[英]How can I get the IP address from a multicast socket that is listening to broadcasts?
我的服务器创建了一个侦听UDP数据包的多播套接字。 它正在接收发送到网络广播地址的数据包,但我无法获得发送方的IP地址:
multisocket.getInetAddress().getHostAddress();
回报
"::"
(我猜这是因为空的getInetAddress)。
如何获取发送者的IP地址?
提示:我想这与套接字没有被绑定以及基本上整个广播有关,因为那些数据包不专门发送给我,而是发送给我,但发送给整个网络,但是它们不应该保留发送者的IP地址吗? 请赐教。
这是代码:
public void run() {
try {
Thread.sleep(5000);
Log.i("SERVERUDP", "Connecting...");
MulticastSocket multisocket = new MulticastSocket(SERVERPORT);
multisocket.setBroadcast(true);
Log.i("SERVERUDP","Server's IP is: " + multisocket.getLocalAddress().getHostAddress());
getLocalIpAddress();
while(true){
byte[] b = new byte[65535];
ByteArrayInputStream b_in = new ByteArrayInputStream(b);
DatagramPacket dgram = new DatagramPacket(b, b.length);
multisocket.receive(dgram); // blocks
ObjectInputStream o_in = new ObjectInputStream(b_in);
Object o = o_in.readObject();
dgram.setLength(b.length);
b_in.reset();
if(o.getClass().getSimpleName().equalsIgnoreCase("Request")){
Request request = (Request)o;
String inetaddress = multisocket.getInetAddress().getHostAddress();
Log.i("SERVERUDP-if", "Sending request to IP: " + inetaddress);
new Thread(new ClientTCP(inetaddress, createRequestFromBroadcast(request))).start();
}else if(o.getClass().getSimpleName().equalsIgnoreCase("String")){
Log.e("SERVERUDP-elseif-string", "WTF received a string: " + (String)o);
}else{
Log.e("SERVERUDP-else", "Unrecognized object of type: " + o.getClass().getSimpleName());
}
o_in.close();
//iteration done only once for testing!
break;
}
multisocket.close();
} catch (Exception e) {
Log.e("SERVERUDP", "Error", e);
}
}
您收到的每个数据包可能具有不同的源地址。 所以我不确定为什么您要尝试使用multisocket
来找出源地址。
我必须承认我还没有尝试过,但是dgram.getSocketAddress ()
是否在multisocket.receive
调用返回后为您提供所需的内容?
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