1 #include <unistd.h> 2 #include <errno.h> 3 #include <string.h> 4 #include <stdio.h> 5 #include <sys/types.h> 6 #include <netdb.h> 7 8 int main( int argc, char** argv ) 9 { 10 char* hostname = "localhost"; 11 struct hostent* hent; 12 int i, ret; 13 14 if (argc > 1) 15 hostname = argv[1]; 16 17 hent = gethostbyname(hostname); 18 if (hent == NULL) { 19 printf("gethostbyname(%s) returned NULL !!\n", hostname); 20 return 1; 21 } 22 printf( "gethostbyname(%s) returned:\n", hostname); 23 printf( " name: %s\n", hent->h_name ); 24 printf( " aliases:" ); 25 for (i = 0; hent->h_aliases[i] != NULL; i++) 26 printf( " %s", hent->h_aliases[i] ); 27 printf( "\n" ); 28 printf( " address type: " ); 29 switch (hent->h_addrtype) { 30 case AF_INET: printf( "AF_INET\n"); break; 31 case AF_INET6: printf( "AF_INET6\n"); break; 32 default: printf("UNKNOWN (%d)\n", hent->h_addrtype); 33 } 34 printf( " address: " ); 35 switch (hent->h_addrtype) { 36 case AF_INET: 37 { 38 const char* dot = ""; 39 for (i = 0; i < hent->h_length; i++) { 40 printf("%s%d", dot, ((unsigned char*)hent->h_addr)[i]); 41 dot = "."; 42 } 43 } 44 break; 45 46 default: 47 for (i = 0; i < hent->h_length; i++) { 48 printf( "%02x", ((unsigned char*)hent->h_addr)[i] ); 49 } 50 } 51 printf("\n"); 52 return 0; 53 } 54
