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简介:本文重点在代理网关自身的设计与实现,而非代理资源的治理与保护。
作者 | 新然
起源 | 阿里技术公众号
一 问题背景
- 平台端购买一批裸代理,来做广告异地展示审核。从内部购买的代理,应用形式为:
- 通过给定的 HTTP 的 API 提取代理 IP:PORT,返回的后果会给出代理的无效时长 3~5 分钟,以及代理所属地区;
从提取的代理中,选取指定地区,增加认证信息,申请获取后果;
本文设计实现一个通过的代理网关:
- 治理保护代理资源,并做代理的认证鉴权;
- 对外裸露对立的代理入口,而非动态变化的代理 IP:PORT;
- 流量过滤及限流,比方:动态资源不走代理;
本文重点在代理网关自身的设计与实现,而非代理资源的治理与保护。
注:本文蕴含大量可执行的 JAVA 代码以解释代理相干的原理
二 技术路线
本文的技术路线。在实现代理网关之前,首先介绍下代理相干的原理及如何实现
- 通明代理;
- 非通明代理;
- 通明的上游代理;
- 非通明的上游代理;
最初,本文要构建代理网关,实质上就是一个非通明的上游代理,并给出具体的设计与实现。
1 通明代理
通明代理是代理网关的根底,本文采纳 JAVA 原生的 NIO 进行具体介绍。在实现代理网关时,理论应用的为 NETTY 框架。原生 NIO 的实现对了解 NETTY 的实现有帮忙。
通明代理设计三个交互方,客户端、代理服务、服务端,其原理是:
- 代理服务在收到连贯申请时,断定:如果是 CONNECT 申请,须要回应代理连贯胜利音讯到客户端;
- CONNECT 申请回应完结后,代理服务须要连贯到 CONNECT 指定的近程服务器,而后间接转发客户端和近程服务通信;
- 代理服务在收到非 CONNECT 申请时,须要解析出申请的近程服务器,而后间接转发客户端和近程服务通信;
须要留神的点是:
- 通常 HTTPS 申请,在通过代理前,会发送 CONNECT 申请;连贯胜利后,会在信道上进行加密通信的握手协定;因而连贯近程的机会是在 CONNECT 申请收到时,因为尔后是加密数据;
- 通明代理在收到 CONNECT 申请时,不须要传递到近程服务(近程服务不辨认此申请);
- 通明代理在收到非 CONNECT 申请时,要无条件转发;
残缺的通明代理的实现不到约 300 行代码,残缺摘录如下:
@Slf4j
public class SimpleTransProxy {public static void main(String[] args) throws IOException {
int port = 8006;
ServerSocketChannel localServer = ServerSocketChannel.open();
localServer.bind(new InetSocketAddress(port));
Reactor reactor = new Reactor();
// REACTOR 线程
GlobalThreadPool.REACTOR_EXECUTOR.submit(reactor::run);
// WORKER 单线程调试
while (localServer.isOpen()) {
// 此处阻塞期待连贯
SocketChannel remoteClient = localServer.accept();
// 工作线程
GlobalThreadPool.WORK_EXECUTOR.submit(new Runnable() {
@SneakyThrows
@Override
public void run() {
// 代理到近程
SocketChannel remoteServer = new ProxyHandler().proxy(remoteClient);
// 通明传输
reactor.pipe(remoteClient, remoteServer)
.pipe(remoteServer, remoteClient);
}
});
}
}
}
@Data
class ProxyHandler {
private String method;
private String host;
private int port;
private SocketChannel remoteServer;
private SocketChannel remoteClient;
/**
* 原始信息
*/
private List<ByteBuffer> buffers = new ArrayList<>();
private StringBuilder stringBuilder = new StringBuilder();
/**
* 连贯到近程
* @param remoteClient
* @return
* @throws IOException
*/
public SocketChannel proxy(SocketChannel remoteClient) throws IOException {
this.remoteClient = remoteClient;
connect();
return this.remoteServer;
}
public void connect() throws IOException {
// 解析 METHOD, HOST 和 PORT
beforeConnected();
// 链接 REMOTE SERVER
createRemoteServer();
// CONNECT 申请回应,其余申请 WRITE THROUGH
afterConnected();}
protected void beforeConnected() throws IOException {
// 读取 HEADER
readAllHeader();
// 解析 HOST 和 PORT
parseRemoteHostAndPort();}
/**
* 创立近程连贯
* @throws IOException
*/
protected void createRemoteServer() throws IOException {remoteServer = SocketChannel.open(new InetSocketAddress(host, port));
}
/**
* 连贯建设后预处理
* @throws IOException
*/
protected void afterConnected() throws IOException {
// 当 CONNECT 申请时,默认写入 200 到 CLIENT
if ("CONNECT".equalsIgnoreCase(method)) {
// CONNECT 默认为 443 端口,依据 HOST 再解析
remoteClient.write(ByteBuffer.wrap("HTTP/1.0 200 Connection Established\r\nProxy-agent: nginx\r\n\r\n".getBytes()));
