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ARES_SET_SERVERS(3) Library Functions Manual ARES_SET_SERVERS(3)


ares_set_servers, ares_set_servers_ports - Initialize name server configuration for an ares channel. (deprecated)


#include <ares.h>
int ares_set_servers(ares_channel_t *channel,

const struct ares_addr_node *servers) int ares_set_servers_ports(ares_channel_t *channel,
const struct ares_addr_port_node *servers)


The ares_set_servers(3) function initializes name servers configuration for the channel data identified by channel, from a servers pointer to a linked list of ares_addr_node structs holding name servers address data.

The name server linked list pointer argument may be the result of a previous call to ares_get_servers(3) or a linked list of ares_addr_node structs set up by other means.

The ares_set_servers_ports(3) function also allows the specification of UDP and TCP ports to be used for communication on a per-server basis. The provided linked list argument may be the result of a previous call to ares_get_servers_ports(3) or a linked list of ares_addr_port_node structs set up by other means.

This function replaces any potentially previously configured name servers with the ones given in the linked list. So, in order to configure a channel with more than one name server all the desired ones must be specified in a single list. Though not recommended, passing NULL 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 function does not take ownership of the linked list argument. The caller is responsible for freeing the linked list when no longer needed.

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

As of v1.22.0 this function can be called on an active channel with running queries, previously it would return ARES_ENOTIMP.


ares_set_servers(3) may return any of the following values:

The name servers configuration was successfully initialized.
The process's available memory was exhausted.
The channel data identified by channel was invalid.
c-ares library initialization not yet performed.


ares_set_servers_csv(3), ares_get_servers(3), ares_init_options(3), ares_dup(3)


Deprecated functions as of c-ares 1.24.0 due to inability to set all available server options. Use ares_set_servers_csv(3).


ares_set_servers(3) was added in c-ares 1.7.1; ares_set_servers_ports(3) was added in c-ares 1.11.0.

5 March 2010