linux获取网络接口信息需要用到的函数为ioctl（），结构体struct ifreq，struct ifconf
1.ioctl（）函数原型及作用
1 #include <sys/ioctl.h> 2 3 int ioctl(int d, int request, ...); 4 5 //参数 6 //int d：是一个文件描述符 7 //int request ：表示要请求的信息。如IP地址、网络掩码等 8 //......:可变参数，根据request而定
下面是ioctl请求的request参数以及arg地址必须指向的数据类型：
2.struct ifreq结构体
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
1 /* Interface request structure used for socket ioctl‘s. All interface
2 ioctl‘s must have parameter definitions which begin with ifr_name.
3 The remainder may be interface specific. */
4
5 struct ifreq
6 {
7 # define IFHWADDRLEN 6
8 # define IFNAMSIZ IF_NAMESIZE
9 union
10 {
11 char ifrn_name[IFNAMSIZ]; /* Interface name, e.g. "en0". */
12 } ifr_ifrn;
13
14 union
15 {
16 struct sockaddr ifru_addr;
17 struct sockaddr ifru_dstaddr;
18 struct sockaddr ifru_broadaddr;
19 struct sockaddr ifru_netmask;
20 struct sockaddr ifru_hwaddr;
21 short int ifru_flags;
22 int ifru_ivalue;
23 int ifru_mtu;
24 struct ifmap ifru_map;
25 char ifru_slave[IFNAMSIZ]; /* Just fits the size */
26 char ifru_newname[IFNAMSIZ];
27 __caddr_t ifru_data;
28 } ifr_ifru;
29 };
30 # define ifr_name ifr_ifrn.ifrn_name /* interface name */
31 # define ifr_hwaddr ifr_ifru.ifru_hwaddr /* MAC address */
32 # define ifr_addr ifr_ifru.ifru_addr /* address */
33 # define ifr_dstaddr ifr_ifru.ifru_dstaddr /* other end of p-p lnk */
34 # define ifr_broadaddr ifr_ifru.ifru_broadaddr /* broadcast address */
35 # define ifr_netmask ifr_ifru.ifru_netmask /* interface net mask */
36 # define ifr_flags ifr_ifru.ifru_flags /* flags */
37 # define ifr_metric ifr_ifru.ifru_ivalue /* metric */
38 # define ifr_mtu ifr_ifru.ifru_mtu /* mtu */
39 # define ifr_map ifr_ifru.ifru_map /* device map */
40 # define ifr_slave ifr_ifru.ifru_slave /* slave device */
41 # define ifr_data ifr_ifru.ifru_data /* for use by interface */
42 # define ifr_ifindex ifr_ifru.ifru_ivalue /* interface index */
43 # define ifr_bandwidth ifr_ifru.ifru_ivalue /* link bandwidth */
44 # define ifr_qlen ifr_ifru.ifru_ivalue /* queue length */
45 # define ifr_newname ifr_ifru.ifru_newname /* New name */
46 # define _IOT_ifreq _IOT(_IOTS(char),IFNAMSIZ,_IOTS(char),16,0,0)
47 # define _IOT_ifreq_short _IOT(_IOTS(char),IFNAMSIZ,_IOTS(short),1,0,0)
48 # define _IOT_ifreq_int _IOT(_IOTS(char),IFNAMSIZ,_IOTS(int),1,0,0)
3.struct ifconf
ifreq包含在ifconf结构中。而ifconf结构通常是用来保存所有接口的信息的。
1 /* Structure used in SIOCGIFCONF request. Used to retrieve interface
2 configuration for machine (useful for programs which must know all
3 networks accessible). */
4
5 struct ifconf
6 {
7 int ifc_len; /* Size of buffer. */
8 union
9 {
10 __caddr_t ifcu_buf;
11 struct ifreq *ifcu_req;
12 } ifc_ifcu;
13 };
14 # define ifc_buf ifc_ifcu.ifcu_buf /* Buffer address. */
15 # define ifc_req ifc_ifcu.ifcu_req /* Array of structures. */
16 # define _IOT_ifconf _IOT(_IOTS(struct ifconf),1,0,0,0,0) /* not right */
17 #endif /* Misc. */
下面程序是获取本机的IP地址
1 #include <stdio.h>
2 #include <sys/socket.h>
3 #include <string.h>
4 #include <sys/types.h>
5 #include <netinet/in.h>
6 #include <sys/ioctl.h>
7 #include <net/if.h>
8
9 //#define ETH_NAME "eth0"
10 //#define NET_NAME "wlan1"
11
12 int main(int argc, char *argv[])
13 {
14 if(argc != 2) {
15 printf("using %s <ETH_NAME>\n", argv[0]);
16 return 0;
17 }
18
19 int sock = 0;
20 struct sockaddr_in sin;
21 struct ifreq ifr;//用来保存接口的信息
22
23 sock = socket(AF_INET, SOCK_DGRAM, 0);
24 if(sock == -1) {
25 perror("socket");
26 return 1;
27 }
28
29 strcpy(ifr.ifr_name, argv[1]);
30 int ret = ioctl(sock, SIOCGIFADDR, &ifr);//SIOCGIFADDR 获取接口地址
31 if(ret < 0) {
32 perror("ioctl");
33 return 1;
34 }
35
36 memcpy(&sin, &ifr.ifr_addr, sizeof(sin));//将获得地址拷贝到 sockaddr_in 结构体中
37 printf("%s\n", inet_ntoa(sin.sin_addr));//显示
38 return 0;
39
40 }
运行结果如下：
时间： 2024-10-10 20:41:36