} else {writeThrouth();
}
}
protected void writeThrouth() {
buffers.forEach(byteBuffer -> {
try {remoteServer.write(byteBuffer);
} catch (IOException e) {e.printStackTrace();
}
});
}
/**
* 读取申请内容
* @throws IOException
*/
protected void readAllHeader() throws IOException {while (true) {ByteBuffer clientBuffer = newByteBuffer();
int read = remoteClient.read(clientBuffer);
clientBuffer.flip();
appendClientBuffer(clientBuffer);
if (read < clientBuffer.capacity()) {break;}
}
}
/**
* 解析出 HOST 和 PROT
* @throws IOException
*/
protected void parseRemoteHostAndPort() throws IOException {
// 读取第一批,获取到 METHOD
method = parseRequestMethod(stringBuilder.toString());
// 默认为 80 端口,依据 HOST 再解析
port = 80;
if ("CONNECT".equalsIgnoreCase(method)) {port = 443;}
this.host = parseHost(stringBuilder.toString());
URI remoteServerURI = URI.create(host);
host = remoteServerURI.getHost();
if (remoteServerURI.getPort() > 0) {port = remoteServerURI.getPort();
}
}
protected void appendClientBuffer(ByteBuffer clientBuffer) {buffers.add(clientBuffer);
stringBuilder.append(new String(clientBuffer.array(), clientBuffer.position(), clientBuffer.limit()));
}
protected static ByteBuffer newByteBuffer() {
// buffer 必须大于 7,保障能读到 method
return ByteBuffer.allocate(128);
}
private static String parseRequestMethod(String rawContent) {
// create uri
return rawContent.split("\r\n")[0].split(" ")[0];
}
private static String parseHost(String rawContent) {String[] headers = rawContent.split("\r\n");
String host = "host:";
for (String header : headers) {if (header.length() > host.length()) {String key = header.substring(0, host.length());
String value = header.substring(host.length()).trim();
if (host.equalsIgnoreCase(key)) {if (!value.startsWith("http://") && !value.startsWith("https://")) {value = "http://" + value;}
return value;
}
}
}
return "";
}
}
@Slf4j
@Data
class Reactor {
private Selector selector;
private volatile boolean finish = false;
@SneakyThrows
public Reactor() {selector = Selector.open();
}
@SneakyThrows
public Reactor pipe(SocketChannel from, SocketChannel to) {from.configureBlocking(false);
from.register(selector, SelectionKey.OP_READ, new SocketPipe(this, from, to));
return this;
}
@SneakyThrows
public void run() {
try {while (!finish) {if (selector.selectNow() > 0) {Iterator<SelectionKey> it = selector.selectedKeys().iterator();
while (it.hasNext()) {SelectionKey selectionKey = it.next();
if (selectionKey.isValid() && selectionKey.isReadable()) {((SocketPipe) selectionKey.attachment()).pipe();}
it.remove();}
}
}
} finally {close();
}
}
@SneakyThrows
public synchronized void close() {if (finish) {return;}
finish = true;
if (!selector.isOpen()) {return;}
for (SelectionKey key : selector.keys()) {closeChannel(key.channel());
key.cancel();}
if (selector != null) {selector.close();
}
}
public void cancel(SelectableChannel channel) {SelectionKey key = channel.keyFor(selector);
if (Objects.isNull(key)) {return;}
key.cancel();}
@SneakyThrows
public void closeChannel(Channel channel) {SocketChannel socketChannel = (SocketChannel)channel;
