/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              Definitions for the AF_INET socket handler.
 *
 * Version:     @(#)sock.h      1.0.4   05/13/93
 *
 * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *              Corey Minyard <wf-rch!minyard@relay.EU.net>
 *              Florian La Roche <flla@stud.uni-sb.de>
 *
 * Fixes:
 *              Alan Cox        :       Volatiles in skbuff pointers. See
 *                                      skbuff comments. May be overdone,
 *                                      better to prove they can be removed
 *                                      than the reverse.
 *              Alan Cox        :       Added a zapped field for tcp to note
 *                                      a socket is reset and must stay shut up
 *              Alan Cox        :       New fields for options
 *      Pauline Middelink       :       identd support
 *              Alan Cox        :       Eliminate low level recv/recvfrom
 *              David S. Miller :       New socket lookup architecture.
 *              Steve Whitehouse:       Default routines for sock_ops
 *              Arnaldo C. Melo :       removed net_pinfo, tp_pinfo and made
 *                                      protinfo be just a void pointer, as the
 *                                      protocol specific parts were moved to
 *                                      respective headers and ipv4/v6, etc now
 *                                      use private slabcaches for its socks
 *              Pedro Hortas    :       New flags field for socket options
 *
 *
 *              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.
 */
#ifndef _SOCK_H
#define _SOCK_H

#include <linux/config.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/cache.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>       /* struct sk_buff */
#include <linux/security.h>

#include <linux/filter.h>

#include <asm/atomic.h>
#include <net/dst.h>

/*
 * This structure really needs to be cleaned up.
 * Most of it is for TCP, and not used by any of
 * the other protocols.
 */

/* Define this to get the sk->sk_debug debugging facility. */
#define SOCK_DEBUGGING
#ifdef SOCK_DEBUGGING
#define SOCK_DEBUG(sk, msg...) do { if ((sk) && ((sk)->sk_debug)) \
                                        printk(KERN_DEBUG msg); } while (0)
#else
#define SOCK_DEBUG(sk, msg...) do { } while (0)
#endif

/* This is the per-socket lock.  The spinlock provides a synchronization
 * between user contexts and software interrupt processing, whereas the
 * mini-semaphore synchronizes multiple users amongst themselves.
 */
struct sock_iocb;
typedef struct {
        spinlock_t              slock;
        struct sock_iocb        *owner;
        wait_queue_head_t       wq;
} socket_lock_t;

#define sock_lock_init(__sk) \
do {    spin_lock_init(&((__sk)->sk_lock.slock)); \
        (__sk)->sk_lock.owner = NULL; \
        init_waitqueue_head(&((__sk)->sk_lock.wq)); \
} while(0)

struct sock;

/**
  *     struct sock_common - minimal network layer representation of sockets
  *     @skc_family - network address family
  *     @skc_state - Connection state
  *     @skc_reuse - %SO_REUSEADDR setting
  *     @skc_bound_dev_if - bound device index if != 0
  *     @skc_node - main hash linkage for various protocol lookup tables
  *     @skc_bind_node - bind hash linkage for various protocol lookup tables
  *     @skc_refcnt - reference count
  *
  *     This is the minimal network layer representation of sockets, the header
  *     for struct sock and struct tcp_tw_bucket.
  */
struct sock_common {
        unsigned short          skc_family;
        volatile unsigned char  skc_state;
        unsigned char           skc_reuse;
        int                     skc_bound_dev_if;
        struct hlist_node       skc_node;
        struct hlist_node       skc_bind_node;
        atomic_t                skc_refcnt;
};

