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import time
import socket
import threading
import os

# 组播组IP和端口
ANY = "0.0.0.0"
mcast_group_ip = '239.255.0.181'
mcast_group_port = 38090

def thread_recv(sock):
    while True:
        try:
            message, addr = sock.recvfrom(1024)
            print(f'{time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())}: Rece{addr}: {message.decode()}')
        except :
            print("while receive message error occur")


def multicast():
    # 建立发送socket，和正常UDP数据包没区别
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
    # 允许端口复用
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    # 绑定监听多播数据包的端口
    sock.bind((ANY, mcast_group_port))
    # 声明该socket为多播类型
    sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 255)
    # 加入多播组，组地址由第三个参数制定
    sock.setsockopt(
        socket.IPPROTO_IP,
        socket.IP_ADD_MEMBERSHIP,
        socket.inet_aton(mcast_group_ip) + socket.inet_aton(ANY)
    )
    # 设置是否收到自己发送的消息
    sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_LOOP, 0)
    threading.Thread(target=thread_recv, args=(sock,)).start()
    # 每十秒发送一遍消息
    while True:
        try:
            message = "python multicast msg!"
            # 发送写法和正常UDP数据包的还是完全没区别
            # 猜测只可能是网卡自己在识别到目的ip是组播地址后，自动将目的mac地址设为多播mac地址
            sock.sendto(message.encode(), (mcast_group_ip, mcast_group_port))
            print(f'{time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())}: msg send finish.')
            time.sleep(10)
        except KeyboardInterrupt:
            print('exit.')
            sock.close()
            os._exit(0)

            

if __name__ == "__main__":
    multicast()