学步园

//name:gethostbyname.c
//NOTE: h_addr_list[] conversion
#include<netdb.h>
#include<stdio.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#include<netinet/in.h>

int main(int argc,char **argv)
{
        struct hostent *hp;
        int x,x2;

        if(argc<2)
        {
                printf("usage:%s hostname/n",argv[0]);
                exit(1);
        }

        for(x=1;x<argc;x++)
        {
                hp=gethostbyname(argv[x]);
                if(!hp)
                {
                    printf("%s:%s",hstrerror(h_errno),argv[x]);
                        continue;
                }
                printf("HOST:%s/n",argv[x]);
                printf("official name:%s/n",hp->h_name);
                printf("alias:/n");
                for(x2=0;hp->h_aliases[x2];x2++)
                printf("%s/n",hp->h_aliases[x2]);

                printf("host address type:%s/n",hp->h_addrtype==AF_INET?"AF_INET":"AF_INET6");
                printf("list of addresses:/n");
                for(x2=0;hp->h_addr_list[x2];x2++)
                printf("%s/n",inet_ntoa(*(struct in_addr*)hp->h_addr_list[x2]));
                putchar('/n');
                putchar('/n');
        }
        return 0;
}