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 #include <arpa/inet.h> 9 10 #ifndef IFNAMESZ 11 #define IFNAMESZ 16 12 #endif 13 14 int main(int argc, char *argv[]) 15 { 16 if (argc != 2) { 17 printf("using %s <ETH_NAME>\n", argv[0]); 18 return 0; 19 } 20 21 int sock = 0; 22 struct sockaddr_in sin; 23 struct ifreq ifr;//用来保存接口的信息 24 25 sock = socket(AF_INET, SOCK_DGRAM, 0); 26 if (sock == -1) { 27 perror("socket"); 28 return 1; 29 } 30 memcpy(ifr.ifr_name, argv[1], IFNAMESZ); 31 ifr.ifr_name[IFNAMESZ - 1] = '\0'; 32 33 if (ioctl(sock, SIOCGIFADDR, &ifr) == 0) { //SIOCGIFADDR 获取接口地址 34 memcpy(&sin, &ifr.ifr_addr, sizeof(sin)); //将获得地址拷贝到 sockaddr_in 结构体中 35 printf("Ip: %s\n", inet_ntoa(sin.sin_addr)); 36 } 37 38 if (ioctl(sock, SIOCGIFNETMASK, &ifr) == 0) { 39 memcpy(&sin, &ifr.ifr_netmask, sizeof(sin)); 40 printf("netmask: %s\n", inet_ntoa(sin.sin_addr)); 41 } 42 close(sock); 43 44 return 0; 45 }
运行结果如下：