//
// #include <netdb.h>
//
// struct hostent *gethostbyname(const char *);
//
// struct hostent {
// char *h_name; /* official name of host */
// char **h_aliases; /* alias list */
// int h_addrtype; /* host address type */
// int h_length; /* length of address */
// char **h_addr_list; /* list of addresses from name server */
// };
// #define h_addr h_addr_list[0] /* address, for backward compatiblity */
//
//
#include <stdio.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
int main(int argc, char *argv[])
{
struct hostent *myHostEnt;
struct in_addr myInAddr; /*IP 주소를 저장할 구조체*/
int i;
if(argc != 2) {
fprintf(stderr, "Usage : %s host_name(domain name)\n", argv[0]); fflush(stderr);
exit(0);
}
myHostEnt = gethostbyname(argv[1]); /* hostent 구조체 구하기 */
if(myHostEnt == NULL) {
fprintf(stderr, "ERROR_FAIL gethostbyname\n"); fflush(stderr);
exit(0);
}
fprintf(stdout, "official host name : %s\n", myHostEnt->h_name); fflush(stdout); /*공식적인호스트이름 출력*/
i = 0;
while(myHostEnt->h_aliases[i] != NULL) {
fprintf(stdout, "alias list name : %s\n", myHostEnt->h_aliases[i]); fflush(stdout); /*호스트별명 출력*/
i++;
}
fprintf(stdout, "host address type : %d\n", myHostEnt->h_addrtype); fflush(stdout); /*호스트주소타입 출력*/
if( myHostEnt->h_addrtype == AF_INET ) {
fprintf(stdout, "AF_INET\n"); fflush(stdout);
}
else if( myHostEnt->h_addrtype == AF_INET6 ) {
fprintf(stdout, "AF_INET6\n"); fflush(stdout);
}
else {
fprintf(stdout, "ETC.....\n"); fflush(stdout);
}
fprintf(stdout, "length of host address :%d\n", myHostEnt->h_length); fflush(stdout); /*호스트주소길이 출력*/
i = 0;
while(myHostEnt->h_addr_list[i] != NULL) {
myInAddr.s_addr = *((u_long *)(myHostEnt->h_addr_list[i]));
fprintf(stdout, "IP address : %s\n", inet_ntoa(myInAddr)); fflush(stdout); /*호스트주소를 dotted-decimal형태로 출력*/
i++;
}
return 0;
}