if (socketChannel.isConnected() && socketChannel.isOpen()) {socketChannel.shutdownOutput();
socketChannel.shutdownInput();}
socketChannel.close();}
}
@Data
@AllArgsConstructor
class SocketPipe {
private Reactor reactor;
private SocketChannel from;
private SocketChannel to;
@SneakyThrows
public void pipe() {
// 勾销监听
clearInterestOps();
GlobalThreadPool.PIPE_EXECUTOR.submit(new Runnable() {
@SneakyThrows
@Override
public void run() {
int totalBytesRead = 0;
ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
while (valid(from) && valid(to)) {byteBuffer.clear();
int bytesRead = from.read(byteBuffer);
totalBytesRead = totalBytesRead + bytesRead;
byteBuffer.flip();
to.write(byteBuffer);
if (bytesRead < byteBuffer.capacity()) {break;}
}
if (totalBytesRead < 0) {reactor.closeChannel(from);
reactor.cancel(from);
} else {
// 重置监听
resetInterestOps();}
}
});
}
protected void clearInterestOps() {from.keyFor(reactor.getSelector()).interestOps(0);
to.keyFor(reactor.getSelector()).interestOps(0);
}
protected void resetInterestOps() {from.keyFor(reactor.getSelector()).interestOps(SelectionKey.OP_READ);
to.keyFor(reactor.getSelector()).interestOps(SelectionKey.OP_READ);
}
private boolean valid(SocketChannel channel) {return channel.isConnected() && channel.isRegistered() && channel.isOpen();
}
}
以上,借鉴 NETTY:
- 首先初始化 REACTOR 线程,而后开启代理监听,当收到代理申请时解决。
- 代理服务在收到代理申请时,首先做代理的预处理,而后又 SocketPipe 做客户端和近程服务端双向转发。
- 代理预处理,首先读取第一个 HTTP 申请,解析出 METHOD, HOST, PORT。
- 如果是 CONNECT 申请,发送回应 Connection Established,而后连贯近程服务端,并返回 SocketChannel
- 如果是非 CONNECT 申请,连贯近程服务端,写入原始申请,并返回 SocketChannel
- SocketPipe 在客户端和近程服务端,做双向的转发;其自身是将客户端和服务端的 SocketChannel 注册到 REACTOR
- REACTOR 在监测到 READABLE 的 CHANNEL,派发给 SocketPipe 做双向转发。
测试
代理的测试比较简单,指向代码后,代理服务监听 8006 端口,此时:
curl -x ‘localhost:8006’ http://httpbin.org/get 测试 HTTP 申请
curl -x ‘localhost:8006’ https://httpbin.org/get 测试 HTTPS 申请
留神,此时代理服务代理了 HTTPS 申请,然而并不需要 - k 选项,批示非平安的代理。因为代理服务自身并没有作为一个中间人,并没有解析出客户端和近程服务端通信的内容。在非通明代理时,须要解决这个问题。
2 非通明代理
非通明代理,须要解析出客户端和近程服务端传输的内容,并做相应的解决。
当传输为 HTTP 协定时,SocketPipe 传输的数据即为明文的数据,能够拦挡后间接做解决。
当传输为 HTTPS 协定时,SocketPipe 传输的无效数据为加密数据,并不能通明解决。
另外,无论是传输的 HTTP 协定还是 HTTPS 协定,SocketPipe 读到的都为非残缺的数据,须要做聚批的解决。
- SocketPipe 聚批问题,能够采纳相似 BufferedInputStream 对 InputStream 做 Decorate 的模式来实现,绝对比较简单;具体能够参考 NETTY 的 HttpObjectAggregator;
- HTTPS 原始申请和后果数据的加密和解密的解决,须要实现的 NIO 的 SOCKET CHANNEL;
SslSocketChannel 封装原理
思考到目前 JDK 自带的 NIO 的 SocketChannel 并不反对 SSL;已有的 SSLSocket 是阻塞的 OIO。如图:
能够看出
- 每次入站数据和出站数据都须要 SSL SESSION 做握手;
- 入站数据做解密,出站数据做加密;
- 握手,数据加密和数据解密是对立的一套状态机;
以下,代码实现 SslSocketChannel
public class SslSocketChannel {
/**
* 握手加解密须要的四个存储
*/
protected ByteBuffer myAppData; // 明文
protected ByteBuffer myNetData; // 密文
protected ByteBuffer peerAppData; // 明文
protected ByteBuffer peerNetData; // 密文
/**
* 握手加解密过程中用到的异步执行器
*/
protected ExecutorService executor = Executors.newSingleThreadExecutor();
/**
* 原 NIO 的 CHANNEL
*/
protected SocketChannel socketChannel;
/**
* SSL 引擎
*/
protected SSLEngine engine;
public SslSocketChannel(SSLContext context, SocketChannel socketChannel, boolean clientMode) throws Exception {
