直接上代码：HttpProxyServer
import io.netty.bootstrap.Bootstrap;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
/**
* HTTP/HTTPS代理服务器
* 三个角色：真实客户端，代理客户端，目标主机
*
* 数据流向：
*
* ------->> 代理客户端 --------->>
* 真实客户端 目标主机
* <<-------- 代理客户端 <<--------
*
*/
public class HttpProxyServer {
int port;
public HttpProxyServer(int port) {
this.port = port;
}
public static void main(String[] args) throws Exception {
new HttpProxyServer(8443).run();
}
public void run() throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup(1);
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(
new LoggingHandler(LogLevel.DEBUG),
new HttpProxyClientHandler());
}
})
.bind(port).sync().channel().closeFuture().sync();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
/**
* 代理客户端去请求目标主机
*/
private static class HttpProxyClientHandler extends ChannelInboundHandlerAdapter {
/*代理服务端channel*/
private Channel clientChannel;
/*目标主机channel*/
private Channel remoteChannel;
/*解析真实客户端的header*/
private HttpProxyClientHeader header = new HttpProxyClientHeader();
@Override
public void channelActive(ChannelHandlerContext ctx) {
clientChannel = ctx.channel();
}
/**
* 注意在真实客户端请求一个页面的时候，此方法不止调用一次，
* 这是TCP底层决定的（拆包/粘包）
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
if (header.isComplete()) {
/*如果在真实客户端的本次请求中已经解析过header了，
说明代理客户端已经在目标主机建立了连接，直接将真实客户端的数据写给目标主机*/
remoteChannel.writeAndFlush(msg); // just forward
return;
}
ByteBuf in = (ByteBuf) msg;
header.digest(in);/*解析目标主机信息*/
if (!header.isComplete()) {
/*如果解析过一次header之后未完成解析，直接返回，释放buf*/
in.release();
return;
}
// disable AutoRead until remote connection is ready
clientChannel.config().setAutoRead(false);
if (header.isHttps()) { // if https, respond 200 to create tunnel
clientChannel.writeAndFlush(Unpooled.wrappedBuffer("HTTP/1.1 200 Connection Establishedrnrn".getBytes()));
}
/**
*
* 下面为真实客户端第一次来到的时候，代理客户端向目标客户端发起连接
*/
Bootstrap b = new Bootstrap();
b.group(clientChannel.eventLoop()) // use the same EventLoop
.channel(clientChannel.getClass())
.handler(new HttpProxyRemoteHandler(clientChannel));
ChannelFuture f = b.connect(header.getHost(), header.getPort());
remoteChannel = f.channel();
f.addListener((ChannelFutureListener) future -> {
if (future.isSuccess()) {
// connection is ready, enable AutoRead
clientChannel.config().setAutoRead(true);
// forward header and remaining bytes
if (!header.isHttps()) {
//in读取一次缓冲区就没有了，header.byteBuf里面存了一份
remoteChannel.writeAndFlush(header.getByteBuf());
}
} else {
in.release();
clientChannel.close();
}
});
}
@Override
public void channelInactive(ChannelHandlerContext ctx) {
flushAndClose(remoteChannel);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) {
e.printStackTrace();
flushAndClose(clientChannel);
}
private void flushAndClose(Channel ch) {
if (ch != null && ch.isActive()) {
ch.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
}
}
}
/**
* 代理客户端请求目标主机处理器
*/
private static class HttpProxyRemoteHandler extends ChannelInboundHandlerAdapter {
private Channel clientChannel;
private Channel remoteChannel;
public HttpProxyRemoteHandler(Channel clientChannel) {
this.clientChannel = clientChannel;
}
@Override
public void channelActive(ChannelHandlerContext ctx) {
this.remoteChannel = ctx.channel();
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
clientChannel.writeAndFlush(msg); // just forward
}
@Override
public void channelInactive(ChannelHandlerContext ctx) {
flushAndClose(clientChannel);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable e) {
e.printStackTrace();
flushAndClose(remoteChannel);
}
private void flushAndClose(Channel ch) {
if (ch != null && ch.isActive()) {
ch.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
}
}
}
/**
* 真实主机的请求头信息
*/
private static class HttpProxyClientHeader {
private String method;//请求类型
private String host;//目标主机
private int port;//目标主机端口
private boolean https;//是否是https
private boolean complete;//是否完成解析
private ByteBuf byteBuf = Unpooled.buffer();
private final StringBuilder lineBuf = new StringBuilder();
public String getMethod() {