/**
  *     struct sock - network layer representation of sockets
  *     @__sk_common - shared layout with tcp_tw_bucket
  *     @sk_zapped - ax25 & ipx means !linked
  *     @sk_shutdown - mask of %SEND_SHUTDOWN and/or %RCV_SHUTDOWN
  *     @sk_use_write_queue - wheter to call sk->sk_write_space in sock_wfree
  *     @sk_userlocks - %SO_SNDBUF and %SO_RCVBUF settings
  *     @sk_lock -      synchronizer
  *     @sk_rcvbuf - size of receive buffer in bytes
  *     @sk_sleep - sock wait queue
  *     @sk_dst_cache - destination cache
  *     @sk_dst_lock - destination cache lock
  *     @sk_policy - flow policy
  *     @sk_rmem_alloc - receive queue bytes committed
  *     @sk_receive_queue - incoming packets
  *     @sk_wmem_alloc - transmit queue bytes committed
  *     @sk_write_queue - Packet sending queue
  *     @sk_omem_alloc - "o" is "option" or "other"
  *     @sk_wmem_queued - persistent queue size
  *     @sk_forward_alloc - space allocated forward
  *     @sk_allocation - allocation mode
  *     @sk_sndbuf - size of send buffer in bytes
  *     @sk_flags - %SO_LINGER (l_onoff), %SO_BROADCAST, %SO_KEEPALIVE, %SO_OOBINLINE settings
  *     @sk_no_check - %SO_NO_CHECK setting, wether or not checkup packets
  *     @sk_debug - %SO_DEBUG setting
  *     @sk_rcvtstamp - %SO_TIMESTAMP setting
  *     @sk_no_largesend - whether to sent large segments or not
  *     @sk_route_caps - route capabilities (e.g. %NETIF_F_TSO)
  *     @sk_lingertime - %SO_LINGER l_linger setting
  *     @sk_hashent - hash entry in several tables (e.g. tcp_ehash)
  *     @sk_pair - socket pair (e.g. AF_UNIX/unix_peer)
  *     @sk_backlog - always used with the per-socket spinlock held
  *     @sk_callback_lock - used with the callbacks in the end of this struct
  *     @sk_error_queue - rarely used
  *     @sk_prot - protocol handlers inside a network family
  *     @sk_err - last error
  *     @sk_err_soft - errors that don't cause failure but are the cause of a persistent failure not just 'timed out'
  *     @sk_ack_backlog - current listen backlog
  *     @sk_max_ack_backlog - listen backlog set in listen()
  *     @sk_priority - %SO_PRIORITY setting
  *     @sk_type - socket type (%SOCK_STREAM, etc)
  *     @sk_localroute - route locally only, %SO_DONTROUTE setting
  *     @sk_protocol - which protocol this socket belongs in this network family
  *     @sk_peercred - %SO_PEERCRED setting
  *     @sk_rcvlowat - %SO_RCVLOWAT setting
  *     @sk_rcvtimeo - %SO_RCVTIMEO setting
  *     @sk_sndtimeo - %SO_SNDTIMEO setting
  *     @sk_filter - socket filtering instructions
  *     @sk_protinfo - private area, net family specific, when not using slab
  *     @sk_slab - the slabcache this instance was allocated from
  *     @sk_timer - sock cleanup timer
  *     @sk_stamp - time stamp of last packet received
  *     @sk_socket - Identd and reporting IO signals
  *     @sk_user_data - RPC layer private data
  *     @sk_owner - module that owns this socket
  *     @sk_state_change - callback to indicate change in the state of the sock
  *     @sk_data_ready - callback to indicate there is data to be processed
  *     @sk_write_space - callback to indicate there is bf sending space available
  *     @sk_error_report - callback to indicate errors (e.g. %MSG_ERRQUEUE)
  *     @sk_backlog_rcv - callback to process the backlog
  *     @sk_destruct - called at sock freeing time, i.e. when all refcnt == 0
 */
struct sock {
        /*
         * Now struct tcp_tw_bucket also uses sock_common, so please just
         * don't add nothing before this first member (__sk_common) --acme
         */
        struct sock_common      __sk_common;
#define sk_family               __sk_common.skc_family
#define sk_state                __sk_common.skc_state
#define sk_reuse                __sk_common.skc_reuse
#define sk_bound_dev_if         __sk_common.skc_bound_dev_if
#define sk_node                 __sk_common.skc_node
#define sk_bind_node            __sk_common.skc_bind_node
#define sk_refcnt               __sk_common.skc_refcnt
        volatile unsigned char  sk_zapped;
        unsigned char           sk_shutdown;
        unsigned char           sk_use_write_queue;
        unsigned char           sk_userlocks;
        socket_lock_t           sk_lock;
        int                     sk_rcvbuf;
        wait_queue_head_t       *sk_sleep;
        struct dst_entry        *sk_dst_cache;
        rwlock_t                sk_dst_lock;
        struct xfrm_policy      *sk_policy[2];
        atomic_t                sk_rmem_alloc;
        struct sk_buff_head     sk_receive_queue;
        atomic_t                sk_wmem_alloc;
        struct sk_buff_head     sk_write_queue;
        atomic_t                sk_omem_alloc;
        int                     sk_wmem_queued;
        int                     sk_forward_alloc;
        unsigned int            sk_allocation;
        int                     sk_sndbuf;
        unsigned long           sk_flags;
        char                    sk_no_check;
        unsigned char           sk_debug;
        unsigned char           sk_rcvtstamp;
        unsigned char           sk_no_largesend;
        int                     sk_route_caps;
        unsigned long           sk_lingertime;
        int                     sk_hashent;
        struct sock             *sk_pair;
        /*
         * The backlog queue is special, it is always used with
         * the per-socket spinlock held and requires low latency
         * access. Therefore we special case it's implementation.
         */
        struct {
                struct sk_buff *head;
                struct sk_buff *tail;
        } sk_backlog;
        rwlock_t                sk_callback_lock;
        struct sk_buff_head     sk_error_queue;
        struct proto            *sk_prot;
        int                     sk_err,
                                sk_err_soft;
        unsigned short          sk_ack_backlog;
        unsigned short          sk_max_ack_backlog;
        __u32                   sk_priority;
        unsigned short          sk_type;
        unsigned char           sk_localroute;
        unsigned char           sk_protocol;
        struct ucred            sk_peercred;
        int                     sk_rcvlowat;
        long                    sk_rcvtimeo;
        long                    sk_sndtimeo;
        struct sk_filter        *sk_filter;
        void                    *sk_protinfo;
        kmem_cache_t            *sk_slab;
        struct timer_list       sk_timer;
        struct timeval          sk_stamp;
        struct socket           *sk_socket;
        void                    *sk_user_data;
        struct module           *sk_owner;
        void                    (*sk_state_change)(struct sock *sk);
        void                    (*sk_data_ready)(struct sock *sk, int bytes);
        void                    (*sk_write_space)(struct sock *sk);
        void                    (*sk_error_report)(struct sock *sk);
        int                     (*sk_backlog_rcv)(struct sock *sk,
                                                  struct sk_buff *skb);  
        void                    (*sk_destruct)(struct sock *sk);
};

