.\"
.\" Copyright 1998 by the Massachusetts Institute of Technology.
.\" Copyright (C) 2008-2010 by Daniel Stenberg
.\"
.\" Permission to use, copy, modify, and distribute this
.\" software and its documentation for any purpose and without
.\" fee is hereby granted, provided that the above copyright
.\" notice appear in all copies and that both that copyright
.\" notice and this permission notice appear in supporting
.\" documentation, and that the name of M.I.T. not be used in
.\" advertising or publicity pertaining to distribution of the
.\" software without specific, written prior permission.
.\" M.I.T. makes no representations about the suitability of
.\" this software for any purpose.  It is provided "as is"
.\" without express or implied warranty.
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.\" SPDX-License-Identifier: MIT
.\"
.TH ARES_GET_SERVERS 3 "5 March 2010"
.SH NAME
ares_get_servers, ares_get_servers_ports \- Retrieve name servers from an initialized ares_channel
.SH SYNOPSIS
.nf
#include <ares.h>

int ares_get_servers(ares_channel \fIchannel\fP,
                     struct ares_addr_node **\fIservers\fP)

int ares_get_servers_ports(ares_channel \fIchannel\fP,
                           struct ares_addr_port_node **\fIservers\fP)
.fi
.SH DESCRIPTION
The \fBares_get_servers(3)\fP function retrieves name servers configuration
from the
channel data identified by
.IR channel ,
as a linked list of ares_addr_node structs storing a pointer to the first
node at the address specified by
.IR servers .

The \fBares_get_servers_ports(3)\fP function also retrieves any per-server
port information that may have been previously configured, returning a linked
list of ares_addr_port structures.

Function caller may traverse the returned name server linked list, or may use
it directly as suitable input for the \fBares_set_servers(3)\fP /
\fBares_set_servers_ports(3)\fP functions, but
shall not shrink or extend the list on its own.

Each node of the name server linked list is stored in memory dynamically
allocated and managed by c-ares. It is the caller's responsibility to free
the resulting linked list, using \fBares_free_data(3)\fP , once the caller
does not need it any longer.

This function is capable of handling IPv4 and IPv6 name server
addresses simultaneously, rendering \fBares_save_options(3)\fP with
optmask \fBARES_OPT_SERVERS\fP functionally obsolete except for
IPv4-only name server usage.

.SH RETURN VALUES
This function may return any of the following values:
.TP 15
.B ARES_SUCCESS
The name servers configuration was successfully retrieved
.TP 15
.B ARES_ENOMEM
The memory was exhausted
.TP 15
.B ARES_ENODATA
The channel data identified by
.IR channel
was invalid.
.SH SEE ALSO
.BR ares_set_servers (3),
.BR ares_init_options (3),
.BR ares_save_options(3)
.SH AVAILABILITY
\fBares_get_servers(3)\fP was added in c-ares 1.7.1;
\fBares_get_servers_ports(3)\fP was added in c-ares 1.11.0.
.SH AUTHOR
Implementation of this function and associated library internals are based
on code, comments and feedback provided in November and December of 2008 by
Daniel Stenberg, Gregor Jasny, Phil Blundell and Yang Tse, December 2009
by Cedric Bail, February 2010 by Jakub Hrozek. On March 2010 Yang Tse
shuffled all the bits and this function popped out.
.br
Copyright 1998 by the Massachusetts Institute of Technology.
.br
Copyright (C) 2008-2010 by Daniel Stenberg