return method;
}
public String getHost() {
return host;
}
public int getPort() {
return port;
}
public boolean isHttps() {
return https;
}
public boolean isComplete() {
return complete;
}
public ByteBuf getByteBuf() {
return byteBuf;
}
/**
* 解析header信息，建立连接
HTTP 请求头如下
GET http://www.baidu.com/ HTTP/1.1
Host: www.baidu.com
User-Agent: curl/7.69.1
Accept: *//*
Proxy-Connection:Keep-Alive
HTTPS请求头如下
CONNECT www.baidu.com:443 HTTP/1.1
Host: www.baidu.com:443
User-Agent: curl/7.69.1
Proxy-Connection: Keep-Alive
* @param in
*/
public void digest(ByteBuf in) {
while (in.isReadable()) {
if (complete) {
throw new IllegalStateException("already complete");
}
String line = readLine(in);
System.out.println(line);
if (line == null) {
return;
}
if (method == null) {
method = line.split(" ")[0]; // the first word is http method name
https = method.equalsIgnoreCase("CONNECT"); // method CONNECT means https
}
if (line.startsWith("Host: ")) {
String[] arr = line.split(":");
host = arr[1].trim();
if (arr.length == 3) {
port = Integer.parseInt(arr[2]);
} else if (https) {
port = 443; // https
} else {
port = 80; // http
}
}
if (line.isEmpty()) {
if (host == null || port == 0) {
throw new IllegalStateException("cannot find header 'Host'");
}
byteBuf = byteBuf.asReadOnly();
complete = true;
break;
}
}
System.out.println(this);
System.out.println("--------------------------------------------------------------------------------");
}
private String readLine(ByteBuf in) {
while (in.isReadable()) {
byte b = in.readByte();
byteBuf.writeByte(b);
lineBuf.append((char) b);
int len = lineBuf.length();
if (len >= 2 && lineBuf.substring(len - 2).equals("rn")) {
String line = lineBuf.substring(0, len - 2);
lineBuf.delete(0, len);
return line;
}
}
return null;
}
@Override
public String toString() {
return "HttpProxyClientHeader{" +
"method='" + method + ''' +
", host='" + host + ''' +
", port=" + port +
", https=" + https +
", complete=" + complete +
'}';
}
}
public static String convertByteBufToString(ByteBuf buf) {
String str;
if (buf.hasArray()) { // 处理堆缓冲区
str = new String(buf.array(), buf.arrayOffset() + buf.readerIndex(), buf.readableBytes());
} else { // 处理直接缓冲区以及复合缓冲区
byte[] bytes = new byte[buf.readableBytes()];
buf.getBytes(buf.readerIndex(), bytes);
str = new String(bytes, 0, buf.readableBytes());
}
return str;
}
}
使用步骤
- 运行代理java HttpProxyServer即可在本机8443端口开启HTTP/HTTPS代理
- 测试HTTP请求 curl -v -x 127.0.0.1 8443 http://www.baidu.com
- 测试HTTPS请求curl -v -x 127.0.0.1 8443 https://www.baidu.com
HTTP和HTTPS的代理请求过程差异是比较大的
- 给代理服务器发请求头
> GET http://www.baidu.com/ HTTP/1.1
> Host: www.baidu.com
> User-Agent: curl/7.69.1
> Accept: */*
> Proxy-Connection: Keep-Alive
>
- 代理客户端发送HTTP请求给目标服务器（带上上面的header）
- 目标服务器返回给代理服务器，代理服务器直接转发给客户端，响应请求
< HTTP/1.1 200 OK
< Accept-Ranges: bytes
< Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform
< Connection: keep-alive
< Content-Length: 2381
< Content-Type: text/html
< Date: Sun, 19 Jul 2020 10:34:15 GMT
< Etag: "588604ec-94d"
< Last-Modified: Mon, 23 Jan 2017 13:28:12 GMT
< Pragma: no-cache
< Server: bfe/1.0.8.18
< Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/
<HTTPS代理请求的过程
- 给代理服务器发送以下请求头
> CONNECT www.baidu.com:443 HTTP/1.1
> Host: www.baidu.com:443
> User-Agent: curl/7.69.1
> Proxy-Connection: Keep-Alive
>
- 代理服务器响应，表示可以建立HTTPS通信隧道，连接建立阶段完成
< HTTP/1.1 200 Connection Established
<
- TLS进行认证...
- 认证通过，客户端才开始发送真正的网页请求头，下面就和HTTP代理请求一样了
> GET / HTTP/1.1
> Host: www.baidu.com
> User-Agent: curl/7.69.1
> Accept: */*
>
- 代理客户端发送HTTP请求给目标服务器（带上上面的header）
- 目标服务器返回给代理服务器，代理服务器直接转发给客户端，响应请求
< HTTP/1.1 200 OK
< Accept-Ranges: bytes
< Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform
< Connection: keep-alive
< Content-Length: 2443
< Content-Type: text/html
< Date: Sun, 19 Jul 2020 10:42:49 GMT
< Etag: "588603e7-98b"
< Last-Modified: Mon, 23 Jan 2017 13:23:51 GMT
< Pragma: no-cache
< Server: bfe/1.0.8.18
< Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/
<
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