代码改变世界

根据网卡名获取IP地址，以及掩码地址

2012-07-11 13:45  Rollen Holt  阅读(1882)  评论(2)  编辑  收藏  举报

nterface name is something like “eth0″ and the ip address of the interface can be retrieved using the ioctl function.
Here is a simple piece of code that demonstrates how :

Code

1 #include <stdio.h>
2 #include <string.h>
3 #include <sys/types.h>
4 #include <sys/socket.h>
5 #include <sys/ioctl.h>
6 #include <netinet/in.h>
7 #include <net/if.h>
8 #include <unistd.h>
9 #include <arpa/inet.h>
10  
11 int main()
12 {
13     int fd;
14     struct ifreq ifr;
15      
16     char iface[] = "eth0";
17      
18     fd = socket(AF_INET, SOCK_DGRAM, 0);
19  
20     //Type of address to retrieve - IPv4 IP address
21     ifr.ifr_addr.sa_family = AF_INET;
22  
23     //Copy the interface name in the ifreq structure
24     strncpy(ifr.ifr_name , iface , IFNAMSIZ-1);
25  
26     ioctl(fd, SIOCGIFADDR, &ifr);
27  
28     close(fd);
29  
30     //display result
31     printf("%s - %s\n" , iface , inet_ntoa(( (struct sockaddr_in *)&ifr.ifr_addr )->sin_addr) );
32  
33     return 0;
34 }

Output

1 $ gcc ioctl.c && ./a.out
2 eth0 - 192.168.0.6

The socket used can be a TCP socket (SOCK_STREAM) as well.

If you also need the netmask then use the SIOCGIFNETMASK value in ioctl like this :

1 #include <stdio.h>
2 #include <string.h>
3 #include <sys/socket.h>
4 #include <sys/ioctl.h>
5 #include <net/if.h>
6 #include <unistd.h>
7 #include <arpa/inet.h>
8  
9 int main()
10 {
11     int fd;
12     struct ifreq ifr;
13      
14     char iface[] = "eth0";
15      
16     fd = socket(AF_INET, SOCK_DGRAM, 0);
17  
18     //Type of address to retrieve - IPv4 IP address
19     ifr.ifr_addr.sa_family = AF_INET;
20  
21     //Copy the interface name in the ifreq structure
22     strncpy(ifr.ifr_name , iface , IFNAMSIZ-1);
23      
24     //get the ip address
25     ioctl(fd, SIOCGIFADDR, &ifr);
26      
27     //display ip
28     printf("IP address of %s - %s\n" , iface , inet_ntoa(( (struct sockaddr_in *)&ifr.ifr_addr )->sin_addr) );
29      
30     //get the netmask ip
31     ioctl(fd, SIOCGIFNETMASK, &ifr);
32      
33     //display netmask
34     printf("Netmask of %s - %s\n" , iface , inet_ntoa(( (struct sockaddr_in *)&ifr.ifr_addr )->sin_addr) );
35      
36     close(fd);
37      
38     return 0;
39 }

Output :

view source
print?
1 $ gcc ioctl.c && ./a.out
2 IP address of eth0 - 192.168.0.6
3 Netmask of eth0 - 255.255.255.0