sock.h

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 *
 *		union or struct {
 *			ax25;
 *		} ll_pinfo;
 *	
 *		union {
 *			ipv4;
 *			ipv6;
 *			ipx;
 *			netrom;
 *			rose;
 * 			x25;
 *		} net_pinfo;
 *
 *		union {
 *			tcp;
 *			udp;
 *			spx;
 *			netrom;
 *		} tp_pinfo;
 *
 *	}
 *
 * The idea failed because IPv6 transition asssumes dual IP/IPv6 sockets.
 * So, net_pinfo is IPv6 are really, and protinfo unifies all another
 * private areas.
 */

/* Define this to get the sk->debug debugging facility. */
#define SOCK_DEBUGGING
#ifdef SOCK_DEBUGGING
#define SOCK_DEBUG(sk, msg...) do { if((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.
 */
typedef struct {
	spinlock_t		slock;
	unsigned int		users;
	wait_queue_head_t	wq;
} socket_lock_t;

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

struct sock {
	/* Socket demultiplex comparisons on incoming packets. */
	__u32			daddr;		/* Foreign IPv4 addr			*/
	__u32			rcv_saddr;	/* Bound local IPv4 addr		*/
	__u16			dport;		/* Destination port			*/
	unsigned short		num;		/* Local port				*/
	int			bound_dev_if;	/* Bound device index if != 0		*/

	/* Main hash linkage for various protocol lookup tables. */
	struct sock		*next;
	struct sock		**pprev;
	struct sock		*bind_next;
	struct sock		**bind_pprev;

	volatile unsigned char	state,		/* Connection state			*/
				zapped;		/* In ax25 & ipx means not linked	*/
	__u16			sport;		/* Source port				*/

	unsigned short		family;		/* Address family			*/
	unsigned char		reuse;		/* SO_REUSEADDR setting			*/
	unsigned char		shutdown;
	atomic_t		refcnt;		/* Reference count			*/

	socket_lock_t		lock;		/* Synchronizer...			*/
	int			rcvbuf;		/* Size of receive buffer in bytes	*/

	wait_queue_head_t	*sleep;		/* Sock wait queue			*/
	struct dst_entry	*dst_cache;	/* Destination cache			*/
	rwlock_t		dst_lock;
	atomic_t		rmem_alloc;	/* Receive queue bytes committed	*/
	struct sk_buff_head	receive_queue;	/* Incoming packets			*/
	atomic_t		wmem_alloc;	/* Transmit queue bytes committed	*/
	struct sk_buff_head	write_queue;	/* Packet sending queue			*/
	atomic_t		omem_alloc;	/* "o" is "option" or "other" */
	int			wmem_queued;	/* Persistent queue size */
	int			forward_alloc;	/* Space allocated forward. */
	__u32			saddr;		/* Sending source			*/
	unsigned int		allocation;	/* Allocation mode			*/
	int			sndbuf;		/* Size of send buffer in bytes		*/
	struct sock		*prev;

	/* Not all are volatile, but some are, so we might as well say they all are.
	 * XXX Make this a flag word -DaveM
	 */
	volatile char		dead,
				done,
				urginline,
				keepopen,
				linger,
				destroy,
				no_check,
				broadcast,
				bsdism;
	unsigned char		debug;
	unsigned char		rcvtstamp;
	unsigned char		use_write_queue;
	unsigned char		userlocks;
	/* Hole of 3 bytes. Try to pack. */
	int			route_caps;
	int			proc;
	unsigned long	        lingertime;

	int			hashent;
	struct sock		*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;
	} backlog;

	rwlock_t		callback_lock;

	/* Error queue, rarely used. */
	struct sk_buff_head	error_queue;

	struct proto		*prot;

#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
	union {
		struct ipv6_pinfo	af_inet6;
	} net_pinfo;
#endif

	union {
		struct tcp_opt		af_tcp;
#if defined(CONFIG_INET) || defined (CONFIG_INET_MODULE)
		struct raw_opt		tp_raw4;
#endif
#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
		struct raw6_opt		tp_raw;
#endif /* CONFIG_IPV6 */
#if defined(CONFIG_SPX) || defined (CONFIG_SPX_MODULE)
		struct spx_opt		af_spx;
#endif /* CONFIG_SPX */

	} tp_pinfo;

	int			err, err_soft;	/* Soft holds errors that don't
						   cause failure but are the cause
						   of a persistent failure not just
						   'timed out' */
	unsigned short		ack_backlog;
	unsigned short		max_ack_backlog;
	__u32			priority;
	unsigned short		type;
	unsigned char		localroute;	/* Route locally only */
	unsigned char		protocol;
	struct ucred		peercred;
	int			rcvlowat;
	long			rcvtimeo;
	long			sndtimeo;