// 原始的 NIO SOCKET
this.socketChannel = socketChannel;
// 初始化 BUFFER
SSLSession dummySession = context.createSSLEngine().getSession();
myAppData = ByteBuffer.allocate(dummySession.getApplicationBufferSize());
myNetData = ByteBuffer.allocate(dummySession.getPacketBufferSize());
peerAppData = ByteBuffer.allocate(dummySession.getApplicationBufferSize());
peerNetData = ByteBuffer.allocate(dummySession.getPacketBufferSize());
dummySession.invalidate();
engine = context.createSSLEngine();
engine.setUseClientMode(clientMode);
engine.beginHandshake();}
/**
* 参考 https://docs.oracle.com/javase/8/docs/technotes/guides/security/jsse/JSSERefGuide.html
* 实现的 SSL 的握手协定
* @return
* @throws IOException
*/
protected boolean doHandshake() throws IOException {
SSLEngineResult result;
HandshakeStatus handshakeStatus;
int appBufferSize = engine.getSession().getApplicationBufferSize();
ByteBuffer myAppData = ByteBuffer.allocate(appBufferSize);
ByteBuffer peerAppData = ByteBuffer.allocate(appBufferSize);
myNetData.clear();
peerNetData.clear();
handshakeStatus = engine.getHandshakeStatus();
while (handshakeStatus != HandshakeStatus.FINISHED && handshakeStatus != HandshakeStatus.NOT_HANDSHAKING) {switch (handshakeStatus) {
case NEED_UNWRAP:
if (socketChannel.read(peerNetData) < 0) {if (engine.isInboundDone() && engine.isOutboundDone()) {return false;}
try {engine.closeInbound();
} catch (SSLException e) {log.debug("收到 END OF STREAM,敞开连贯.", e);
}
engine.closeOutbound();
handshakeStatus = engine.getHandshakeStatus();
break;
}
peerNetData.flip();
try {result = engine.unwrap(peerNetData, peerAppData);
peerNetData.compact();
handshakeStatus = result.getHandshakeStatus();} catch (SSLException sslException) {engine.closeOutbound();
handshakeStatus = engine.getHandshakeStatus();
break;
}
switch (result.getStatus()) {
case OK:
break;
case BUFFER_OVERFLOW:
peerAppData = enlargeApplicationBuffer(engine, peerAppData);
break;
case BUFFER_UNDERFLOW:
peerNetData = handleBufferUnderflow(engine, peerNetData);
break;
case CLOSED:
if (engine.isOutboundDone()) {return false;} else {engine.closeOutbound();
handshakeStatus = engine.getHandshakeStatus();
break;
}
default:
throw new IllegalStateException("有效的握手状态:" + result.getStatus());
}
break;
case NEED_WRAP:
myNetData.clear();
try {result = engine.wrap(myAppData, myNetData);
handshakeStatus = result.getHandshakeStatus();} catch (SSLException sslException) {engine.closeOutbound();
handshakeStatus = engine.getHandshakeStatus();
break;
}
switch (result.getStatus()) {
case OK :
myNetData.flip();
while (myNetData.hasRemaining()) {socketChannel.write(myNetData);
}
break;
case BUFFER_OVERFLOW:
myNetData = enlargePacketBuffer(engine, myNetData);
break;
case BUFFER_UNDERFLOW:
throw new SSLException("加密后音讯内容为空,报错");
case CLOSED:
try {myNetData.flip();
while (myNetData.hasRemaining()) {socketChannel.write(myNetData);
}
peerNetData.clear();} catch (Exception e) {handshakeStatus = engine.getHandshakeStatus();
}
break;
default:
throw new IllegalStateException("有效的握手状态:" + result.getStatus());
