我不相信这可以通过公共 API 完成。您可以获取会话ID，但没有公共接口来获取密钥。
但是，我能够结合使用反射和本机代码来访问底层 OpenSSL struct，它确实包含会话 ID 和主密钥。所以这是可能的，但它根本不安全，因为隐藏的成员和库不能保证保持不变。事实上，看起来 OpenSSL 主分支上的结构布局已经改变，所以如果/当它被拉入 Android 时，下面的解析代码将需要更新。
我使用URL.openConnection() 而不是DefaultHttpClient 来建立HTTPS 连接，因为后者现在已被弃用。这是调用URL.openConnection() 并替换默认SSLSocketFactory 的类（这里没什么有趣的）：
public class MyConnection implements Runnable {
@Override
public void run() {
try {
// Create the connection.
URL url = new URL("https://www.google.com");
HttpsURLConnection urlConnection = (HttpsURLConnection) url.openConnection();
// Replace the default SSLSocketFactory with our own.
MySSLSocketFactory sslSocketFactory = new MySSLSocketFactory();
urlConnection.setSSLSocketFactory(sslSocketFactory);
// Establish the TLS connection.
int statusCode = urlConnection.getResponseCode();
Log.i("MyConnection", String.format("status %d", statusCode));
// Get SSL details from the captured socket.
sslSocketFactory.getSessionInfo();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
这里是自定义的SSLSocketFactory，大部分魔法都在这里。它所做的只是将重写的方法转发给真正的SSLSocketFactory，缓存创建的SSLSocket 实例。还有两个新的（非覆盖）方法 - 下面进一步显示的本机方法和 getSessionInfo()，它使用 SSLSocket 上的反射来获取本机 OpenSSL ssl_session_st 指针并解析（和日志）感兴趣的字段。请注意，您可以使用支持的SSLSession.getId() 获取会话 ID；它得到了需要偷偷摸摸的关键。
// Use Decorator pattern to capture the SSL socket from the default SSLSocketFactory.
class MySSLSocketFactory extends SSLSocketFactory {
// Load NDK shared library.
static {
System.loadLibrary("my_native_helper");
}
// All overridden methods will be forwarded to the real SSLSocketFactory.
// The only addition is that the SSLSocket returned by createSocket() is
// cached.
SSLSocketFactory realFactory_ = HttpsURLConnection.getDefaultSSLSocketFactory();
SSLSocket s_;
// This native method copies data from a native pointer into a ByteBuffer.
native void readNative(long pointer, ByteBuffer dst);
// Use the cached SSLSocket to access native OpenSSL session data.
void getSessionInfo() throws NoSuchFieldException, IllegalAccessException {
// Get the protected OpenSSL ssl_session_st pointer. Note that this
// is not part of the API and could change across Android versions.
// See https://android.googlesource.com/platform/external/conscrypt/+/lollipop-mr1-dev/src/main/java/org/conscrypt/OpenSSLSessionImpl.java
SSLSession session = s_.getSession();
Field field = session.getClass().getDeclaredField("sslSessionNativePointer");
field.setAccessible(true);
long sessionPointer = field.getLong(session);
// Read as many bytes as we need from the native pointer.
ByteBuffer byteBuffer = ByteBuffer.allocateDirect(104);
byteBuffer.order(ByteOrder.nativeOrder());
readNative(sessionPointer, byteBuffer);
// Parse the OpenSSL ssl_session_st. Note that the layout of this structure
// may change with OpenSSL versions and different compilers/platforms (e.g.
// 32-bit vs. 64-bit).
// See https://github.com/openssl/openssl/blob/OpenSSL_1_0_0-stable/ssl/ssl.h#L451
IntBuffer intBuffer = byteBuffer.asIntBuffer();
Log.i("MyConnection", String.format("SSL version %04x", intBuffer.get(0)));
int master_key_length = intBuffer.get(4);
String master_key = "";
for (int i = 0; i < master_key_length; ++i)
master_key += String.format("%02x", byteBuffer.get(20 + i));
Log.i("MyConnection", String.format("Master key %s", master_key));
int session_id_length = intBuffer.get(17);
String session_id = "";
for (int i = 0; i < session_id_length; ++i)
session_id += String.format("%02x", byteBuffer.get(72 + i));
Log.i("MyConnection", String.format("Session ID %s", session_id));
}
@Override
public String[] getDefaultCipherSuites() {
return realFactory_.getDefaultCipherSuites();
}
@Override
public String[] getSupportedCipherSuites() {
return realFactory_.getSupportedCipherSuites();
}
@Override
public Socket createSocket(Socket s, String host, int port, boolean autoClose) throws IOException {
s_ = (SSLSocket)realFactory_.createSocket(s, host, port, autoClose);
return s_;
}
@Override
public Socket createSocket(String host, int port) throws IOException {
s_ = (SSLSocket)realFactory_.createSocket(host, port);
return s_;
}
@Override
public Socket createSocket(String host, int port, InetAddress localHost, int localPort) throws IOException {
s_ = (SSLSocket)realFactory_.createSocket(host, port, localHost, localPort);
return s_;
}
@Override
public Socket createSocket(InetAddress host, int port) throws IOException {
s_ = (SSLSocket)realFactory_.createSocket(host, port);
return s_;
}
@Override
public Socket createSocket(InetAddress address, int port, InetAddress localAddress, int localPort) throws IOException {
s_ = (SSLSocket)realFactory_.createSocket(address, port, localAddress, localPort);
return s_;
}
}
最后，这里是本机 C 代码，它可以将内存从本机指针读入 ByteBuffer。这需要使用 Android NDK 构建并加载，如 MySSLSocketFactory 顶部所示。
#include <jni.h>
#include <string.h>
JNIEXPORT
void JNICALL Java_com_example_mysocketfactory_MySSLSocketFactory_readNative(
JNIEnv *env, jobject o,
jlong pointer, jobject buffer) {
const char *p = (const char *)pointer;
memcpy(
(*env)->GetDirectBufferAddress(env, buffer),
p,
(*env)->GetDirectBufferCapacity(env, buffer));
}
就是这样。在我的 KitKat 设备上调用 MyConnection.run() 时，日志显示：
I/MyConnection﹕ status 200
I/MyConnection﹕ SSL version 0301
I/MyConnection﹕ Master key 81ef39c5f8f7f796a34b307ff453511378fd081d14c37eb2e912fa829edf280e0fa7a499c370fdc156b8499758373d67
I/MyConnection﹕ Session ID b9ee4ae0c7738909430d47e9b0d6d60420d34a17d08181f21996e55a463aa5cf
我确实对DefaultHttpClient 进行了一次简短的尝试，但是当我无法弄清楚如何访问默认的SchemeRegistry 时放弃了它。我认为可以通过在构造DefaultHttpClient 时指定ClientConnectionManager 来完成，但我不想再追求弃用的路径。如果您想尝试，那么您可能会使用类似的方法来拦截处理连接的SSLSessionImpl 实例。这个类有一个master_secret 成员，所以不需要本地代码，只需要反射（这个代码路径不使用 OpenSSL）。