linux kernel 1.0 网络模块代码分析——space.c

/*
 * Space.c    Defines which protocol modules and I/O device drivers get
 *        linked into the LINUX kernel. Currently, this is only used
 *        by the NET layer of LINUX, but it eventually might move to
 *        an upper directory of the system.
 *
 * Version:    @(#)Space.c    1.0.2    04/22/93
 *
 * Author:    Fred N. van Kempen, <[e-mail]>
 */
/*Space.c    定义了当前链接到LINUX Kernel的协议模块和I/O设备驱动。当前仅有LINUX的网络层使用，但它最后会在整个系统中使用。*/
#include <linux/config.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/ddi.h>


#define CONFIG_UNIX        YES        /* always present...    */


/*
 * Section A:    Networking Protocol Handlers.
 *        This section defines which networking protocols get
 *        linked into the SOCKET layer of the Linux kernel.
 *        Currently, these are AF_UNIX (always) and AF_INET.
 */
/*Section A: 网络协议管理器.
 *    定义了链接到Linux内核的SOCKET层的网络协议。当前有AF_UNIX和AF_INET
*/
#ifdef    CONFIG_UNIX
#  include "unix/unix.h"
#endif
#ifdef    CONFIG_INET
#  include "inet/inet.h"
#endif
#ifdef CONFIG_IPX
#include "inet/ipxcall.h"
#endif
#ifdef CONFIG_AX25
#include "inet/ax25call.h"
#endif

/*定义了全局protocols数组，将在ddi.c中被调用*/

struct ddi_proto protocols[] = {
#ifdef    CONFIG_UNIX
  { "UNIX",    unix_proto_init    },
#endif
#ifdef  CONFIG_IPX
  { "IPX",    ipx_proto_init },
#endif
#ifdef CONFIG_AX25
  { "AX.25",    ax25_proto_init },
#endif
#ifdef    CONFIG_INET
  { "INET",    inet_proto_init    },
#endif
  { NULL,    NULL        }
};


/*
 * Section B:    Device Driver Modules.
 *        This section defines which network device drivers
 *        get linked into the Linux kernel. It is currently
 *        only used by the INET protocol. Any takers for the
 *        other protocols like XNS or Novell?
 *
 * WARNING:    THIS SECTION IS NOT YET USED BY THE DRIVERS !!!!!
 */
/* Section B:    设备驱动模块
 *        定义了哪些网络设备驱动链接到Linux内核。当前仅被INET协议使用。
 *警告：    当前还没有驱动使用这儿定义的数据
 *
 **/
/*#include "drv/we8003/we8003.h"    Western Digital WD-80[01]3    */
/*#include "drv/dp8390/dp8390.h"    Donald Becker's DP8390 kit    */
/*#inclde "drv/slip/slip.h"        Laurence Culhane's SLIP kit    */

/*定义全局的devices数组，在ddi.c中使用*/
struct ddi_device devices[] = {
#if CONF_WE8003
  { "WD80x3[EBT]",
    "",    0,    1,    we8003_init,    NULL,
    19,    0,    DDI_FCHRDEV,
    { 0x280,    0,    15,    0,    32768,    0xD0000        }    },
#endif
#if CONF_DP8390
  { "DP8390/WD80x3",
    "",    0,    1,    dpwd8003_init,    NULL,
    20,    0,    DDI_FCHRDEV,
    {    0,    0,    0,    0,    0,    0,        }    },
  { "DP8390/NE-x000",
    "",    0,    1,    dpne2000_init,    NULL,
    20,    8,    DDI_FCHRDEV,
    {    0,    0,    0,    0,    0,    0,        }    },
  { "DP8390/3C50x",
    "",    0,    1,    dpec503_init,    NULL,
    20,    16,    DDI_FCHRDEV,
    {    0,    0,    0,    0,    0,    0,        }    },
#endif
  { NULL,
    "",    0,    0,    NULL,        NULL,
    0,    0,    0,
    {    0,    0,    0,    0,    0,    0        }    }
};

