ares_cancel3

Usage

#include <ares.h>
void ares_cancel(ares_channel_t *channel)

Overview

The ares_cancel(3) function cancels all lookups/requests made on the the name service channel identified by channel. ares_cancel(3) invokes the callbacks for each pending query on the channel, passing a status of ARES_ECANCELLED. These calls give the callbacks a chance to clean up any state which might have been stored in their arguments. If such a callback invocation adds a new request to the channel, that request will not be cancelled by the current invocation of ares_cancel(3).

Reentrancy

A callback invoked by ares_cancel(3) may call c-ares functions on the same channel. The channel lock is recursive, and each query is unlinked from the library's internal structures before its callback runs, so a reentrant call cannot encounter a query that is part-way through being torn down.

This includes starting new lookups, as described above, and reconfiguring the server list with ares_set_servers_csv(3) and related functions.

Notes

This function was added in c-ares 1.2.0

c-ares 1.6.0 and earlier pass a status of ARES_ETIMEOUT instead of ARES_ECANCELLED.