Name

ares_cancel - Cancel a resolve

Synopsis

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

Description

The ares_cancel function cancels all lookups/requests made on the the name service channel identified by channel. ares_cancel 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.

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.

Availability

The reentrancy guarantee described above applies as of c-ares version 1.35.0, and c-ares version 1.34.9 on the 1.34 branch.

See also

ares_init(3) ares_destroy(3)

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.

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