Question

我正在编写一个LAN设备检测测试，该测试可以向多播组239.255.255.250发送请求并从同一LAN中的设备获得响应，

Wireshark告诉我，加入组（IGMPv2）很好，发送（UDP）很好，接收（UDP）很好，但是在我的代码中，当recvfrom（）时它始终返回-1，无论我尝试了什么，总是-1 ... 我曾经在Windows中尝试过3rd party应用，它可以正常发送和接收。

有人能给我一个线索吗？提前谢谢。

    socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP));
    setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
    setsockopt(socket, SOL_SOCKET, SO_IFDEVICE, &i8IfIndex, sizeof(i8IfIndex));
    setsockopt(socket, SOL_SOCKET, SO_BROADCAST, &u8On, sizeof(int));
    /*all aboved checked alright*/

    /*join to multicast group*/
    struct ip_mreq mreq;
    mreq.imr_multiaddr.s_addr = htonl(0xEFFFFFFA); /*239.255.255.250*/
    mreq.imr_interface.s_addr = INADDR_ANY; 
    setsockopt(socket, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)); 

    memset(&socket_address, 0, sizeof(socket_address));
    socket_address.sin_addr.s_addr = htonl(0xEFFFFFFA); 
    socket_address.sin_family = AF_INET;
    socket_address.sin_port = htons(37020);     
    //no help:bind(socket, (PSA) &socket_address, sizeof(socket_address));

    memset(&socket_address2, 0, sizeof(socket_address2));
    socket_address2.sin_addr.s_addr = INADDR_ANY; 
    socket_address2.sin_family = AF_INET;
    socket_address2.sin_port = 0;   

    /*send & recv*/
    int8 i8Result = 0xcc;
    char *inquryStr = "<?xml version=\"1.0\" encoding=\"utf-8\"?><Probe><Uuid>232B1234-FBcC-48B5-AC06-AE1F77051280</Uuid><Types>inquiry</Types></Probe>";
    if(i8Result = sendto(socket, inquryStr, strlen(inquryStr), 0, (PSA) &socket_address, sizeof(socket_address))) {
        //wireshark detected ,i8Result shows 0x7C sent
        if(i8Result = recvfrom(socket, g_HjtOsdComm.u8TRBuf, 1024, 0, (PSA) &socket_address2, sizeof(socket_address2))) {
            //wireshark detected ,but i8Result get-1
        }
    }

    /*leave group*/
    setsockopt(socket, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));

    fdClose(HjtOsdSocket);

为什么从多播组地址获取recvfrom（）时得到-1？

0 个答案: