skbuff.h

来自「Linux Kernel 2.6.9 for OMAP1710」· C头文件 代码 · 共 1,184 行 · 第 1/3 页

/*
 *	Definitions for the 'struct sk_buff' memory handlers.
 *
 *	Authors:
 *		Alan Cox, <[e-mail]>
 *		Florian La Roche, <[e-mail]>
 *
 *	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 _LINUX_SKBUFF_H
#define _LINUX_SKBUFF_H

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/compiler.h>
#include <linux/time.h>
#include <linux/cache.h>

#include <asm/atomic.h>
#include <asm/types.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/poll.h>
#include <linux/net.h>
#include <net/checksum.h>

#define HAVE_ALLOC_SKB		/* For the drivers to know */
#define HAVE_ALIGNABLE_SKB	/* Ditto 8)		   */
#define SLAB_SKB 		/* Slabified skbuffs 	   */

#define CHECKSUM_NONE 0
#define CHECKSUM_HW 1
#define CHECKSUM_UNNECESSARY 2

#define SKB_DATA_ALIGN(X)	(((X) + (SMP_CACHE_BYTES - 1)) & \
				 ~(SMP_CACHE_BYTES - 1))
#define SKB_MAX_ORDER(X, ORDER)	(((PAGE_SIZE << (ORDER)) - (X) - \
				  sizeof(struct skb_shared_info)) & \
				  ~(SMP_CACHE_BYTES - 1))
#define SKB_MAX_HEAD(X)		(SKB_MAX_ORDER((X), 0))
#define SKB_MAX_ALLOC		(SKB_MAX_ORDER(0, 2))

/* A. Checksumming of received packets by device.
 *
 *	NONE: device failed to checksum this packet.
 *		skb->csum is undefined.
 *
 *	UNNECESSARY: device parsed packet and wouldbe verified checksum.
 *		skb->csum is undefined.
 *	      It is bad option, but, unfortunately, many of vendors do this.
 *	      Apparently with secret goal to sell you new device, when you
 *	      will add new protocol to your host. F.e. IPv6. 8)
 *
 *	HW: the most generic way. Device supplied checksum of _all_
 *	    the packet as seen by netif_rx in skb->csum.
 *	    NOTE: Even if device supports only some protocols, but
 *	    is able to produce some skb->csum, it MUST use HW,
 *	    not UNNECESSARY.
 *
 * B. Checksumming on output.
 *
 *	NONE: skb is checksummed by protocol or csum is not required.
 *
 *	HW: device is required to csum packet as seen by hard_start_xmit
 *	from skb->h.raw to the end and to record the checksum
 *	at skb->h.raw+skb->csum.
 *
 *	Device must show its capabilities in dev->features, set
 *	at device setup time.
 *	NETIF_F_HW_CSUM	- it is clever device, it is able to checksum
 *			  everything.
 *	NETIF_F_NO_CSUM - loopback or reliable single hop media.
 *	NETIF_F_IP_CSUM - device is dumb. It is able to csum only
 *			  TCP/UDP over IPv4. Sigh. Vendors like this
 *			  way by an unknown reason. Though, see comment above
 *			  about CHECKSUM_UNNECESSARY. 8)
 *
 *	Any questions? No questions, good. 		--ANK
 */

#ifdef __i386__
#define NET_CALLER(arg) (*(((void **)&arg) - 1))
#else
#define NET_CALLER(arg) __builtin_return_address(0)
#endif

struct net_device;

#ifdef CONFIG_NETFILTER
struct nf_conntrack {
	atomic_t use;
	void (*destroy)(struct nf_conntrack *);
};

#ifdef CONFIG_BRIDGE_NETFILTER
struct nf_bridge_info {
	atomic_t use;
	struct net_device *physindev;
	struct net_device *physoutdev;
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
	struct net_device *netoutdev;
#endif
	unsigned int mask;
	unsigned long data[32 / sizeof(unsigned long)];
};
#endif

#endif

struct sk_buff_head {
	/* These two members must be first. */
	struct sk_buff	*next;
	struct sk_buff	*prev;

	__u32		qlen;
	spinlock_t	lock;
};

struct sk_buff;

