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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.net;
import android.annotation.NonNull;
import android.util.Log;
import java.io.IOException;
import java.net.InetSocketAddress;
import javax.net.SocketFactory;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
/**
* Class for testing connectivity to DNS-over-TLS servers.
* {@hide}
*/
public class PrivateDnsConnectivityChecker {
private static final String TAG = "NetworkUtils";
private static final int PRIVATE_DNS_PORT = 853;
private static final int CONNECTION_TIMEOUT_MS = 5000;
private PrivateDnsConnectivityChecker() { }
/**
* checks that a provided host can perform a TLS handshake on port 853.
* @param hostname host to connect to.
*/
public static boolean canConnectToPrivateDnsServer(@NonNull String hostname) {
final SocketFactory factory = SSLSocketFactory.getDefault();
TrafficStats.setThreadStatsTag(TrafficStats.TAG_SYSTEM_APP);
try (SSLSocket socket = (SSLSocket) factory.createSocket()) {
socket.setSoTimeout(CONNECTION_TIMEOUT_MS);
socket.connect(new InetSocketAddress(hostname, PRIVATE_DNS_PORT));
if (!socket.isConnected()) {
Log.w(TAG, String.format("Connection to %s failed.", hostname));
return false;
}
socket.startHandshake();
Log.w(TAG, String.format("TLS handshake to %s succeeded.", hostname));
return true;
} catch (IOException e) {
Log.w(TAG, String.format("TLS handshake to %s failed.", hostname), e);
return false;
}
}
}
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