getdns_cancel_callback(3) getdns getdns_cancel_callback(3)NAMEgetdns_cancel_callback-- cancel an outstanding asyn getdns request
LIBRARY
DNS Resolver library (libgetdns, -lgetdns)
SYNOPSIS
#include <getdns.h>
getdns_return_t
getdns_cancel_callback (getdns_context_t context,
getdns_transaction_t *transaction_id)
DESCRIPTION
To cancel an outstanding callback, use getdns_cancel_callback. This
causes the API to call the callback with a callback_type of
GETDNS_CALLBACK_CANCEL if the callback for this transaction_id has not
already been called. The callback code for cancellation should clean up
any memory related to the identified call, such as to deallocate the
memory for the userarg. getdns_cancel_callback() may return immedi‐
ately, even before the callback finishes its work and returns.
context see getdns_context (3)
transaction_id populated by the API and used to identify the callback
(for example to getdns_cancel_callback), can be NULL, set to 0 if
the function fails
RETURN VALUES
Upon successful completion the functions return GETDNS_RETURN_GOOD ,
otherwise the following error values are returned:
GETDNS_RETURN_INVALID_PARAMETER if context == NULL
GETDNS_RETURN_UNKNOWN_TRANSACTION if the transaction_id that is unknown
or belongs to a callback that has already been called
EXAMPLES
TBD
FILES
/etc/hosts
/etc/resolv.conf
SEE ALSOlibgetdns(3), getdns_context(3), getdns_general(3), getdns_hostname(3),
getdns_service(3),
getdns 0.9.0 December 2015 getdns_cancel_callback(3)
