The current code was inefficient when replies exceeded the initial
buffer size because the res_nsend() function switched to VC to get the
full reply, but that wouldn't fit our buffer before we enlarged it. This
commit tells res_nsend() to only use UDP or only use TCP, avoiding the
two unnecessary transactions in the lookup.
Since we don't get that second TCP reply now that would tell us the size
of the reply, we must allocate the largest possible buffer for a DNS
reply.
Change-Id: I3e3bfef633af4130a03afffd175e73d2e9fa9bf1
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
5ecdce0c35