/***
 *
 *  ipv4/udp.c - UDP implementation for RTnet
 *
 *  Copyright (C) 1999, 2000 Zentropic Computing, LLC
 *                2002       Ulrich Marx <marx@kammer.uni-hannover.de>
 *                2003-2005  Jan Kiszka <jan.kiszka@web.de>
 *
 *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/moduleparam.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/err.h>
#include <linux/udp.h>
#include <linux/tcp.h>
#include <linux/list.h>

#include <rtdm/compat.h>
#include <rtskb.h>
#include <rtnet_internal.h>
#include <rtnet_checksum.h>
#include <rtnet_port.h>
#include <rtnet_iovec.h>
#include <rtnet_socket.h>
#include <ipv4/ip_fragment.h>
#include <ipv4/ip_output.h>
#include <ipv4/ip_sock.h>
#include <ipv4/protocol.h>
#include <ipv4/route.h>
#include <ipv4/udp.h>

/***
 *  This structure is used to register a UDP socket for reception. All
 +  structures are kept in the port_registry array to increase the cache
 *  locality during the critical port lookup in rt_udp_v4_lookup().
 */
struct udp_socket {
	u16 sport; /* local port */
	u32 saddr; /* local ip-addr */
	struct rtsocket *sock;
	struct hlist_node link;
};

/***
 *  Automatic port number assignment

 *  The automatic assignment of port numbers to unbound sockets is realised as
 *  a simple addition of two values:
 *   - the socket ID (lower 8 bits of file descriptor) which is set during
 *     initialisation and left unchanged afterwards
 *   - the start value auto_port_start which is a module parameter

 *  auto_port_mask, also a module parameter, is used to define the range of
 *  port numbers which are used for automatic assignment. Any number within
 *  this range will be rejected when passed to bind_rt().

 */
static unsigned int auto_port_start = 1024;
static unsigned int auto_port_mask = ~(RT_UDP_SOCKETS - 1);
static int free_ports = RT_UDP_SOCKETS;
#define RT_PORT_BITMAP_WORDS                                                   \
	((RT_UDP_SOCKETS + BITS_PER_LONG - 1) / BITS_PER_LONG)
static unsigned long port_bitmap[RT_PORT_BITMAP_WORDS];
static struct udp_socket port_registry[RT_UDP_SOCKETS];
static DEFINE_RTDM_LOCK(udp_socket_base_lock);

static struct hlist_head port_hash[RT_UDP_SOCKETS * 2];
#define port_hash_mask (RT_UDP_SOCKETS * 2 - 1)

MODULE_LICENSE("GPL");

module_param(auto_port_start, uint, 0444);
module_param(auto_port_mask, uint, 0444);
MODULE_PARM_DESC(auto_port_start, "Start of automatically assigned port range");
MODULE_PARM_DESC(auto_port_mask,
		 "Mask that defines port range for automatic assignment");

static inline struct udp_socket *port_hash_search(u32 saddr, u16 sport)
{
	unsigned bucket = sport & port_hash_mask;
	struct udp_socket *sock;

	hlist_for_each_entry (sock, &port_hash[bucket], link)
		if (sock->sport == sport &&
		    (saddr == INADDR_ANY || sock->saddr == saddr ||
		     sock->saddr == INADDR_ANY))
			return sock;

	return NULL;
}

static inline int port_hash_insert(struct udp_socket *sock, u32 saddr,
				   u16 sport)
{
	unsigned bucket;

	if (port_hash_search(saddr, sport))
		return -EADDRINUSE;

	bucket = sport & port_hash_mask;
	sock->saddr = saddr;
	sock->sport = sport;
	hlist_add_head(&sock->link, &port_hash[bucket]);
	return 0;
}

static inline void port_hash_del(struct udp_socket *sock)
{
	hlist_del(&sock->link);
}