}
break;
case NEED_TASK:
Runnable task;
while ((task = engine.getDelegatedTask()) != null) {executor.execute(task);
}
handshakeStatus = engine.getHandshakeStatus();
break;
case FINISHED:
break;
case NOT_HANDSHAKING:
break;
default:
throw new IllegalStateException("有效的握手状态:" + handshakeStatus);
}
}
return true;
}
/**
* 参考 https://docs.oracle.com/javase/8/docs/technotes/guides/security/jsse/JSSERefGuide.html
* 实现的 SSL 的传输读取协定
* @param consumer
* @throws IOException
*/
public void read(Consumer<ByteBuffer> consumer) throws IOException {
// BUFFER 初始化
peerNetData.clear();
int bytesRead = socketChannel.read(peerNetData);
if (bytesRead > 0) {peerNetData.flip();
while (peerNetData.hasRemaining()) {peerAppData.clear();
SSLEngineResult result = engine.unwrap(peerNetData, peerAppData);
switch (result.getStatus()) {
case OK:
log.debug("收到近程的返回后果音讯为:" + new String(peerAppData.array(), 0, peerAppData.position()));
consumer.accept(peerAppData);
peerAppData.flip();
break;
case BUFFER_OVERFLOW:
peerAppData = enlargeApplicationBuffer(engine, peerAppData);
break;
case BUFFER_UNDERFLOW:
peerNetData = handleBufferUnderflow(engine, peerNetData);
break;
case CLOSED:
log.debug("收到近程连贯敞开音讯.");
closeConnection();
return;
default:
throw new IllegalStateException("有效的握手状态:" + result.getStatus());
}
}
} else if (bytesRead < 0) {log.debug("收到 END OF STREAM,敞开连贯.");
handleEndOfStream();}
}
public void write(String message) throws IOException {write(ByteBuffer.wrap(message.getBytes()));
}
/**
* 参考 https://docs.oracle.com/javase/8/docs/technotes/guides/security/jsse/JSSERefGuide.html
* 实现的 SSL 的传输写入协定
* @param message
* @throws IOException
*/
public void write(ByteBuffer message) throws IOException {myAppData.clear();
myAppData.put(message);
myAppData.flip();
while (myAppData.hasRemaining()) {myNetData.clear();
SSLEngineResult result = engine.wrap(myAppData, myNetData);
switch (result.getStatus()) {
case OK:
myNetData.flip();
while (myNetData.hasRemaining()) {socketChannel.write(myNetData);
}
log.debug("写入近程的音讯为: {}", message);
break;
case BUFFER_OVERFLOW:
myNetData = enlargePacketBuffer(engine, myNetData);
break;
case BUFFER_UNDERFLOW:
throw new SSLException("加密后音讯内容为空.");
case CLOSED:
closeConnection();
return;
default:
throw new IllegalStateException("有效的握手状态:" + result.getStatus());
}
}
}
/**
* 敞开连贯
* @throws IOException
*/
public void closeConnection() throws IOException {engine.closeOutbound();
doHandshake();
socketChannel.close();
executor.shutdown();}
/**
* END OF STREAM(-1)默认是敞开连贯
* @throws IOException
*/
protected void handleEndOfStream() throws IOException {
try {engine.closeInbound();
} catch (Exception e) {log.error("END OF STREAM 敞开失败.", e);
}
closeConnection();}
}
以上:
- 基于 SSL 协定,实现对立的握手动作;
- 别离实现读取的解密,和写入的加密办法;
- 将 SslSocketChannel 实现为 SocketChannel 的 Decorator;
SslSocketChannel 测试服务端
基于以上封装,简略测试服务端如下
@Slf4j
public class NioSslServer {public static void main(String[] args) throws Exception {NioSslServer sslServer = new NioSslServer("127.0.0.1", 8006);
sslServer.start();