/*
 * Hashed lists helper routines
 */
static inline struct sock *__sk_head(struct hlist_head *head)
{
        return hlist_entry(head->first, struct sock, sk_node);
}

static inline struct sock *sk_head(struct hlist_head *head)
{
        return hlist_empty(head) ? NULL : __sk_head(head);
}

static inline struct sock *sk_next(struct sock *sk)
{
        return sk->sk_node.next ?
                hlist_entry(sk->sk_node.next, struct sock, sk_node) : NULL;
}

static inline int sk_unhashed(struct sock *sk)
{
        return hlist_unhashed(&sk->sk_node);
}

static inline int sk_hashed(struct sock *sk)
{
        return sk->sk_node.pprev != NULL;
}

static __inline__ void sk_node_init(struct hlist_node *node)
{
        node->pprev = NULL;
}

static __inline__ void __sk_del_node(struct sock *sk)
{
        __hlist_del(&sk->sk_node);
}

static __inline__ int __sk_del_node_init(struct sock *sk)
{
        if (sk_hashed(sk)) {
                __sk_del_node(sk);
                sk_node_init(&sk->sk_node);
                return 1;
        }
        return 0;
}

static inline void __sock_put(struct sock *sk);

static __inline__ int sk_del_node_init(struct sock *sk)
{
        int rc = __sk_del_node_init(sk);

        if (rc) {
                /* paranoid for a while -acme */
                WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
                __sock_put(sk);
        }
        return rc;
}

static __inline__ void __sk_add_node(struct sock *sk, struct hlist_head *list)
{
        hlist_add_head(&sk->sk_node, list);
}

static inline void sock_hold(struct sock *sk);

static __inline__ void sk_add_node(struct sock *sk, struct hlist_head *list)
{
        sock_hold(sk);
        __sk_add_node(sk, list);
}

static __inline__ void __sk_del_bind_node(struct sock *sk)
{
        __hlist_del(&sk->sk_bind_node);
}

static __inline__ void sk_add_bind_node(struct sock *sk,
                                        struct hlist_head *list)
{
        hlist_add_head(&sk->sk_bind_node, list);
}

#define sk_for_each(__sk, node, list) \
        hlist_for_each_entry(__sk, node, list, sk_node)
#define sk_for_each_from(__sk, node) \
        if (__sk && ({ node = &(__sk)->sk_node; 1; })) \
                hlist_for_each_entry_from(__sk, node, sk_node)
#define sk_for_each_continue(__sk, node) \
        if (__sk && ({ node = &(__sk)->sk_node; 1; })) \
                hlist_for_each_entry_continue(__sk, node, sk_node)
#define sk_for_each_safe(__sk, node, tmp, list) \
        hlist_for_each_entry_safe(__sk, node, tmp, list, sk_node)
#define sk_for_each_bound(__sk, node, list) \
        hlist_for_each_entry(__sk, node, list, sk_bind_node)