/***
 *  rt_udp_v4_lookup
 */
static inline struct rtsocket *rt_udp_v4_lookup(u32 daddr, u16 dport)
{
	rtdm_lockctx_t context;
	struct udp_socket *sock;

	rtdm_lock_get_irqsave(&udp_socket_base_lock, context);
	sock = port_hash_search(daddr, dport);
	if (sock && rt_socket_reference(sock->sock) == 0) {
		rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);

		return sock->sock;
	}

	rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);

	return NULL;
}

/***
 *  rt_udp_bind - bind socket to local address
 *  @s:     socket
 *  @addr:  local address
 */
int rt_udp_bind(struct rtdm_fd *fd, struct rtsocket *sock,
		const struct sockaddr __user *addr, socklen_t addrlen)
{
	struct sockaddr_in _sin, *sin;
	rtdm_lockctx_t context;
	int index;
	int err = 0;

	if (addrlen < sizeof(struct sockaddr_in))
		return -EINVAL;

	sin = rtnet_get_arg(fd, &_sin, addr, sizeof(_sin));
	if (IS_ERR(sin))
		return PTR_ERR(sin);

	if ((sin->sin_port & auto_port_mask) == auto_port_start)
		return -EINVAL;

	rtdm_lock_get_irqsave(&udp_socket_base_lock, context);

	if ((index = sock->prot.inet.reg_index) < 0) {
		/* socket is being closed */
		err = -EBADF;
		goto unlock_out;
	}
	if (sock->prot.inet.state != TCP_CLOSE) {
		err = -EINVAL;
		goto unlock_out;
	}

	port_hash_del(&port_registry[index]);
	if (port_hash_insert(&port_registry[index], sin->sin_addr.s_addr,
			     sin->sin_port ?: index + auto_port_start)) {
		port_hash_insert(&port_registry[index],
				 port_registry[index].saddr,
				 port_registry[index].sport);
		rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);
		return -EADDRINUSE;
	}

	/* set the source-addr */
	sock->prot.inet.saddr = port_registry[index].saddr;

	/* set source port, if not set by user */
	sock->prot.inet.sport = port_registry[index].sport;

unlock_out:
	rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);

	return err;
}

/***
 *  rt_udp_connect
 */
int rt_udp_connect(struct rtdm_fd *fd, struct rtsocket *sock,
		   const struct sockaddr __user *serv_addr, socklen_t addrlen)
{
	struct sockaddr _sa, *sa;
	struct sockaddr_in _sin, *sin;
	rtdm_lockctx_t context;
	int index;

	if (addrlen < sizeof(struct sockaddr))
		return -EINVAL;

	sa = rtnet_get_arg(fd, &_sa, serv_addr, sizeof(_sa));
	if (IS_ERR(sa))
		return PTR_ERR(sa);

	if (sa->sa_family == AF_UNSPEC) {
		if ((index = sock->prot.inet.reg_index) < 0)
			/* socket is being closed */
			return -EBADF;

		rtdm_lock_get_irqsave(&udp_socket_base_lock, context);

		sock->prot.inet.saddr = INADDR_ANY;
		/* Note: The following line differs from standard
		   stacks, and we also don't remove the socket from
		   the port list. Might get fixed in the future... */
		sock->prot.inet.sport = index + auto_port_start;
		sock->prot.inet.daddr = INADDR_ANY;
		sock->prot.inet.dport = 0;
		sock->prot.inet.state = TCP_CLOSE;

		rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);
	} else {
		if (addrlen < sizeof(struct sockaddr_in))
			return -EINVAL;

		sin = rtnet_get_arg(fd, &_sin, serv_addr, sizeof(_sin));
		if (IS_ERR(sin))
			return PTR_ERR(sin);

		if (sin->sin_family != AF_INET)
			return -EINVAL;

		rtdm_lock_get_irqsave(&udp_socket_base_lock, context);

		if (sock->prot.inet.state != TCP_CLOSE) {
			rtdm_lock_put_irqrestore(&udp_socket_base_lock,
						 context);
			return -EINVAL;
		}

		sock->prot.inet.state = TCP_ESTABLISHED;
		sock->prot.inet.daddr = sin->sin_addr.s_addr;
		sock->prot.inet.dport = sin->sin_port;

		rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);
	}

	return 0;
}

/***
 *  rt_udp_socket - create a new UDP-Socket
 *  @s: socket
 */
int rt_udp_socket(struct rtdm_fd *fd)
{
	struct rtsocket *sock = rtdm_fd_to_private(fd);
	int ret;
	int i;
	int index;
	rtdm_lockctx_t context;

	if ((ret = rt_socket_init(fd, IPPROTO_UDP)) != 0)
		return ret;

	sock->prot.inet.saddr = INADDR_ANY;
	sock->prot.inet.state = TCP_CLOSE;
	sock->prot.inet.tos = 0;

	rtdm_lock_get_irqsave(&udp_socket_base_lock, context);