// 应用 curl -vv -k 'https://localhost:8006' 连贯
}
private SSLContext context;
private Selector selector;
public NioSslServer(String hostAddress, int port) throws Exception {
// 初始化 SSL Context
context = serverSSLContext();
// 注册监听器
selector = SelectorProvider.provider().openSelector();
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.configureBlocking(false);
serverSocketChannel.socket().bind(new InetSocketAddress(hostAddress, port));
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
}
public void start() throws Exception {log.debug("期待连贯中.");
while (true) {selector.select();
Iterator<SelectionKey> selectedKeys = selector.selectedKeys().iterator();
while (selectedKeys.hasNext()) {SelectionKey key = selectedKeys.next();
selectedKeys.remove();
if (!key.isValid()) {continue;}
if (key.isAcceptable()) {accept(key);
} else if (key.isReadable()) {((SslSocketChannel)key.attachment()).read(buf->{});
// 间接回应一个 OK
((SslSocketChannel)key.attachment()).write("HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\nOK\r\n\r\n");
((SslSocketChannel)key.attachment()).closeConnection();}
}
}
}
private void accept(SelectionKey key) throws Exception {log.debug("接管新的申请.");
SocketChannel socketChannel = ((ServerSocketChannel)key.channel()).accept();
socketChannel.configureBlocking(false);
SslSocketChannel sslSocketChannel = new SslSocketChannel(context, socketChannel, false);
if (sslSocketChannel.doHandshake()) {socketChannel.register(selector, SelectionKey.OP_READ, sslSocketChannel);
} else {socketChannel.close();
log.debug("握手失败,敞开连贯.");
}
}
}
以上:
- 因为是 NIO,简略的测试须要用到 NIO 的根底组件 Selector 进行测试;
- 首先初始化 ServerSocketChannel,监听 8006 端口;
- 接管到申请后,将 SocketChannel 封装为 SslSocketChannel,注册到 Selector
- 接管到数据后,通过 SslSocketChannel 做 read 和 write;
SslSocketChannel 测试客户端
基于以上服务端封装,简略测试客户端如下
@Slf4j
public class NioSslClient {public static void main(String[] args) throws Exception {NioSslClient sslClient = new NioSslClient("httpbin.org", 443);
sslClient.connect();
// 申请 'https://httpbin.org/get'
}
private String remoteAddress;
private int port;
private SSLEngine engine;
private SocketChannel socketChannel;
private SSLContext context;
/**
* 须要近程的 HOST 和 PORT
* @param remoteAddress
* @param port
* @throws Exception
*/
public NioSslClient(String remoteAddress, int port) throws Exception {
this.remoteAddress = remoteAddress;
this.port = port;
context = clientSSLContext();
engine = context.createSSLEngine(remoteAddress, port);
engine.setUseClientMode(true);
}
public boolean connect() throws Exception {socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
socketChannel.connect(new InetSocketAddress(remoteAddress, port));
while (!socketChannel.finishConnect()) {
// 通过 REACTOR,不会呈现期待状况
//log.debug("连贯中..");
}
SslSocketChannel sslSocketChannel = new SslSocketChannel(context, socketChannel, true);
sslSocketChannel.doHandshake();
// 握手实现后,开启 SELECTOR
Selector selector = SelectorProvider.provider().openSelector();
socketChannel.register(selector, SelectionKey.OP_READ, sslSocketChannel);
// 写入申请
sslSocketChannel.write("GET /get HTTP/1.1\r\n"
