我正在使用此方法获取mac地址:
#include <sys/ioctl.h>
#include <net/if.h>
#include <unistd.h>
#include <netinet/in.h>
#include <string.h>
int main()
{
ifreq ifr;
ifconf ifc;
char buf[1024];
int success = 0;
int sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
if (sock == -1) { /* handle error*/ };
ifc.ifc_len = sizeof(buf);
ifc.ifc_buf = buf;
if (ioctl(sock, SIOCGIFCONF, &ifc) == -1) { /* handle error */ }
ifreq* it = ifc.ifc_req;
const ifreq* const end = it + (ifc.ifc_len / sizeof(ifreq));
for (; it != end; ++it) {
strcpy(ifr.ifr_name, it->ifr_name);
if (ioctl(sock, SIOCGIFFLAGS, &ifr) == 0) {
if (! (ifr.ifr_flags & IFF_LOOPBACK)) { // don't count loopback
if (ioctl(sock, SIOCGIFHWADDR, &ifr) == 0) {
success = 1;
break;
}
}
}
}
unsigned char mac_address[6];
if (success) memcpy(mac_address, ifr.ifr_hwaddr.sa_data, 6);
}
(取自How to get MAC address of your machine using a C program?)
但是,当我从Wifi网络断开连接时,第一次调用ioctl会返回一个空列表。
你能解释一下这种行为吗?