If the connection is closed while we're processing the request
we might access TCPDNS outerhandle which is already reset. Check
for this condition and call the callback with ISC_R_CANCELED result.
(cherry picked from commit c41ce8e0c9)
If the connection is closed while we're processing the request
we might access TCPDNS outerhandle which is already reset. Check
for this condition and call the callback with ISC_R_CANCELED result.
(cherry picked from commit c41ce8e0c9)