+ "Host: httpbin.org:443\r\n"
+ "User-Agent: curl/7.62.0\r\n"
+ "Accept: */*\r\n"
+ "\r\n");
// 读取后果
while (true) {selector.select();
Iterator<SelectionKey> selectedKeys = selector.selectedKeys().iterator();
while (selectedKeys.hasNext()) {SelectionKey key = selectedKeys.next();
selectedKeys.remove();
if (key.isValid() && key.isReadable()) {((SslSocketChannel)key.attachment()).read(buf->{log.info("{}", new String(buf.array(), 0, buf.position()));
});
((SslSocketChannel)key.attachment()).closeConnection();
return true;
}
}
}
}
}
以上:
客户端的封装测试,是为了验证封装 SSL 协定双向都是 OK 的,
在后文的非通明上游代理中,会同时应用 SslSocketChannel 做服务端和客户端
以上封装与服务端封装相似,不同的是初始化 SocketChannel,做 connect 而非 bind
总结
以上:
- 非通明代理须要拿到残缺的申请数据,能够通过 Decorator 模式,聚批实现;
- 非通明代理须要拿到解密后的 HTTPS 申请数据,能够通过 SslSocketChannel 对原始的 SocketChannel 做封装实现;
- 最初,拿到申请后,做相应的解决,最终实现非通明的代理。
3 通明上游代理
通明上游代理相比通明代理要简略,区别是
- 通明代理须要响应 CONNECT 申请,通明上游代理不须要,间接转发即可;
- 通明代理须要解析 CONNECT 申请中的 HOST 和 PORT,并连贯服务端;通明上游代理只须要连贯上游代理的 IP:PORT,间接转发申请即可;
- 通明的上游代理,只是一个简略的 SocketChannel 管道;确定上游的代理服务端,连贯转发申请;
只须要对通明代理做以上简略的批改,即可实现通明的上游代理。
4 非通明上游代理
非通明的上游代理,相比非通明的代理要简单一些
以上,分为四个组件:客户端,代理服务(ServerHandler),代理服务(ClientHandler),服务端
- 如果是 HTTP 的申请,数据间接通过 客户端 <->ServerHandler<->ClientHandler<-> 服务端,代理网关只须要做简略的申请聚批,就能够利用相应的管理策略;
- 如果是 HTTPS 申请,代理作为客户端和服务端的中间人,只能拿到加密的数据;因而,代理网关须要作为 HTTPS 的服务方与客户端通信;而后作为 HTTPS 的客户端与服务端通信;
- 代理作为 HTTPS 服务方时,须要思考到其自身是个非通明的代理,须要实现非通明代理相干的协定;
- 代理作为 HTTPS 客户端时,须要思考到其上游是个通明的代理,真正的服务方是客户端申请的服务方;
三 设计与实现
本文须要构建的是非通明上游代理,以下采纳 NETTY 框架给出具体的设计实现。上文将对立代理网关分为两大部分,ServerHandler 和 ClientHandler,以下
- 介绍代理网关服务端相干实现;
- 介绍代理网关客户端相干实现;
1 代理网关服务端
次要包含
- 初始化代理网关服务端
- 初始化服务端处理器
- 服务端协定降级与解决
初始化代理网关服务
public void start() {HookedExecutors.newSingleThreadExecutor().submit(() ->{log.info("开始启动代理服务器,监听端口:{}", auditProxyConfig.getProxyServerPort());
EventLoopGroup bossGroup = new NioEventLoopGroup(auditProxyConfig.getBossThreadCount());
EventLoopGroup workerGroup = new NioEventLoopGroup(auditProxyConfig.getWorkThreadCount());
try {ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.handler(new LoggingHandler(LogLevel.DEBUG))
.childHandler(new ServerChannelInitializer(auditProxyConfig))
.bind(auditProxyConfig.getProxyServerPort()).sync().channel().closeFuture().sync();
} catch (InterruptedException e) {log.error("代理服务器被中断.", e);
Thread.currentThread().interrupt();
} finally {bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();}
});
}
代理网关初始化绝对简略,
- bossGroup 线程组,负责接管申请
- workerGroup 线程组,负责解决接管的申请数据,具体解决逻辑封装在 ServerChannelInitializer 中。
代理网关服务的申请处理器在 ServerChannelInitializer 中定义为
@Override
protected void initChannel(SocketChannel ch) throws Exception {ch.pipeline()
.addLast(new HttpRequestDecoder())
.addLast(new HttpObjectAggregator(auditProxyConfig.getMaxRequestSize()))
.addLast(new ServerChannelHandler(auditProxyConfig));
}
首先解析 HTTP 申请,而后做聚批的解决,最初 ServerChannelHandler 实现代理网关协定;
代理网关协定:
- 断定是否是 CONNECT 申请,如果是,会存储 CONNECT 申请;暂停读取,发送代
- 理胜利的响应,并在回应胜利后,降级协定;
- 降级引擎,实质上是采纳 SslSocketChannel 对原 SocketChannel 做通明的封装;
- 最初依据 CONNECT 申请连贯近程服务端;
具体实现为:
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {FullHttpRequest request = (FullHttpRequest)msg;