/* Sock flags */
enum sock_flags {
        SOCK_DEAD,
        SOCK_DONE,
        SOCK_URGINLINE,
        SOCK_KEEPOPEN,
        SOCK_LINGER,
        SOCK_DESTROY,
        SOCK_BROADCAST,
};

static inline void sock_set_flag(struct sock *sk, enum sock_flags flag)
{
        __set_bit(flag, &sk->sk_flags);
}

static inline void sock_reset_flag(struct sock *sk, enum sock_flags flag)
{
        __clear_bit(flag, &sk->sk_flags);
}

static inline int sock_flag(struct sock *sk, enum sock_flags flag)
{
        return test_bit(flag, &sk->sk_flags);
}

/* The per-socket spinlock must be held here. */
#define sk_add_backlog(__sk, __skb)                             \
do {    if (!(__sk)->sk_backlog.tail) {                         \
                (__sk)->sk_backlog.head =                       \
                     (__sk)->sk_backlog.tail = (__skb);         \
        } else {                                                \
                ((__sk)->sk_backlog.tail)->next = (__skb);      \
                (__sk)->sk_backlog.tail = (__skb);              \
        }                                                       \
        (__skb)->next = NULL;                                   \
} while(0)

/* IP protocol blocks we attach to sockets.
 * socket layer -> transport layer interface
 * transport -> network interface is defined by struct inet_proto
 */
struct proto {
        void                    (*close)(struct sock *sk, 
                                        long timeout);
        int                     (*connect)(struct sock *sk,
                                        struct sockaddr *uaddr, 
                                        int addr_len);
        int                     (*disconnect)(struct sock *sk, int flags);

        struct sock *           (*accept) (struct sock *sk, int flags, int *err);

        int                     (*ioctl)(struct sock *sk, int cmd,
                                         unsigned long arg);
        int                     (*init)(struct sock *sk);
        int                     (*destroy)(struct sock *sk);
        void                    (*shutdown)(struct sock *sk, int how);
        int                     (*setsockopt)(struct sock *sk, int level, 
                                        int optname, char *optval, int optlen);
        int                     (*getsockopt)(struct sock *sk, int level, 
                                        int optname, char *optval, 
                                        int *option);    
        int                     (*sendmsg)(struct kiocb *iocb, struct sock *sk,
                                           struct msghdr *msg, int len);
        int                     (*recvmsg)(struct kiocb *iocb, struct sock *sk,
                                           struct msghdr *msg,
                                        int len, int noblock, int flags, 
                                        int *addr_len);
        int                     (*sendpage)(struct sock *sk, struct page *page,
                                        int offset, size_t size, int flags);
        int                     (*bind)(struct sock *sk, 
                                        struct sockaddr *uaddr, int addr_len);

        int                     (*backlog_rcv) (struct sock *sk, 
                                                struct sk_buff *skb);

        /* Keeping track of sk's, looking them up, and port selection methods. */
        void                    (*hash)(struct sock *sk);
        void                    (*unhash)(struct sock *sk);
        int                     (*get_port)(struct sock *sk, unsigned short snum);

        char                    name[32];

        struct {
                int inuse;
                u8  __pad[SMP_CACHE_BYTES - sizeof(int)];
        } stats[NR_CPUS];
};

static __inline__ void sk_set_owner(struct sock *sk, struct module *owner)
{
        /*
         * One should use sk_set_owner just once, after struct sock creation,
         * be it shortly after sk_alloc or after a function that returns a new
         * struct sock (and that down the call chain called sk_alloc), e.g. the
         * IPv4 and IPv6 modules share tcp_create_openreq_child, so if
         * tcp_create_openreq_child called sk_set_owner IPv6 would have to
         * change the ownership of this struct sock, with one not needed
         * transient sk_set_owner call.
         */
        if (unlikely(sk->sk_owner != NULL))
                BUG();
        sk->sk_owner = owner;
        __module_get(owner);
}

/* Called with local bh disabled */
static __inline__ void sock_prot_inc_use(struct proto *prot)
{
        prot->stats[smp_processor_id()].inuse++;
}

static __inline__ void sock_prot_dec_use(struct proto *prot)
{
        prot->stats[smp_processor_id()].inuse--;
}

/* About 10 seconds */
#define SOCK_DESTROY_TIME (10*HZ)

/* Sockets 0-1023 can't be bound to unless you are superuser */
#define PROT_SOCK       1024

#define SHUTDOWN_MASK   3
#define RCV_SHUTDOWN    1
#define SEND_SHUTDOWN   2

#define SOCK_SNDBUF_LOCK        1
#define SOCK_RCVBUF_LOCK        2
#define SOCK_BINDADDR_LOCK      4
#define SOCK_BINDPORT_LOCK      8

/* sock_iocb: used to kick off async processing of socket ios */
struct sock_iocb {
        struct list_head        list;

        int                     flags;
        int                     size;
        struct socket           *sock;
        struct sock             *sk;
        struct scm_cookie       *scm;
        struct msghdr           *msg, async_msg;
        struct iovec            async_iov;
};

static inline struct sock_iocb *kiocb_to_siocb(struct kiocb *iocb)
{
        BUG_ON(sizeof(struct sock_iocb) > KIOCB_PRIVATE_SIZE);
        return (struct sock_iocb *)iocb->private;
}

static inline struct kiocb *siocb_to_kiocb(struct sock_iocb *si)
{
        return container_of((void *)si, struct kiocb, private);
}

struct socket_alloc {
        struct socket socket;
        struct inode vfs_inode;
};

static inline struct socket *SOCKET_I(struct inode *inode)
{
        return &container_of(inode, struct socket_alloc, vfs_inode)->socket;
}

static inline struct inode *SOCK_INODE(struct socket *socket)
{
        return &container_of(socket, struct socket_alloc, socket)->vfs_inode;
}

/* Used by processes to "lock" a socket state, so that
 * interrupts and bottom half handlers won't change it
 * from under us. It essentially blocks any incoming
 * packets, so that we won't get any new data or any
 * packets that change the state of the socket.
 *
 * While locked, BH processing will add new packets to
 * the backlog queue.  This queue is processed by the
 * owner of the socket lock right before it is released.
 *
 * Since ~2.3.5 it is also exclusive sleep lock serializing
 * accesses from user process context.
 */
extern void __lock_sock(struct sock *sk);
extern void __release_sock(struct sock *sk);
#define sock_owned_by_user(sk)  ((sk)->sk_lock.owner)

extern void lock_sock(struct sock *sk);
extern void release_sock(struct sock *sk);

/* BH context may only use the following locking interface. */
#define bh_lock_sock(__sk)      spin_lock(&((__sk)->sk_lock.slock))
#define bh_unlock_sock(__sk)    spin_unlock(&((__sk)->sk_lock.slock))

extern struct sock *            sk_alloc(int family, int priority, int zero_it,
                                         kmem_cache_t *slab);
extern void                     sk_free(struct sock *sk);

extern struct sk_buff           *sock_wmalloc(struct sock *sk,
                                              unsigned long size, int force,
                                              int priority);
extern struct sk_buff           *sock_rmalloc(struct sock *sk,
                                              unsigned long size, int force,
                                              int priority);
extern void                     sock_wfree(struct sk_buff *skb);
extern void                     sock_rfree(struct sk_buff *skb);

extern int                      sock_setsockopt(struct socket *sock, int level,
                                                int op, char __user *optval,
                                                int optlen);

extern int                      sock_getsockopt(struct socket *sock, int level,
                                                int op, char __user *optval, 
                                                int __user *optlen);
extern struct sk_buff           *sock_alloc_send_skb(struct sock *sk,
                                                     unsigned long size,
                                                     int noblock,
                                                     int *errcode);
extern struct sk_buff           *sock_alloc_send_pskb(struct sock *sk,
                                                      unsigned long header_len,
                                                      unsigned long data_len,
                                                      int noblock,
                                                      int *errcode);
extern void *sock_kmalloc(struct sock *sk, int size, int priority);
extern void sock_kfree_s(struct sock *sk, void *mem, int size);
extern void sk_send_sigurg(struct sock *sk);

/*
 * Functions to fill in entries in struct proto_ops when a protocol
 * does not implement a particular function.
 */
extern int                      sock_no_release(struct socket *);
extern int                      sock_no_bind(struct socket *, 
                                             struct sockaddr *, int);
extern int                      sock_no_connect(struct socket *,
                                                struct sockaddr *, int, int);
extern int                      sock_no_socketpair(struct socket *,
                                                   struct socket *);
extern int                      sock_no_accept(struct socket *,
                                               struct socket *, int);
extern int                      sock_no_getname(struct socket *,
                                                struct sockaddr *, int *, int);
extern unsigned int             sock_no_poll(struct file *, struct socket *,
                                             struct poll_table_struct *);
extern int                      sock_no_ioctl(struct socket *, unsigned int,
                                              unsigned long);
extern int                      sock_no_listen(struct socket *, int);
extern int                      sock_no_shutdown(struct socket *, int);
extern int                      sock_no_getsockopt(struct socket *, int , int,
                                                   char *, int *);
extern int                      sock_no_setsockopt(struct socket *, int, int,
                                                   char *, int);
extern int                      sock_no_sendmsg(struct kiocb *, struct socket *,
                                                struct msghdr *, int);
extern int                      sock_no_recvmsg(struct kiocb *, struct socket *,
                                                struct msghdr *, int, int);
extern int                      sock_no_mmap(struct file *file,
                                             struct socket *sock,
                                             struct vm_area_struct *vma);
extern ssize_t                  sock_no_sendpage(struct socket *sock,
                                                struct page *page,
                                                int offset, size_t size, 
                                                int flags);

