linux 系统获取网络ip, mask, gateway, dns信息小程序

net_util.c

#define WIRED_DEV "eth0"

#define WIRELESS_DEV "ra0"

#define PPPOE_DEV "ppp0"

#define DEBUG_PRT(fmt, arg...) printf(fmt,##arg)

/**

* get ip address.

* @param net_dev net device.

* @param ipaddr a pointer to save ip address.

* @return 0 success, or fail.

*/

int get_ipaddr(const char *net_dev, char *ipaddr)

{

struct ifreq ifr;

int fd = 0;

struct sockaddr_in *pAddr;

if((NULL == net_dev) || (NULL == ipaddr))

{

DEBUG_PRT("illegal call function SetGeneralIP! \n");

return -1;

}

if((fd = socket(AF_INET,SOCK_DGRAM,0)) < 0)

{

DEBUG_PRT("open socket failed \n");

return -1;

}

memset(&ifr,0,sizeof(ifr));

strcpy(ifr.ifr_name, net_dev);

if(ioctl(fd, SIOCGIFADDR, &ifr) < 0)

{

DEBUG_PRT("SIOCGIFADDR socket failed \n");

close(fd);

return -1;

}

pAddr = (struct sockaddr_in *)&(ifr.ifr_addr);

strcpy(ipaddr, inet_ntoa(pAddr->sin_addr));



close(fd);



return 0;

}

/**

* get gateway.

* @param gateway a pointer to save geteway.

* @return none.

*/

void get_gateway(ITI_CHAR *gateway)

{

char buf[1024]={0};

char *p = NULL;

char *q = NULL;

int count = 0;

if(NULL == gateway)

{

DEBUG_PRT("gateway is NULL \n");

return;

}

cmd_run("route | grep default", buf, 1024);

if(0 == strlen(buf))

{

DEBUG_PRT("get gateway error \n");

return;

}

p = strstr2(buf, "default");

q = p;

while(*q == ' ')

{

q++;

}

p = q;

while(*p != ' ')

{

p++;

count++;

}

if(NULL != q)

{

memcpy(gateway, q, count);

}

gateway[count] = '\0';

}

/**

* get mask.

* @param net_dev net device.

* @param mask a pointer to save mask.

* @return none.

*/

void get_mask(const char *net_dev, ITI_CHAR *mask)

{

char buf[1024]={0};

char *p = NULL;

if(NULL == mask)

{

DEBUG_PRT("mask is NULL \n");

return;

}

if(0 == (memcmp(WIRED_DEV, net_dev, sizeof(WIRED_DEV))))

{

cmd_run("ifconfig eth0 | grep Mask", buf, 1024);

}

else if(0 == (memcmp(WIRELESS_DEV, net_dev, sizeof(WIRELESS_DEV))))

{

cmd_run("ifconfig ra0 | grep Mask", buf, 1024);

}

else if(0 == (memcmp(PPPOE_DEV, net_dev, sizeof(PPPOE_DEV))))

{

cmd_run("ifconfig ppp0 | grep Mask", buf, 1024);

}

else

{

DEBUG_PRT("net device not support \n");

return;

}



if(0 == strlen(buf))

{

DEBUG_PRT("get mask error \n");

return;

}

p = strstr2(buf, "Mask:");

if(NULL == p)

{

DEBUG_PRT("get mask error \n");

return;

}

strcpy(mask, p);

}

/**

* get dns.

* @param dns1 a pointer to save first dns.

* @param dns2 a pointer to save second dns.

* @return 0 success, or fail.

