ares_get_servers

Name

ares_get_servers, ares_get_servers_ports - Retrieve name servers from an initialized ares_channel (deprecated)

Synopsis

#include <ares.h>
 
int ares_get_servers(const ares_channel_t *channel,
                     struct ares_addr_node **servers)
 
int ares_get_servers_ports(const ares_channel_t *channel,
                           struct ares_addr_port_node **servers)

Description

The ares_get_servers function retrieves name servers configuration from the channel data identified by channel, as a linked list of ares_addr_node structs storing a pointer to the first node at the address specified by servers.

The ares_get_servers_ports 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 / ares_set_servers_ports 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 , 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 with optmask ARES_OPT_SERVERS functionally obsolete except for IPv4-only name server usage.

Return values

This function may return any of the following values:

ARES_SUCCESS The name servers configuration was successfully retrieved

ARES_ENOMEM The memory was exhausted

ARES_ENODATA The channel data identified by channel was invalid.

See also

ares_set_servers(3), ares_init_options(3), ares_save_options

Availability

ares_get_servers was added in c-ares 1.7.1; ares_get_servers_ports was added in c-ares 1.11.0.

Notes

As of c-ares 1.24, these functions are deprecated due to their lack of ability to store the entire server configuration. Use ares_get_servers_csv.

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