/*
 *      Default socket callbacks and setup code
 */
 
extern void sock_def_destruct(struct sock *);

/* Initialise core socket variables */
extern void sock_init_data(struct socket *sock, struct sock *sk);

/**
 *      sk_filter - run a packet through a socket filter
 *      @sk: sock associated with &sk_buff
 *      @skb: buffer to filter
 *      @needlock: set to 1 if the sock is not locked by caller.
 *
 * Run the filter code and then cut skb->data to correct size returned by
 * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
 * than pkt_len we keep whole skb->data. This is the socket level
 * wrapper to sk_run_filter. It returns 0 if the packet should
 * be accepted or -EPERM if the packet should be tossed.
 *
 */

static inline int sk_filter(struct sock *sk, struct sk_buff *skb, int needlock)
{
        int err;
        
        err = security_sock_rcv_skb(sk, skb);
        if (err)
                return err;
        
        if (sk->sk_filter) {
                struct sk_filter *filter;
                
                if (needlock)
                        bh_lock_sock(sk);
                
                filter = sk->sk_filter;
                if (filter) {
                        int pkt_len = sk_run_filter(skb, filter->insns,
                                                    filter->len);
                        if (!pkt_len)
                                err = -EPERM;
                        else
                                skb_trim(skb, pkt_len);
                }

                if (needlock)
                        bh_unlock_sock(sk);
        }
        return err;
}

/**
 *      sk_filter_release: Release a socket filter
 *      @sk: socket
 *      @fp: filter to remove
 *
 *      Remove a filter from a socket and release its resources.
 */
 
static inline void sk_filter_release(struct sock *sk, struct sk_filter *fp)
{
        unsigned int size = sk_filter_len(fp);

        atomic_sub(size, &sk->sk_omem_alloc);

        if (atomic_dec_and_test(&fp->refcnt))
                kfree(fp);
}

static inline void sk_filter_charge(struct sock *sk, struct sk_filter *fp)
{
        atomic_inc(&fp->refcnt);
        atomic_add(sk_filter_len(fp), &sk->sk_omem_alloc);
}

/*
 * Socket reference counting postulates.
 *
 * * Each user of socket SHOULD hold a reference count.
 * * Each access point to socket (an hash table bucket, reference from a list,
 *   running timer, skb in flight MUST hold a reference count.
 * * When reference count hits 0, it means it will never increase back.
 * * When reference count hits 0, it means that no references from
 *   outside exist to this socket and current process on current CPU
 *   is last user and may/should destroy this socket.
 * * sk_free is called from any context: process, BH, IRQ. When
 *   it is called, socket has no references from outside -> sk_free
 *   may release descendant resources allocated by the socket, but
 *   to the time when it is called, socket is NOT referenced by any
 *   hash tables, lists etc.
 * * Packets, delivered from outside (from network or from another process)
 *   and enqueued on receive/error queues SHOULD NOT grab reference count,
 *   when they sit in queue. Otherwise, packets will leak to hole, when
 *   socket is looked up by one cpu and unhasing is made by another CPU.
 *   It is true for udp/raw, netlink (leak to receive and error queues), tcp
 *   (leak to backlog). Packet socket does all the processing inside
 *   BR_NETPROTO_LOCK, so that it has not this race condition. UNIX sockets
 *   use separate SMP lock, so that they are prone too.
 */

/* Grab socket reference count. This operation is valid only
   when sk is ALREADY grabbed f.e. it is found in hash table
   or a list and the lookup is made under lock preventing hash table
   modifications.
 */

static inline void sock_hold(struct sock *sk)
{
        atomic_inc(&sk->sk_refcnt);
}

/* Ungrab socket in the context, which assumes that socket refcnt
   cannot hit zero, f.e. it is true in context of any socketcall.
 */
static inline void __sock_put(struct sock *sk)
{
        atomic_dec(&sk->sk_refcnt);
}

/* Ungrab socket and destroy it, if it was the last reference. */
static inline void sock_put(struct sock *sk)
{
        if (atomic_dec_and_test(&sk->sk_refcnt))
                sk_free(sk);
}