	/* enforce maximum number of UDP sockets */
	if (free_ports == 0) {
		rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);
		rt_socket_cleanup(fd);
		return -EAGAIN;
	}
	free_ports--;

	/* find free auto-port in bitmap */
	for (i = 0; i < RT_PORT_BITMAP_WORDS; i++)
		if (port_bitmap[i] != (unsigned long)-1)
			break;
	index = ffz(port_bitmap[i]);
	set_bit(index, &port_bitmap[i]);
	index += i * BITS_PER_LONG;
	sock->prot.inet.reg_index = index;
	sock->prot.inet.sport = index + auto_port_start;

	/* register UDP socket */
	port_hash_insert(&port_registry[index], INADDR_ANY,
			 sock->prot.inet.sport);
	port_registry[index].sock = sock;

	rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);

	return 0;
}

/***
 *  rt_udp_close
 */
void rt_udp_close(struct rtdm_fd *fd)
{
	struct rtsocket *sock = rtdm_fd_to_private(fd);
	struct rtskb *del;
	int port;
	rtdm_lockctx_t context;

	rtdm_lock_get_irqsave(&udp_socket_base_lock, context);

	sock->prot.inet.state = TCP_CLOSE;

	if (sock->prot.inet.reg_index >= 0) {
		port = sock->prot.inet.reg_index;
		clear_bit(port % BITS_PER_LONG,
			  &port_bitmap[port / BITS_PER_LONG]);
		port_hash_del(&port_registry[port]);

		free_ports++;

		sock->prot.inet.reg_index = -1;
	}

	rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);

	/* cleanup already collected fragments */
	rt_ip_frag_invalidate_socket(sock);

	/* free packets in incoming queue */
	while ((del = rtskb_dequeue(&sock->incoming)) != NULL)
		kfree_rtskb(del);

	rt_socket_cleanup(fd);
}

int rt_udp_ioctl(struct rtdm_fd *fd, unsigned int request, void __user *arg)
{
	struct rtsocket *sock = rtdm_fd_to_private(fd);
	struct _rtdm_setsockaddr_args args;
	bool do_bind = false;
	int ret;

	/* fast path for common socket IOCTLs */
	if (_IOC_TYPE(request) == RTIOC_TYPE_NETWORK)
		return rt_socket_common_ioctl(fd, request, arg);

	switch (request) {
	COMPAT_CASE(_RTIOC_BIND):
		do_bind = true;
		fallthrough;
	COMPAT_CASE(_RTIOC_CONNECT):
		ret = rtdm_fd_get_setsockaddr_args(fd, &args, arg);
		if (ret)
			return ret;

		if (do_bind)
			return rt_udp_bind(fd, sock, args.addr, args.addrlen);

		return rt_udp_connect(fd, sock, args.addr, args.addrlen);

	default:
		return rt_ip_ioctl(fd, request, arg);
	}
}

/***
 *  rt_udp_recvmsg
 */
/***
 *  rt_udp_recvmsg
 */
ssize_t rt_udp_recvmsg(struct rtdm_fd *fd, struct user_msghdr *msg,
		       int msg_flags)
{
	struct rtsocket *sock = rtdm_fd_to_private(fd);
	size_t len;
	struct rtskb *skb;
	struct rtskb *first_skb;
	size_t copied = 0;
	size_t block_size;
	size_t data_len;
	struct udphdr *uh;
	struct sockaddr_in sin;
	nanosecs_rel_t timeout = sock->timeout;
	int ret, flags;
	socklen_t namelen;
	struct iovec iov_fast[RTDM_IOV_FASTMAX], *iov;

	if (msg->msg_iovlen < 0)
		return -EINVAL;

	if (msg->msg_iovlen == 0)
		return 0;

	ret = rtdm_get_iovec(fd, &iov, msg, iov_fast);
	if (ret)
		return ret;

