199025/gethostbyname.c

   1 #define _GNU_SOURCE
   2 #include <netdb.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6 #include <arpa/inet.h>
   7 #include <netinet/in.h>
   8 #include <sys/socket.h>
   9
  10 int main(int argc, char *argv[])
  11 {
  12         const char *name = (argc > 1 ? argv[1] : "localhost");
  13         printf("looking up '%s'\n", name);
  14
  15         struct hostent *hent = gethostbyname(name);
  16         if (!hent) {
  17                 herror("gethostbyname() failed");
  18                 return 1;
  19         }
  20
  21         size_t i;
  22         printf("h_name = %s\n", hent->h_name);
  23         printf("h_aliases = { ");
  24         for (i = 0; hent->h_aliases[i]; ++i)
  25                 printf("%s'%s'", (i ? ", " : ""), hent->h_aliases[i]);
  26         printf(" }\n");
  27         printf("h_addr_list = { ");
  28         for (i = 0; hent->h_addr_list[i]; ++i) {
  29                 struct in_addr addr;
  30                 memcpy(&addr, hent->h_addr_list[i], sizeof(addr));
  31                 printf("%s'%s'", (i ? ", " : ""), inet_ntoa(addr));
  32         }
  33         printf(" }\n");
  34
  35         return 0;
  36 }