This commit fix the problems that arose when moving the dns_message_t
object from fetchctx_t to the query structure.
Since the lifetime of query objects are different than that of a
fetchctx and the dns_message_t object held by the query may be being
used by some external module, e.g. validator, even after the query
may have been destroyed, propery handling of the references to the
message were added in this commit to avoid accessing an already
destroyed object.
Specifically, in rctx_done(), a reference to the message is attached
at the beginning of the function and detached at the end, since a
possible call to fctx_cancelquery() would release the dns_message_t
object, and in the next lines of code a call to rctx_nextserver()
or rctx_chaseds() would require a valid pointer to the same object.
In valcreate() a new reference is attached to the message object,
this ensures that if the corresponding query object is destroyed
before the validator attempts to access it, no invalid pointer
access occurs.
In validated() we have to attach a new reference to the message,
since we destroy the validator object at the beginning of the
function, and we need access to the message in the next lines of
the same function.
rctx_nextserver() and rctx_chaseds() functions were adapted to
receive a new parameter of dns_message_t* type, this was so they
could receive a valid reference to a dns_message_t since using the
response context respctx_t to access the message through
rctx->query->rmessage could lead to an already released reference
due to the query being canceled.
(cherry picked from commit cde6227a68)
f557681472