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gethostbyaddr.c
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gethostbyaddr.c
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netdb.h>
void error_handling(char *message);
int main(int argc, char *argv[])
{
int i;
struct hostent *host;
struct sockaddr_in addr;
if (argc != 2)
{
printf("Usage : %s <IP>\n", argv[0]);
exit(1);
}
memset(&addr, 0, sizeof(addr));
addr.sin_addr.s_addr = inet_addr(argv[1]);
host = gethostbyaddr((char *)&addr.sin_addr, 4, AF_INET);
if (!host)
error_handling("gethost... error");
printf("Official name: %s \n", host->h_name);
for (i = 0; host->h_aliases[i]; i++)
printf("Aliases %d:%s \n", i + 1, host->h_aliases[i]);
printf("Address type: %s \n",
(host->h_addrtype == AF_INET) ? "AF_INET" : "AF_INET6");
for (i = 0; host->h_addr_list[i]; i++)
printf("IP addr %d: %s \n", i + 1,
inet_ntoa(*(struct in_addr *)host->h_addr_list[i]));
return 0;
}
void error_handling(char *message)
{
fputs(message, stderr);
fputc('\n', stderr);
exit(1);
}