skbuff.h

sparc硬件平台上的红外协议

/*
*    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 SKBUFF_H
#define SKBUFF_H

#include <sys/time.h>
#include <malloc.h>
#include <string.h>
#include <time.h>
#include "irda.h"
#include "../../public/pub_emmi.h"
#include "types.h"

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

/* Don't change this without changing skb_csum_unnecessary! */
#define CHECKSUM_NONE 0
#define CHECKSUM_UNNECESSARY 1
#define CHECKSUM_COMPLETE 2
#define CHECKSUM_PARTIAL 3

#define kfree_skb(a) skb_free(a)
#define dev_kfree_skb(a) skb_free(a)
/* 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)
*
*    COMPLETE: 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 COMPLETE,
*        not UNNECESSARY.
*
*    PARTIAL: identical to the case for output below.  This may occur
*        on a packet received directly from another Linux OS, e.g.,
*        a virtualised Linux kernel on the same host.  The packet can
*        be treated in the same way as UNNECESSARY except that on
*        output (i.e., forwarding) the checksum must be filled in
*        by the OS or the hardware.
*
* B. Checksumming on output.
*
*    NONE: skb is checksummed by protocol or csum is not required.
*
*    PARTIAL: device is required to csum packet as seen by hard_start_xmit
*    from skb->csum_start to the end and to record the checksum
*    at skb->csum_start + skb->csum_offset.
*
*    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)
*    NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead.
*
*    Any questions? No questions, good.         --ANK
*/

struct sk_buff_head 
{
    /* These two members must be first. */
    struct sk_buff    *next;
    struct sk_buff    *prev;
	
    D_UINT32        qlen;
    
};

struct sk_buff;

/* 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.  A clone of a headerless skb holds the length of
* the header in skb->hdr_len.
*
* 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)


enum 
{
    SKB_FCLONE_UNAVAILABLE,
		SKB_FCLONE_ORIG,
		SKB_FCLONE_CLONE,
};

enum 
{
    SKB_GSO_TCPV4 = 1 << 0,
		SKB_GSO_UDP = 1 << 1,
		
		/* This indicates the skb is from an untrusted source. */
		SKB_GSO_DODGY = 1 << 2,
		
		/* This indicates the tcp segment has CWR set. */
		SKB_GSO_TCP_ECN = 1 << 3,
		
		SKB_GSO_TCPV6 = 1 << 4,
};


//#define NET_SKBUFF_DATA_USES_OFFSET 1

typedef unsigned char *sk_buff_data_t;

/** 
*    struct sk_buff - socket buffer
*    @next: Next buffer in list
*    @prev: Previous buffer in list
*    @sk: Socket we are owned by
*    @tstamp: Time we arrived
*    @dev: Device we arrived on/are leaving by
*    @transport_header: Transport layer header
*    @network_header: Network layer header
*    @mac_header: 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
*    @hdr_len: writable header length of cloned skb
*    @csum: Checksum (must include start/offset pair)
*    @csum_start: Offset from skb->head where checksumming should start
*    @csum_offset: Offset from csum_start where checksum should be stored
*    @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
*    @fclone: skbuff clone status
*    @ip_summed: Driver fed us an IP checksum
*    @priority: Packet queueing priority
*    @users: User count - see {datagram,tcp}.c
*    @protocol: Packet protocol from driver
*    @truesize: Buffer size 
*    @head: Head of buffer
*    @data: Data head pointer
*    @tail: Tail pointer
*    @end: End pointer
*    @destructor: Destruct function
*    @mark: Generic packet mark
*    @nfct: Associated connection, if any
*    @ipvs_property: skbuff is owned by ipvs
*    @nf_trace: netfilter packet trace flag
*    @nfctinfo: Relationship of this skb to the connection
*    @nfct_reasm: netfilter conntrack re-assembly pointer
*    @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
*    @iif: ifindex of device we arrived on
*    @queue_mapping: Queue mapping for multiqueue devices
*    @tc_index: Traffic control index
*    @tc_verd: traffic control verdict
*    @dma_cookie: a cookie to one of several possible DMA operations
*        done by skb DMA functions
*    @secmark: security marking
*/

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

    struct net_device    *dev;
	
    /*
	* 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[48];//此数组作为 SKB 的控制块，具体的协议可用它来存储与每个包相关的私有数据
	
	
    unsigned int        len,////真实数据区的长度，即整个packet的大小
		data_len;//当SKB是由多个页面缓冲组成的时候，表示分片大小

//	    //以下都是作为flag用,只用了一个byte的8个bit
//	    D_UINT8        local_df:1,//允许local分片标志
//								  /*为四苎杆俚囊