	/* non-blocking receive? */
	if (msg_flags & MSG_DONTWAIT)
		timeout = -1;

	ret = rtdm_sem_timeddown(&sock->pending_sem, timeout, NULL);
	if (unlikely(ret < 0))
		switch (ret) {
		default:
			ret = -EBADF; /* socket has been closed */
			fallthrough;
		case -EWOULDBLOCK:
		case -ETIMEDOUT:
		case -EINTR:
			rtdm_drop_iovec(iov, iov_fast);
			return ret;
		}

	skb = rtskb_dequeue_chain(&sock->incoming);
	RTNET_ASSERT(skb != NULL, return -EFAULT;);
	uh = skb->h.uh;
	first_skb = skb;

	/* copy the address if required. */
	if (msg->msg_name) {
		memset(&sin, 0, sizeof(sin));
		sin.sin_family = AF_INET;
		sin.sin_port = uh->source;
		sin.sin_addr.s_addr = skb->nh.iph->saddr;

		if (msg->msg_namelen < 0) {
			ret = -EINVAL;
			goto fail;
		}
		namelen = min(sizeof(sin), (size_t)msg->msg_namelen);

		ret = rtnet_put_arg(fd, msg->msg_name, &sin, namelen);
		if (ret)
			goto fail;

		msg->msg_namelen = sizeof(sin);
	}

	data_len = ntohs(uh->len) - sizeof(struct udphdr);

	/* remove the UDP header */
	__rtskb_pull(skb, sizeof(struct udphdr));

	flags = msg->msg_flags & ~MSG_TRUNC;
	len = rtdm_get_iov_flatlen(iov, msg->msg_iovlen);

	/* iterate over all IP fragments */
	do {
		rtskb_trim(skb, data_len);

		block_size = skb->len;
		copied += block_size;
		data_len -= block_size;

		/* The data must not be longer than the available buffer size */
		if (copied > len) {
			block_size -= copied - len;
			copied = len;
			flags |= MSG_TRUNC;
		}

		/* copy the data */
		ret = rtnet_write_to_iov(fd, iov, msg->msg_iovlen, skb->data,
					 block_size);
		if (ret)
			goto fail;

		/* next fragment */
		skb = skb->next;
	} while (skb && !(flags & MSG_TRUNC));

	/* did we copied all bytes? */
	if (data_len > 0)
		flags |= MSG_TRUNC;

	msg->msg_flags = flags;
out:
	if ((msg_flags & MSG_PEEK) == 0)
		kfree_rtskb(first_skb);
	else {
		__rtskb_push(first_skb, sizeof(struct udphdr));
		rtskb_queue_head(&sock->incoming, first_skb);
		rtdm_sem_up(&sock->pending_sem);
	}
	rtdm_drop_iovec(iov, iov_fast);

	return copied;
fail:
	copied = ret;
	goto out;
}

/***
 *  struct udpfakehdr
 */
struct udpfakehdr {
	struct udphdr uh;
	u32 daddr;
	u32 saddr;
	struct rtdm_fd *fd;
	struct iovec *iov;
	int iovlen;
	u32 wcheck;
};

/***
 *
 */
static int rt_udp_getfrag(const void *p, unsigned char *to, unsigned int offset,
			  unsigned int fraglen)
{
	struct udpfakehdr *ufh = (struct udpfakehdr *)p;
	int ret;

	// We should optimize this function a bit (copy+csum...)!
	if (offset) {
		ret = rtnet_read_from_iov(ufh->fd, ufh->iov, ufh->iovlen, to,
					  fraglen);
		return ret < 0 ? ret : 0;
	}

	ret = rtnet_read_from_iov(ufh->fd, ufh->iov, ufh->iovlen,
				  to + sizeof(struct udphdr),
				  fraglen - sizeof(struct udphdr));
	if (ret < 0)
		return ret;

	/* Checksum of the complete data part of the UDP message: */
	ufh->wcheck =
		rtnet_csum(to + sizeof(struct udphdr),
			   fraglen - sizeof(struct udphdr), ufh->wcheck);