/* Detach socket from process context.
 * Announce socket dead, detach it from wait queue and inode.
 * Note that parent inode held reference count on this struct sock,
 * we do not release it in this function, because protocol
 * probably wants some additional cleanups or even continuing
 * to work with this socket (TCP).
 */
static inline void sock_orphan(struct sock *sk)
{
        write_lock_bh(&sk->sk_callback_lock);
        sock_set_flag(sk, SOCK_DEAD);
        sk->sk_socket = NULL;
        sk->sk_sleep  = NULL;
        write_unlock_bh(&sk->sk_callback_lock);
}

static inline void sock_graft(struct sock *sk, struct socket *parent)
{
        write_lock_bh(&sk->sk_callback_lock);
        sk->sk_sleep = &parent->wait;
        parent->sk = sk;
        sk->sk_socket = parent;
        write_unlock_bh(&sk->sk_callback_lock);
}

static inline int sock_i_uid(struct sock *sk)
{
        int uid;

        read_lock(&sk->sk_callback_lock);
        uid = sk->sk_socket ? SOCK_INODE(sk->sk_socket)->i_uid : 0;
        read_unlock(&sk->sk_callback_lock);
        return uid;
}

static inline unsigned long sock_i_ino(struct sock *sk)
{
        unsigned long ino;

        read_lock(&sk->sk_callback_lock);
        ino = sk->sk_socket ? SOCK_INODE(sk->sk_socket)->i_ino : 0;
        read_unlock(&sk->sk_callback_lock);
        return ino;
}

static inline struct dst_entry *
__sk_dst_get(struct sock *sk)
{
        return sk->sk_dst_cache;
}

static inline struct dst_entry *
sk_dst_get(struct sock *sk)
{
        struct dst_entry *dst;

        read_lock(&sk->sk_dst_lock);
        dst = sk->sk_dst_cache;
        if (dst)
                dst_hold(dst);
        read_unlock(&sk->sk_dst_lock);
        return dst;
}

static inline void
__sk_dst_set(struct sock *sk, struct dst_entry *dst)
{
        struct dst_entry *old_dst;

        old_dst = sk->sk_dst_cache;
        sk->sk_dst_cache = dst;
        dst_release(old_dst);
}

static inline void
sk_dst_set(struct sock *sk, struct dst_entry *dst)
{
        write_lock(&sk->sk_dst_lock);
        __sk_dst_set(sk, dst);
        write_unlock(&sk->sk_dst_lock);
}

static inline void
__sk_dst_reset(struct sock *sk)
{
        struct dst_entry *old_dst;

        old_dst = sk->sk_dst_cache;
        sk->sk_dst_cache = NULL;
        dst_release(old_dst);
}

static inline void
sk_dst_reset(struct sock *sk)
{
        write_lock(&sk->sk_dst_lock);
        __sk_dst_reset(sk);
        write_unlock(&sk->sk_dst_lock);
}

static inline struct dst_entry *
__sk_dst_check(struct sock *sk, u32 cookie)
{
        struct dst_entry *dst = sk->sk_dst_cache;

        if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
                sk->sk_dst_cache = NULL;
                return NULL;
        }

        return dst;
}

static inline struct dst_entry *
sk_dst_check(struct sock *sk, u32 cookie)
{
        struct dst_entry *dst = sk_dst_get(sk);

        if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
                sk_dst_reset(sk);
                return NULL;
        }

        return dst;
}


/*
 *      Queue a received datagram if it will fit. Stream and sequenced
 *      protocols can't normally use this as they need to fit buffers in
 *      and play with them.
 *
 *      Inlined as it's very short and called for pretty much every
 *      packet ever received.
 */

static inline void skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
{
        sock_hold(sk);
        skb->sk = sk;
        skb->destructor = sock_wfree;
        atomic_add(skb->truesize, &sk->sk_wmem_alloc);
}

static inline void skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
{
        skb->sk = sk;
        skb->destructor = sock_rfree;
        atomic_add(skb->truesize, &sk->sk_rmem_alloc);
}

static inline int sock_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
        int err = 0;
        int skb_len;

        /* Cast skb->rcvbuf to unsigned... It's pointless, but reduces
           number of warnings when compiling with -W --ANK
         */
        if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
            (unsigned)sk->sk_rcvbuf) {
                err = -ENOMEM;
                goto out;
        }

        /* It would be deadlock, if sock_queue_rcv_skb is used
           with socket lock! We assume that users of this
           function are lock free.
        */
        err = sk_filter(sk, skb, 1);
        if (err)
                goto out;

        skb->dev = NULL;
        skb_set_owner_r(skb, sk);

