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);
}