问如何使用LWIP和FreeRTOS使多播在stm32f7上工作

EN

int Bind(int sock, uint16_t port) {
    //struct sockaddr_in serv_addr;
    memset((char*) &serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(port);
    if (bind(sock, (struct sockaddr* ) &serv_addr,
            (socklen_t ) sizeof(serv_addr)) < 0)
        return -1;
    return 0;
}

int JoinGroup(int sock, const char *join_ip) {
    ip_mreq mreq;
    mreq.imr_multiaddr.s_addr = inet_addr(join_ip);
    ip4_addr_t localAddress = MX_LWIP_Get_IP();//Gets the local IP interface address
    mreq.imr_interface.s_addr = localAddress.addr;
    ;
    if (setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char*) &mreq,
            sizeof(mreq)) < 0)
        return -1;
    return 0;
}

int MulticastStart() {
    int sock = socket(AF_INET, SOCK_DGRAM, 0);
    int reuse = 1;
/* Dont know if SO_REUSEADDER is nenecessary doesn't seem to make a difference*/
    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char*) &reuse,
            sizeof(reuse)) < 0) {
        perror("Setting SO_REUSEADDR error");
    } else
        printf("Setting SO_REUSEADDR...OK.\n");

    Bind(sock, 60003);
    JoinGroup(sock, "239.192.0.4");
    return sock;
    // Now you can do recvfrom() in RTOS task.
}

void StartLWIPReceiverTask(void const *argument) {
    osSemaphoreWait(LWIPsemaphore, osWaitForever); // Wait indefinitely for a free semaphore
    int sock = MulticastStart();
    char test[256];
    memset(&test, 0, sizeof(test));
    int addrlen = sizeof(serv_addr);
    /* Infinite loop */
    for (;;) {
        int nbytes = recvfrom(sock, test, 255, 0,
                (struct sockaddr* ) &serv_addr, (socklen_t* )&addrlen);
        if (nbytes > 0) {
            HAL_UART_Transmit(&huart3, (uint8_t*) test, (uint16_t) strlen(test),
                    1000);
            memset(&test, 0, sizeof(test));
        }
        osDelay(1);
    }
}

#define LWIP_IGMP 1

#define LWIP_IPV4 1

#define LWIP_SOCKET 1

#define LWIP_UDP 1

#define SO_REUSE 1 

netif->flags |= NETIF_FLAG_IGMP; //in low_level_init function

macinit.PromiscuousMode = ETH_PROMISCUOUS_MODE_ENABLE;
macinit.MulticastFramesFilter = ETH_MULTICASTFRAMESFILTER_NONE;