最近在做项目过程中，由于在多线程中使用system函数，有时候出现莫名程序异常终止，最后决定替换所有的system函数，但是对于设置mac地址这个函数试了很多次都没有成功；今天在此总结下原因：
1. 编写的关闭/打开网卡函数没有延时；（一般情况设置开关网卡可能需要初始化，所以如果开关连续可能没有初始化成功，你可以试试在嵌入式Linux命令行下快速的开关网卡，也是没有反应的）
2. 类型转换问题；（由于为了便捷，使用sscanf提取mac字符串，如果使用8bit提取%x,转换出错，最后只能使用32bit，再一个个赋值即可）
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
typedef signed char INT8S;
typedef unsigned char INT8U;
typedef signed short INT16S;
typedef unsigned short INT16U;
typedef signed int INT32S;
typedef unsigned int INT32U;
//add by lightd, 2014-06-04
//============================================================================
//Function: ifconfig_ethx_down_API
//Description: 关闭本地指定网卡 - eg: ifconfig eth0 down
//Input:
//Output:
//Return:
//Others: None
//============================================================================
INT8S ifconfig_ethx_down_API(const INT8U *interface_name)
{
INT32S sock_fd;
struct ifreq ifr;
int selector;
//传入参数合法性检测
if(interface_name == NULL)
{
fprintf(stdout, "%s:%d: args invalid!", __FUNCTION__, __LINE__);
return -1;
}
//禁止关闭回环
if(strncmp((char *)interface_name, (char *)"lo", 2) == 0)
{
fprintf(stdout, "%s:%d: You can't pull down interface lo!", __FUNCTION__, __LINE__);
return 0;
}
sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
if(sock_fd < 0)
{
fprintf(stdout, "%s:%d: socket failed!", __FUNCTION__, __LINE__);
return -2;
}
sprintf(ifr.ifr_name, "%s", interface_name);
if(ioctl(sock_fd, SIOCGIFFLAGS, &ifr) < 0)
{
fprintf(stdout, "%s:%d: ioctl failed 1!", __FUNCTION__, __LINE__);
return -3;
}
selector = IFF_UP;
ifr.ifr_flags &= ~selector;
if(ioctl(sock_fd, SIOCSIFFLAGS, &ifr) < 0)
{
fprintf(stdout, "%s:%d: ioctl failed 2!", __FUNCTION__, __LINE__);
return -4;
}
close( sock_fd );
return 0;
}
//add by lightd, 2014-06-04
//============================================================================
//Function: ifconfig_ethx_up_API
//Description: 打开本地指定网卡 - eg: ifconfig eth0 up
//Input:
//Output:
//Return:
//Others: None
//============================================================================
INT8S ifconfig_ethx_up_API(const INT8U *interface_name)
{
INT32S sock_fd;
struct ifreq ifr;
int selector;
//传入参数合法性检测
if(interface_name == NULL)
{
fprintf(stdout, "%s:%d: args invalid!", __FUNCTION__, __LINE__);
return -1;
}
sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
if(sock_fd < 0)
{
fprintf(stdout, "%s:%d: create socket failed!", __FUNCTION__, __LINE__);
return -2;
}
sprintf(ifr.ifr_name, "%s", interface_name);
if(ioctl(sock_fd, SIOCGIFFLAGS, &ifr) < 0)
{
fprintf(stdout, "%s:%d: ioctl error 1", __FUNCTION__, __LINE__);
return -3;
}
selector = (IFF_UP | IFF_RUNNING);
ifr.ifr_flags |= selector;
if(ioctl(sock_fd, SIOCSIFFLAGS, &ifr) < 0)
{
fprintf(stdout, "%s:%d: ioctl error 2", __FUNCTION__, __LINE__);
return -4;
}
close( sock_fd );
return 0;
}
//add by lightd, 2014-06-04
//============================================================================
//Function: SetLocalMACAddr_API
//Description: 设置本地指定网卡的MAC
//Input:
//Output:
//Return:
//Others: None
//Test result: 测试结果 - 连续调用20次不出错
//============================================================================
INT8S SetLocalMACAddr_API(const INT8U *interface_name, const INT8U *str_macaddr)
{
int ret;
int sock_fd;
struct ifreq ifr;
INT32U mac2bit[6];
//传入参数合法性检测
if(interface_name == NULL || str_macaddr == NULL)
{
fprintf(stdout, "%s:%d: args invalid!", __FUNCTION__, __LINE__);
return -1;
}
//提取mac格式
