linux下的ioctl函数原型如下：
#include <sys/ioctl.h>
int ioctl(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：
类别 | Request | 说明 | 数据类型 |
套 接 口 | SIOCATMARK SIOCSPGRP SIOCGPGRP | 是否位于带外标记 设置套接口的进程ID 或进程组ID 获取套接口的进程ID 或进程组ID | int int int |
文 件 | FIONBIO FIOASYNC FIONREAD FIOSETOWN FIOGETOWN | 设置/ 清除非阻塞I/O 标志 设置/ 清除信号驱动异步I/O 标志 获取接收缓存区中的字节数 设置文件的进程ID 或进程组ID 获取文件的进程ID 或进程组ID | int int int int int |
接 口 | SIOCGIFCONF SIOCSIFADDR SIOCGIFADDR SIOCSIFFLAGS SIOCGIFFLAGS SIOCSIFDSTADDR SIOCGIFDSTADDR SIOCGIFBRDADDR SIOCSIFBRDADDR SIOCGIFNETMASK SIOCSIFNETMASK SIOCGIFMETRIC SIOCSIFMETRIC SIOCGIFMTU SIOCxxx | 获取所有接口的清单 设置接口地址 获取接口地址 设置接口标志 获取接口标志 设置点到点地址 获取点到点地址 获取广播地址 设置广播地址 获取子网掩码 设置子网掩码 获取接口的测度 设置接口的测度 获取接口MTU （还有很多取决于系统的实现） | struct ifconf struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq |
ARP | SIOCSARP SIOCGARP SIOCDARP | 创建/ 修改ARP 表项 获取ARP 表项 删除ARP 表项 | struct arpreq struct arpreq struct arpreq |
路 由 | SIOCADDRT SIOCDELRT | 增加路径 删除路径 | struct rtentry struct rtentry |
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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",
(unsigned char)ifr.ifr_netmask.sa_data[0],
(unsigned char)ifr.ifr_netmask.sa_data[1],
(unsigned char)ifr.ifr_netmask.sa_data[2],
(unsigned char)ifr.ifr_netmask.sa_data[3],
(unsigned char)ifr.ifr_netmask.sa_data[4],
(unsigned char)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
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 202.96.134.133
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);
}
