Question

为非SSL套接字服务器和客户端全部在一个线程上考虑以下代码：

import java.io.DataInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class ServerClient {
    public static void main(String[] args) throws IOException {
        ServerSocket ss = new ServerSocket(0); // open a random free port.

        Socket c = new Socket(ss.getInetAddress(), ss.getLocalPort());

        Socket s = ss.accept();

        final byte[] bytes = "Hello World!".getBytes();
        final OutputStream out = c.getOutputStream();
        System.out.println("writing to stream");
        out.write(bytes.length);
        out.write(bytes);

        System.out.println("reading from stream");

        final DataInputStream in = new DataInputStream(s.getInputStream());
        int len = in.read();
        final byte[] b = new byte[len];
        in.readFully(b);
        System.out.println(new String(b));

        c.close();
        ss.close();
    }
}

这将产生以下输出：

writing to stream
reading from stream
Hello World!

此过程打开了服务器套接字-与客户端套接字连接。通过套接字传递数据，然后关闭。传递数据没有问题。

考虑一个版本以证明使用SSL套接字的重要性：

import javax.net.ssl.SSLServerSocket;
import javax.net.ssl.SSLServerSocketFactory;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;
import java.util.logging.Logger;

public class SSLServerClient {

    private static Logger log = Logger.getLogger("InfoLogging");

    public static void main(String[] args) throws IOException {

        System.setProperty("javax.net.ssl.keyStore", "/path/KeyStore.jks");
        System.setProperty("javax.net.ssl.keyStorePassword", "password");

        SSLServerSocketFactory sslserversocketfactory = (SSLServerSocketFactory) SSLServerSocketFactory.getDefault();

        SSLServerSocket serverListeningSSLSocket = (SSLServerSocket) sslserversocketfactory.createServerSocket(4380);
        log.info("Server started");

        SSLSocketFactory sslSocketFactory=(SSLSocketFactory) SSLSocketFactory.getDefault();
        SSLSocket clientSocket =  (SSLSocket) sslSocketFactory.createSocket(serverListeningSSLSocket.getInetAddress(),
                serverListeningSSLSocket.getLocalPort());

        SSLSocket serverCommsSSLSocket = (SSLSocket) serverListeningSSLSocket.accept();
        log.info("new client");

        final byte[] bytes = "Hello World!".getBytes();
        final OutputStream out = clientSocket.getOutputStream();
        System.out.println("writing to stream");
        out.write(bytes.length);
        out.write(bytes);

        System.out.println("reading from stream");

        final DataInputStream in = new DataInputStream(serverCommsSSLSocket.getInputStream());
        int len = in.read();
        final byte[] b = new byte[len];
        in.readFully(b);
        System.out.println(new String(b));

        clientSocket.close();
        serverCommsSSLSocket.close();
        serverListeningSSLSocket.close();
    }
}

这将提供以下输出：

Nov 21, 2018 10:23:51 PM com.gamble.ssl.SSLServerClient main INFO: Server started
Nov 21, 2018 10:23:52 PM com.gamble.ssl.SSLServerClient main INFO: new client
writing to stream

ie它阻止了服务器套接字上的启动。

我的问题是：为什么Java中的SSL Server套接字连接会阻塞，而非SSL Server套接字为什么不会阻塞？

Answer 1

“翻转至纯文本”是什么？是什么意思？

这是你在做什么：

创建SSL服务器套接字
创建连接到SSL服务器套接字的普通套接字
从客户端发送一些数据
在服务器端读取一些数据

现在，SSL套接字需要加密的数据传输。但是，您未发送的数据未加密，因此它不是有效的SSL，并且会引发异常-如“未识别的SSL消息”之类，因为您未发送有效的SSL消息，并且为“纯文本连接？”。暗示可能有什么问题。

您必须在连接的两面都使用SSL，否则它们将无法正确通信。

Answer 2

该问题的简单答案是：

因为SSL握手is asynchronous和the non SSL socket不必执行此步骤。

好的-原始SSL代码有两个问题：

没有TrustStore：

System.setProperty( "javax.net.ssl.trustStore", "/path/KeyStore.jks");

因为握手是同步的-您必须在其他线程上启动客户端。即：
```
(new Thread() {
  public void run() {
    // do stuff
  }
 }).start();
```

因此代码如下：

    import javax.net.ssl.SSLServerSocket;
    import javax.net.ssl.SSLServerSocketFactory;
    import javax.net.ssl.SSLSocket;
    import javax.net.ssl.SSLSocketFactory;
    import java.io.DataInputStream;
    import java.io.IOException;
    import java.io.OutputStream;
    import java.util.logging.Logger;

    public class SSLServerClient {

        public static void main(String[] args) throws IOException {

            System.setProperty("javax.net.ssl.keyStore", "/path/KeyStore.jks");
            System.setProperty( "javax.net.ssl.trustStore", "/path/KeyStore.jks");

            System.setProperty("javax.net.ssl.keyStorePassword", "password");

            SSLServerSocketFactory sslserversocketfactory = (SSLServerSocketFactory) SSLServerSocketFactory.getDefault();

            SSLServerSocket serverListeningSSLSocket = (SSLServerSocket) sslserversocketfactory.createServerSocket(4380);
            System.out.println("--server started");

            SSLSocketFactory sslSocketFactory=(SSLSocketFactory) SSLSocketFactory.getDefault();
            SSLSocket clientSocket =  (SSLSocket) sslSocketFactory.createSocket(serverListeningSSLSocket.getInetAddress(),
                    serverListeningSSLSocket.getLocalPort());

            SSLSocket serverCommsSSLSocket = (SSLSocket) serverListeningSSLSocket.accept();
            System.out.println("--new client");

            final byte[] bytes = "--Hello World!".getBytes();
            final OutputStream out = clientSocket.getOutputStream();
            System.out.println("--Gotten output stream");
            final DataInputStream in = new DataInputStream(serverCommsSSLSocket.getInputStream());

            (new Thread() {
                public void run() {
                    System.out.println("--reading from stream");

                    int len = 0;
                    try {
                        len = in.read();
                        final byte[] b = new byte[len];
                        in.readFully(b);
                        System.out.println(new String(b));

                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }).start();


            System.out.println("--writing to stream");
            out.write(bytes.length);
            System.out.println("--writing to stream - length");
            out.write(bytes);

            clientSocket.close();
            serverCommsSSLSocket.close();
            serverListeningSSLSocket.close();
        }
    }

输出看起来像

    --server started
    --new client
    --Gotten output stream
    --writing to stream
    --reading from stream
    --writing to stream - length
    --Hello World!

    Process finished with exit code 0

完成

（请注意，我在输出中添加了前导--，以帮助读取SSL调试输出。

为什么Java中的SSL Server套接字连接会阻塞而非SSL Server套接字却不会？

2 个答案: