uv dns api

dns.c

typedef enum {
  UV_DNS_A,
  UV_DNS_AAAA,
  UV_DNS_PTR,
  UV_DNS_MX,
  UV_DNS_SRV,
  ... etc ...
} uv_dns_type_t;


typedef struct  {
  uv_dns_type_t type;
  union {
    struct {
      unsigned int addr;
    } a;
    struct {
      unsigned char addr[16];
    } aaaa;
    struct {
      /* name may not be null-terminated. observe name_len. */
      char* name;
      size_t name_len;
    } ptr;
    struct {
      char* name;
      size_t name_len;
      unsigned short port;
      unsigned short priority;
      unsigned short weight;
    } srv;
    struct {
      char* name;
      size_t name_len;
      unsigned short preference;
    } mx;
  };
} uv_dns_record_t;


int uv_dns_query(uv_req_t* req, char* name, uv_dns_type_t class);


void dns_cb(uv_req_t* req, int status) {
  char *name;

  assert(status == 0);
  uv_dns_record_t record;

  while (uv_dns_get_record(req, &record)) {
    switch (record->type) {
      case UV_DNS_A:
        printf("addr is %u\n", record.a.addr);
        break;

      case UV_DNS_PTR:
        name = strndup(record.ptr.name, record.ptr.name_len);
        printf("points to %s\n", name);
        free(name);
        break;

      case UV_DNS_SRV:
        name = strndup(record.ptr.name, record.ptr.name_len);
        printf("%s %hu %hu %hu\n", name, record.srv.port, record.srv.priority, record.srv.weight);
        free(name);
        break;

      ... etc ...
    }
  }

  /* Allow uv to free the dns result buffer associated with the req. */
  /* This implies that all string pointers reported by uv_dns_get_record (eg record.ptr.name) become invalid. */
  uv_dns_cleanup(req);
}


int main() {
  uv_handle_t handle;
  uv_req_t req;

  ...

  uv_dns_init(&handle, NULL, NULL); /* Do we really need a handle for it? */
  uv_req_init(&req, &handle, dns_cb);
  uv_dns_query(&req, "www.cloudkick.com", UV_DNS_A);

  ...
}