OkHttp的SSL握手溯源

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OkHttpClient.Builder builder = new OkHttpClient.Builder();

// 添加自定义的SSLSocketFactory和X509TrustManager
builder.sslSocketFactory(sslInput.mSSLSocketFactory, sslInput.mX509TrustManager);

// 域名验证
builder.hostnameVerifier((hostname, session) ->
        true
);

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if (builder.sslSocketFactory != null || !isTLS) {
    //如果builder设置了sslSocketFactory就用builder的
    this.sslSocketFactory = builder.sslSocketFactory;
    this.certificateChainCleaner = builder.certificateChainCleaner;
} else {
    // 如果没有设置过builder的ssSocketFactory就用系统默认的
    X509TrustManager trustManager = systemDefaultTrustManager();
    this.sslSocketFactory = systemDefaultSslSocketFactory(trustManager);
    this.certificateChainCleaner = CertificateChainCleaner.get(trustManager);
}

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private SSLSocketFactory systemDefaultSslSocketFactory(X509TrustManager trustManager) {
    try {
      // 获取到平台的SSLContext
      SSLContext sslContext = Platform.get().getSSLContext();
      sslContext.init(null, new TrustManager[] { trustManager }, null);
      return sslContext.getSocketFactory();
    } catch (GeneralSecurityException e) {
      throw assertionError("No System TLS", e); // The system has no TLS. Just give up.
    }
  }

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public class Platform {

  // 静态加载方式
  private static final Platform PLATFORM = findPlatform();

  public static Platform get() {
    return PLATFORM;
  }

  private static Platform findPlatform() {

    // 优先加载安卓平台
    Platform android = AndroidPlatform.buildIfSupported();

    if (android != null) {
      return android;
    }

    // 其他的都是jdk中的安全策略
    ...
  }
}

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public static Platform buildIfSupported() {
    // Attempt to find Android 2.3+ APIs.
    try {
      Class<?> sslParametersClass;
      try {
        sslParametersClass = Class.forName("com.android.org.conscrypt.SSLParametersImpl");
      } catch (ClassNotFoundException e) {
        // Older platform before being unbundled.
        sslParametersClass = Class.forName(
            "org.apache.harmony.xnet.provider.jsse.SSLParametersImpl");
      }

      ...

      return new AndroidPlatform(sslParametersClass, setUseSessionTickets, setHostname,
          getAlpnSelectedProtocol, setAlpnProtocols);
    } catch (ClassNotFoundException ignored) {
      // This isn't an Android runtime.
    }

    return null;
  }

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import sun.security.jca.GetInstance;

public SSLContext getSSLContext() {
  try {
    return SSLContext.getInstance("TLS");
  } catch (NoSuchAlgorithmException e) {
    throw new IllegalStateException("No TLS provider", e);
  }
}

public static SSLContext getInstance(String protocol)
            throws NoSuchAlgorithmException {
    GetInstance.Instance instance = GetInstance.getInstance
            ("SSLContext", SSLContextSpi.class, protocol);
    return new SSLContext((SSLContextSpi)instance.impl, instance.provider,
            protocol);
}

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/**
 * @param type = "SSLContext"
 * @param clazz = SSLContextSpi.class
 * @param algorithm = "TLS"
 **/
public static Instance getInstance(String type, Class<?> clazz,
        String algorithm) throws NoSuchAlgorithmException {

    ProviderList list = Providers.getProviderList();
    Service firstService = list.getService(type, algorithm);
    if (firstService == null) {
        throw new NoSuchAlgorithmException
                (algorithm + " " + type + " not available");
    }
    NoSuchAlgorithmException failure;
    try {
        return getInstance(firstService, clazz);
    } catch (NoSuchAlgorithmException e) {
        failure = e;
    }
    
    for (Service s : list.getServices(type, algorithm)) {
        if (s == firstService) {
            // do not retry initial failed service
            continue;
        }
        try {
            return getInstance(s, clazz);
        } catch (NoSuchAlgorithmException e) {
            failure = e;
        }
    }
    throw failure;
}

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public static ProviderList getProviderList() {
    ProviderList list = getThreadProviderList();
    if (list == null) {
        list = getSystemProviderList();
    }
    return list;
}

private static void setSystemProviderList(ProviderList list) {
    providerList = list;
}

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public List<Service> getServices(String type, String algorithm) {
    return new ServiceList(type, algorithm);
}

1

NativeCrypto.SSL_do_handshake(ssl, this, fd, handshakeCallbacks, timeoutMillis);

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/**
 * Perform SSL handshake
 */
static void NativeCrypto_SSL_do_handshake(JNIEnv* env, jclass, jlong ssl_address, CONSCRYPT_UNUSED jobject ssl_holder, jobject fdObject,
                                          jobject shc, jint timeout_millis) {
    CHECK_ERROR_QUEUE_ON_RETURN;
    SSL* ssl = to_SSL(env, ssl_address, true);
    JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake fd=%p shc=%p timeout_millis=%d", ssl, fdObject,
              shc, timeout_millis);
    if (ssl == nullptr) {
        return;
    }
    if (fdObject == nullptr) {
        conscrypt::jniutil::throwNullPointerException(env, "fd == null");
        JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake fd == null => exception", ssl);
        return;
    }
    if (shc == nullptr) {
        conscrypt::jniutil::throwNullPointerException(env, "sslHandshakeCallbacks == null");
        JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake sslHandshakeCallbacks == null => exception",
                  ssl);
        return;
    }

