/* Find a dhcp client node by ip address */
static struct dhcp_client_node* dhcp_client_find_by_ip(struct dhcp_server *dhcpserver, const ip4_addr_t *ip)
/* Find a dhcp client node by ip address */
static struct dhcp_client_node* dhcp_client_find_by_ip(struct dhcp_server *dhcpserver, const ip4_addr_t *ip)
{
    struct dhcp_client_node *node;
    for (node = dhcpserver->node_list; node != NULL; node = node->next)
    {
        if (ip4_addr_cmp(&node->ipaddr, ip))
        {
            return node;
        }
    }
    return NULL;
}