#ifdef CONFIG_FILTER
	/* Socket Filtering Instructions */
	struct sk_filter      	*filter;
#endif /* CONFIG_FILTER */

	/* This is where all the private (optional) areas that don't
	 * overlap will eventually live. 
	 */
	union {
		void *destruct_hook;
	  	struct unix_opt	af_unix;
#if defined(CONFIG_INET) || defined (CONFIG_INET_MODULE)
		struct inet_opt af_inet;
#endif
#if defined(CONFIG_ATALK) || defined(CONFIG_ATALK_MODULE)
		struct atalk_sock	af_at;
#endif
#if defined(CONFIG_IPX) || defined(CONFIG_IPX_MODULE)
		struct ipx_opt		af_ipx;
#endif
#if defined (CONFIG_DECNET) || defined(CONFIG_DECNET_MODULE)
		struct dn_scp           dn;
#endif
#if defined (CONFIG_PACKET) || defined(CONFIG_PACKET_MODULE)
		struct packet_opt	*af_packet;
#endif
#if defined(CONFIG_X25) || defined(CONFIG_X25_MODULE)
		x25_cb			*x25;
#endif
#if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
		ax25_cb			*ax25;
#endif
#if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE)
		nr_cb			*nr;
#endif
#if defined(CONFIG_ROSE) || defined(CONFIG_ROSE_MODULE)
		rose_cb			*rose;
#endif
#if defined(CONFIG_PPPOE) || defined(CONFIG_PPPOE_MODULE)
		struct pppox_opt	*pppox;
#endif
		struct netlink_opt	*af_netlink;
#if defined(CONFIG_ECONET) || defined(CONFIG_ECONET_MODULE)
		struct econet_opt	*af_econet;
#endif
#if defined(CONFIG_ATM) || defined(CONFIG_ATM_MODULE)
		struct atm_vcc		*af_atm;
#endif
#if defined(CONFIG_IRDA) || defined(CONFIG_IRDA_MODULE)
		struct irda_sock        *irda;
#endif
#if defined(CONFIG_WAN_ROUTER) || defined(CONFIG_WAN_ROUTER_MODULE)
               struct wanpipe_opt      *af_wanpipe;
#endif
	} protinfo;  		


	/* This part is used for the timeout functions. */
	struct timer_list	timer;		/* This is the sock cleanup timer. */
	struct timeval		stamp;

	/* Identd and reporting IO signals */
	struct socket		*socket;

	/* RPC layer private data */
	void			*user_data;
  
	/* Callbacks */
	void			(*state_change)(struct sock *sk);
	void			(*data_ready)(struct sock *sk,int bytes);
	void			(*write_space)(struct sock *sk);
	void			(*error_report)(struct sock *sk);

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

/* The per-socket spinlock must be held here. */
#define sk_add_backlog(__sk, __skb)			\
do {	if((__sk)->backlog.tail == NULL) {		\
		(__sk)->backlog.head =			\
		     (__sk)->backlog.tail = (__skb);	\
	} else {					\
		((__sk)->backlog.tail)->next = (__skb);	\
		(__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 sock *sk, struct msghdr *msg,
					   int len);
	int			(*recvmsg)(struct sock *sk, struct msghdr *msg,
					int len, int noblock, int flags, 
					int *addr_len);
	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];
};

/* 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


/* 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 lock_sock(__sk) \
do {	spin_lock_bh(&((__sk)->lock.slock)); \
	if ((__sk)->lock.users != 0) \
		__lock_sock(__sk); \
	(__sk)->lock.users = 1; \
	spin_unlock_bh(&((__sk)->lock.slock)); \
} while(0)

#define release_sock(__sk) \
do {	spin_lock_bh(&((__sk)->lock.slock)); \
	if ((__sk)->backlog.tail != NULL) \
		__release_sock(__sk); \
	(__sk)->lock.users = 0; \
        if (waitqueue_active(&((__sk)->lock.wq))) wake_up(&((__sk)->lock.wq)); \
	spin_unlock_bh(&((__sk)->lock.slock)); \
} while(0)

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

extern struct sock *		sk_alloc(int family, int priority, int zero_it);
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 *optval,
						int optlen);

extern int			sock_getsockopt(struct socket *sock, int level,
						int op, char *optval, 
						int *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);

/*
 * 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_fcntl(struct socket *, 
					      unsigned int, unsigned long);
extern int                      sock_no_sendmsg(struct socket *,
						struct msghdr *, int,
						struct scm_cookie *);
extern int                      sock_no_recvmsg(struct socket *,
						struct msghdr *, int, int,
						struct scm_cookie *);
extern int			sock_no_mmap(struct file *file,
					     struct socket *sock,
					     struct vm_area_struct *vma);