Sorry i forgot some important informations so i repost this message..
I encountered a strange problem with this simple program, is simply runs
ioctl() to get the IP of an interface given at command line.
When I run it under kernel 2.1.11* it simply works.. no problem.
But if I run it under kernel 2.0.35, there is a strange fact i can't explain.
If I comment "bzero(&ifr sizeof(struct ifreq));", it works, but if I uncomment
this line, it outputs a wrong IP.
My system is a Pentium 90, Libc-5.4.44, gcc-2.7.2.1
Have I mentionned enough properties of my system?
If yes, Could someone explain to me where is the problem?
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#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>
main(int argc, char *argv[])
{
struct ifreq ifr;
struct sockaddr_in isa;
int sockfd;
sockfd=socket(AF_INET, SOCK_RAW, 255);
/* Just try to uncomment the following line */
/* bzero(&ifr, sizeof(struct ifreq)); */
strcpy(ifr.ifr_name, argv[1]);
if (ioctl(sockfd, SIOCGIFADDR, &ifr) < 0) {
perror("ioctl()");
exit(0);
}
bcopy(&ifr.ifr_addr, &isa, sizeof(struct sockaddr_in));
printf("Address: %s\n", inet_ntoa(isa.sin_addr.s_addr));
close(sockfd);
}
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