gethostbyaddr
March 28th, 2006
ipaddress to hostname without a single shred of error checking. This code will take an ipaddress as an argument and return the hostname associated with it using gethostbyaddr. It should have more error checking and a lot of other stuff, but this is just to show the base code. Cut and paste away.
#include <unistd.h>
#include <netdb.h>
#include <netinet/in.h>
int main(int argc, char **argv) {
struct hostent *hostname = malloc(sizeof(struct hostent));
extern int h_errno;
struct in_addr *ipaddr = malloc(sizeof(struct in_addr));
ipaddr->s_addr=inet_addr(argv[1]) ;
if ( (hostname = gethostbyaddr((char *) ipaddr,sizeof(ipaddr),AF_INET)) == NULL ) {
printf ("%s\n","unknown");
exit(1);
}
printf ("%s\n",hostname -> h_name);
}