/* To allow 64K frame to be packed as single skb without frag_list */
#define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)

typedef struct skb_frag_struct skb_frag_t;

struct skb_frag_struct {
	struct page *page;
	__u16 page_offset;
	__u16 size;
};

/* This data is invariant across clones and lives at
 * the end of the header data, ie. at skb->end.
 */
struct skb_shared_info {
	atomic_t	dataref;
	unsigned int	nr_frags;
	unsigned short	tso_size;
	unsigned short	tso_segs;
	struct sk_buff	*frag_list;
	skb_frag_t	frags[MAX_SKB_FRAGS];
};

/** 
 *	struct sk_buff - socket buffer
 *	@next: Next buffer in list
 *	@prev: Previous buffer in list
 *	@list: List we are on
 *	@sk: Socket we are owned by
 *	@stamp: Time we arrived
 *	@dev: Device we arrived on/are leaving by
 *	@input_dev: Device we arrived on
 *      @real_dev: The real device we are using
 *	@h: Transport layer header
 *	@nh: Network layer header
 *	@mac: Link layer header
 *	@dst: FIXME: Describe this field
 *	@cb: Control buffer. Free for use by every layer. Put private vars here
 *	@len: Length of actual data
 *	@data_len: Data length
 *	@mac_len: Length of link layer header
 *	@csum: Checksum
 *	@__unused: Dead field, may be reused
 *	@cloned: Head may be cloned (check refcnt to be sure)
 *	@pkt_type: Packet class
 *	@ip_summed: Driver fed us an IP checksum
 *	@priority: Packet queueing priority
 *	@users: User count - see {datagram,tcp}.c
 *	@protocol: Packet protocol from driver
 *	@security: Security level of packet
 *	@truesize: Buffer size 
 *	@head: Head of buffer
 *	@data: Data head pointer
 *	@tail: Tail pointer
 *	@end: End pointer
 *	@destructor: Destruct function
 *	@nfmark: Can be used for communication between hooks
 *	@nfcache: Cache info
 *	@nfct: Associated connection, if any
 *	@nfctinfo: Relationship of this skb to the connection
 *	@nf_debug: Netfilter debugging
 *	@nf_bridge: Saved data about a bridged frame - see br_netfilter.c
 *      @private: Data which is private to the HIPPI implementation
 *	@tc_index: Traffic control index
 */

struct sk_buff {
	/* These two members must be first. */
	struct sk_buff		*next;
	struct sk_buff		*prev;

	struct sk_buff_head	*list;
	struct sock		*sk;
	struct timeval		stamp;
	struct net_device	*dev;
	struct net_device	*input_dev;
	struct net_device	*real_dev;

	union {
		struct tcphdr	*th;
		struct udphdr	*uh;
		struct icmphdr	*icmph;
		struct igmphdr	*igmph;
		struct iphdr	*ipiph;
		struct ipv6hdr	*ipv6h;
		unsigned char	*raw;
	} h;

	union {
		struct iphdr	*iph;
		struct ipv6hdr	*ipv6h;
		struct arphdr	*arph;
		unsigned char	*raw;
	} nh;

	union {
	  	unsigned char 	*raw;
	} mac;

	struct  dst_entry	*dst;
	struct	sec_path	*sp;

	/*
	 * This is the control buffer. It is free to use for every
	 * layer. Please put your private variables there. If you
	 * want to keep them across layers you have to do a skb_clone()
	 * first. This is owned by whoever has the skb queued ATM.
	 */
	char			cb[40];

	unsigned int		len,
				data_len,
				mac_len,
				csum;
	unsigned char		local_df,
				cloned,
				pkt_type,
				ip_summed;
	__u32			priority;
	unsigned short		protocol,
				security;

	void			(*destructor)(struct sk_buff *skb);
#ifdef CONFIG_NETFILTER
        unsigned long		nfmark;
	__u32			nfcache;
	__u32			nfctinfo;
	struct nf_conntrack	*nfct;
#ifdef CONFIG_NETFILTER_DEBUG
        unsigned int		nf_debug;
#endif
#ifdef CONFIG_BRIDGE_NETFILTER
	struct nf_bridge_info	*nf_bridge;
#endif
#endif /* CONFIG_NETFILTER */
#if defined(CONFIG_HIPPI)
	union {
		__u32		ifield;
	} private;
#endif
#ifdef CONFIG_NET_SCHED
       __u32			tc_index;        /* traffic control index */
#ifdef CONFIG_NET_CLS_ACT
	__u32           tc_verd;               /* traffic control verdict */
	__u32           tc_classid;            /* traffic control classid */
#endif

