Question

我有一个用C ++编写的服务器，它将使用此代码在网络上发送UDP广播（将代码减少到所需的最低数量，因此此处可能存在一两个语法错误）：

bool open_socket()
{
    sockfd_ = ::socket(AF_INET, SOCK_DGRAM | SOCK_NONBLOCK, 0);
    if (sockfd_ == -1)
    {
        logger_.error("Error creating socket (%d).", errno);
        return false;
    }

    int bc = broadcast ? 1 : 0;
    if (::setsockopt(sockfd_, SOL_SOCKET, SO_BROADCAST, (void *)&bc, sizeof(bc)) < 0)
    {
        logger_.error("Could not set broadcast option.");
        return false;
    }
    else
    {
        is_broadcast_ = broadcast;
    }
    return true;
}

int write_to_socket(const std::string &address, uint16_t port, uint8_t *buffer, int bufsize)
{
    struct hostent *h = ::gethostbyname(address.c_str());
    if (!h)
    {
        logger_.error("Could not resolve %s", address.c_str());
        return 0;
    }
    struct sockaddr_in remote_server;
    ::memset(&remote_server, 0, sizeof(remote_server));
    remote_server.sin_family = h->h_addrtype;
    remote_server.sin_port = htons(port);
    ::memcpy ( (char *) &remote_server.sin_addr.s_addr, h->h_addr_list[0], h->h_length);
    int res = ::sendto(sockfd_, buffer, bufsize, 0, (struct sockaddr *)&remote_server, sizeof(remote_server));
    if (res == -1)
    {
        logger_.error("Could not send to \"%s\" (%d)", address.c_str(), errno);
    }
    return res;
}

我将代码用于：

socket_.write("192.168.42.255", 18997, (uint8_t *)magic_packet_.c_str(), magic_packet_.size() + 1);

其中magic_packet_是值std::string的{{1}}；

使用此代码时，我可以看到该软件包正确出现在wirehark中。其他C ++程序也可以接收广播，因此我认为代码可以正常工作。

现在我有一个Android应用程序，它将接收所述广播数据包。事实是该软件包将不会显示，并且SPCCBC函数将无限期阻塞。这是代码（请注意，这是在不同于主线程的另一个线程上执行的！）：

receive

Android设备位于同一网络中，并且IP地址在此范围内（该设备具有package net.dev_shack.silentplayerpartyclient; import android.util.Log; import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.SocketException; import java.net.UnknownHostException; import java.util.concurrent.atomic.AtomicBoolean; public class UdpBroadcastListener extends Thread { private DatagramSocket socket; AtomicBoolean running = new AtomicBoolean(false); @Override public void run() { synchronized (this) { try { socket = new DatagramSocket(18997);//, InetAddress.getByName("0.0.0.0")); } catch (SocketException e) { Log.e("UdpBroadcastListener", "Could not create DatagramListenSocket"); notify(); e.printStackTrace(); return; } /*catch (UnknownHostException e) { notify(); e.printStackTrace(); return; }*/ running.set(true); notify(); } while (running.get()) { byte[] message = new byte[1500]; DatagramPacket packet = new DatagramPacket(message, message.length); try { socket.receive(packet); } catch (IOException e) { continue; } Log.i("UdpBroadcastReceiver", "Got: " + packet.toString()); } } public void stop_listener() { running.set(false); if (socket != null) { socket.close(); } } }，发送方具有192.168.42.116，网络是192.168.42.5，其网络掩码为{{1 }}。

java代码是否有问题？请注意注释为192.168.42.0的注释，无论是否使用，我都尝试过。

Android未收到UDP广播

0 个答案: