Section: C Library Functions (3)
Updated: 5 March 2010
ares_get_servers, ares_get_servers_ports - Retrieve name servers from an initialized ares_channel
int ares_get_servers(ares_channel channel, struct ares_addr_node **servers)
int ares_get_servers_ports(ares_channel channel, struct ares_addr_port_node **servers)
function retrieves name servers configuration
channel data identified by
as a linked list of ares_addr_node structs storing a pointer to the first
node at the address specified by
The ares_get_servers_ports(3) 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 ares_set_servers(3) /
ares_set_servers_ports(3) 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 ares_free_data(3) , once the caller
does not need it any longer.
This function is capable of handling IPv4 and IPv6 name server
addresses simultaneously, rendering ares_save_options(3) with
optmask ARES_OPT_SERVERS functionally obsolete except for
IPv4-only name server usage.
This function may return any of the following values:
The name servers configuration was successfully retrieved
The memory was exhausted
The channel data identified by
was added in c-ares 1.7.1;
was added in c-ares 1.11.0.
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.
Copyright 1998 by the Massachusetts Institute of Technology.
Copyright (C) 2008-2010 by Daniel Stenberg