try {if (isConnectRequest(request)) {
// CONNECT 申请,存储待处理
saveConnectRequest(ctx, request);
// 禁止读取
ctx.channel().config().setAutoRead(false);
// 发送回应
connectionEstablished(ctx, ctx.newPromise().addListener(future -> {if (future.isSuccess()) {
// 降级
if (isSslRequest(request) && !isUpgraded(ctx)) {upgrade(ctx);
}
// 凋谢音讯读取
ctx.channel().config().setAutoRead(true);
ctx.read();}
}));
} else {
// 其余申请,断定是否已降级
if (!isUpgraded(ctx)) {
// 降级引擎
upgrade(ctx);
}
// 连贯近程
connectRemote(ctx, request);
}
} finally {ctx.fireChannelRead(msg);
}
}
2 代理网关客户端
代理网关服务端须要连贯近程服务,进入代理网关客户端局部。
代理网关客户端初始化:
/**
* 初始化近程连贯
* @param ctx
* @param httpRequest
*/
protected void connectRemote(ChannelHandlerContext ctx, FullHttpRequest httpRequest) {Bootstrap b = new Bootstrap();
b.group(ctx.channel().eventLoop()) // use the same EventLoop
.channel(ctx.channel().getClass())
.handler(new ClientChannelInitializer(auditProxyConfig, ctx, safeCopy(httpRequest)));
// 动静连贯代理
FullHttpRequest originRequest = ctx.channel().attr(CONNECT_REQUEST).get();
if (originRequest == null) {originRequest = httpRequest;}
ChannelFuture cf = b.connect(new InetSocketAddress(calculateHost(originRequest), calculatePort(originRequest)));
Channel cch = cf.channel();
ctx.channel().attr(CLIENT_CHANNEL).set(cch);
}
以上:
- 复用代理网关服务端的 workerGroup 线程组;
- 申请和后果的解决封装在 ClientChannelInitializer;
- 连贯的近程服务端的 HOST 和 PORT 在服务端收到的申请中能够解析到。
代理网关客户端的处理器的初始化逻辑:
@Override
protected void initChannel(SocketChannel ch) throws Exception {SocketAddress socketAddress = calculateProxy();
if (!Objects.isNull(socketAddress)) {ch.pipeline().addLast(new HttpProxyHandler(calculateProxy(), auditProxyConfig.getUserName(), auditProxyConfig
.getPassword()));
}
if (isSslRequest()) {String host = host();
int port = port();
if (StringUtils.isNoneBlank(host) && port > 0) {ch.pipeline().addLast(new SslHandler(sslEngine(host, port)));
}
}
ch.pipeline().addLast(new ClientChannelHandler(clientContext, httpRequest));
}
以上:
- 如果上游是代理,那么会采纳 HttpProxyHandler,经由上游代理与近程服务端通信;
- 如果以后须要降级为 SSL 协定,会对 SocketChannel 做通明的封装,实现 SSL 通信。
- 最初,ClientChannelHandler 只是简略音讯的转发;惟一的不同是,因为代理网关拦挡了第一个申请,此时须要将拦挡的申请,转发到服务端。
四 其余问题
代理网关实现可能面临的问题:
1 内存问题
代理通常面临的问题是 OOM。本文在实现代理网关时保障内存中缓存时以后正在解决的 HTTP/HTTPS 申请体。内存应用的下限实践上为实时处理的申请数量 * 申请体的均匀大小,HTTP/HTTPS 的申请后果,间接应用堆外内存,零拷贝转发。
2 性能问题
性能问题不应提前思考。本文应用 NETTY 框架实现的代理网关,外部大量应用堆外内存,零拷贝转发,防止了性能问题。
代理网关一期上线后曾面临一个长连贯导致的性能问题,
- CLIENT 和 SERVER 建设 TCP 长连贯后(比方,TCP 心跳检测),通常要么是 CLIENT 敞开 TCP 连贯,或者是 SERVER 敞开;
- 如果单方长时间占用 TCP 连贯资源而不敞开,就会导致 SOCKET 资源透露;景象是:CPU 资源爆满,解决闲暇连贯;新连贯无奈建设;
应用 IdleStateHandler 定时监控闲暇的 TCP 连贯,强制敞开;解决了该问题。
五 总结
本文聚焦于对立代理网关的外围,具体介绍了代理相干的技术原理。
代理网关的治理局部,能够在 ServerHandler 局部保护,也能够在 ClientHandler 局部保护;
- ServerHandler 能够拦挡转换申请
- ClientHanlder 可管制申请的进口
注:本文应用 Netty 的零拷贝;存储申请以解析解决;但并未实现对 RESPONSE 的解决;也就是 RESPONSE 是间接通过网关,此方面防止了常见的代理实现,内存透露 OOM 相干问题;
最初,本文实现代理网关后,针对代理的资源和流经代理网关的申请做了相应的管制,次要包含:
当遇到动态资源的申请时,代理网关会间接申请近程服务端,不会通过上游代理
当申请 HEADER 中蕴含地区标识时,代理网关会尽力保障申请打入指定的地区代理,经由地区代理拜访近程服务端。
原文链接
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