计算机网络 GBN实验.zip

package GoBackN_BJTU; import java.util.LinkedList; import java.util.Queue; import java.util.Timer; import java.util.TimerTask; import java.io.IOException; import java.net.*; public class RdtProto { private CommEndType commEndType; UdtChannel udtChannel; private Queue<byte[]> packetQueue = new LinkedList<byte[]>(); byte[] data = new byte[1440]; int base = 0, bases = 0; LinkedList<byte[]> Link = new LinkedList<byte[]>(); LinkedList<byte[]> LinkList = new LinkedList<byte[]>(); int nextseqnum = 0; int N = 4; int ack = 0; Timer timers = new Timer(); public RdtProto(CommEndType endType) { commEndType = endType; udtChannel = new UdtChannel(endType); udtChannel.setBandwidth(1); // 设置带宽为1Mbps udtChannel.setLossRatio(3); // 设置丢包率为3% udtChannel.setBRT(0.5); // 设置误比特率为万分之0.5 udtChannel.setPropDelay(5, 15); if (endType == CommEndType.COMM_SENDER) { Thread t = new Thread(new Processor()); t.start(); } } public void openChannel(String peerIpAddr) { udtChannel.setPeerAddress(peerIpAddr); udtChannel.open(); } public void closeChannel() { udtChannel.close(); } public void rdtSend(byte[] buffer, int len) { while (nextseqnum >= base + N) { try { Thread.sleep(10); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } byte[] a = new byte[len]; System.arraycopy(buffer,0,a,0,len); Link.add(a); data = Link.get(nextseqnum); udtChannel.udtSend(data, len); if (nextseqnum == base) { if (timers != null) timers.cancel(); timers = new Timer(); timers.schedule(new TTask(), 3000); } nextseqnum++; }; class Processor implements Runnable { @Override public void run() { while (true) { byte[] buffer = new byte[1440]; int leng = udtChannel.udtRecv(buffer); int ack = buffer[1] * 128 + buffer[0]; if (ack >= 0) { System.out.println("Have send a packet, id = " + ack + ", size = " + leng); base = ack + 1; if (base == nextseqnum) { timers.cancel(); } else { if (timers != null) timers.cancel(); timers = new Timer(); timers.schedule(new TTask(), 3000); } } else { ack = -ack; System.out.println("Have send a packet, id = " + ack + ", size = " + leng); } } } } class TTask extends TimerTask { public void run() { for (int i = base; i < nextseqnum; i++) { System.out.println("Resend a packet, id = " + i + ", size = " + Link.get(i).length); udtChannel.udtSend(Link.get(i), Link.get(i).length); } } } public int rdtRecv(byte[] buffer) { int len = udtChannel.udtRecv(buffer); int id = buffer[1] * 128 + buffer[0]; if (id == ack) { udtChannel.udtSend(buffer, len); byte[] a = new byte[len]; System.arraycopy(buffer,0,a,0,len); LinkList.add(a); ack++; } else{ udtChannel.udtSend(LinkList.get(ack - 1), LinkList.get(ack - 1).length); } return len; } }