	/* Checksum of the udp header: */
	ufh->wcheck = rtnet_csum((unsigned char *)ufh, sizeof(struct udphdr),
				 ufh->wcheck);

	ufh->uh.check =
		csum_tcpudp_magic(ufh->saddr, ufh->daddr, ntohs(ufh->uh.len),
				  IPPROTO_UDP, ufh->wcheck);

	if (ufh->uh.check == 0)
		ufh->uh.check = -1;

	memcpy(to, ufh, sizeof(struct udphdr));

	return 0;
}

/***
 *  rt_udp_sendmsg
 */
ssize_t rt_udp_sendmsg(struct rtdm_fd *fd, const struct user_msghdr *msg,
		       int msg_flags)
{
	struct rtsocket *sock = rtdm_fd_to_private(fd);
	size_t len;
	int ulen;
	struct sockaddr_in _sin, *sin;
	struct udpfakehdr ufh;
	struct dest_route rt;
	u32 saddr;
	u32 daddr;
	u16 dport;
	int err;
	rtdm_lockctx_t context;
	struct iovec iov_fast[RTDM_IOV_FASTMAX], *iov;

	if (msg_flags & MSG_OOB) /* Mirror BSD error message compatibility */
		return -EOPNOTSUPP;

	if (msg_flags & ~(MSG_DONTROUTE | MSG_DONTWAIT))
		return -EINVAL;

	if (msg->msg_iovlen < 0)
		return -EINVAL;

	if (msg->msg_iovlen == 0)
		return 0;

	err = rtdm_get_iovec(fd, &iov, msg, iov_fast);
	if (err)
		return err;

	len = rtdm_get_iov_flatlen(iov, msg->msg_iovlen);
	if ((len < 0) ||
	    (len > 0xFFFF - sizeof(struct iphdr) - sizeof(struct udphdr))) {
		err = -EMSGSIZE;
		goto out;
	}

	ulen = len + sizeof(struct udphdr);

	if (msg->msg_name && msg->msg_namelen == sizeof(*sin)) {
		sin = rtnet_get_arg(fd, &_sin, msg->msg_name, sizeof(_sin));
		if (IS_ERR(sin)) {
			err = PTR_ERR(sin);
			goto out;
		}

		if (sin->sin_family != AF_INET &&
		    sin->sin_family != AF_UNSPEC) {
			err = -EINVAL;
			goto out;
		}

		daddr = sin->sin_addr.s_addr;
		dport = sin->sin_port;
		rtdm_lock_get_irqsave(&udp_socket_base_lock, context);
	} else {
		rtdm_lock_get_irqsave(&udp_socket_base_lock, context);

		if (sock->prot.inet.state != TCP_ESTABLISHED) {
			rtdm_lock_put_irqrestore(&udp_socket_base_lock,
						 context);
			err = -ENOTCONN;
			goto out;
		}

		daddr = sock->prot.inet.daddr;
		dport = sock->prot.inet.dport;
	}

	saddr = sock->prot.inet.saddr;
	ufh.uh.source = sock->prot.inet.sport;

	rtdm_lock_put_irqrestore(&udp_socket_base_lock, context);

	if ((daddr | dport) == 0) {
		err = -EINVAL;
		goto out;
	}

	/* get output route */
	err = rt_ip_route_output(&rt, daddr, saddr);
	if (err)
		goto out;

	/* we found a route, remember the routing dest-addr could be the netmask */
	ufh.saddr = saddr != INADDR_ANY ? saddr : rt.rtdev->local_ip;
	ufh.daddr = daddr;
	ufh.uh.dest = dport;
	ufh.uh.len = htons(ulen);
	ufh.uh.check = 0;
	ufh.fd = fd;
	ufh.iov = iov;
	ufh.iovlen = msg->msg_iovlen;
	ufh.wcheck = 0;

	err = rt_ip_build_xmit(sock, rt_udp_getfrag, &ufh, ulen, &rt,
			       msg_flags);

	/* Drop the reference obtained in rt_ip_route_output() */
	rtdev_dereference(rt.rtdev);
out:
	rtdm_drop_iovec(iov, iov_fast);

	return err ?: len;
}

/***
 *  rt_udp_check
 */
static inline unsigned short rt_udp_check(struct udphdr *uh, int len,
					  unsigned long saddr,
					  unsigned long daddr,
					  unsigned long base)
{
	return (csum_tcpudp_magic(saddr, daddr, len, IPPROTO_UDP, base));
}

struct rtsocket *rt_udp_dest_socket(struct rtskb *skb)
{
	struct udphdr *uh = skb->h.uh;
	unsigned short ulen = ntohs(uh->len);
	u32 saddr = skb->nh.iph->saddr;
	u32 daddr = skb->nh.iph->daddr;
	struct rtnet_device *rtdev = skb->rtdev;

