199025/getaddrinfo.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 #include <sys/types.h>
  10
  11 void doit(const char *name, const char *family_name, int family)
  12 {
  13         printf("--- looking up '%s' for family %s (%i)\n", name, family_name, family);
  14
  15         struct addrinfo hints;
  16         memset(&hints, 0, sizeof(hints));
  17         hints.ai_socktype = SOCK_STREAM;
  18         hints.ai_flags = AI_NUMERICHOST;
  19         hints.ai_family = family;
  20
  21         struct addrinfo *hostaddr = 0;
  22         int res = getaddrinfo(name, "telnet", &hints, &hostaddr);
  23         if (res == EAI_NONAME) {
  24                 printf("getaddrinfo(...) = EAI_NONAME, trying again with AI_CANONNAME\n");
  25                 hints.ai_flags = AI_CANONNAME;
  26                 res = getaddrinfo(name, "telnet", &hints, &hostaddr);
  27         }
  28         if (res == EAI_NONAME) {
  29                 printf("getaddrinfo(...) = EAI_NONAME ... FAIL\n");
  30         } else if (res) {
  31                 printf("getaddrinfo(...) = %i ... FAIL\n", res);
  32         } else {
  33                 printf("getaddrinfo(...) = %i\n", res);
  34
  35                 while (hostaddr) {
  36                         char name[1024], service[1024];
  37                         res = getnameinfo(hostaddr->ai_addr, hostaddr->ai_addrlen,
  38                                 name, sizeof(name), service, sizeof(service),
  39                                 NI_NUMERICHOST | NI_NUMERICSERV);
  40                         printf("getnameinfo(...) = %i\n", res);
  41                         printf("\tname = %s\n", name);
  42                         printf("\tservice = %s\n", service);
  43                         hostaddr = hostaddr->ai_next;
  44                 }
  45         }
  46
  47         freeaddrinfo(hostaddr);
  48 }
  49
  50 int main(int argc, char *argv[])
  51 {
  52         const char *name = (argc > 1 ? argv[1] : "localhost");
  53
  54 #define doit(name, family) doit(name, #family, family)
  55         doit(name, 0);
  56         doit(name, AF_INET);
  57         doit(name, AF_INET6);
  58
  59         puts("");
  60
  61         return 0;
  62 }