struct ifconf和struct ifreq，获取网线插入状态

这两天看用C获取当前网口的插入网线状态的程序，遇见了这两个不熟悉的结构体，看了头文件中的说明和详细。

struct ifreq

这个结构定义在include/net/if.h，用来配置ip地址，激活接口，配置MTU等接口信息的

/* Interface request structure used for socket ioctl's.  All interface
   ioctl's must have parameter definitions which begin with ifr_name.
   The remainder may be interface specific.  */

struct ifreq
  {
# define IFHWADDRLEN    6
# define IFNAMSIZ   IF_NAMESIZE
    union
      {
    char ifrn_name[IFNAMSIZ];   /* Interface name, e.g. "en0".  */
      } ifr_ifrn;

    union
      {
    struct sockaddr ifru_addr;
    struct sockaddr ifru_dstaddr;
    struct sockaddr ifru_broadaddr;
    struct sockaddr ifru_netmask;
    struct sockaddr ifru_hwaddr;
    short int ifru_flags;
    int ifru_ivalue;
    int ifru_mtu;
    struct ifmap ifru_map;
    char ifru_slave[IFNAMSIZ];  /* Just fits the size */
    char ifru_newname[IFNAMSIZ];
    __caddr_t ifru_data;
      } ifr_ifru;
  };
# define ifr_name   ifr_ifrn.ifrn_name  /* interface name   */
# define ifr_hwaddr ifr_ifru.ifru_hwaddr    /* MAC address      */
# define ifr_addr   ifr_ifru.ifru_addr  /* address      */
# define ifr_dstaddr    ifr_ifru.ifru_dstaddr   /* other end of p-p lnk */
# define ifr_broadaddr  ifr_ifru.ifru_broadaddr /* broadcast address    */
# define ifr_netmask    ifr_ifru.ifru_netmask   /* interface net mask   */
# define ifr_flags  ifr_ifru.ifru_flags /* flags        */
# define ifr_metric ifr_ifru.ifru_ivalue    /* metric       */
# define ifr_mtu    ifr_ifru.ifru_mtu   /* mtu          */
# define ifr_map    ifr_ifru.ifru_map   /* device map       */
# define ifr_slave  ifr_ifru.ifru_slave /* slave device     */
# define ifr_data   ifr_ifru.ifru_data  /* for use by interface */
# define ifr_ifindex    ifr_ifru.ifru_ivalue    /* interface index      */
# define ifr_bandwidth  ifr_ifru.ifru_ivalue    /* link bandwidth   */
# define ifr_qlen   ifr_ifru.ifru_ivalue    /* queue length     */
# define ifr_newname    ifr_ifru.ifru_newname   /* New name     */
# define _IOT_ifreq _IOT(_IOTS(char),IFNAMSIZ,_IOTS(char),16,0,0)
# define _IOT_ifreq_short _IOT(_IOTS(char),IFNAMSIZ,_IOTS(short),1,0,0)
# define _IOT_ifreq_int _IOT(_IOTS(char),IFNAMSIZ,_IOTS(int),1,0,0)

struct  ifconf

通常是用来保存所有接口信息的

/* Structure used in SIOCGIFCONF request.  Used to retrieve interface
   configuration for machine (useful for programs which must know all
   networks accessible).  */

struct ifconf
  {
    int ifc_len;            /* Size of buffer.  */
    union
      {
    __caddr_t ifcu_buf;
    struct ifreq *ifcu_req;
      } ifc_ifcu;
  };
# define ifc_buf    ifc_ifcu.ifcu_buf   /* Buffer address.  */
# define ifc_req    ifc_ifcu.ifcu_req   /* Array of structures.  */
# define _IOT_ifconf _IOT(_IOTS(struct ifconf),1,0,0,0,0) /* not right */

应用

想要获取当前网口网线插入状态，需要用到ifreq结构体，获取网卡的信息，然后socket结合网卡驱动的ioctl，就可以得到与网线插入状态相关的数据。
另外推荐一个百度文库的文章，包含代码

http://wenku.baidu.com/view/59f4508d680203d8ce2f2412.html