/*
 * UNIX        An implementation of the AF_UNIX network domain for the
 *        LINUX operating system. UNIX is implemented using the
 *        BSD Socket interface as the means of communication with
 *        the user level.
 *
 *        This file descibes some things of the UNIX protocol family
 *        module. It is mainly used for the "proc" sub-module now,
 *        but it may be useful for cleaning up the UNIX module as a
 *        whole later.
 *
 * UNIX    LINUX操作系统的AF_UNIX网络域的实现。UNIX使用BSD Socket接口作为其与用户空间程序通信来实现的。这个文件描述了UNIX协议族模块的一些东西
 *        它目前主要用于“proc”子模块，但它迟些对于整体清除UNIX模块可能是有用的(这一句不知道是什么意思)。
 *
 *
 *
 * Version:    @(#)unix.h    1.0.3    05/25/93
 *
 * Authors:    Orest Zborowski, <[e-mail]>
 *        Ross Biro, <[e-mail]>
 *        Fred N. van Kempen, <[e-mail]>
 *
 * Fixes:
 *        Dmitry Gorodchanin    -    proc locking
 *
 *        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.
 */


#ifdef _LINUX_UN_H /*在内核代码的include/linux/un.h中定义*/

/*存储AF_UNIX协议数据的数据结构，其中个别成员还不知道含义，等后面再补全*/
struct unix_proto_data {
    int        refcnt;        /* cnt of reference 0=free    *//*引用计数*/
                    /* -1=not initialised    -bgm    */
    struct socket    *socket;    /* socket we're bound to    *//*绑定的socket*/
    int        protocol;
    struct sockaddr_un    sockaddr_un; /*绑定地址*/
    short        sockaddr_len;    /* >0 if name bound        */
    char        *buf;
    int        bp_head, bp_tail;
    struct inode    *inode;
    struct unix_proto_data    *peerupd;
    struct wait_queue *wait;    /* Lock across page faults (FvK) */
    int        lock_flag;
};

extern struct unix_proto_data unix_datas[NSOCKETS]; /*全局数组声明，该数组大小代表着所能创建的UNIX套接字的个数，在net/unix/sock.c中定义*/


#define last_unix_data        (unix_datas + NSOCKETS - 1)


#define UN_DATA(SOCK)         ((struct unix_proto_data *)(SOCK)->data)
#define UN_PATH_OFFSET        ((unsigned long)((struct sockaddr_un *)0) \
                            ->sun_path)

/*
 * Buffer size must be power of 2. buffer mgmt inspired by pipe code.
 * note that buffer contents can wraparound, and we can write one byte less
 * than full size to discern full vs empty.
 */
/*缓冲区大小必须是2的冥数。buffer mgmt inspired by pipe code.note that buffer contents can wraparound,我们能够写一个字节，这比总大小要小，
来判断缓冲区是满还是空*/
#define BUF_SIZE        PAGE_SIZE /*缓冲区大小等于一个内存页面大小*/
#define UN_BUF_AVAIL(UPD)    (((UPD)->bp_head - (UPD)->bp_tail) & \
                                (BUF_SIZE-1))   /*计算缓冲区中可用大小*/
#define UN_BUF_SPACE(UPD)    ((BUF_SIZE-1) - UN_BUF_AVAIL(UPD)) /*这个应该是计算已用大小？*/