        /* Cache the SKB length before we tack it onto the receive
         * queue.  Once it is added it no longer belongs to us and
         * may be freed by other threads of control pulling packets
         * from the queue.
         */
        skb_len = skb->len;

        skb_queue_tail(&sk->sk_receive_queue, skb);

        if (!sock_flag(sk, SOCK_DEAD))
                sk->sk_data_ready(sk, skb_len);
out:
        return err;
}

static inline int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb)
{
        /* Cast skb->rcvbuf to unsigned... It's pointless, but reduces
           number of warnings when compiling with -W --ANK
         */
        if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
            (unsigned)sk->sk_rcvbuf)
                return -ENOMEM;
        skb_set_owner_r(skb, sk);
        skb_queue_tail(&sk->sk_error_queue, skb);
        if (!sock_flag(sk, SOCK_DEAD))
                sk->sk_data_ready(sk, skb->len);
        return 0;
}

/*
 *      Recover an error report and clear atomically
 */
 
static inline int sock_error(struct sock *sk)
{
        int err = xchg(&sk->sk_err, 0);
        return -err;
}

static inline unsigned long sock_wspace(struct sock *sk)
{
        int amt = 0;

        if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
                amt = sk->sk_sndbuf - atomic_read(&sk->sk_wmem_alloc);
                if (amt < 0) 
                        amt = 0;
        }
        return amt;
}

static inline void sk_wake_async(struct sock *sk, int how, int band)
{
        if (sk->sk_socket && sk->sk_socket->fasync_list)
                sock_wake_async(sk->sk_socket, how, band);
}

#define SOCK_MIN_SNDBUF 2048
#define SOCK_MIN_RCVBUF 256

/*
 *      Default write policy as shown to user space via poll/select/SIGIO
 */
static inline int sock_writeable(struct sock *sk) 
{
        return atomic_read(&sk->sk_wmem_alloc) < (sk->sk_sndbuf / 2);
}

static inline int gfp_any(void)
{
        return in_softirq() ? GFP_ATOMIC : GFP_KERNEL;
}

static inline long sock_rcvtimeo(struct sock *sk, int noblock)
{
        return noblock ? 0 : sk->sk_rcvtimeo;
}

static inline long sock_sndtimeo(struct sock *sk, int noblock)
{
        return noblock ? 0 : sk->sk_sndtimeo;
}

static inline int sock_rcvlowat(struct sock *sk, int waitall, int len)
{
        return (waitall ? len : min_t(int, sk->sk_rcvlowat, len)) ? : 1;
}

/* Alas, with timeout socket operations are not restartable.
 * Compare this to poll().
 */
static inline int sock_intr_errno(long timeo)
{
        return timeo == MAX_SCHEDULE_TIMEOUT ? -ERESTARTSYS : -EINTR;
}

static __inline__ void
sock_recv_timestamp(struct msghdr *msg, struct sock *sk, struct sk_buff *skb)
{
        if (sk->sk_rcvtstamp)
                put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP, sizeof(skb->stamp), &skb->stamp);
        else
                sk->sk_stamp = skb->stamp;
}

/* 
 *      Enable debug/info messages 
 */

#if 0
#define NETDEBUG(x)     do { } while (0)
#else
#define NETDEBUG(x)     do { x; } while (0)
#endif

/*
 * Macros for sleeping on a socket. Use them like this:
 *
 * SOCK_SLEEP_PRE(sk)
 * if (condition)
 *      schedule();
 * SOCK_SLEEP_POST(sk)
 *
 * N.B. These are now obsolete and were, afaik, only ever used in DECnet
 * and when the last use of them in DECnet has gone, I'm intending to
 * remove them.
 */

#define SOCK_SLEEP_PRE(sk)      { struct task_struct *tsk = current; \
                                DECLARE_WAITQUEUE(wait, tsk); \
                                tsk->state = TASK_INTERRUPTIBLE; \
                                add_wait_queue((sk)->sk_sleep, &wait); \
                                release_sock(sk);

#define SOCK_SLEEP_POST(sk)     tsk->state = TASK_RUNNING; \
                                remove_wait_queue((sk)->sk_sleep, &wait); \
                                lock_sock(sk); \
                                }

static inline void sock_valbool_flag(struct sock *sk, int bit, int valbool)
{
        if (valbool)
                sock_set_flag(sk, bit);
        else
                sock_reset_flag(sk, bit);
}

extern __u32 sysctl_wmem_max;
extern __u32 sysctl_rmem_max;

int siocdevprivate_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg);

#endif  /* _SOCK_H */