Linux下获取所有可用网卡信息

在Linux下开发网络程序时，经常会遇到需要取本地网络接口名、IP、广播地址、子网掩码或者MAC地址等信息的需求，最常见的办法是配合宏SIOCGIFHWADDR、SIOCGIFADDR、SIOCGIFBRDADDR与SIOCGIFNETMASK作为参数调用函数ioctl分别获得MAC地址、IP地址、广播地址与子网掩码来实现。一次性获取此类信息的C语言代码实现如下。 ? ??

#include <stdio.h>#include <string.h>#include <net/if.h>#include <sys/ioctl.h>#include <arpa/inet.h>#include <errno.h>int getLocalInfo(void){   int fd;   int interfaceNum = 0;   struct ifreq buf[16];   struct ifconf ifc;   struct ifreq ifrcopy;   char mac[16] = {0};   char ip[32] = {0};   char broadAddr[32] = {0};   char subnetMask[32] = {0};   if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)   {      perror("socket");      close(fd);      return -1;   }   ifc.ifc_len = sizeof(buf);   ifc.ifc_buf = (caddr_t)buf;   if (!ioctl(fd, SIOCGIFCONF, (char *)&ifc))   {      interfaceNum = ifc.ifc_len / sizeof(struct ifreq);      printf("interface num = %d\n", interfaceNum);      while (interfaceNum-- > 0)      {             printf("\ndevice name: %s\n", buf[interfaceNum].ifr_name);             //ignore the interface that not up or not runing             ifrcopy = buf[interfaceNum];             if (ioctl(fd, SIOCGIFFLAGS, &ifrcopy))             {                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);                close(fd);                return -1;             }             //get the mac of this interface             if (!ioctl(fd, SIOCGIFHWADDR, (char *)(&buf[interfaceNum])))             {                memset(mac, 0, sizeof(mac));                snprintf(mac, sizeof(mac), "%02x%02x%02x%02x%02x%02x",                            (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[0],                            (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[1],                            (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[2],                            (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[3],                            (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[4],                            (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[5]);                printf("device mac: %s\n", mac);             }            else            {                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);                close(fd);                return -1;            }            //get the IP of this interface            if (!ioctl(fd, SIOCGIFADDR, (char *)&buf[interfaceNum]))            {                snprintf(ip, sizeof(ip), "%s",                            (char *)inet_ntoa(((struct sockaddr_in *)&(buf[interfaceNum].ifr_addr))->sin_addr));                printf("device ip: %s\n", ip);            }            else            {                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);                close(fd);                return -1;            }            //get the broad address of this interface            if (!ioctl(fd, SIOCGIFBRDADDR, &buf[interfaceNum]))            {                snprintf(broadAddr, sizeof(broadAddr), "%s",                            (char *)inet_ntoa(((struct sockaddr_in *)&(buf[interfaceNum].ifr_broadaddr))->sin_addr));                printf("device broadAddr: %s\n", broadAddr);            }            else            {                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);                close(fd);                return -1;            }            //get the subnet mask of this interface            if (!ioctl(fd, SIOCGIFNETMASK, &buf[interfaceNum]))            {                snprintf(subnetMask, sizeof(subnetMask), "%s",                            (char *)inet_ntoa(((struct sockaddr_in *)&(buf[interfaceNum].ifr_netmask))->sin_addr));                printf("device subnetMask: %s\n", subnetMask);            }            else            {                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);                close(fd);                return -1;            }        }    }    else    {        printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);        close(fd);        return -1;    }    close(fd);    return 0;}int main(void){    getLocalInfo();    return 0;}

使用ioctl函数虽然可以获取所有的信息，但是使用起来比较麻烦，如果不需要获取MAC地址，那么使用getifaddrs函数来获取更加方便与简洁。值得一提的是，在MacOS或iOS系统上（如iPhone程序开发），上述iotcl函数没法获得mac地址跟子网掩码，这个使用，使用getifaddrs函数便更有优势了。下面是使用getiaddrs函数获取网卡信息的C语言代码实现。

#include <stdio.h>#include <ifaddrs.h>#include <arpa/inet.h>int getSubnetMask(){    struct sockaddr_in *sin = NULL;    struct ifaddrs *ifa = NULL, *ifList;    if (getifaddrs(&ifList) < 0) return -1;    for (ifa = ifList; ifa != NULL; ifa = ifa->ifa_next)    {        if(ifa->ifa_addr->sa_family == AF_INET)        {            printf("\n>>> interfaceName: %s\n", ifa->ifa_name);            sin = (struct sockaddr_in *)ifa->ifa_addr;            printf(">>> ipAddress: %s\n", inet_ntoa(sin->sin_addr));            sin = (struct sockaddr_in *)ifa->ifa_dstaddr;            printf(">>> broadcast: %s\n", inet_ntoa(sin->sin_addr));            sin = (struct sockaddr_in *)ifa->ifa_netmask;            printf(">>> subnetMask: %s\n", inet_ntoa(sin->sin_addr));        }    }    freeifaddrs(ifList);    return 0;}int main(void){    getSubnetMask();    return 0;}