ares_set_local_ip4 - Man Page

#include <ares.h>

void ares_set_local_ip4(ares_channel_t *channel, unsigned int local_ip)

The ares_set_local_ip4 function sets the IP address for outbound requests.  The parameter local_ip is specified in host byte order.  This allows users to specify outbound interfaces when used on multi-homed systems.

ares_set_local_ip6(3)

This function was added in c-ares 1.7.4

ares_set_local_dev(3), ares_set_local_ip6(3).