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21.gethostbyaddr.c
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21.gethostbyaddr.c
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//
// Created by satellite on 2023-05-25.
//
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "unistd.h"
#include "arpa/inet.h"
#include "netdb.h"
void error_handling(char* message)
{
fputs(message,stderr);
fputc('\n',stderr);
exit(1);
}
int main(int argc , char * argv[])
{
struct hostent * host;
struct sockaddr_in addr;
if(argc != 2) {
printf("usage : %s <IP>", 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("gethostbyaddr error");
printf("Official name %s \n",host->h_name);
for(int i=0;host->h_aliases[i];i++)
printf("Aliases %d : %s \n",i+1,host->h_aliases[i]);
printf("Address type is %s \n",
(host->h_addrtype == AF_INET) ? "AF_INET" : "AF_INET6");
for(int 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;
}