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/*

 * NETLINK      An implementation of a loadable kernel mode driver providing

 *              multiple kernel/user space bidirectional communications links.

 *

 *              Author:         Alan Cox <alan@redhat.com>

 *

 *              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.

 *

 *      Now netlink devices are emulated on the top of netlink sockets

 *      by compatibility reasons. Remove this file after a period. --ANK

 *

 */

#include <linux/module.h>

#include <linux/errno.h>

#include <linux/kernel.h>

#include <linux/major.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/skbuff.h>

#include <linux/netlink.h>

#include <linux/poll.h>

#include <linux/init.h>

#include <linux/devfs_fs_kernel.h>

#include <linux/smp_lock.h>

#include <asm/bitops.h>

#include <asm/system.h>

#include <asm/uaccess.h>

static long open_map;

static struct socket *netlink_user[MAX_LINKS];

/*

 *      Device operations

 */

static unsigned int netlink_poll(struct file *file, poll_table * wait)

{

        struct socket *sock = netlink_user[MINOR(file->f_dentry->d_inode->i_rdev)];

        if (sock->ops->poll==NULL)

                return 0;

        return sock->ops->poll(file, sock, wait);

}

/*

 *      Write a message to the kernel side of a communication link

 */

static ssize_t netlink_write(struct file * file, const char * buf,

                             size_t count, loff_t *pos)

{

        struct inode *inode = file->f_dentry->d_inode;

        struct socket *sock = netlink_user[MINOR(inode->i_rdev)];

        struct msghdr msg;

        struct iovec iov;

        iov.iov_base = (void*)buf;

        iov.iov_len = count;

        msg.msg_name=NULL;

        msg.msg_namelen=0;

        msg.msg_controllen=0;

        msg.msg_flags=0;

        msg.msg_iov=&iov;

        msg.msg_iovlen=1;

        return sock_sendmsg(sock, &msg, count);

}

/*

 *      Read a message from the kernel side of the communication link

 */

static ssize_t netlink_read(struct file * file, char * buf,

                            size_t count, loff_t *pos)

{

        struct inode *inode = file->f_dentry->d_inode;

        struct socket *sock = netlink_user[MINOR(inode->i_rdev)];

        struct msghdr msg;

        struct iovec iov;

        iov.iov_base = buf;

        iov.iov_len = count;

        msg.msg_name=NULL;

        msg.msg_namelen=0;

        msg.msg_controllen=0;

        msg.msg_flags=0;

        msg.msg_iov=&iov;

        msg.msg_iovlen=1;

        if (file->f_flags&O_NONBLOCK)

                msg.msg_flags=MSG_DONTWAIT;

        return sock_recvmsg(sock, &msg, count, msg.msg_flags);

}

static int netlink_open(struct inode * inode, struct file * file)

{

        unsigned int minor = MINOR(inode->i_rdev);

        struct socket *sock;

        struct sockaddr_nl nladdr;

        int err;

        if (minor>=MAX_LINKS)

                return -ENODEV;

        if (test_and_set_bit(minor, &open_map))

                return -EBUSY;

        err = sock_create(PF_NETLINK, SOCK_RAW, minor, &sock);

        if (err < 0)

                goto out;

        memset(&nladdr, 0, sizeof(nladdr));

        nladdr.nl_family = AF_NETLINK;

        nladdr.nl_groups = ~0;

        if ((err = sock->ops->bind(sock, (struct sockaddr*)&nladdr, sizeof(nladdr))) < 0) {

                sock_release(sock);

                goto out;

        }

        netlink_user[minor] = sock;

        return 0;

out:

        clear_bit(minor, &open_map);

        return err;

}

static int netlink_release(struct inode * inode, struct file * file)

{

        unsigned int minor = MINOR(inode->i_rdev);

        struct socket *sock;

        sock = netlink_user[minor];

        netlink_user[minor] = NULL;

        clear_bit(minor, &open_map);

        sock_release(sock);

        return 0;

}

static int netlink_ioctl(struct inode *inode, struct file *file,

                    unsigned int cmd, unsigned long arg)

{

        unsigned int minor = MINOR(inode->i_rdev);

        int retval = 0;

        if (minor >= MAX_LINKS)

                return -ENODEV;

        switch ( cmd ) {

                default:

                        retval = -EINVAL;

        }

        return retval;

}

static struct file_operations netlink_fops = {

        owner:          THIS_MODULE,

        llseek:         no_llseek,

        read:           netlink_read,

        write:          netlink_write,

        poll:           netlink_poll,

        ioctl:          netlink_ioctl,

        open:           netlink_open,

        release:        netlink_release,

};

static devfs_handle_t devfs_handle;

static void __init make_devfs_entries (const char *name, int minor)

{

        devfs_register (devfs_handle, name, DEVFS_FL_DEFAULT,

                        NETLINK_MAJOR, minor,

                        S_IFCHR | S_IRUSR | S_IWUSR,

                        &netlink_fops, NULL);

}

int __init init_netlink(void)

{

        if (devfs_register_chrdev(NETLINK_MAJOR,"netlink", &netlink_fops)) {

                printk(KERN_ERR "netlink: unable to get major %d\n", NETLINK_MAJOR);

                return -EIO;

        }

        devfs_handle = devfs_mk_dir (NULL, "netlink", NULL);

        /*  Someone tell me the official names for the uppercase ones  */

        make_devfs_entries ("route", 0);

        make_devfs_entries ("skip", 1);

        make_devfs_entries ("usersock", 2);

        make_devfs_entries ("fwmonitor", 3);

        make_devfs_entries ("tcpdiag", 4);

        make_devfs_entries ("arpd", 8);

        make_devfs_entries ("route6", 11);

        make_devfs_entries ("ip6_fw", 13);

        make_devfs_entries ("dnrtmsg", 13);

        devfs_register_series (devfs_handle, "tap%u", 16, DEVFS_FL_DEFAULT,

                               NETLINK_MAJOR, 16,

                               S_IFCHR | S_IRUSR | S_IWUSR,

                               &netlink_fops, NULL);

        return 0;

}

#ifdef MODULE

MODULE_LICENSE("GPL");

int init_module(void)

{

        printk(KERN_INFO "Network Kernel/User communications module 0.04\n");

        return init_netlink();

}

void cleanup_module(void)

{

        devfs_unregister (devfs_handle);

        devfs_unregister_chrdev(NETLINK_MAJOR, "netlink");

}

#endif