*/

int get_dns(char *dns1, char *dns2)

{

int fd = -1;

int size = 0;

char strBuf[100];

char tmpBuf[100];

int buf_size = sizeof(strBuf);

char *p = NULL;

char *q = NULL;

int i = 0;

int j = 0;

int count = 0;



fd = open("/etc/resolv.conf", O_RDONLY);

if(-1 == fd)

{

DEBUG_PRT("%s open error \n", __func__);

return -1;

}

size = read(fd, strBuf, buf_size);

if(size < 0)

{

DEBUG_PRT("%s read file len error \n", __func__);

close(fd);

return -1;

}

strBuf[buf_size] = '\0';

close(fd);

while(i < buf_size)

{

if((p = strstr2(&strBuf[i], "nameserver")) != NULL)

{

j++;

p += 1;

count = 0;



memset(tmpBuf, 0xff, 100);

memcpy(tmpBuf, p, 100);

tmpBuf[sizeof(tmpBuf) -1 ] = '\0';



q = p;

while(*q != '\n')

{

q++;

count++;

}

i += (sizeof("nameserver") + count);



if(1 == j)

{

memcpy(dns1, p, count);

dns1[count]='\0';

}

else if(2 == j)

{

memcpy(dns2, p, count);

dns2[count]='\0';

}

}

else

{

i++;

}

}

return 0;

}

main.c

void main(void)

{

#define WIRED_DEV "eth0"

#define WIRELESS_DEV "ra0"

#define PPPOE_DEV "ppp0"

char buf[1024] = {'\0'};

extern int get_ipaddr(const char *net_dev, char *ipaddr);

get_ipaddr(WIRED_DEV, buf);

printf("get_ipaddr: %s \n", buf);

memset(buf, '\0', sizeof(buf));



extern void get_mask(const char *net_dev, ITI_CHAR *mask);

get_mask(WIRED_DEV, buf);

printf("get_mask: %s \n", buf);

memset(buf, '\0', sizeof(buf));



extern void get_gateway(ITI_CHAR *gateway);

get_gateway(buf);

printf("get_gateway: %s \n", buf);

memset(buf, '\0', sizeof(buf));

extern int get_dns(char *dns1, char *dns2);

get_dns(buf, &buf[100]);

printf("get_dns: %s %s\n", buf, &buf[100]);

memset(buf, '\0', sizeof(buf));

}

makefile:

gcc main.c net_util.c -o get_net_info

./get_net_info

运行结果:

get_ipaddr: 192.168.9.142

get_mask: 255.255.255.0

get_gateway: 192.168.9.254

get_dns: 192.168.9.11 192.168.9.10

为提高执行效率, 更新获取网关和子网掩码程序:

static void get_gateway(const char *net_dev, char *gateway)

{

FILE *fp;

char buf[1024];

char iface[16];

unsigned char tmp[100]={'\0'};

unsigned int dest_addr=0, gate_addr=0;

if(NULL == gateway)

{

DEBUG_PRT("gateway is NULL \n");

return;

}

fp = fopen("/proc/net/route", "r");

if(fp == NULL){

DEBUG_PRT("fopen error \n");

return;

}



fgets(buf, sizeof(buf), fp);

while(fgets(buf, sizeof(buf), fp))

{

if((sscanf(buf, "%s\t%X\t%X", iface, &dest_addr, &gate_addr) == 3)

&& (memcmp(net_dev, iface, strlen(net_dev)) == 0)

&& gate_addr != 0)

{

memcpy(tmp, (unsigned char *)&gate_addr, 4);

sprintf(gateway, "%d.%d.%d.%d", (unsigned char)*tmp, (unsigned char)*(tmp+1), (unsigned char)*(tmp+2), (unsigned char)*(tmp+3));

break;

}

}



fclose(fp);

}

static void get_mask(const char *net_dev, ITI_CHAR *mask)

{

struct sockaddr_in *pAddr;

struct ifreq ifr;

int sockfd;

sockfd = socket(AF_INET,SOCK_DGRAM,0);

memset(&ifr,0,sizeof(ifr));

strcpy(ifr.ifr_name, net_dev);



if(ioctl(sockfd, SIOCGIFNETMASK, &ifr) < 0){

DEBUG_PRT("SIOCGIFADDR socket failed \n");

close(sockfd);

return ;

}

pAddr = (struct sockaddr_in *)&(ifr.ifr_addr);

strcpy(mask, (char *)(inet_ntoa(pAddr->sin_addr)));



close(sockfd);

}