Problem when non using default ctx

[Iñaki Baz Castillo]

Hi, I show two codes with are very similar, but second one doesn't use
the default context (just it):

---------------- code 1
----------------------------------------------------------------
int main(int argc, char **argv) {
  struct dns_rr_a4 *res_A;
  char *domain;
  in_addr_t ip_binary;
  char *ip = (char *)malloc(sizeof(char) * 16);
  int i;

  if (argc != 2) {
    fprintf(stderr, "ERROR: a domain must be provided as argument\n");
    return 1;
  }
  domain = argv[1];

  if (dns_init(NULL, 1) < 0) {
    fprintf(stderr, "FATAL: unable to initialize dns library\n");
    return 1;
  }

  res_A = dns_resolve_a4(NULL, domain, 0);

  if (! res_A) {
    fprintf(stderr, "ERROR: no DNS result\n");
    return 2;
  }

  ip = (char *)dns_ntop(AF_INET, &res_A->dnsa4_addr[0].s_addr, ip, 16);
  printf("- IP: %s\n", ip);

  return 0;
}
--------------------------------------------------------------------------------------------


---------------- code 2
----------------------------------------------------------------
int main(int argc, char **argv) {
  struct dns_ctx *dns_context;
  struct dns_rr_a4 *res_A;
  char *domain;
  in_addr_t ip_binary;
  char *ip = (char *)malloc(sizeof(char) * 16);
  int i;

  if (argc != 2) {
    fprintf(stderr, "ERROR: a domain must be provided as argument\n");
    return 1;
  }
  domain = argv[1];

  if (dns_init(NULL, 0) < 0) {
    fprintf(stderr, "FATAL: unable to initialize dns library\n");
    return 1;
  }
  dns_context = dns_new(NULL);
  dns_open(dns_context);

  res_A = dns_resolve_a4(dns_context, domain, 0);

  if (! res_A) {
    fprintf(stderr, "ERROR: no DNS result\n");
    return 2;
  }

  ip = (char *)dns_ntop(AF_INET, &res_A->dnsa4_addr[0].s_addr, ip, 16);
  printf("- IP: %s\n", ip);

  return 0;
}
--------------------------------------------------------------------------------------------


Ok, if I run the first code1 quering a non existing domain I get res_A = NULL:

./code1 postfix.org
ERROR: no DNS result

But using code2 it blocks and performs lot of queries to all the DNS
servers in /etc/hosts. Finally it returns the same.

./code2 postfix.org
[...]
[...]
[...]
ERROR: no DNS result


Theorically in code2 the context "dns_context" is a copy of the
deafult context so, why the difference? what is happening?

Thanks for your help (again).



-- 
Iñaki Baz Castillo
<ibc at aliax.net>