Linux下利用ioctl函数获取网卡信息

linux下的ioctl函数原型如下：

#include<sys/ioctl.h>

intioctl(int handle, int cmd, [int *argc, int argv])

函数成功返回0，失败返回-1.

其相关命令接口如下：

 

在这里我们需要用到的结构体

#include<netinet/in.h>

struct sockaddr_in {

short sin_family; /* Address family */

unsigned short sin_port; /* Port number */

struct in_addr sin_addr; /* Internet address */

unsigned char sin_zero[8]; /* Same size as struct sockaddr */

};

 

#include <net/if.h>

struct ifreq
{
#define IFHWADDRLEN 6
union
{
charifrn_name[IFNAMSIZ]; 
} ifr_ifrn;

union {
structsockaddr ifru_addr;
structsockaddr ifru_dstaddr;
structsockaddr ifru_broadaddr;
structsockaddr ifru_netmask;
struct sockaddr ifru_hwaddr;
shortifru_flags;
intifru_ivalue;
intifru_mtu;
struct ifmap ifru_map;
charifru_slave[IFNAMSIZ]; 
charifru_newname[IFNAMSIZ];
void __user * ifru_data;
structif_settings ifru_settings;
} ifr_ifru;
};

#define ifr_name ifr_ifrn.ifrn_name 
#define ifr_hwaddr ifr_ifru.ifru_hwaddr 
#defineifr_addr ifr_ifru.ifru_addr 
#defineifr_dstaddr ifr_ifru.ifru_dstaddr 
#defineifr_broadaddr ifr_ifru.ifru_broadaddr 
#defineifr_netmask ifr_ifru.ifru_netmask
#defineifr_flags ifr_ifru.ifru_flags 
#defineifr_metric ifr_ifru.ifru_ivalue
#defineifr_mtu ifr_ifru.ifru_mtu
#define ifr_map ifr_ifru.ifru_map
#define ifr_slave ifr_ifru.ifru_slave
#defineifr_data ifr_ifru.ifru_data 
#define ifr_ifindex ifr_ifru.ifru_ivalue
#define ifr_bandwidth ifr_ifru.ifru_ivalue 
#define ifr_qlen ifr_ifru.ifru_ivalue
#define ifr_newname ifr_ifru.ifru_newname
#define ifr_settings ifr_ifru.ifru_setting

ioctl函数能获取到IP地址、子网掩码、广播地址、硬件MAC地址等信息，至于网关及路由表比较复杂，在此不讨论。

 

具体代码如下：（测试通过）

#include<stdio.h>

#include<stdlib.h>

#include<net/if.h>

#include<unistd.h>

#include<sys/ioctl.h>

#include<arpa/inet.h>

#include<sys/stat.h>

#include<sys/types.h>

#include<errno.h>

#include<fcntl.h>

#include<netinet/in.h>

#include<net/route.h>

#include<string.h>

#include<net/if_arp.h>

 

int main()

{

  struct sockaddr_in *sin;

  struct ifreq ifr;

  FILE *dns;

  FILE *gw;

  char *ip = new char(16);

  char *netmask = new char(16);

  char *broadcast = new char(16);

  //char *ip = (char *)malloc(16);

  char *mac = new  char(32);

  //char *mac = (char *)malloc(32);

  int socket_fd;

 

      if((socket_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0){

              perror("socket");

              exit(1);

      }

 

      memset(&ifr, 0, sizeof(ifr));

      strcpy(ifr.ifr_name, "eth0");

      memset(&sin, 0, sizeof(sin));

//获取IP地址

      if(ioctl(socket_fd, SIOCGIFADDR, &ifr) != -1){

              sin = (struct sockaddr_in*)&ifr.ifr_addr;

              strcpy(ip,inet_ntoa(sin->sin_addr));

              printf("IP address is%s\n", ip);

      }

//获取广播地址

 

      if(ioctl(socket_fd, SIOCGIFBRDADDR, &ifr) != -1){

              sin = (struct sockaddr_in*)&ifr.ifr_broadaddr;

              strcpy(broadcast,inet_ntoa(sin->sin_addr));

              printf("Broadcast is%s\n", broadcast);

      }

//获取子网掩码

 

      if(ioctl(socket_fd, SIOCGIFNETMASK, &ifr) != -1){

              sin = (struct sockaddr_in*)&ifr.ifr_broadaddr;

              strcpy(netmask,inet_ntoa(sin->sin_addr));

              printf("Net-mask is%s\n", netmask);

      }

//获取硬件MAC地址

 

      if(ioctl(socket_fd, SIOCGIFHWADDR, &ifr) != -1){

              sin = (struct sockaddr_in*)&ifr.ifr_netmask;

              sprintf(mac,"%02x:%02x:%02x:%02x:%02x:%02x",

              (unsignedchar)ifr.ifr_netmask.sa_data[0],

              (unsignedchar)ifr.ifr_netmask.sa_data[1],

              (unsignedchar)ifr.ifr_netmask.sa_data[2],

              (unsignedchar)ifr.ifr_netmask.sa_data[3],

              (unsignedchar)ifr.ifr_netmask.sa_data[4],

              (unsignedchar)ifr.ifr_netmask.sa_data[5]);

              printf("Mac address is%s\n", mac);

      }

  return 0;

}

 

至于获取网关以及DNS，我是通过相关命令获得的。

主要代码如下：

//获取网关，利用route -n命令可以看到相关的网关。连接标志是‘UG’

if(gw_fd= popen("route -n | grep 'UG'", "r")){

  fread(temp,1,128, gw_fd);

  sscanf(temp, "%*s%s", szNetGate);

  printf("Gateway is %s\n", szNetGate);

}

//获取DNS；一般DNS保存在/etc/reslov.conf文件中。具体获得方法要根据实际情况而定。

我的配置文件中是这样的

root@nill:/home/arm-none-linux#cat /etc/resolv.conf

 

# Dynamicresolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)

#    DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN

nameserver202.96.134.133  

上面的202.96.134.133就是我需要获取的主DNS，没有备用DNS

if(dns_fd= popen("cat /etc/reslov.conf | grep 'nameserver'", "r")){

  fread(temp,1,128, gw_fd);

  sscanf(temp, "%*s%s%*s%s", szDNS1,szDNS2);

  printf("DNS1 is %s",szDNS1);

  printf("DNS2is %s", szDNS2);

}