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我试图从数据包中获取源地址和目标地址。这就是我在读包:从ByteBuffer获取IP数据包数据
private void debugPacket(ByteBuffer packet)
{
int buffer = packet.get();
int version;
int headerlength;
version = buffer >> 4;
headerlength = buffer & 0x0F;
headerlength *= 4;
Log.d(TAG, "IP Version:"+version);
Log.d(TAG, "Header Length:"+headerlength);
String status = "";
status += "Header Length:"+headerlength;
buffer = packet.get(); //DSCP + EN
buffer = packet.getChar(); //Total Length
Log.d(TAG, "Total Length:"+buffer);
buffer = packet.getChar(); //Identification
buffer = packet.getChar(); //Flags + Fragment Offset
buffer = packet.get(); //Time to Live
buffer = packet.get(); //Protocol
Log.d(TAG, "Protocol:"+buffer);
status += " Protocol:"+buffer;
buffer = packet.getChar(); //Header checksum
String sourceIP = "";
buffer = packet.get(); //Source IP 1st Octet
sourceIP += ((int) buffer) & 0xFF;
sourceIP += ".";
buffer = packet.get(); //Source IP 2nd Octet
sourceIP += ((int) buffer) & 0xFF;
sourceIP += ".";
buffer = packet.get(); //Source IP 3rd Octet
sourceIP += ((int) buffer) & 0xFF;
sourceIP += ".";
buffer = packet.get(); //Source IP 4th Octet
sourceIP += ((int) buffer) & 0xFF;
Log.d(TAG, "Source IP:"+sourceIP);
status += " Source IP:"+sourceIP;
String destIP = "";
buffer = packet.get(); //Destination IP 1st Octet
destIP += ((int) buffer) & 0xFF;
destIP += ".";
buffer = packet.get(); //Destination IP 2nd Octet
destIP += ((int) buffer) & 0xFF;
destIP += ".";
buffer = packet.get(); //Destination IP 3rd Octet
destIP += ((int) buffer) & 0xFF;
destIP += ".";
buffer = packet.get(); //Destination IP 4th Octet
destIP += ((int) buffer) & 0xFF;
Log.d(TAG, "Destination IP:" + destIP);
status += " Destination IP:"+destIP;
try {
InetAddress addr = InetAddress.getByName(destIP);
String host = addr.getHostName();
Log.d(TAG, "Hostname:" + host);
}
catch (UnknownHostException e) {
Log.d(TAG,"Unknown host");
}
}
它工作正常,在最初的几个包,但随后有时我在packet.get()
线一赠一BufferUnderflowException。我怎样才能防止这个?
除非您知道完全使用缓冲区,否则您应该调用'packet.compact()',而不是'packet.clear()'。 – EJP