.\"
.\" Copyright 2010 by Ben Greear <greearb@candelatech.com>
.\" SPDX-License-Identifier: MIT
.\"
.TH ARES_SET_SERVERS_CSV 3 "5 Dec 2023"
.SH NAME
ares_set_servers_csv, ares_set_servers_ports_csv, ares_get_servers_csv \- Set
or Get a list of DNS servers used for queries.
.SH SYNOPSIS
.nf
#include <ares.h>

int ares_set_servers_csv(ares_channel_t *\fIchannel\fP, const char* \fIservers\fP)

int ares_set_servers_ports_csv(ares_channel_t *\fIchannel\fP, const char* \fIservers\fP)

char *ares_get_servers_csv(ares_channel_t *\fIchannel\fP)
.fi
.SH DESCRIPTION
The \fBares_set_servers_csv\fP and \fBares_set_servers_ports_csv\fP functions set
the list of DNS servers that c-ares will query.  As of v1.22.0 this function can
be called on an active channel with running queries, previously it would return
ARES_ENOTIMP.

Though not recommended, passing NULL for servers will clear all configured
servers and make an inoperable channel, this may be advantageous for test
simulation but unlikely to be useful in production.

The \fBares_get_servers_csv\fP retrieves the list of servers in comma delimited
format.

The input and output format is a comma separated list of servers.  Each server
entry may contain these forms:

ip[:port][%iface]

The \fBip\fP may be encapsulated in square brackets ([ ]), and must be if
using ipv6 and also specifying a port.

The \fBport\fP is optional, and will default to 53 or the value specified in
\fBares_init_options(3)\fP.

The \fBiface\fP is specific to IPv6 link-local servers (fe80::/10) and should
not otherwise be used.

For example:

192.168.1.100,192.168.1.101:53,[1:2:3::4]:53,[fe80::1]:53%eth0
.PP
As of c-ares 1.24.0, \fBares_set_servers_csv\fP and \fBares_set_servers_ports_csv\fP
are identical.  Prior versions would simply omit ports in \fBares_set_servers_csv\fP
but due to the addition of link local interface support, this difference was
removed.

.SH RETURN VALUES
.B ares_set_servers_csv(3)
and
.B ares_set_servers_ports_csv(3)
may return any of the following values:
.TP 15
.B ARES_SUCCESS
The name servers configuration was successfully initialized.
.TP 15
.B ARES_ENOMEM
The process's available memory was exhausted.
.TP 15
.B ARES_ENODATA
The channel data identified by
.IR channel
was invalid.
.TP 15
.B ARES_ENOTINITIALIZED
c-ares library initialization not yet performed.
.PP
.B ares_get_servers_csv(3)
returns a string representing the servers configured which must be freed with
\fBares_free_string(3)\fP.  If it returns NULL, this is an out of memory condition.
.SH SEE ALSO
.BR ares_set_servers (3)
.SH AVAILABILITY
\fBares_set_servers_csv\fP was added in c-ares 1.7.2
\fBares_set_servers_ports_csv\fP was added in c-ares 1.11.0.
\fBares_get_servers_csv\fP was added in c-ares 1.24.0.
.SH AUTHOR
Ben Greear