source: svn/trunk/newcon3bcm2_21bu/toolchain/mipsel-linux-uclibc/include/linux/skbuff.h @ 29

/*
 *      Definitions for the 'struct sk_buff' memory handlers.
 *
 *      Authors:
 *              Alan Cox, <gw4pts@gw4pts.ampr.org>
 *              Florian La Roche, <rzsfl@rz.uni-sb.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.
 */

#ifndef _LINUX_SKBUFF_H
#define _LINUX_SKBUFF_H

#include <linux/kernel.h>
#include <sys/time.h>
#include <linux/cache.h>

#include <asm/types.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
 */

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];
};

/* We divide dataref into two halves.  The higher 16 bits hold references
 * to the payload part of skb->data.  The lower 16 bits hold references to
 * the entire skb->data.  It is up to the users of the skb to agree on
 * where the payload starts.
 *
 * All users must obey the rule that the skb->data reference count must be
 * greater than or equal to the payload reference count.
 *
 * Holding a reference to the payload part means that the user does not
 * care about modifications to the header part of skb->data.
 */
#define SKB_DATAREF_SHIFT 16
#define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)

/** 
 *      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: destination entry
 *      @sp: the security path, used for xfrm
 *      @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
 *      @local_df: allow local fragmentation
 *      @cloned: Head may be cloned (check refcnt to be sure)
 *      @nohdr: Payload reference only, must not modify header
 *      @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
 *      @tc_verd: traffic control verdict
 *      @tc_classid: traffic control classid
 */

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:1,
                                nohdr:1,
                                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;
};


#endif  /* _LINUX_SKBUFF_H */