#endif    /* _LINUX_UN_H */


extern void    unix_proto_init(struct ddi_proto *pro); /*系统启动时初始化调用该函数，在ddi.c中*/

/*
 * 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.
 *
 *        General Definitions for the TCP/IP (INET) module. This is
 *        mostly a bunch of "general" macros, plus the PROTOCOL link
 *        code and data.
 *        LINUX操作系统的TCP/IP协议簇的实现。INET的实现，使用BSD Socket接口，作为与用户空间通信的手段。
 *        TCP/IP(INET)模块的通用定义。This is mostly a bunch of "general" macros, plus the PROTOCOL link code and data.
 *
 * Version:    @(#)inet.h    1.0.6    05/25/93
 *
 * Author:    Fred N. van Kempen, <[e-mail]>
 *
 *        This work was derived friom Ross Biro's inspirational work
 *        for the LINUX operating system. His version numbers were:
 *
 *        $Id: Space.c,v     0.8.4.5  1992/12/12 19:25:04 bir7 Exp $
 *        $Id: arp.c,v       0.8.4.6  1993/01/28 22:30:00 bir7 Exp $
 *        $Id: arp.h,v       0.8.4.6  1993/01/28 22:30:00 bir7 Exp $
 *        $Id: dev.c,v       0.8.4.13 1993/01/23 18:00:11 bir7 Exp $
 *        $Id: dev.h,v       0.8.4.7  1993/01/23 18:00:11 bir7 Exp $
 *        $Id: eth.c,v       0.8.4.4  1993/01/22 23:21:38 bir7 Exp $
 *        $Id: eth.h,v       0.8.4.1  1992/11/10 00:17:18 bir7 Exp $
 *        $Id: icmp.c,v      0.8.4.9  1993/01/23 18:00:11 bir7 Exp $
 *        $Id: icmp.h,v      0.8.4.2  1992/11/15 14:55:30 bir7 Exp $
 *         $Id: ip.c,v        0.8.4.8  1992/12/12 19:25:04 bir7 Exp $
 *         $Id: ip.h,v        0.8.4.2  1993/01/23 18:00:11 bir7 Exp $
 *         $Id: loopback.c,v  0.8.4.8  1993/01/23 18:00:11 bir7 Exp $
 *         $Id: packet.c,v    0.8.4.7  1993/01/26 22:04:00 bir7 Exp $
 *        $Id: protocols.c,v 0.8.4.3  1992/11/15 14:55:30 bir7 Exp $
 *        $Id: raw.c,v       0.8.4.12 1993/01/26 22:04:00 bir7 Exp $
 *        $Id: sock.c,v      0.8.4.6  1993/01/28 22:30:00 bir7 Exp $
 *        $Id: sock.h,v      0.8.4.7  1993/01/26 22:04:00 bir7 Exp $
 *        $Id: tcp.c,v       0.8.4.16 1993/01/26 22:04:00 bir7 Exp $
 *        $Id: tcp.h,v       0.8.4.7  1993/01/22 22:58:08 bir7 Exp $
 *        $Id: timer.c,v     0.8.4.8  1993/01/23 18:00:11 bir7 Exp $
 *        $Id: timer.h,v     0.8.4.2  1993/01/23 18:00:11 bir7 Exp $
 *        $Id: udp.c,v       0.8.4.12 1993/01/26 22:04:00 bir7 Exp $
 *        $Id: udp.h,v       0.8.4.1  1992/11/10 00:17:18 bir7 Exp $
 *        $Id: we.c,v        0.8.4.10 1993/01/23 18:00:11 bir7 Exp $
 *        $Id: wereg.h,v     0.8.4.1  1992/11/10 00:17:18 bir7 Exp $
 *
 *        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 _INET_H
#define _INET_H


#include <linux/ddi.h>


#define NET16(x)    ((((x) >> 8) & 0x00FF) | (((x) << 8) & 0xFF00)) /*调换x的低8位和高8位的位置*/


#undef    INET_DEBUG
#ifdef    INET_DEBUG
#  define    DPRINTF(x)    dprintf x
#else
#   define    DPRINTF(x)    do ; while (0)
#endif

/*调试级别。每个模块一个。*/

/* Debug levels. One per module. */
#define DBG_OFF        0            /* no debugging        */
#define DBG_INET    1            /* sock.c        */
#define DBG_RT        2            /* route.c        */
#define DBG_DEV        3            /* dev.c        */
#define DBG_ETH        4            /* eth.c        */
#define DBG_PROTO    5            /* protocol.c        */
#define DBG_TMR        6            /* timer.c        */
#define DBG_PKT        7            /* packet.c        */
#define DBG_RAW        8            /* raw.c        */

#define DBG_LOOPB    10            /* loopback.c        */
#define DBG_SLIP    11            /* slip.c        */

#define DBG_ARP        20            /* arp.c        */
#define DBG_IP        21            /* ip.c            */
#define DBG_ICMP    22            /* icmp.c        */
#define DBG_TCP        23            /* tcp.c        */
#define DBG_UDP        24            /* udp.c        */


extern int        inet_debug;


extern void        inet_proto_init(struct ddi_proto *pro); /*inet协议簇的初始化函数*/
extern char        *in_ntoa(unsigned long in);
extern unsigned long    in_aton(char *str);

extern void        dprintf(int level, char *fmt, ...);

extern int        dbg_ioctl(void *arg, int level);

#endif    /* _INET_H */

#ifndef _LINUX_UN_H
#define _LINUX_UN_H

        
        /*定义UNIX套接字对应的地址信息*/

struct sockaddr_un {
    unsigned short sun_family;    /* AF_UNIX */
    char sun_path[108];        /* pathname */
};

#endif /* _LINUX_UN_H */