java - 使用 Jpcap 创建反向代理

Question

我需要创建一个程序来接收 HTTP 请求并将这些请求转发到网络服务器。

Diagram http://img269.imageshack.us/img269/1862/h98trsly.jpg

我仅使用 Java 套接字就成功地实现了这一点，但客户需要在 Jpcap 中实现该程序。我想知道这是否可能以及我应该为这个项目阅读哪些文献。

这就是我现在通过将 Jpcap 教程中的片段拼接在一起而得到的:

import java.net.InetAddress;
import java.io.*;
import jpcap.*;
import jpcap.packet.*;


public class Router {
    public static void main(String args[]) {
        //Obtain the list of network interfaces
        NetworkInterface[] devices = JpcapCaptor.getDeviceList();

        //for each network interface
        for (int i = 0; i < devices.length; i++) {
            //print out its name and description
            System.out.println(i+": "+devices[i].name + "(" + devices[i].description+")");

            //print out its datalink name and description
            System.out.println(" datalink: "+devices[i].datalink_name + "(" + devices[i].datalink_description+")");

            //print out its MAC address
            System.out.print(" MAC address:");
            for (byte b : devices[i].mac_address)
                System.out.print(Integer.toHexString(b&0xff) + ":");
            System.out.println();

            //print out its IP address, subnet mask and broadcast address
            for (NetworkInterfaceAddress a : devices[i].addresses)
                System.out.println(" address:"+a.address + " " + a.subnet + " "+ a.broadcast);
        }

        int index = 1;  // set index of the interface that you want to open.

        //Open an interface with openDevice(NetworkInterface intrface, int snaplen, boolean promics, int to_ms)
        JpcapCaptor captor = null;
        try {
            captor = JpcapCaptor.openDevice(devices[index], 65535, false, 20);
            captor.setFilter("port 80 and host 192.168.56.1", true);
        } catch(java.io.IOException e) {
            System.err.println(e);
        }

        //call processPacket() to let Jpcap call PacketPrinter.receivePacket() for every packet capture.
        captor.loopPacket(-1,new PacketPrinter());

        captor.close();
    }
}

class PacketPrinter implements PacketReceiver {
    //this method is called every time Jpcap captures a packet
    public void receivePacket(Packet p) {
        JpcapSender sender = null;
        try {
            NetworkInterface[] devices = JpcapCaptor.getDeviceList();
            sender = JpcapSender.openDevice(devices[1]);
        } catch(IOException e) {
            System.err.println(e);
        }


        IPPacket packet = (IPPacket)p;

        try {
            // IP Address of machine sending HTTP requests (the client)
            // It's still on the same LAN as the servers for testing purposes.
            packet.dst_ip = InetAddress.getByName("192.168.56.2");
        } catch(java.net.UnknownHostException e) {
            System.err.println(e);
        }

        //create an Ethernet packet (frame)
        EthernetPacket ether=new EthernetPacket();
        //set frame type as IP
        ether.frametype=EthernetPacket.ETHERTYPE_IP;
        //set source and destination MAC addresses

        // MAC Address of machine running reverse proxy server
        ether.src_mac = new MacAddress("08:00:27:00:9C:80").getAddress();
        // MAC Address of machine running web server
        ether.dst_mac = new MacAddress("08:00:27:C7:D2:4C").getAddress();

        //set the datalink frame of the packet as ether
        packet.datalink=ether;

        //send the packet
        sender.sendPacket(packet);

        sender.close();

        //just print out a captured packet
        System.out.println(packet);
    }
}

如有任何帮助，我们将不胜感激。谢谢。

Answer 1

为什么？他的理由是什么？他真的愿意为你已经做过的同样事情付出十倍的代价吗？

您不需要 Jpcap 来实现 HTTP 代理。它可以完全在 java.net 或 java.nio 中完成。