sscanf((char *)str_macaddr, "%02X:%02X:%02X:%02X:%02X:%02X", (INT8U *)&mac2bit[0], (INT8U *)&mac2bit[1], (INT8U *)&mac2bit[2], (INT8U *)&mac2bit[3], (INT8U *)&mac2bit[4], (INT8U *)&mac2bit[5]);
sock_fd = socket(PF_INET, SOCK_DGRAM, 0);
if (sock_fd < 0)
{
perror("socket error");
return -2;
}
//设置mac前，必须关闭对应的网卡 - 否则出错
ret = ifconfig_ethx_down_API( interface_name );
if(ret < 0)
{
fprintf(stdout, "%s:%d: close eth0 error", __FUNCTION__, __LINE__);
return -3;
}
sleep(1); //等待网卡关闭OK
sprintf(ifr.ifr_ifrn.ifrn_name, "%s", interface_name);
ifr.ifr_ifru.ifru_hwaddr.sa_family = 1;
ifr.ifr_ifru.ifru_hwaddr.sa_data[0] = mac2bit[0];
ifr.ifr_ifru.ifru_hwaddr.sa_data[1] = mac2bit[1];
ifr.ifr_ifru.ifru_hwaddr.sa_data[2] = mac2bit[2];
ifr.ifr_ifru.ifru_hwaddr.sa_data[3] = mac2bit[3];
ifr.ifr_ifru.ifru_hwaddr.sa_data[4] = mac2bit[4];
ifr.ifr_ifru.ifru_hwaddr.sa_data[5] = mac2bit[5];
ret = ioctl(sock_fd, SIOCSIFHWADDR, &ifr);
if (ret != 0)
{
perror("set mac address erorr");
return -4;
}
close( sock_fd );
ret = ifconfig_ethx_up_API( interface_name );
if(ret < 0)
{
fprintf(stdout, "%s:%d: open eth0 error!", __FUNCTION__, __LINE__);
return -5;
}
sleep(2); //等待网卡打开OK
return 0;
}
//add by lightd, 2014-06-04
//============================================================================
//Function: GetLocalMACAddr_API
//Description: 获取本地指定网卡的MAC
//Input:
//Output:
//Return:
//Others: None
//============================================================================
INT8S GetLocalMACAddr_API(const INT8U *interface_name, INT8U *str_macaddr)
{
INT32S sock_fd;
struct ifreq ifr_mac;
//传入参数合法性检测
if(interface_name == NULL || str_macaddr == NULL)
{
fprintf(stdout, "%s:%d: args invalid!", __FUNCTION__, __LINE__);
return -1;
}
sock_fd = socket( AF_INET, SOCK_STREAM, 0 );
if( sock_fd == -1)
{
perror("create socket failed");
sprintf((char *)str_macaddr, "00:00:00:00:00:00");
return -2;
}
//指定网卡
memset(&ifr_mac, 0, sizeof(ifr_mac));
sprintf(ifr_mac.ifr_name, "%s", interface_name);
//获取指定网卡的mac地址
if( (ioctl( sock_fd, SIOCGIFHWADDR, &ifr_mac)) < 0 )
{
perror("mac ioctl error");
sprintf((char *)str_macaddr, "00:00:00:00:00:00");
return -3;
}
close( sock_fd );
sprintf((char *)str_macaddr,"%02x:%02x:%02x:%02x:%02x:%02x",
(unsigned char)ifr_mac.ifr_hwaddr.sa_data[0],
(unsigned char)ifr_mac.ifr_hwaddr.sa_data[1],
(unsigned char)ifr_mac.ifr_hwaddr.sa_data[2],
(unsigned char)ifr_mac.ifr_hwaddr.sa_data[3],
(unsigned char)ifr_mac.ifr_hwaddr.sa_data[4],
(unsigned char)ifr_mac.ifr_hwaddr.sa_data[5]);
printf("local mac:<%s> \n", str_macaddr);
return 0;
}
int main(void)
{
INT8U str_macaddr[20];
memset(str_macaddr, 0, sizeof(str_macaddr));
GetLocalMACAddr_API("eth0", str_macaddr);
fprintf(stdout, "1 mac: %s\n", str_macaddr);
//ifconfig_ethx_down_API("eth0");
//system("ifconfig eth0 down");
//usleep(500000);
//system("ifconfig eth0 up");
//usleep(500000);
//sleep(1); //10ms
//ifconfig_ethx_down_API("eth0");
//sleep(1);
SetLocalMACAddr_API("eth0", "08:00:11:22:33:44");
//ifconfig_ethx_up_API("eth0");
//ifconfig_ethx_up_API("eth0");
//sleep(2);
memset(str_macaddr, 0, sizeof(str_macaddr));
GetLocalMACAddr_API("eth0", str_macaddr);
fprintf(stdout, "2 mac: %s\n", str_macaddr);
system("ping 200.200.200.100");
//usleep(50000);
//ifconfig_ethx_down_API("eth0");
//ifconfig_ethx_up_API("eth0");
//memset(str_macaddr, 0, sizeof(str_macaddr));
//GetLocalMACAddr_API("eth0", str_macaddr);
fprintf(stdout, "2 mac: %s\n", str_macaddr);
return 0;
}