#endif


	/* These elements must be at the end, see alloc_skb() for details.  */
	unsigned int		truesize;
	atomic_t		users;
	unsigned char		*head,
				*data,
				*tail,
				*end;
};

#ifdef __KERNEL__
/*
 *	Handling routines are only of interest to the kernel
 */
#include <linux/slab.h>

#include <asm/system.h>

extern void	       __kfree_skb(struct sk_buff *skb);
extern struct sk_buff *alloc_skb(unsigned int size, int priority);
extern void	       kfree_skbmem(struct sk_buff *skb);
extern struct sk_buff *skb_clone(struct sk_buff *skb, int priority);
extern struct sk_buff *skb_copy(const struct sk_buff *skb, int priority);
extern struct sk_buff *pskb_copy(struct sk_buff *skb, int gfp_mask);
extern int	       pskb_expand_head(struct sk_buff *skb,
					int nhead, int ntail, int gfp_mask);
extern struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
					    unsigned int headroom);
extern struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
				       int newheadroom, int newtailroom,
				       int priority);
extern struct sk_buff *		skb_pad(struct sk_buff *skb, int pad);
#define dev_kfree_skb(a)	kfree_skb(a)
extern void	      skb_over_panic(struct sk_buff *skb, int len,
				     void *here);
extern void	      skb_under_panic(struct sk_buff *skb, int len,
				      void *here);

/* Internal */
#define skb_shinfo(SKB)		((struct skb_shared_info *)((SKB)->end))

/**
 *	skb_queue_empty - check if a queue is empty
 *	@list: queue head
 *
 *	Returns true if the queue is empty, false otherwise.
 */
static inline int skb_queue_empty(const struct sk_buff_head *list)
{
	return list->next == (struct sk_buff *)list;
}

/**
 *	skb_get - reference buffer
 *	@skb: buffer to reference
 *
 *	Makes another reference to a socket buffer and returns a pointer
 *	to the buffer.
 */
static inline struct sk_buff *skb_get(struct sk_buff *skb)
{
	atomic_inc(&skb->users);
	return skb;
}

/*
 * If users == 1, we are the only owner and are can avoid redundant
 * atomic change.
 */

/**
 *	kfree_skb - free an sk_buff
 *	@skb: buffer to free
 *
 *	Drop a reference to the buffer and free it if the usage count has
 *	hit zero.
 */
static inline void kfree_skb(struct sk_buff *skb)
{
	if (atomic_read(&skb->users) == 1 || atomic_dec_and_test(&skb->users))
		__kfree_skb(skb);
}

/* Use this if you didn't touch the skb state [for fast switching] */
static inline void kfree_skb_fast(struct sk_buff *skb)
{
	if (atomic_read(&skb->users) == 1 || atomic_dec_and_test(&skb->users))
		kfree_skbmem(skb);
}

/**
 *	skb_cloned - is the buffer a clone
 *	@skb: buffer to check
 *
 *	Returns true if the buffer was generated with skb_clone() and is
 *	one of multiple shared copies of the buffer. Cloned buffers are
 *	shared data so must not be written to under normal circumstances.
 */
static inline int skb_cloned(const struct sk_buff *skb)
{
	return skb->cloned && atomic_read(&skb_shinfo(skb)->dataref) != 1;
}

/**
 *	skb_shared - is the buffer shared
 *	@skb: buffer to check
 *
 *	Returns true if more than one person has a reference to this
 *	buffer.
 */
static inline int skb_shared(const struct sk_buff *skb)
{
	return atomic_read(&skb->users) != 1;
}

/**
 *	skb_share_check - check if buffer is shared and if so clone it
 *	@skb: buffer to check
 *	@pri: priority for memory allocation
 *
 *	If the buffer is shared the buffer is cloned and the old copy