path: root/ares_get_servers.3
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authorYang Tse <>2010-03-05 20:01:47 (GMT)
committerYang Tse <>2010-03-05 20:01:47 (GMT)
commit8fe746fcf2d5b54242a828840ccac630f7a4075a (patch)
tree0ae06cf5be407aea2129f1b47c59c1f433d425db /ares_get_servers.3
parent249fc61b8cf1848c4444bef60fc6248930bd0d20 (diff)
Added IPv6 name servers support
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+.\" $Id$
+.\" 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.
+.TH ARES_GET_SERVERS 3 "5 March 2010"
+ares_get_servers \- Retrieve name servers from an initialized ares_channel
+.B #include <ares.h>
+.B int ares_get_servers(ares_channel \fIchannel\fP, struct ares_addr_node **\fIservers\fP)
+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 .
+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 function, 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.
+.B ares_get_servers(3)
+may return any of the following values:
+.TP 15
+The name servers configuration was successfuly retrieved
+.TP 15
+The memory was exhausted
+.TP 15
+The channel data identified by
+.IR channel
+was invalid.
+.BR ares_set_servers (3),
+.BR ares_init_options (3),
+.BR ares_save_options(3)
+ares_get_servers(3) was added in c-ares 1.7.1
+Implementation of this function and associated library internals are based
+on code, comments and feedback provided 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.
+Copyright 1998 by the Massachusetts Institute of Technology.
+Copyright (C) 2008-2010 by Daniel Stenberg