static void append_dn(void *ctx, const void *buf, size_t len)
{
  struct cafile_parser *ca = ctx;

  if(ca->err != CURLE_OK || !ca->in_cert)
    return;
  if(sizeof(ca->dn) - ca->dn_len < len) {
    ca->err = CURLE_FAILED_INIT;
    return;
  }
  memcpy(ca->dn + ca->dn_len, buf, len);
  ca->dn_len += len;
}
static void append_dn(void *ctx, const void *buf, size_t len)
{
  struct cafile_parser *ca = ctx;

  if(ca->err != CURLE_OK || !ca->in_cert)
    return;
  if(sizeof(ca->dn) - ca->dn_len < len) {
    ca->err = CURLE_FAILED_INIT;
    return;
  }
  memcpy(ca->dn + ca->dn_len, buf, len);
  ca->dn_len += len;
}