如何在Contiki-NG中将单播数据包发送到邻居？

#include "contiki.h"
#include "net/ipv6/uip.h"
#include "net/ipv6/uip-udp-packet.h"

PROCESS(example_process, "Example Process");
AUTOSTART_PROCESSES(&example_process);

PROCESS_THREAD(example_process, ev, data)
{
  PROCESS_BEGIN();

  // 创建一个数据包
  static struct uip_udp_conn *udp_conn;
  udp_conn = udp_new(NULL, UIP_HTONS(0), NULL);
  if (udp_conn == NULL) {
    PROCESS_EXIT();
  }

  // 设置目标地址为邻居节点的地址
  uip_ipaddr_t dest_ipaddr;
  uip_ip6addr(&dest_ipaddr, 0xfe80, 0, 0, 0, 0x0201, 0x0201, 0x0201, 0x0201);
  udp_bind(udp_conn, UIP_HTONS(12345));
  uip_udp_packet_sendto(udp_conn, "Hello, neighbor!", sizeof("Hello, neighbor!"), &dest_ipaddr, UIP_HTONS(12345));

  PROCESS_END();
}