UDP 广播

代码1：

int set = 1;
	//接收数据
	if((sockListen = socket(AF_INET, SOCK_DGRAM, 0)) == -1){
		printf("socket fail\n");
		return ;
	}
	setsockopt(sockListen, SOL_SOCKET, SO_REUSEADDR, &set, sizeof(int));
	memset(&recvAddr, 0, sizeof(struct sockaddr_in));
	recvAddr.sin_family = AF_INET;
	recvAddr.sin_port = htons(DRIVER_PORT_NUM);
	recvAddr.sin_addr.s_addr = INADDR_ANY;
	// 必须绑定，否则无法监听
	if(bind(sockListen, (struct sockaddr *)&recvAddr, sizeof(struct sockaddr)) == -1){
		printf("bind fail\n");
		return ;
	}
    recvbytes = recvfrom(sockListen, recvbuf, 1024, 0,
						(struct sockaddr *)&recvAddr, &addrLen)) != -1

代码2：

	int brdcFd;
	int optval = 1;//这个值一定要设置，否则可能导致sendto()失败
	struct sockaddr_in theirAddr;
	int sendBytes;


	if((brdcFd = socket(PF_INET, SOCK_DGRAM, 0)) == -1){
		printf("socket fail\n");
		return ;
	}
	setsockopt(brdcFd, SOL_SOCKET, SO_BROADCAST | SO_REUSEADDR, &optval, sizeof(int));
	memset(&theirAddr, 0, sizeof(struct sockaddr_in));
	theirAddr.sin_family = AF_INET;
	theirAddr.sin_addr.s_addr = inet_addr("255.255.255.255");
	theirAddr.sin_port = htons(MODEL_PORT_NUM);
	if((sendBytes = sendto(brdcFd, buff2, len, 0,
					(struct sockaddr *)&theirAddr, sizeof(struct sockaddr))) == -1){
		printf("sendto model fail, errno=%d\n", errno);
		return ;
	}
	printf("send meg success...\n");