    NetFd fd(env, fdObject);
    if (fd.isClosed()) {
        // SocketException thrown by NetFd.isClosed
        JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake fd.isClosed() => exception", ssl);
        return;
    }

    int ret = SSL_set_fd(ssl, fd.get());
    JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake s=%d", ssl, fd.get());

    if (ret != 1) {
        conscrypt::jniutil::throwSSLExceptionWithSslErrors(env, ssl, SSL_ERROR_NONE,
                                                           "Error setting the file descriptor");
        JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake SSL_set_fd => exception", ssl);
        return;
    }

    /*
     * Make socket non-blocking, so SSL_connect SSL_read() and SSL_write() don't hang
     * forever and we can use select() to find out if the socket is ready.
     */
    if (!conscrypt::netutil::setBlocking(fd.get(), false)) {
        conscrypt::jniutil::throwSSLExceptionStr(env, "Unable to make socket non blocking");
        JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake setBlocking => exception", ssl);
        return;
    }

    AppData* appData = toAppData(ssl);
    if (appData == nullptr) {
        conscrypt::jniutil::throwSSLExceptionStr(env, "Unable to retrieve application data");
        JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake appData => exception", ssl);
        return;
    }

    ret = 0;
    SslError sslError;
    while (appData->aliveAndKicking) {
        errno = 0;

        if (!appData->setCallbackState(env, shc, fdObject)) {
            // SocketException thrown by NetFd.isClosed
            JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake setCallbackState => exception", ssl);
            return;
        }
        ret = SSL_do_handshake(ssl);
        appData->clearCallbackState();
        // cert_verify_callback threw exception
        if (env->ExceptionCheck()) {
            ERR_clear_error();
            JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake exception => exception", ssl);
            return;
        }
        // success case
        if (ret == 1) {
            break;
        }
        // retry case
        if (errno == EINTR) {
            continue;
        }
        // error case
        sslError.reset(ssl, ret);
        JNI_TRACE(
                "ssl=%p NativeCrypto_SSL_do_handshake ret=%d errno=%d sslError=%d "
                "timeout_millis=%d",
                ssl, ret, errno, sslError.get(), timeout_millis);

        /*
         * If SSL_do_handshake doesn't succeed due to the socket being
         * either unreadable or unwritable, we use sslSelect to
         * wait for it to become ready. If that doesn't happen
         * before the specified timeout or an error occurs, we
         * cancel the handshake. Otherwise we try the SSL_connect
         * again.
         */
        if (sslError.get() == SSL_ERROR_WANT_READ || sslError.get() == SSL_ERROR_WANT_WRITE) {
            appData->waitingThreads++;
            int selectResult = sslSelect(env, sslError.get(), fdObject, appData, timeout_millis);

            if (selectResult == THROWN_EXCEPTION) {
                // SocketException thrown by NetFd.isClosed
                JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake sslSelect => exception", ssl);
                return;
            }
            if (selectResult == -1) {
                conscrypt::jniutil::throwSSLExceptionWithSslErrors(
                        env, ssl, SSL_ERROR_SYSCALL, "handshake error",
                        conscrypt::jniutil::throwSSLHandshakeExceptionStr);
                JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake selectResult == -1 => exception",
                          ssl);
                return;
            }
            if (selectResult == 0) {
                conscrypt::jniutil::throwSocketTimeoutException(env, "SSL handshake timed out");
                ERR_clear_error();
                JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake selectResult == 0 => exception",
                          ssl);
                return;
            }
        } else {
            // ALOGE("Unknown error %d during handshake", error);
            break;
        }
    }

    // clean error. See SSL_do_handshake(3SSL) man page.
    if (ret == 0) {
        /*
         * The other side closed the socket before the handshake could be
         * completed, but everything is within the bounds of the TLS protocol.
         * We still might want to find out the real reason of the failure.
         */
        if (sslError.get() == SSL_ERROR_NONE ||
            (sslError.get() == SSL_ERROR_SYSCALL && errno == 0) ||
            (sslError.get() == SSL_ERROR_ZERO_RETURN)) {
            conscrypt::jniutil::throwSSLHandshakeExceptionStr(env, "Connection closed by peer");
        } else {
            conscrypt::jniutil::throwSSLExceptionWithSslErrors(
                    env, ssl, sslError.release(), "SSL handshake terminated",
                    conscrypt::jniutil::throwSSLHandshakeExceptionStr);
        }
        JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake clean error => exception", ssl);
        return;
    }

    // unclean error. See SSL_do_handshake(3SSL) man page.
    if (ret < 0) {
        /*
         * Translate the error and throw exception. We are sure it is an error
         * at this point.
         */
        conscrypt::jniutil::throwSSLExceptionWithSslErrors(
                env, ssl, sslError.release(), "SSL handshake aborted",
                conscrypt::jniutil::throwSSLHandshakeExceptionStr);
        JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake unclean error => exception", ssl);
        return;
    }
    JNI_TRACE("ssl=%p NativeCrypto_SSL_do_handshake => success", ssl);
}