	if (uh->check == 0)
		skb->ip_summed = CHECKSUM_UNNECESSARY;
	/* ip_summed (yet) never equals CHECKSUM_PARTIAL
    else
        if (skb->ip_summed == CHECKSUM_PARTIAL) {
            skb->ip_summed = CHECKSUM_UNNECESSARY;

            if ( !rt_udp_check(uh, ulen, saddr, daddr, skb->csum) )
                return NULL;

            skb->ip_summed = CHECKSUM_NONE;
        }*/

	if (skb->ip_summed != CHECKSUM_UNNECESSARY)
		skb->csum =
			csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);

	/* patch broadcast daddr */
	if (daddr == rtdev->broadcast_ip)
		daddr = rtdev->local_ip;

	/* find the destination socket */
	skb->sk = rt_udp_v4_lookup(daddr, uh->dest);

	return skb->sk;
}

/***
 *  rt_udp_rcv
 */
void rt_udp_rcv(struct rtskb *skb)
{
	struct rtsocket *sock = skb->sk;
	void (*callback_func)(struct rtdm_fd *, void *);
	void *callback_arg;
	rtdm_lockctx_t context;

	rtskb_queue_tail(&sock->incoming, skb);
	rtdm_sem_up(&sock->pending_sem);

	rtdm_lock_get_irqsave(&sock->param_lock, context);
	callback_func = sock->callback_func;
	callback_arg = sock->callback_arg;
	rtdm_lock_put_irqrestore(&sock->param_lock, context);

	if (callback_func)
		callback_func(rt_socket_fd(sock), callback_arg);
}

/***
 *  rt_udp_rcv_err
 */
void rt_udp_rcv_err(struct rtskb *skb)
{
	rtdm_printk("RTnet: rt_udp_rcv err\n");
}

/***
 *  UDP-Initialisation
 */
static struct rtinet_protocol udp_protocol = { .protocol = IPPROTO_UDP,
					       .dest_socket =
						       &rt_udp_dest_socket,
					       .rcv_handler = &rt_udp_rcv,
					       .err_handler = &rt_udp_rcv_err,
					       .init_socket = &rt_udp_socket };

static struct rtdm_driver udp_driver = {
    .profile_info =     RTDM_PROFILE_INFO(udp,
                                        RTDM_CLASS_NETWORK,
                                        RTDM_SUBCLASS_RTNET,
                                        RTNET_RTDM_VER),
    .device_flags =     RTDM_PROTOCOL_DEVICE,
    .device_count =	1,
    .context_size =     sizeof(struct rtsocket),

    .protocol_family =  PF_INET,
    .socket_type =      SOCK_DGRAM,

    /* default is UDP */
    .ops = {
        .socket =       rt_inet_socket,
        .close =        rt_udp_close,
        .ioctl_rt =     rt_udp_ioctl,
        .ioctl_nrt =    rt_udp_ioctl,
        .recvmsg_rt =   rt_udp_recvmsg,
        .sendmsg_rt =   rt_udp_sendmsg,
        .select =       rt_socket_select_bind,
    },
};

static struct rtdm_device udp_device = {
	.driver = &udp_driver,
	.label = "udp",
};

/***
 *  rt_udp_init
 */
static int __init rt_udp_init(void)
{
	int i, err;

	if ((auto_port_start < 0) ||
	    (auto_port_start >= 0x10000 - RT_UDP_SOCKETS))
		auto_port_start = 1024;
	auto_port_start = htons(auto_port_start & (auto_port_mask & 0xFFFF));
	auto_port_mask = htons(auto_port_mask | 0xFFFF0000);

	rt_inet_add_protocol(&udp_protocol);

	for (i = 0; i < ARRAY_SIZE(port_hash); i++)
		INIT_HLIST_HEAD(&port_hash[i]);

	err = rtdm_dev_register(&udp_device);
	if (err)
		rt_inet_del_protocol(&udp_protocol);
	return err;
}

/***
 *  rt_udp_release
 */
static void __exit rt_udp_release(void)
{
	rtdm_dev_unregister(&udp_device);
	rt_inet_del_protocol(&udp_protocol);
}

module_init(rt_udp_init);
module_exit(rt_udp_release);