NAME

       getdns_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 immediately, 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 ALSO

       libgetdns(3), getdns_context(3), getdns_general(3), getdns_hostname(3), getdns_service(3),