#include <sys/ioctl.h> 
#include <sys/types.h> 
#include <sys/stat.h> 
#include <sys/socket.h> 
#include <unistd.h> 
#include <netinet/in.h> 
#include <arpa/inet.h> 
#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <net/if.h> 
 
#include <arpa/inet.h> 
 
typedef struct _ifinfo 
{ 
    struct sockaddr_in *sin; 
    char ifname[40]; 
    int  fd;     
    struct ifreq *ifr; 
    struct ifconf ifcfg; 
    int  ifnum; 
} IF;  
 
IF  *ifopen(); 
IF  *ifget(IF *); 
int ifclose(IF *); 
 
IF *ifopen() 
{ 
    struct sockaddr_in *sin; 
    int numreqs = 30; 
    IF *LIF; 
 
    LIF = (IF *)malloc(sizeof(&LIF)); 
    memset((void *)LIF, 0x00,sizeof(&LIF)); 
 
    LIF->fd = socket(AF_INET, SOCK_DGRAM, 0); 
 
    memset(&ifcfg, 0, sizeof(ifcfg)); 
    ifcfg.ifc_buf = NULL; 
    ifcfg.ifc_len = sizeof(struct ifreq) * numreqs; 
    ifcfg.ifc_buf = malloc(ifcfg.ifc_len); 
    ifcfg.ifc_len = sizeof(struct ifreq) * numreqs; 
    ifcfg.ifc_buf = realloc(ifcfg.ifc_buf, ifcfg.ifc_len); 
    if (ioctl(LIF->fd, SIOCGIFCONF, (char *)&ifcfg) < 0) 
    { 
        perror("SIOCGIFCONF "); 
        return (IF *)NULL; 
    } 
    //printf("%d : %d \n", ifcfg.ifc_len, sizeof(struct ifreq)); 
    LIF->ifr = ifcfg.ifc_req; 
    return LIF; 
} 
 
IF *ifget(IF *AIF) 
{ 
    if (AIF->ifnum > 0) 
    { 
        AIF->ifr++; 
    } 
    if (AIF->ifnum < AIF->ifr.ifc_len) 
    { 
        AIF->ifnum += sizeof(struct ifreq); 
        strncpy(AIF->ifname, AIF->ifr->ifr_name, 40); 
        AIF->sin = (struct sockaddr_in *)&AIF->ifr->ifr_addr;  
        return AIF->ifr; 
    } 
    else 
        return (IF *)NULL; 
         
    /* 
    for (n = 0; n < ifcfg.ifc_len; n+= sizeof(struct ifreq)) 
    { 
        printf("%s\n", ifr->ifr_name); 
        sin = (struct sockaddr_in *)&ifr->ifr_addr; 
        printf("IP    %s\n", inet_ntoa(sin->sin_addr) ); 
        if ( (sin->sin_addr.s_addr) == INADDR_LOOPBACK) 
        { 
            printf("Loop Back\n"); 
        } 
     
        ioctl(fd,  SIOCGIFBRDADDR, (char *)ifr); 
        sin = (struct sockaddr_in *)&ifr->ifr_broadaddr; 
        printf("BROD  %s\n", inet_ntoa(sin->sin_addr)); 
 
        ioctl(fd, SIOCGIFNETMASK, (char *)ifr); 
        sin = (struct sockaddr_in *)&ifr->ifr_addr; 
        printf("MASK  %s\n", inet_ntoa(sin->sin_addr)); 
 
        ioctl(fd, SIOCGIFMTU, (char *)ifr); 
        printf("MTU   %d\n", ifr->ifr_mtu); 
 
        ioctl(fd, SIOCGIFINDEX, (char *)ifr); 
        printf("BAND  %d %d\n", ifr->ifr_ifindex, ifr->ifr_bandwidth); 
 
        printf("\n"); 
        ifr++; 
    } 
    */ 
} 
 
int infget(IF *AIF) 
{ 
    close(AIF->fd); 
    free(AIF); 
} 
 
int main() 
{ 
    IF *ifp; 
 
    ifp = ifopen(); 
    if (ifp == NULL) 
    { 
        perror("error "); 
    } 
    while((ifp = ifget(ifp)) != NULL) 
    { 
        printf("GET GET\n"); 
    } 
}