[OT] Resolver API: problem with RES_USEVC

[Stephane Bortzmeyer]

[Sorry, I do not find a better mailing list for discussing the
resolver API, res_query and friends.]

I cannot perform TCP requests with res_query. My code includes:

  if (use_tcp)
    {
      _res.options &= RES_USEVC;
    }

and, even when use_tcp is true, requests are always made with UDP
(checked with tcpdump and with nameservers refusing TCP).

If I use another resolver option (for instance RES_NORECURSE), it is
taken into account. But RES_USEVC seems a noop?

Tested with NetBSD and Debian.