.\"
.\" Copyright 1998 by the Massachusetts Institute of Technology.
.\" SPDX-License-Identifier: MIT
.\"
.TH ARES_CANCEL 3 "31 March 2004"
.SH NAME
ares_cancel \- Cancel a resolve
.SH SYNOPSIS
.nf
#include <ares.h>

void ares_cancel(ares_channel_t *\fIchannel\fP)
.fi
.SH DESCRIPTION
The \fBares_cancel(3)\fP function cancels all lookups/requests made on the the
name service channel identified by \fIchannel\fP.  \fBares_cancel(3)\fP
invokes the callbacks for each pending query on the channel, passing a status
of
.BR 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 \fInot\fP be cancelled by the
current invocation of \fBares_cancel(3)\fP.
.SH REENTRANCY
A callback invoked by
.BR 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
.BR ares_set_servers_csv (3)
and related functions.

.SH 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.

.SH SEE ALSO
.BR ares_init (3)
.BR ares_destroy (3)
.SH NOTES
This function was added in c-ares 1.2.0

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