebix	1.1	skb = skb_peek(&v->queue);
550			if (skb)
551			count = skb->len;
552	cebix	1.4	#ifdef LINUX_24
553			spin_unlock_irqrestore(&v->queue.lock, flags);
554			#else
555			sti();
556			#endif
557	cebix	1.1	return put_user(count, (int *)arg);
558			}
559
560	cebix	1.4	case SIOC_MOL_GET_IPFILTER:
561			return put_user(v->ipfilter, (int *)arg);
562
563			case SIOC_MOL_SET_IPFILTER:
564			v->ipfilter = arg;
565			return 0;
566
567	cebix	1.1	default:
568			return -ENOIOCTLCMD;
569			}
570			}
571
572
573			/*
574			* Packet receiver function
575			*/
576
577	cebix	1.4	static int sheep_net_receiver(struct sk_buff skb, struct net_device dev, struct packet_type *pt)
578	cebix	1.1	{
579			struct SheepVars v = (struct SheepVars )pt->data;
580	cebix	1.4	struct sk_buff *skb2;
581			int fake;
582			int multicast;
583	cebix	1.1	D(bug("sheep_net: packet received\n"));
584
585	cebix	1.4	multicast = (skb->mac.ethernet->h_dest[0] & ETH_ADDR_MULTICAST);
586			fake = is_fake_addr(v, &skb->mac.ethernet->h_dest);
587
588			/* Packet sent by us? Then discard */
589			if (is_fake_addr(v, &skb->mac.ethernet->h_source) \|\| skb->protocol == PROT_MAGIC)
590			goto drop;
591
592			/* If the packet is not meant for this host, discard it */
593			if (!is_local_addr(v, &skb->mac.ethernet->h_dest) && !multicast && !fake)
594			goto drop;
595
596			/* Discard packets if queue gets too full */
597			if (skb_queue_len(&v->queue) > MAX_QUEUE)
598			goto drop;
599
600			/* Apply any filters here (if fake is true, then we know we want this packet) */
601			if (!fake) {
602			if ((skb->protocol == htons(ETH_P_IP))
603			&& (!v->ipfilter \|\| (ntohl(skb->h.ipiph->daddr) != v->ipfilter && !multicast)))
604			goto drop;
605	cebix	1.1	}
606
607	cebix	1.4	/* Masquerade (we are typically a clone - best to make a real copy) */
608			skb2 = skb_copy(skb, GFP_ATOMIC);
609			if (!skb2)
610			goto drop;
611			kfree_skb(skb);
612			skb = skb2;
613			masquerade(v, skb);
614	cebix	1.1
615	cebix	1.4	/* We also want the Ethernet header */
616	cebix	1.1	skb_push(skb, skb->data - skb->mac.raw);
617
618	cebix	1.4	/* Enqueue packet */
619	cebix	1.1	skb_queue_tail(&v->queue, skb);
620
621	cebix	1.4	/* Unblock blocked read */
622	cebix	1.1	wake_up(&v->wait);
623	cebix	1.4	return 0;
624
625			drop:
626			kfree_skb(skb);
627	cebix	1.1	return 0;
628			}